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de5f3984 |
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25-Jan-2024 |
Nathan Chancellor <nathan@kernel.org> |
riscv: remove MCOUNT_NAME workaround Now that the minimum supported version of LLVM for building the kernel has been bumped to 13.0.1, the condition for using _mcount as MCOUNT_NAME is always true, as the build will fail during the configuration stage for older LLVM versions. Replace MCOUNT_NAME with _mcount directly. This effectively reverts commit 7ce047715030 ("riscv: Workaround mcount name prior to clang-13"). Link: https://lkml.kernel.org/r/20240125-bump-min-llvm-ver-to-13-0-1-v1-7-f5ff9bda41c5@kernel.org Signed-off-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: "Aneesh Kumar K.V (IBM)" <aneesh.kumar@kernel.org> Cc: Ard Biesheuvel <ardb@kernel.org> Cc: Borislav Petkov (AMD) <bp@alien8.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Conor Dooley <conor@kernel.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Naveen N. Rao" <naveen.n.rao@linux.ibm.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Nicolas Schier <nicolas@fjasle.eu> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Russell King <linux@armlinux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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#
0df8e970 |
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24-Nov-2023 |
Masahiro Yamada <masahiroy@kernel.org> |
scripts: clean up IA-64 code A little more janitorial work after commit cf8e8658100d ("arch: Remove Itanium (IA-64) architecture"). Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
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aec499c7 |
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02-Mar-2022 |
Alan Kao <alankao@andestech.com> |
nds32: Remove the architecture The nds32 architecture, also known as AndeStar V3, is a custom 32-bit RISC target designed by Andes Technologies. Support was added to the kernel in 2016 as the replacement RISC-V based V5 processors were already announced, and maintained by (current or former) Andes employees. As explained by Alan Kao, new customers are now all using RISC-V, and all known nds32 users are already on longterm stable kernels provided by Andes, with no development work going into mainline support any more. While the port is still in a reasonably good shape, it only gets worse over time without active maintainers, so it seems best to remove it before it becomes unusable. As always, if it turns out that there are mainline users after all, and they volunteer to maintain the port in the future, the removal can be reverted. Link: https://lore.kernel.org/linux-mm/YhdWNLUhk+x9RAzU@yamatobi.andestech.com/ Link: https://lore.kernel.org/lkml/20220302065213.82702-1-alankao@andestech.com/ Link: https://www.andestech.com/en/products-solutions/andestar-architecture/ Signed-off-by: Alan Kao <alankao@andestech.com> [arnd: rewrite changelog to provide more background] Signed-off-by: Arnd Bergmann <arnd@arndb.de>
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4eb1782e |
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23-Dec-2021 |
Heiko Carstens <hca@linux.ibm.com> |
recordmcount.pl: fix typo in s390 mcount regex Commit 85bf17b28f97 ("recordmcount.pl: look for jgnop instruction as well as bcrl on s390") added a new alternative mnemonic for the existing brcl instruction. This is required for the combination old gcc version (pre 9.0) and binutils since version 2.37. However at the same time this commit introduced a typo, replacing brcl with bcrl. As a result no mcount locations are detected anymore with old gcc versions (pre 9.0) and binutils before version 2.37. Fix this by using the correct mnemonic again. Reported-by: Miroslav Benes <mbenes@suse.cz> Cc: Jerome Marchand <jmarchan@redhat.com> Cc: <stable@vger.kernel.org> Fixes: 85bf17b28f97 ("recordmcount.pl: look for jgnop instruction as well as bcrl on s390") Link: https://lore.kernel.org/r/alpine.LSU.2.21.2112230949520.19849@pobox.suse.cz Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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#
85bf17b2 |
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10-Dec-2021 |
Jerome Marchand <jmarchan@redhat.com> |
recordmcount.pl: look for jgnop instruction as well as bcrl on s390 On s390, recordmcount.pl is looking for "bcrl 0,<xxx>" instructions in the objdump -d outpout. However since binutils 2.37, objdump -d display "jgnop <xxx>" for the same instruction. Update the mcount_regex so that it accepts both. Signed-off-by: Jerome Marchand <jmarchan@redhat.com> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: <stable@vger.kernel.org> Link: https://lore.kernel.org/r/20211210093827.1623286-1-jmarchan@redhat.com Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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#
be358af1 |
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14-Oct-2021 |
Steven Rostedt <rostedt@goodmis.org> |
nds32/ftrace: Fix Error: invalid operands (*UND* and *UND* sections) for `^' I received a build failure for a new patch I'm working on the nds32 architecture, and when I went to test it, I couldn't get to my build error, because it failed to build with a bunch of: Error: invalid operands (*UND* and *UND* sections) for `^' issues with various files. Those files were temporary asm files that looked like: kernel/.tmp_mc_fork.s I decided to look deeper, and found that the "mc" portion of that name stood for "mcount", and was created by the recordmcount.pl script. One that I wrote over a decade ago. Once I knew the source of the problem, I was able to investigate it further. The way the recordmcount.pl script works (BTW, there's a C version that simply modifies the ELF object) is by doing an "objdump" on the object file. Looks for all the calls to "mcount", and creates an offset of those locations from some global variable it can use (usually a global function name, found with <.*>:). Creates a asm file that is a table of references to these locations, using the found variable/function. Compiles it and links it back into the original object file. This asm file is called ".tmp_mc_<object_base_name>.s". The problem here is that the objdump produced by the nds32 object file, contains things that look like: 0000159a <.L3^B1>: 159a: c6 00 beqz38 $r6, 159a <.L3^B1> 159a: R_NDS32_9_PCREL_RELA .text+0x159e 159c: 84 d2 movi55 $r6, #-14 159e: 80 06 mov55 $r0, $r6 15a0: ec 3c addi10.sp #0x3c Where ".L3^B1 is somehow selected as the "global" variable to index off of. Then the assembly file that holds the mcount locations looks like this: .section __mcount_loc,"a",@progbits .align 2 .long .L3^B1 + -5522 .long .L3^B1 + -5384 .long .L3^B1 + -5270 .long .L3^B1 + -5098 .long .L3^B1 + -4970 .long .L3^B1 + -4758 .long .L3^B1 + -4122 [...] And when it is compiled back to an object to link to the original object, the compile fails on the "^" symbol. Simple solution for now, is to have the perl script ignore using function symbols that have an "^" in the name. Link: https://lkml.kernel.org/r/20211014143507.4ad2c0f7@gandalf.local.home Cc: stable@vger.kernel.org Acked-by: Greentime Hu <green.hu@gmail.com> Fixes: fbf58a52ac088 ("nds32/ftrace: Add RECORD_MCOUNT support") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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b18b851b |
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02-Aug-2021 |
Nathan Chancellor <nathan@kernel.org> |
scripts/recordmcount.pl: Remove check_objcopy() and $can_use_local When building ARCH=riscv allmodconfig with llvm-objcopy, the objcopy version warning from this script appears: WARNING: could not find objcopy version or version is less than 2.17. Local function references are disabled. The check_objcopy() function in scripts/recordmcount.pl is set up to parse GNU objcopy's version string, not llvm-objcopy's, which triggers the warning. Commit 799c43415442 ("kbuild: thin archives make default for all archs") made binutils 2.20 mandatory and commit ba64beb17493 ("kbuild: check the minimum assembler version in Kconfig") enforces this at configuration time so just remove check_objcopy() and $can_use_local instead, assuming --globalize-symbol is always available. llvm-objcopy has supported --globalize-symbol since LLVM 7.0.0 in 2018 and the minimum version for building the kernel with LLVM is 10.0.1 so there is no issue introduced: Link: https://github.com/llvm/llvm-project/commit/ee5be798dae30d5f9414b01f76ff807edbc881aa Link: https://lkml.kernel.org/r/20210802210307.3202472-1-nathan@kernel.org Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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#
77a88274 |
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29-Apr-2021 |
Masahiro Yamada <masahiroy@kernel.org> |
kbuild: replace LANG=C with LC_ALL=C LANG gives a weak default to each LC_* in case it is not explicitly defined. LC_ALL, if set, overrides all other LC_* variables. LANG < LC_CTYPE, LC_COLLATE, LC_MONETARY, LC_NUMERIC, ... < LC_ALL This is why documentation such as [1] suggests to set LC_ALL in build scripts to get the deterministic result. LANG=C is not strong enough to override LC_* that may be set by end users. [1]: https://reproducible-builds.org/docs/locales/ Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Reviewed-by: Matthias Maennich <maennich@google.com> Acked-by: Matthieu Baerts <matthieu.baerts@tessares.net> (mptcp) Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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7ce04771 |
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25-Mar-2021 |
Nathan Chancellor <nathan@kernel.org> |
riscv: Workaround mcount name prior to clang-13 Prior to clang 13.0.0, the RISC-V name for the mcount symbol was "mcount", which differs from the GCC version of "_mcount", which results in the following errors: riscv64-linux-gnu-ld: init/main.o: in function `__traceiter_initcall_level': main.c:(.text+0xe): undefined reference to `mcount' riscv64-linux-gnu-ld: init/main.o: in function `__traceiter_initcall_start': main.c:(.text+0x4e): undefined reference to `mcount' riscv64-linux-gnu-ld: init/main.o: in function `__traceiter_initcall_finish': main.c:(.text+0x92): undefined reference to `mcount' riscv64-linux-gnu-ld: init/main.o: in function `.LBB32_28': main.c:(.text+0x30c): undefined reference to `mcount' riscv64-linux-gnu-ld: init/main.o: in function `free_initmem': main.c:(.text+0x54c): undefined reference to `mcount' This has been corrected in https://reviews.llvm.org/D98881 but the minimum supported clang version is 10.0.1. To avoid build errors and to gain a working function tracer, adjust the name of the mcount symbol for older versions of clang in mount.S and recordmcount.pl. Link: https://github.com/ClangBuiltLinux/linux/issues/1331 Signed-off-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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#
2f095504 |
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25-Mar-2021 |
Nathan Chancellor <nathan@kernel.org> |
scripts/recordmcount.pl: Fix RISC-V regex for clang Clang can generate R_RISCV_CALL_PLT relocations to _mcount: $ llvm-objdump -dr build/riscv/init/main.o | rg mcount 000000000000000e: R_RISCV_CALL_PLT _mcount 000000000000004e: R_RISCV_CALL_PLT _mcount After this, the __start_mcount_loc section is properly generated and function tracing still works. Link: https://github.com/ClangBuiltLinux/linux/issues/1331 Signed-off-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Fangrui Song <maskray@google.com> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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b700fc3a |
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22-Mar-2021 |
Steven Rostedt (VMware) <rostedt@goodmis.org> |
scripts/recordmcount.pl: Make vim and emacs indent the same By default, emacs indents Perl files with 4 spaces, but will use tabs where 8 spaces are used. Add a vim command of softtabstop=4, to make vim behave the same. This should remove the issue of developers using vim having causing different indentation. "John (Warthog9) Hawley" <warthog9@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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2cf3af7a |
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22-Mar-2021 |
Steven Rostedt (VMware) <rostedt@goodmis.org> |
scripts/recordmcount.pl: Make indent spacing consistent Emacs by default will have perl files have 4 space indents, where 8 spaces are represented with a single tab. There are some places in recordmcount.pl that has 8 spaces where a tab should be used. Replace them to make the file consistent. No functional changes. Cc: "John (Warthog9) Hawley" <warthog9@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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93ca6963 |
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12-Feb-2021 |
Rong Chen <rong.a.chen@intel.com> |
scripts/recordmcount.pl: support big endian for ARCH sh The kernel test robot reported the following issue: CC [M] drivers/soc/litex/litex_soc_ctrl.o sh4-linux-objcopy: Unable to change endianness of input file(s) sh4-linux-ld: cannot find drivers/soc/litex/.tmp_gl_litex_soc_ctrl.o: No such file or directory sh4-linux-objcopy: 'drivers/soc/litex/.tmp_mx_litex_soc_ctrl.o': No such file The problem is that the format of input file is elf32-shbig-linux, but sh4-linux-objcopy wants to output a file which format is elf32-sh-linux: $ sh4-linux-objdump -d drivers/soc/litex/litex_soc_ctrl.o | grep format drivers/soc/litex/litex_soc_ctrl.o: file format elf32-shbig-linux Link: https://lkml.kernel.org/r/20210210150435.2171567-1-rong.a.chen@intel.com Link: https://lore.kernel.org/linux-mm/202101261118.GbbYSlHu-lkp@intel.com Signed-off-by: Rong Chen <rong.a.chen@intel.com> Reported-by: kernel test robot <lkp@intel.com> Cc: Yoshinori Sato <ysato@users.osdn.me> Cc: Rich Felker <dalias@libc.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c9343637 |
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12-Nov-2020 |
Vasily Gorbik <gor@linux.ibm.com> |
s390/ftrace: assume -mhotpatch or -mrecord-mcount always available Currently the kernel minimal compiler requirement is gcc 4.9 or clang 10.0.1. * gcc -mhotpatch option is supported since 4.8. * A combination of -pg -mrecord-mcount -mnop-mcount -mfentry flags is supported since gcc 9 and since clang 10. Drop support for old -pg function prologues. Which leaves binary compatible -mhotpatch / -mnop-mcount -mfentry prologues in a form: brcl 0,0 Which are also do not require initial nop optimization / conversion and presence of _mcount symbol. Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> Reviewed-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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4f19048f |
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27-May-2019 |
Thomas Gleixner <tglx@linutronix.de> |
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 166 Based on 1 normalized pattern(s): licensed under the terms of the gnu gpl license version 2 extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 62 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Allison Randal <allison@lohutok.net> Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Richard Fontana <rfontana@redhat.com> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070033.929121379@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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#
e46b94d2 |
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27-Apr-2019 |
Daniel Dadap <ddadap@nvidia.com> |
scripts: override locale from environment when running recordmcount.pl recordmcount.pl uses a set of regular expressions to parse the output of objdump(1). However, if objdump(1) output is localized, it may not match the regular expressions, thereby preventing recordmcount.pl from parsing object files correctly. In order to allow recordmcount.pl to function correctly regardless of the current locale settings, set LANG=C when running objdump(1). LC_ALL is already unset in the top-level Makefile, so it is not necessary to also override that environment variable. Signed-off-by: Daniel Dadap <ddadap@nvidia.com> Reviewed-by: Robert Morell <rmorell@nvidia.com> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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28bb030f |
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28-Feb-2019 |
Guo Ren <ren_guo@c-sky.com> |
csky/ftrace: Add dynamic function tracer (include graph tracer) Support dynamic ftrace including dynamic graph tracer. Gcc-csky with -pg will produce call site in every function prologue and we can use these call site to hook trace function. gcc with -pg origin call site: push lr jbsr _mcount nop32 nop32 If the (callee - caller)'s offset is in range of bsr instruction, we'll modify code with: push lr bsr _mcount nop32 nop32 Else if the (callee - caller)'s offset is out of bsr instrunction, we'll modify code with: push lr movih r26, ... ori r26, ... jsr r26 (r26 is reserved for jsr link reg in csky abiv2 spec.) Signed-off-by: Guo Ren <ren_guo@c-sky.com>
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9c8e2f6d |
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20-Nov-2018 |
Joe Lawrence <joe.lawrence@redhat.com> |
scripts/recordmcount.{c,pl}: support -ffunction-sections .text.* section names When building with -ffunction-sections, the compiler will place each function into its own ELF section, prefixed with ".text". For example, a simple test module with functions test_module_do_work() and test_module_wq_func(): % objdump --section-headers test_module.o | awk '/\.text/{print $2}' .text .text.test_module_do_work .text.test_module_wq_func .init.text .exit.text Adjust the recordmcount scripts to look for ".text" as a section name prefix. This will ensure that those functions will be included in the __mcount_loc relocations: % objdump --reloc --section __mcount_loc test_module.o OFFSET TYPE VALUE 0000000000000000 R_X86_64_64 .text.test_module_do_work 0000000000000008 R_X86_64_64 .text.test_module_wq_func 0000000000000010 R_X86_64_64 .init.text Link: http://lkml.kernel.org/r/1542745158-25392-2-git-send-email-joe.lawrence@redhat.com Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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fbf58a52 |
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14-Aug-2018 |
Zong Li <zong@andestech.com> |
nds32/ftrace: Add RECORD_MCOUNT support Recognize NDS32 object files in recordmcount.pl. Signed-off-by: Zong Li <zong@andestech.com> Acked-by: Greentime Hu <greentime@andestech.com> Signed-off-by: Greentime Hu <greentime@andestech.com>
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1421dc6d |
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30-May-2018 |
Nicholas Piggin <npiggin@gmail.com> |
powerpc/kbuild: Use flags variables rather than overriding LD/CC/AS The powerpc toolchain can compile combinations of 32/64 bit and big/little endian, so it's convenient to consider, e.g., `CC -m64 -mbig-endian` To be the C compiler for the purpose of invoking it to build target artifacts. So overriding the CC variable to include these flags works for this purpose. Unfortunately that is not compatible with the way the proposed new Kconfig macro language will work. After previous patches in this series, these flags can be carefully passed in using flags instead. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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a1d2a6b4 |
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12-Feb-2018 |
Alan Kao <alankao@andestech.com> |
riscv/ftrace: Add RECORD_MCOUNT support Now recordmcount.pl recognizes RISC-V object files. For the mechanism to work, we have to disable the linker relaxation. Cc: Greentime Hu <greentime@andestech.com> Signed-off-by: Alan Kao <alankao@andestech.com> Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
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82831598 |
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09-Mar-2018 |
Arnd Bergmann <arnd@arndb.de> |
recordmcount.pl: drop blackin and tile support These two architectures are getting removed, so we no longer need the special cases. Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
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cb77f0d6 |
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07-May-2017 |
Kamil Rytarowski <n54@gmx.com> |
scripts: Switch to more portable Perl shebang The default NetBSD package manager is pkgsrc and it installs Perl along other third party programs under custom and configurable prefix. The default prefix for binary prebuilt packages is /usr/pkg, and the Perl executable lands in /usr/pkg/bin/perl. This change switches "/usr/bin/perl" to "/usr/bin/env perl" as it's the most portable solution that should work for almost everybody. Perl's executable is detected automatically. This change switches -w option passed to the executable with more modern "use warnings;" approach. There is no functional change to the default behavior. While there, drop "require 5" from scripts/namespace.pl (Perl from 1994?). Signed-off-by: Kamil Rytarowski <n54@gmx.com> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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42c269c8 |
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03-Mar-2017 |
Steven Rostedt (VMware) <rostedt@goodmis.org> |
ftrace: Allow for function tracing to record init functions on boot up Adding a hook into free_reserve_area() that informs ftrace that boot up init text is being free, lets ftrace safely remove those init functions from its records, which keeps ftrace from trying to modify text that no longer exists. Note, this still does not allow for tracing .init text of modules, as modules require different work for freeing its init code. Link: http://lkml.kernel.org/r/1488502497.7212.24.camel@linux.intel.com Cc: linux-mm@kvack.org Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Peter Zijlstra <peterz@infradead.org> Requested-by: Todd Brandt <todd.e.brandt@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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08a7e621 |
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27-Feb-2017 |
Masahiro Yamada <yamada.masahiro@socionext.com> |
scripts/spelling.txt: add "swith" pattern and fix typo instances Fix typos and add the following to the scripts/spelling.txt: swith||switch swithable||switchable swithed||switched swithing||switching While we are here, fix the "update" to "updates" in the touched hunk in drivers/net/wireless/marvell/mwifiex/wmm.c. Link: http://lkml.kernel.org/r/1481573103-11329-2-git-send-email-yamada.masahiro@socionext.com Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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6727ad9e |
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07-Oct-2016 |
Chris Metcalf <cmetcalf@mellanox.com> |
nmi_backtrace: generate one-line reports for idle cpus When doing an nmi backtrace of many cores, most of which are idle, the output is a little overwhelming and very uninformative. Suppress messages for cpus that are idling when they are interrupted and just emit one line, "NMI backtrace for N skipped: idling at pc 0xNNN". We do this by grouping all the cpuidle code together into a new .cpuidle.text section, and then checking the address of the interrupted PC to see if it lies within that section. This commit suitably tags x86 and tile idle routines, and only adds in the minimal framework for other architectures. Link: http://lkml.kernel.org/r/1472487169-14923-5-git-send-email-cmetcalf@mellanox.com Signed-off-by: Chris Metcalf <cmetcalf@mellanox.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Daniel Thompson <daniel.thompson@linaro.org> [arm] Tested-by: Petr Mladek <pmladek@suse.com> Cc: Aaron Tomlin <atomlin@redhat.com> Cc: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Russell King <linux@arm.linux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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e436fd61 |
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28-Sep-2016 |
Dmitry Vyukov <dvyukov@google.com> |
scripts/recordmcount.c: account for .softirqentry.text be7635e7287e ("arch, ftrace: for KASAN put hard/soft IRQ entries into separate sections") added .softirqentry.text section, but it was not added to recordmcount. So functions in the section are untracable. Add the section to scripts/recordmcount.c and scripts/recordmcount.pl. Fixes: be7635e7287e ("arch, ftrace: for KASAN put hard/soft IRQ entries into separate sections") Link: http://lkml.kernel.org/r/1474902626-73468-1-git-send-email-dvyukov@google.com Signed-off-by: Dmitry Vyukov <dvyukov@google.com> Acked-by: Steve Rostedt <rostedt@goodmis.org> Cc: <stable@vger.kernel.org> [4.6+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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2e50c4be |
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12-Jan-2016 |
Ulrich Weigand <ulrich.weigand@de.ibm.com> |
scripts/recordmcount.pl: support data in text section on powerpc If a text section starts out with a data blob before the first function start label, disassembly parsing doing in recordmcount.pl gets confused on powerpc, leading to creation of corrupted module objects. This was not a problem so far since the compiler would never create such text sections. However, this has changed with a recent change in GCC 6 to support distances of > 2GB between a function and its assoicated TOC in the ELFv2 ABI, exposing this problem. There is already code in recordmcount.pl to handle such data blobs on the sparc64 platform. This patch uses the same method to handle those on powerpc as well. Cc: stable@vger.kernel.org Acked-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Ulrich Weigand <ulrich.weigand@de.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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e6d60b36 |
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09-Jan-2015 |
Heiko Carstens <hca@linux.ibm.com> |
s390/ftrace: hotpatch support for function tracing Make use of gcc's hotpatch support to generate better code for ftrace function tracing. The generated code now contains only a six byte nop in each function prologue instead of a 24 byte code block which will be runtime patched to support function tracing. With the new code generation the runtime overhead for supporting function tracing is close to zero, while the original code did show a significant performance impact. Acked-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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1caf6aaa |
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17-Jan-2015 |
Michael Karcher <kernel@mkarcher.dialup.fu-berlin.de> |
scripts/recordmcount.pl: There is no -m32 gcc option on Super-H anymore Compiling SH with gcc-4.8 fails due to the -m32 option not being supported. From http://buildd.debian-ports.org/status/fetch.php?pkg=linux&arch=sh4&ver=3.16.7-ckt4-1&stamp=1421425783 CC init/main.o gcc-4.8: error: unrecognized command line option '-m32' ld: cannot find init/.tmp_mc_main.o: No such file or directory objcopy: 'init/.tmp_mx_main.o': No such file rm: cannot remove 'init/.tmp_mx_main.o': No such file or directory rm: cannot remove 'init/.tmp_mc_main.o': No such file or directory Link: http://lkml.kernel.org/r/1421537778-29001-1-git-send-email-kernel@mkarcher.dialup.fu-berlin.de Link: http://lkml.kernel.org/r/54BCBDD4.10102@physik.fu-berlin.de Cc: stable@vger.kernel.org Cc: Matt Fleming <matt@console-pimps.org> Reported-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> Signed-off-by: Michael Karcher <kernel@mkarcher.dialup.fu-berlin.de> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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c933146a |
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14-Oct-2014 |
Heiko Carstens <hca@linux.ibm.com> |
s390/ftrace,kprobes: allow to patch first instruction If the function tracer is enabled, allow to set kprobes on the first instruction of a function (which is the function trace caller): If no kprobe is set handling of enabling and disabling function tracing of a function simply patches the first instruction. Either it is a nop (right now it's an unconditional branch, which skips the mcount block), or it's a branch to the ftrace_caller() function. If a kprobe is being placed on a function tracer calling instruction we encode if we actually have a nop or branch in the remaining bytes after the breakpoint instruction (illegal opcode). This is possible, since the size of the instruction used for the nop and branch is six bytes, while the size of the breakpoint is only two bytes. Therefore the first two bytes contain the illegal opcode and the last four bytes contain either "0" for nop or "1" for branch. The kprobes code will then execute/simulate the correct instruction. Instruction patching for kprobes and function tracer is always done with stop_machine(). Therefore we don't have any races where an instruction is patched concurrently on a different cpu. Besides that also the program check handler which executes the function trace caller instruction won't be executed concurrently to any stop_machine() execution. This allows to keep full fault based kprobes handling which generates correct pt_regs contents automatically. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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53255c9a |
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07-Oct-2014 |
Heiko Carstens <hca@linux.ibm.com> |
s390/ftrace: remove 31 bit ftrace support 31 bit and 64 bit diverge more and more and it is rather painful to keep both parts running. To make things simpler just remove the 31 bit support which nobody uses anyway. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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af64d2aa |
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30-Apr-2014 |
AKASHI Takahiro <takahiro.akashi@linaro.org> |
ftrace: Add arm64 support to recordmcount Recordmcount utility under scripts is run, after compiling each object, to find out all the locations of calling _mcount() and put them into specific seciton named __mcount_loc. Then linker collects all such information into a table in the kernel image (between __start_mcount_loc and __stop_mcount_loc) for later use by ftrace. This patch adds arm64 specific definitions to identify such locations. There are two types of implementation, C and Perl. On arm64, only C version is used to build the kernel now that CONFIG_HAVE_C_RECORDMCOUNT is on. But Perl version is also maintained. This patch also contains a workaround just in case where a header file, elf.h, on host machine doesn't have definitions of EM_AARCH64 nor R_AARCH64_ABS64. Without them, compiling C version of recordmcount will fail. Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
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2d8eedad |
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05-Dec-2013 |
Tony Lu <zlu@tilera.com> |
ftrace: default to tilegx if ARCH=tile is specified This matches the existing behavior in arch/tile/Makefile for defconfig. Reported-by: fengguang.wu@intel.com Acked-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Tony Lu <zlu@tilera.com> Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
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f02b625d |
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05-Nov-2013 |
Jamie Iles <jamie.iles@oracle.com> |
recordmcount.pl: Add support for __fentry__ With gcc 4.6.0 the -mfentry feature places the function profiling call at the start of the function. When this is used, the call is to __fentry__ and not mcount. This is required for Ksplice as the C version of recordmcount doesn't insert section symbols for the __mcount_loc section so we fall back to the perl version. Based on 48bb5dc6cd9d30fe0d594947563da1f8bd9abada (ftrace: Make recordmcount.c handle __fentry__). Link: http://lkml.kernel.org/r/1383648129-10724-1-git-send-email-jamie.iles@oracle.com Signed-off-by: Jamie Iles <jamie.iles@oracle.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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a61fd5e3 |
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09-Aug-2013 |
Tony Lu <zlu@tilera.com> |
tile: support ftrace on tilegx This commit adds support for static ftrace, graph function support, and dynamic tracer support. Signed-off-by: Tony Lu <zlu@tilera.com> Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
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0ef5bf1c |
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10-May-2011 |
Martin Schwidefsky <schwidefsky@de.ibm.com> |
ftrace/s390: mcount offset calculation Do the mcount offset adjustment in the recordmcount.pl/recordmcount.[ch] at compile time and not in ftrace_call_adjust at run time. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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414eb44d |
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10-May-2011 |
Martin Schwidefsky <schwidefsky@de.ibm.com> |
ftrace/x86: mcount offset calculation Do the mcount offset adjustment in the recordmcount.pl/recordmcount.[ch] at compile time and not in ftrace_call_adjust at run time. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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bde66c3f |
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06-Apr-2011 |
Steven Rostedt <srostedt@redhat.com> |
ftrace: Add .kprobe.text section to whitelist for recordmcount.c The .kprobe.text section is safe to modify mcount to nop and tracing. Add it to the whitelist in recordmcount.c and recordmcount.pl. Cc: John Reiser <jreiser@bitwagon.com> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Link: http://lkml.kernel.org/r/20110421023737.743350547@goodmis.org Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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f2963886 |
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10-May-2011 |
Martin Schwidefsky <schwidefsky@de.ibm.com> |
ftrace/s390: mcount offset calculation Do the mcount offset adjustment in the recordmcount.pl/recordmcount.[ch] at compile time and not in ftrace_call_adjust at run time. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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521ccb5c |
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10-May-2011 |
Martin Schwidefsky <schwidefsky@de.ibm.com> |
ftrace/x86: mcount offset calculation Do the mcount offset adjustment in the recordmcount.pl/recordmcount.[ch] at compile time and not in ftrace_call_adjust at run time. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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9f087e76 |
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06-Apr-2011 |
Steven Rostedt <srostedt@redhat.com> |
ftrace: Add .kprobe.text section to whitelist for recordmcount.c The .kprobe.text section is safe to modify mcount to nop and tracing. Add it to the whitelist in recordmcount.c and recordmcount.pl. Cc: John Reiser <jreiser@bitwagon.com> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Link: http://lkml.kernel.org/r/20110421023737.743350547@goodmis.org Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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1274a9c2 |
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11-Feb-2011 |
Steven Rostedt <srostedt@redhat.com> |
ftrace: Add .ref.text as one of the safe areas to trace The section .ref.text will not go away unexpectedly and is safe to trace. Add it to the safe list of sections to allow tracing. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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72dc43a9 |
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10-Aug-2010 |
Rabin Vincent <rabin@rab.in> |
ARM: 6319/1: ftrace: add Thumb-2 support to dynamic ftrace Handle the different nop and call instructions for Thumb-2. Also, we need to adjust the recorded mcount_loc addresses because they have the lsb set. Cc: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Steven Rostedt <rostedt@goodmis.org> [recordmcount.pl change] Signed-off-by: Rabin Vincent <rabin@rab.in> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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3b6c223b |
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10-Aug-2010 |
Rabin Vincent <rabin@rab.in> |
ARM: 6318/1: ftrace: fix and update dynamic ftrace This adds mcount recording and updates dynamic ftrace for ARM to work with the new ftrace dyamic tracing implementation. It also adds support for the mcount format used by newer ARM compilers. With dynamic tracing, mcount() is implemented as a nop. Callsites are patched on startup with nops, and dynamically patched to call to the ftrace_caller() routine as needed. Acked-by: Steven Rostedt <rostedt@goodmis.org> [recordmcount.pl change] Signed-off-by: Rabin Vincent <rabin@rab.in> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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465c6cca |
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06-Aug-2010 |
Mike Frysinger <vapier@gentoo.org> |
tracing: Extend recordmcount to better support Blackfin mcount The mcount call on Blackfin systems includes some stack manipulation around the actual call site, so extend the build time perl script to support this. This way we can avoid doing the calculation at runtime. Signed-off-by: Mike Frysinger <vapier@gentoo.org> LKML-Reference: <1281079584-21205-1-git-send-email-vapier@gentoo.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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a484e54f |
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09-Jul-2010 |
David Daney <ddaney@caviumnetworks.com> |
tracing: Fix $mcount_regex for MIPS in recordmcount.pl I found this issue in a locally patched 2.6.32.x, current kernels have moved the offending code to an __init function which is skipped by recordmcount.pl, so the bug is not currently being exercised. However, I think the patch is still a good idea, to avoid future problems if _mcount were to ever have its address taken in normal code. This is what I originally saw: Although arch/mips/kernel/ftrace.c is built without -pg, and thus contains no calls to _mcount, it does use the address of _mcount in ftrace_make_nop(). This was causing relocations to be emitted for _mcount which recordmcount.pl erronously took to be _mcount call sites. The result was that the text of ftrace_make_nop() would be patched with garbage leading to a system crash. In non-module code, all _mcount call sites will have R_MIPS_26 relocations, so we restrict $mcount_regex to only match on these. Acked-by: Ralf Baechle <ralf@linux-mips.org> Acked-by: Wu Zhangjin <wuzhangjin@gmail.com> Signed-off-by: David Daney <ddaney@caviumnetworks.com> LKML-Reference: <1278712325-12050-1-git-send-email-ddaney@caviumnetworks.com> Cc: Li Hong <lihong.hi@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Matt Fleming <matt@console-pimps.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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b82a4045 |
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11-Jan-2010 |
Jan Kiszka <jan.kiszka@siemens.com> |
tracing/x86: Derive arch from bits argument in recordmcount.pl Let the arch argument be overruled by bits. Otherwise, building of external modules against a i386 target on a x86-64 host (and likely vice versa as well) fails unless ARCH=i386 is explicitly passed to make. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> LKML-Reference: <4B4AFE10.8050109@siemens.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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dfaa9e2c |
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05-Jan-2010 |
Wolfram Sang <wsa@kernel.org> |
tracing: Use appropriate perl constructs in recordmcount.pl Modified recordmcount.pl to use perl constructs that are still understandable by C hackers that are not perl programmers. Signed-off-by: Wolfram Sang <w.sang@pengutronix.de> LKML-Reference: <1262724082-9517-1-git-send-email-w.sang@pengutronix.de> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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#
dc4f8845 |
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05-Jan-2010 |
Wolfram Sang <wsa@kernel.org> |
tracing: optimize recordmcount.pl for offsets-handling - move check for open file in front of the writing loop - use perl-constructs to access the array Signed-off-by: Wolfram Sang <w.sang@pengutronix.de> LKML-Reference: <1262716072-14414-2-git-send-email-w.sang@pengutronix.de> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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538f1952 |
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20-Nov-2009 |
Wu Zhangjin <wuzhangjin@gmail.com> |
MIPS: Tracing: Add dynamic function tracer support With dynamic function tracer, by default, _mcount is defined as an "empty" function, it returns directly without any more action . When enabling it in user-space, it will jump to a real tracing function(ftrace_caller), and do the real job for us. Differ from the static function tracer, dynamic function tracer provides two functions ftrace_make_call()/ftrace_make_nop() to enable/disable the tracing of some indicated kernel functions(set_ftrace_filter). In the -v4 version, the implementation of this support is basically the same as X86 version does: _mcount is implemented as an empty function and ftrace_caller is implemented as a real tracing function respectively. But in this version, to support module tracing with the help of -mlong-calls in arch/mips/Makefile: MODFLAGS += -mlong-calls. The stuff becomes a little more complex. We need to cope with two different type of calling to _mcount. For the kernel part, the calling to _mcount(result of "objdump -hdr vmlinux"). is like this: 108: 03e0082d move at,ra 10c: 0c000000 jal 0 <fpcsr_pending> 10c: R_MIPS_26 _mcount 10c: R_MIPS_NONE *ABS* 10c: R_MIPS_NONE *ABS* 110: 00020021 nop For the module with -mlong-calls, it looks like this: c: 3c030000 lui v1,0x0 c: R_MIPS_HI16 _mcount c: R_MIPS_NONE *ABS* c: R_MIPS_NONE *ABS* 10: 64630000 daddiu v1,v1,0 10: R_MIPS_LO16 _mcount 10: R_MIPS_NONE *ABS* 10: R_MIPS_NONE *ABS* 14: 03e0082d move at,ra 18: 0060f809 jalr v1 In the kernel version, there is only one "_mcount" string for every kernel function, so, we just need to match this one in mcount_regex of scripts/recordmcount.pl, but in the module version, we need to choose one of the two to match. Herein, I choose the first one with "R_MIPS_HI16 _mcount". and In the kernel verion, without module tracing support, we just need to replace "jal _mcount" by "jal ftrace_caller" to do real tracing, and filter the tracing of some kernel functions via replacing it by a nop instruction. but as we have described before, the instruction "jal ftrace_caller" only left 32bit length for the address of ftrace_caller, it will fail when calling from the module space. so, herein, we must replace something else. the basic idea is loading the address of ftrace_caller to v1 via changing these two instructions: lui v1,0x0 addiu v1,v1,0 If we want to enable the tracing, we need to replace the above instructions to: lui v1, HI_16BIT_ftrace_caller addiu v1, v1, LOW_16BIT_ftrace_caller If we want to stop the tracing of the indicated kernel functions, we just need to replace the "jalr v1" to a nop instruction. but we need to replace two instructions and encode the above two instructions oursevles. Is there a simpler solution? Yes! Here it is, in this version, we put _mcount and ftrace_caller together, which means the address of _mcount and ftrace_caller is the same: _mcount: ftrace_caller: j ftrace_stub nop ...(do real tracing here)... ftrace_stub: jr ra move ra, at By default, the kernel functions call _mcount, and then jump to ftrace_stub and return. and when we want to do real tracing, we just need to remove that "j ftrace_stub", and it will run through the two "nop" instructions and then do the real tracing job. what about filtering job? we just need to do this: lui v1, hi_16bit_of_mcount <--> b 1f (0x10000004) addiu v1, v1, low_16bit_of_mcount move at, ra jalr v1 nop 1f: (rec->ip + 12) In linux-mips64, there will be some local symbols, whose name are prefixed by $L, which need to be filtered. thanks goes to Steven for writing the mips64-specific function_regex. In a conclusion, with RISC, things becomes easier with such a "stupid" trick, RISC is something like K.I.S.S, and also, there are lots of "simple" tricks in the whole ftrace support, thanks goes to Steven and the other folks for providing such a wonderful tracing framework! Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com> Cc: Nicholas Mc Guire <der.herr@hofr.at> Cc: zhangfx@lemote.com Cc: Wu Zhangjin <wuzhangjin@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: linux-kernel@vger.kernel.org Cc: linux-mips@linux-mips.org Patchwork: http://patchwork.linux-mips.org/patch/675/ Acked-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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e6299d26 |
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20-Nov-2009 |
Wu Zhangjin <wuzhangjin@gmail.com> |
MIPS: Tracing: Add an endian argument to scripts/recordmcount.pl MIPS and some other architectures need this argument to handle big/little endian respectively. Signed-off-by: Wu Zhangjin <wuzj@lemote.com> Cc: Nicholas Mc Guire <der.herr@hofr.at> Cc: zhangfx@lemote.com Cc: Wu Zhangjin <wuzhangjin@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: linux-kernel@vger.kernel.org Cc: linux-mips@linux-mips.org Patchwork: http://patchwork.linux-mips.org/patch/674/ Acked-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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7d241ff0 |
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10-Dec-2009 |
Michal Simek <monstr@monstr.eu> |
microblaze: ftrace: Add dynamic trace support With dynamic function tracer, by default, _mcount is defined as an "empty" function, it returns directly without any more action. When enabling it in user-space, it will jump to a real tracing function(ftrace_caller), and do the real job for us. Differ from the static function tracer, dynamic function tracer provides two functions ftrace_make_call()/ftrace_make_nop() to enable/disable the tracing of some indicated kernel functions(set_ftrace_filter). In the kernel version, there is only one "_mcount" string for every kernel function, so, we just need to match this one in mcount_regex of scripts/recordmcount.pl. For more information please look at code and Documentation/trace folder. Steven ACK that scripts/recordmcount.pl part. Acked-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Michal Simek <monstr@monstr.eu>
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638adb05 |
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17-Nov-2009 |
Steven Rostedt <srostedt@redhat.com> |
tracing: Only print objcopy version warning once from recordmcount If the user has an older version of objcopy, that can not handle converting local symbols to global and vice versa, then some functions will not be part of the dynamic function tracer. The current code in recordmcount.pl will print a warning in this case. Unfortunately, there exists lots of files that may have this issue with older objcopys and this will cause a warning for every file compiled with this issue. This patch solves this overwhelming output by creating a .tmp_quiet_recordmcount file on the first instance the warning is encountered. The warning will not print if this file exists. The temp file is deleted at the beginning of the compile to ensure that the warning will happen once again on new compiles (because the issue is still present). Reported-by: Andrew Morton <akpm@linux-foundation.org> Cc: Sam Ravnborg <sam@ravnborg.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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c4b8ac2c |
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27-Oct-2009 |
Li Hong <lihong.hi@gmail.com> |
tracing: Exit with error if a weak function is used in recordmcount.pl If a weak function is used as a relocation reference for mcount callers and that function is overridden, it will cause ftrace to fail at run time. The current code should prevent a weak function from being used, but if one is, the code should exit with an error to fail at compile time. Signed-off-by: Li Hong <lihong.hi@gmail.com> LKML-Reference: <20091028050743.GH30758@uhli> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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6092858c |
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27-Oct-2009 |
Li Hong <lihong.hi@gmail.com> |
tracing: Move conditional into update_funcs() in recordmcount.pl Move all the condition validations into the function update_funcs(). Also update_funcs should not die if $ref_func is undefined for there may be more than one valid section in an object file. Signed-off-by: Li Hong <lihong.hi@gmail.com> LKML-Reference: <20091028050703.GG30758@uhli> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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306dcf47 |
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27-Oct-2009 |
Li Hong <lihong.hi@gmail.com> |
tracing: Add regex for weak functions in recordmcount.pl Add a variable to contain the regex needed to find weak functions in the 'nm' output. This will allow other archs to easily override it. Also rename the regex variable $nm_regex to $local_regex to be more descriptive. Signed-off-by: Li Hong <lihong.hi@gmail.com> LKML-Reference: <20091028050619.GF30758@uhli> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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db24c7dc |
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27-Oct-2009 |
Li Hong <lihong.hi@gmail.com> |
tracing: Move mcount section search to front of loop in recordmcount.pl Move the mcount section check to the beginning of the objdump read loop. This makes the code easier to follow since the search for the mcount section is performed first before the mcount callers are processed. Signed-off-by: Li Hong <lihong.hi@gmail.com> LKML-Reference: <20091028050523.GE30758@uhli> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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7b7edc27 |
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27-Oct-2009 |
Li Hong <lihong.hi@gmail.com> |
tracing: Fix objcopy revision check in recordmcount.pl The current logic to check objcopy's version is incorrect. This patch fixes the algorithm and disables the use of local functions as a reference if the objcopy version does not support static to global conversions. Also remove some usused variables. Signed-off-by: Li Hong <lihong.hi@gmail.com> LKML-Reference: <20091028050421.GD30758@uhli> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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bdd3b052 |
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27-Oct-2009 |
Li Hong <lihong.hi@gmail.com> |
tracing: Check absolute path of input file in recordmcount.pl The ftrace.c file may reference the mcount function and this may interfere with the recordmcount.pl processing. To avoid this, the code does not process the kernel/trace/ftrace.o. But currently the check is against a relative path. This patch modifies the check to succeed if the path is an absolute path. Signed-off-by: Li Hong <lihong.hi@gmail.com> LKML-Reference: <20091028050332.GC30758@uhli> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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e2d753fa |
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27-Oct-2009 |
Li Hong <lihong.hi@gmail.com> |
tracing: Correct the check for number of arguments in recordmcount.pl The number of arguments passed into recordmcount.pl is 10, but the code checks if only 7 are passed in. Signed-off-by: Li Hong <lihong.hi@gmail.com> LKML-Reference: <20091027065733.GB22032@uhli> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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d49f6aa7 |
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27-Oct-2009 |
Li Hong <lihong.hi@gmail.com> |
tracing: Amend documentation in recordmcount.pl to reflect implementation The documentation currently says we will use the first function in a section as a reference. The actual algorithm is: choose the first global function we meet as a reference. If there is none, choose the first local one. Change the documentation to be consistent with the code. Also add several other clarifications. Signed-off-by: Li Hong <lihong.hi@gmail.com> LKML-Reference: <20091028050138.GA30758@uhli> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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4d828949 |
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13-Oct-2009 |
Jiri Olsa <jolsa@redhat.com> |
tracing: Enable "__cold" functions Based on the commit: a586df06 "x86: Support __attribute__((__cold__)) in gcc 4.3" some of the functions goes to the ".text.unlikely" section. Looks like there's not many of them (I found printk, panic, __ssb_dma_not_implemented, fat_fs_error), but still worth to include I think. Signed-off-by: Jiri Olsa <jolsa@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> LKML-Reference: <20091013203426.175845614@goodmis.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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7dbdee2e |
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06-Aug-2009 |
Steven Rostedt <srostedt@redhat.com> |
tracing: Fix recordmcount.pl to handle sections with only weak functions Roland Dreier found that a section that contained only a weak function in one of the staging drivers and this caused recordmcount.pl to spit out a warning and fail. Although it is strange that a driver would have a weak function, and this function only be used in one place, it should not be something to make recordmcount.pl fail. This patch fixes the issue in a simple manner: if only weak functions exist in a section, then that section will not be recorded. Reported-by: Roland Dreier <rdreier@cisco.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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3f6e968e |
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05-Aug-2009 |
Steven Rostedt <rostedt@goodmis.org> |
tracing: do not use functions starting with .L in recordmcount.pl On Wed, 5 Aug 2009, Ingo Molnar wrote: > * Dave Airlie <airlied@gmail.com> wrote: > > > Hey, > > > > So I spent 3-4 hrs today (I'm stupid yes) tracking down a .o > > breakage by blaming rawhide gcc/binutils as I was using make > > V=1and seeing only the compiler chain running, > > Hm, is this that powerpc related build bug you just reported? Well we tracked it down and it is powerpc64 specific. Seems that in drivers/hwmon/lm93.c there's a function called: LM93_IN_FROM_REG() But PPC64 has function descriptors and the real function names (the ones you see in objdump) start with a '.'. Thus this in objdump you have: Disassembly of section .text: 0000000000000000 <.LM93_IN_FROM_REG>: 0: 7c 08 02 a6 mflr r0 4: fb 81 ff e0 std r28,-32(r1) The function name used is .LM93_IN_FROM_REG. But gcc considers symbols that start with ".L" as a special symbol that is used inside the assembly stage. The nm passed into recordmcount uses the --synthetic option which shows the ".L" symbols (my runs outside of the build did not include the --synthetic option, so my older patch worked). We see the function as a local. Now to capture all the locations that use "mcount" we need to have a reference to link into the object file a list of mcount callers. We need a reference that will not disappear. We try to use a global function and if that does not work, we use a local function as a reference. But to relink the section back into the object, we need to make it global. In this case, we run objcopy using --globalize-symbol and --localize-symbol to convert the symbol into a global symbol, link the mcount list, then convert it back to a local symbol. This works great except for this case. .L* symbols can not be converted into a global symbol, and the mcount section referencing it will remain unresolved. Reported-by: Dave Airlie <airlied@gmail.com> LKML-Reference: <alpine.DEB.2.00.0908052011590.5010@gandalf.stny.rr.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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bd171d5f |
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23-Jul-2009 |
Matt Fleming <matt@console-pimps.org> |
ftrace: Only update $offset when we update $ref_func The value of $offset should be the offset of $ref_func from the beginning of the object file. Therefore, we should set both variables together. This fixes a bug I was hitting on sh where $offset (which is used to calcualte the addends for the __mcount_loc entries) was being set multiple times and didn't correspond to $ref_func's offset in the object file. The addends in __mcount_loc were calculated incorrectly, resulting in ftrace dynamically modifying addresses that weren't mcount call sites. Signed-off-by: Matt Fleming <matt@console-pimps.org> LKML-Reference: <1248365775-25196-2-git-send-email-matt@console-pimps.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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fc4c7355 |
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23-Jul-2009 |
Matt Fleming <matt@console-pimps.org> |
ftrace: Fix the conditional that updates $ref_func Fix the conditional that checks if we already have a $ref_func and that the new function is weak. The code as previously checking whether either condition was false, and we really need to only update $ref_func is both cconditions are false. Signed-off-by: Matt Fleming <matt@console-pimps.org> LKML-Reference: <1248365775-25196-1-git-send-email-matt@console-pimps.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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d34a4deb |
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16-Jul-2009 |
jolsa@redhat.com <jolsa@redhat.com> |
tracing: Remove .globl in the scripts/recordmcount.pl doc I was reading throught the recordmcount.pl starting comment, and spotted a tiny discrepancy. The second example is about my_func not being global, but the example code has the ".globl my_func" statement just moved. Signed-off-by: Jiri Olsa <jolsa@redhat.com> Cc: rostedt@goodmis.org LKML-Reference: <1247773468-11594-4-git-send-email-jolsa@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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9be12f9b |
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13-Jun-2009 |
David S. Miller <davem@davemloft.net> |
sparc64: Add proper dynamic ftrace support. Signed-off-by: David S. Miller <davem@davemloft.net> Acked-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Ingo Molnar <mingo@elte.hu>
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dfd9f7ab |
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12-Jun-2009 |
Heiko Carstens <hca@linux.ibm.com> |
[S390] ftrace: add dynamic ftrace support Dynamic ftrace support for s390. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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31b6e76e |
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30-Apr-2009 |
Tim Abbott <tabbott@MIT.EDU> |
ftrace: use .sched.text, not .text.sched in recordmcount.pl The only references in the kernel to the .text.sched section are in recordmcount.pl. Since the code it has is intended to be example code it should refer to real kernel sections. So change it to .sched.text instead. [ Impact: consistency in comments ] Signed-off-by: Tim Abbott <tabbott@mit.edu> LKML-Reference: <1241136371-10768-1-git-send-email-tabbott@mit.edu> Acked-by: Sam Ravnborg <sam@ravnborg.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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b43f7093 |
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16-Jan-2009 |
Steven Rostedt <srostedt@redhat.com> |
ftrace: test for running of recordmcount.pl twice on an object Impact: fix failure of dynamic function tracer selftest In a course of development, a developer does several makes on their kernel. Sometimes, the make might do something abnormal. In the case of running the recordmcount.pl script on an object twice, the script will duplicate all the calls to mcount in the __mcount_loc section. On boot up, the dynamic function tracer is careful when it modifies code, and performs several consistency checks. One is to not modify the call site if it is not what it expects it to be. If a function call site is listed twice, the first entry will convert the site to a nop, and the second will fail because it expected to see a call to mcount, but instead it sees a nop. Thus, the function tracer is disabled. Eric Sesterhenn reported seeing: [ 1.055440] ftrace: converting mcount calls to 0f 1f 44 00 00 [ 1.055568] ftrace: allocating 29418 entries in 116 pages [ 1.061000] ------------[ cut here ]------------ [ 1.061000] WARNING: at kernel/trace/ftrace.c:441 [...] [ 1.060000] ---[ end trace 4eaa2a86a8e2da23 ]--- [ 1.060000] ftrace failed to modify [<c0118072>] check_corruption+0x3/0x2d [ 1.060000] actual: 0f:1f:44:00:00 This warning shows that check_corruption+0x3 already had a nop in its place (0x0f1f440000). After compiling another kernel the problem went away. Later Eric Paris notice the same type of issue. Luckily, he saved the vmlinux file that caused it. In the file we found a bunch of duplicate mcount call site records, which lead us to the script. Perhaps this problem only happens to people named Eric. This patch changes the script to test if the __mcount_loc already exists in the object file, and if it does, it will print out an error message and kill the compile. Reported-by: Eric Sesterhenn <snakebyte@gmx.de> Reported-by: Eric Paris <eparis@redhat.com> Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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418071eb |
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08-Jan-2009 |
Shaohua Li <shaohua.li@intel.com> |
ftrace, ia64: Add recordmcount for ia64 Add recordmcount for ia64. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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25aac9dc |
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08-Jan-2009 |
Shaohua Li <shaohua.li@intel.com> |
ftrace, ia64: explictly ignore a file in recordmcount.pl In IA64, a function pointer isn't a 'unsigned long' but a 'struct {unsigned long ip, unsigned long gp}'. MCOUNT_ADDR is determined at link time not compile time, so explictly ignore kernel/trace/ftrace.o in recordmcount.pl. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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18c167fd |
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11-Jan-2009 |
Shaohua Li <shaohua.li@intel.com> |
ftrace, ia64: make recordmcount distinct module compile In IA64, module build and kernel build use different option. Make recordmcount.pl differentiate the two cases. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Acked-by: Sam Ravnborg <sam@ravnborg.org> Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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fad57feb |
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12-Nov-2008 |
Matt Fleming <mjf@gentoo.org> |
sh: dynamic ftrace support. First cut at dynamic ftrace support. Signed-off-by: Matt Fleming <mjf@gentoo.org> Signed-off-by: Paul Mundt <lethal@linux-sh.org>
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a0343e82 |
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09-Dec-2008 |
Frederic Weisbecker <fweisbec@gmail.com> |
tracing/function-graph-tracer: add a new .irqentry.text section Impact: let the function-graph-tracer be aware of the irq entrypoints Add a new .irqentry.text section to store the irq entrypoints functions inside the same section. This way, the tracer will be able to signal an interrupts triggering on output by recognizing these entrypoints. Also, make this section recordable for dynamic tracing. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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d144d5ee |
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25-Nov-2008 |
Liming Wang <liming.wang@windriver.com> |
ftrace: adding other non-leaving .text sections Impact: widen the scope of recordmcount.pl Besides .text section, there are three .text sections that won't be freed after kernel booting. They are: .sched.text, .spinlock.text and .kprobes.text, which contain functions we can trace. But the last section ".kprobes.text" is particular, which has been marked as "notrace", we ignore it. Thus we add other two sections. Signed-off-by: Liming Wang <liming.wang@windriver.com> Acked-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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e58918ab |
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20-Nov-2008 |
Jim Radford <radford@galvanix.com> |
ftrace: scripts/recordmcount.pl support for ARM Impact: extend scripts/recordmcount.pl to ARM Arm uses %progbits instead of @progbits and requires only 4 byte alignment. [ Thanks to Sam Ravnborg for mentioning that ARM uses %progbits ] Signed-off-by: Jim Radford <radford@galvanix.com> Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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3a3d04ae |
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20-Nov-2008 |
Matt Fleming <mjf@gentoo.org> |
ftrace: specify $alignment for sh architecture Impact: extend scripts/recordmcount.pl with default alignment for SH Set $alignment=2 for the sh architecture so that a ".align 2" directive will be emitted for all __mcount_loc sections. Fix a whitspace error while I'm here (converted spaces to tabs). Signed-off-by: Matt Fleming <mjf@gentoo.org> Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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c204f726 |
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20-Nov-2008 |
Steven Rostedt <srostedt@redhat.com> |
ftrace: create default variables for archs in recordmcount.pl Impact: cleanup of recordmcount.pl Now that more architectures are being ported to the MCOUNT_RECORD method, there is no reason to have each declare their own arch specific variable if most of them share the same value. This patch creates a set of default values for the arch specific variables based off of i386. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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42e007d0 |
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20-Nov-2008 |
Steven Rostedt <srostedt@redhat.com> |
ftrace: add support for powerpc to recordmcount.pl script Impact: Add PowerPC port to recordmcount.pl script This patch updates the recordmcount.pl script to process PowerPC. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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0da85c09 |
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12-Nov-2008 |
Matt Fleming <mjf@gentoo.org> |
sh: dynamic ftrace support. First cut at dynamic ftrace support. [ Steven Rostedt - only updated the recordmcount.pl file. There are updates for PowerPC that will conflict with this, and we need to base off of these changes. ] Signed-off-by: Matt Fleming <mjf@gentoo.org> Signed-off-by: Paul Mundt <lethal@linux-sh.org> Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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7d5222a6 |
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07-Nov-2008 |
Matt Fleming <matthew.fleming@imgtec.com> |
ftrace: align __mcount_loc sections Impact: add alignment option for recordmcount.pl script Align the __mcount_loc sections so that architectures with strict alignment requirements need not worry about performing unaligned accesses. This fixes an issue where I was seeing unaligned accesses, which are not supported on our architecture (the results of an unaligned access are undefined). Signed-off-by: Matt Fleming <matthew.fleming@imgtec.com> Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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34698bcb |
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23-Oct-2008 |
Steven Rostedt <rostedt@goodmis.org> |
ftrace: dynamic ftrace process only text section The text section stays in memory without ever leaving. With the exception of modules, but modules know how to handle that case. With the dynamic ftrace tracer, we need to make sure that it does not try to modify code that no longer exists. The only safe section is .text. This patch changes the recordmcount script to only record the mcount calls in the .text sections. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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dce9d18a |
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23-Oct-2008 |
Steven Rostedt <rostedt@goodmis.org> |
ftrace: handle generic arch calls The recordmcount script requires that the actual arch is passed in. This works well when ARCH=i386 or ARCH=x86_64 but does not handle the case of ARCH=x86. This patch adds a parameter to the function to pass in the number of bits of the architecture. So that it can determine if x86 should be run for x86_64 or i386 archs. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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d53475b5 |
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27-Aug-2008 |
Steven Rostedt <rostedt@goodmis.org> |
ftrace: remove warning of old objcopy and local functions The warning messages about old objcopy and local functions spam the user quite drastically. Remove the warning until we can find a nicer way of tell the user to upgrade their objcopy. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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f2f8458e |
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25-Aug-2008 |
Steven Rostedt <srostedt@redhat.com> |
ftrace: objcopy version test for local symbols The --globalize-symbols option came out in objcopy version 2.17. If the kernel is being compiled on a system with a lower version of objcopy, then we can not use the globalize / localize trick to link to symbols pointing to local functions. This patch tests the version of objcopy and will only use the trick if the version is greater than or equal to 2.17. Otherwise, if an object has only local functions within a section, it will give a nice warning and recommend the user to upgrade their objcopy. Leaving the symbols unrecorded is not that big of a deal, since the mcount record method changes the actual mcount code to be a simple "ret" without recording registers or anything. Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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8feff1ca |
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20-Aug-2008 |
Steven Rostedt <rostedt@goodmis.org> |
ftrace: handle weak symbol functions During tests and checks, I've discovered that there were failures to convert mcount callers into nops. Looking deeper into these failures, code that was attempted to be changed was not an mcount caller. The current code only updates if the code being changed is what it expects, but I still investigate any time there is a failure. What was happening is that a weak symbol was being used as a reference for other mcount callers. That weak symbol was also referenced elsewhere so the offsets were using the strong symbol and not the function symbol that it was referenced from. This patch changes the setting up of the mcount_loc section to search for a global function that is not weak. It will pick a local over a weak but if only a weak is found in a section, a warning is printed and the mcount location is not recorded (just to be safe). Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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d74fcd1e |
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15-Aug-2008 |
Steven Rostedt <rostedt@goodmis.org> |
ftrace: update recordmount.pl arch changes I'm trying to keep all the arch changes in recordmcount.pl in one place. I moved your code into that area, by adding the flags to the commands that were passed in. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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3989cce8 |
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09-Jun-2008 |
Ingo Molnar <mingo@elte.hu> |
ftrace: scripts/recordmcount.pl cross-build hack hack around: ld: Relocatable linking with relocations from format elf32-i386 (init/.tmp_gl_calibrate.o) to format elf64-x86-64 (init/.tmp_mx_calibrate.o) i CC arch/x86/mm/extable.o objcopy: 'init/.tmp_mx_calibrate.o': No such file rm: cannot remove `init/.tmp_mx_calibrate.o': No such file or directory ld: Relocatable linking with relocations from format elf32-i386 (arch/x86/mm/extable.o) to format elf64-x86-64 (arch/x86/mm/.tmp_mx_extable.o) is not supported mv: cannot stat `arch/x86/mm/.tmp_mx_extable.o': No such file or directory ld: Relocatable linking with relocations from format elf32-i386 (arch/x86/mm/fault.o) to format elf64-x86-64 (arch/x86/mm/.tmp_mx_fault.o) is not supported Signed-off-by: Ingo Molnar <mingo@elte.hu>
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8da3821b |
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14-Aug-2008 |
Steven Rostedt <rostedt@goodmis.org> |
ftrace: create __mcount_loc section This patch creates a section in the kernel called "__mcount_loc". This will hold a list of pointers to the mcount relocation for each call site of mcount. For example: objdump -dr init/main.o [...] Disassembly of section .text: 0000000000000000 <do_one_initcall>: 0: 55 push %rbp [...] 000000000000017b <init_post>: 17b: 55 push %rbp 17c: 48 89 e5 mov %rsp,%rbp 17f: 53 push %rbx 180: 48 83 ec 08 sub $0x8,%rsp 184: e8 00 00 00 00 callq 189 <init_post+0xe> 185: R_X86_64_PC32 mcount+0xfffffffffffffffc [...] We will add a section to point to each function call. .section __mcount_loc,"a",@progbits [...] .quad .text + 0x185 [...] The offset to of the mcount call site in init_post is an offset from the start of the section, and not the start of the function init_post. The mcount relocation is at the call site 0x185 from the start of the .text section. .text + 0x185 == init_post + 0xa We need a way to add this __mcount_loc section in a way that we do not lose the relocations after final link. The .text section here will be attached to all other .text sections after final link and the offsets will be meaningless. We need to keep track of where these .text sections are. To do this, we use the start of the first function in the section. do_one_initcall. We can make a tmp.s file with this function as a reference to the start of the .text section. .section __mcount_loc,"a",@progbits [...] .quad do_one_initcall + 0x185 [...] Then we can compile the tmp.s into a tmp.o gcc -c tmp.s -o tmp.o And link it into back into main.o. ld -r main.o tmp.o -o tmp_main.o mv tmp_main.o main.o But we have a problem. What happens if the first function in a section is not exported, and is a static function. The linker will not let the tmp.o use it. This case exists in main.o as well. Disassembly of section .init.text: 0000000000000000 <set_reset_devices>: 0: 55 push %rbp 1: 48 89 e5 mov %rsp,%rbp 4: e8 00 00 00 00 callq 9 <set_reset_devices+0x9> 5: R_X86_64_PC32 mcount+0xfffffffffffffffc The first function in .init.text is a static function. 00000000000000a8 t __setup_set_reset_devices 000000000000105f t __setup_str_set_reset_devices 0000000000000000 t set_reset_devices The lowercase 't' means that set_reset_devices is local and is not exported. If we simply try to link the tmp.o with the set_reset_devices we end up with two symbols: one local and one global. .section __mcount_loc,"a",@progbits .quad set_reset_devices + 0x10 00000000000000a8 t __setup_set_reset_devices 000000000000105f t __setup_str_set_reset_devices 0000000000000000 t set_reset_devices U set_reset_devices We still have an undefined reference to set_reset_devices, and if we try to compile the kernel, we will end up with an undefined reference to set_reset_devices, or even worst, it could be exported someplace else, and then we will have a reference to the wrong location. To handle this case, we make an intermediate step using objcopy. We convert set_reset_devices into a global exported symbol before linking it with tmp.o and set it back afterwards. 00000000000000a8 t __setup_set_reset_devices 000000000000105f t __setup_str_set_reset_devices 0000000000000000 T set_reset_devices 00000000000000a8 t __setup_set_reset_devices 000000000000105f t __setup_str_set_reset_devices 0000000000000000 T set_reset_devices 00000000000000a8 t __setup_set_reset_devices 000000000000105f t __setup_str_set_reset_devices 0000000000000000 t set_reset_devices Now we have a section in main.o called __mcount_loc that we can place somewhere in the kernel using vmlinux.ld.S and access it to convert all these locations that call mcount into nops before starting SMP and thus, eliminating the need to do this with kstop_machine. Note, A well documented perl script (scripts/recordmcount.pl) is used to do all this in one location. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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