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2b2fe605 |
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27-Jun-2023 |
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
selftests/rseq: Use rseq_unqual_scalar_typeof in macros Use rseq_unqual_scalar_typeof() rather than typeof() in macros to remove the volatile qualifier (if there is one in the input argument), thus generating better assembly code in those scenarios. Also add extra brackets around the "p" parameter in RSEQ_READ_ONCE(), RSEQ_WRITE_ONCE(), and rseq_unqual_scalar_typeof() across architectures to preserve expectations of operator priority. Here is an example that shows how operator priority may be an issue with missing parentheses: #define m(p) \ do { \ __typeof__(*p) v = 0; \ } while (0) void fct(unsigned long long *p1) { m(p1 + 1); /* works */ m(1 + p1); /* broken */ } Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
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5bf4aba3 |
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22-Nov-2022 |
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
selftests/rseq: arm: Template memory ordering and percpu access mode Introduce a rseq-arm-bits.h template header which is internally included to generate the static inline functions covering: - relaxed and release memory ordering, - per-cpu-id and per-mm-cid per-cpu data access. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20221122203932.231377-13-mathieu.desnoyers@efficios.com
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72cb1d7f |
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22-Nov-2022 |
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
selftests/rseq: Remove RSEQ_SKIP_FASTPATH code This code is not currently build by the test Makefile, adds complexity, and is not overall useful considering that the abort handling loops to retry the fast-path. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20221122203932.231377-10-mathieu.desnoyers@efficios.com
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b53823fb |
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23-Jan-2022 |
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
selftests/rseq: Fix: work-around asm goto compiler bugs gcc and clang each have their own compiler bugs with respect to asm goto. Implement a work-around for compiler versions known to have those bugs. gcc prior to 4.8.2 miscompiles asm goto. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670 gcc prior to 8.1.0 miscompiles asm goto at O1. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103908 clang prior to version 13.0.1 miscompiles asm goto at O2. https://github.com/llvm/llvm-project/issues/52735 Work around these issues by adding a volatile inline asm with memory clobber in the fallthrough after the asm goto and at each label target. Emit this for all compilers in case other similar issues are found in the future. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220124171253.22072-14-mathieu.desnoyers@efficios.com
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94c5cf2a |
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23-Jan-2022 |
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
selftests/rseq: Remove arm/mips asm goto compiler work-around The arm and mips work-around for asm goto size guess issues are not properly documented, and lack reference to specific compiler versions, upstream compiler bug tracker entry, and reproducer. I can only find a loosely documented patch in my original LKML rseq post refering to gcc < 7 on ARM, but it does not appear to be sufficient to track the exact issue. Also, I am not sure MIPS really has the same limitation. Therefore, remove the work-around until we can properly document this. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/lkml/20171121141900.18471-17-mathieu.desnoyers@efficios.com/
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26dc8a6d |
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23-Jan-2022 |
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
selftests/rseq: Fix ppc32 offsets by using long rather than off_t The semantic of off_t is for file offsets. We mean to use it as an offset from a pointer. We really expect it to fit in a single register, and not use a 64-bit type on 32-bit architectures. Fix runtime issues on ppc32 where the offset is always 0 due to inconsistency between the argument type (off_t -> 64-bit) and type expected by the inline assembler (32-bit). Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220124171253.22072-11-mathieu.desnoyers@efficios.com
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24d1136a |
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23-Jan-2022 |
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
selftests/rseq: Fix ppc32: wrong rseq_cs 32-bit field pointer on big endian ppc32 incorrectly uses padding as rseq_cs pointer field. Fix this by using the rseq_cs.arch.ptr field. Use this field across all architectures. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220124171253.22072-9-mathieu.desnoyers@efficios.com
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e546cd48 |
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23-Jan-2022 |
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
selftests/rseq: Introduce rseq_get_abi() helper This is done in preparation for the selftest uplift to become compatible with glibc-2.35. glibc-2.35 exposes the rseq per-thread data in the TCB, accessible at an offset from the thread pointer, rather than through an actual Thread-Local Storage (TLS) variable, as the kernel selftests initially expected. Introduce a rseq_get_abi() helper, initially using the __rseq_abi TLS variable, in preparation for changing this userspace ABI for one which is compatible with glibc-2.35. Note that the __rseq_abi TLS and glibc-2.35's ABI for per-thread data cannot actively coexist in a process, because the kernel supports only a single rseq registration per thread. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220124171253.22072-6-mathieu.desnoyers@efficios.com
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ee8a84c6 |
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30-Jun-2019 |
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
rseq/selftests: Fix Thumb mode build failure on arm32 Using ".arm .inst" for the arm signature introduces build issues for programs compiled in Thumb mode because the assembler stays in the arm mode for the rest of the inline assembly. Revert to using a ".word" to express the signature as data instead. The choice of signature is a valid trap instruction on arm32 little endian, where both code and data are little endian. ARMv6+ big endian (BE8) generates mixed endianness code vs data: little-endian code and big-endian data. The data value of the signature needs to have its byte order reversed to generate the trap instruction. Prior to ARMv6, -mbig-endian generates big-endian code and data (which match), so the endianness of the data representation of the signature should not be reversed. However, the choice between BE32 and BE8 is done by the linker, so we cannot know whether code and data endianness will be mixed before the linker is invoked. So rather than try to play tricks with the linker, the rseq signature is simply data (not a trap instruction) prior to ARMv6 on big endian. This is why the signature is expressed as data (.word) rather than as instruction (.inst) in assembler. Because a ".word" is used to emit the signature, it will be interpreted as a literal pool by a disassembler, not as an actual instruction. Considering that the signature is not meant to be executed except in scenarios where the program execution is completely bogus, this should not be an issue. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Acked-by: Will Deacon <will.deacon@arm.com> CC: Peter Zijlstra <peterz@infradead.org> CC: Thomas Gleixner <tglx@linutronix.de> CC: Joel Fernandes <joelaf@google.com> CC: Catalin Marinas <catalin.marinas@arm.com> CC: Dave Watson <davejwatson@fb.com> CC: Will Deacon <will.deacon@arm.com> CC: Shuah Khan <shuah@kernel.org> CC: Andi Kleen <andi@firstfloor.org> CC: linux-kselftest@vger.kernel.org CC: "H . Peter Anvin" <hpa@zytor.com> CC: Chris Lameter <cl@linux.com> CC: Russell King <linux@arm.linux.org.uk> CC: Michael Kerrisk <mtk.manpages@gmail.com> CC: "Paul E . McKenney" <paulmck@linux.vnet.ibm.com> CC: Paul Turner <pjt@google.com> CC: Boqun Feng <boqun.feng@gmail.com> CC: Josh Triplett <josh@joshtriplett.org> CC: Steven Rostedt <rostedt@goodmis.org> CC: Ben Maurer <bmaurer@fb.com> CC: linux-api@vger.kernel.org CC: Andy Lutomirski <luto@amacapital.net> CC: Andrew Morton <akpm@linux-foundation.org> CC: Linus Torvalds <torvalds@linux-foundation.org> CC: Carlos O'Donell <carlos@redhat.com> CC: Florian Weimer <fweimer@redhat.com> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
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2b845d4b |
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03-May-2019 |
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
rseq/selftests: arm: use udf instruction for RSEQ_SIG Use udf as the guard instruction for the restartable sequence abort handler. Previously, the chosen signature was not a valid instruction, based on the assumption that it could always sit in a literal pool. However, there are compilation environments in which literal pools are not available, for instance execute-only code. Therefore, we need to choose a signature value that is also a valid instruction. Handle compiling with -mbig-endian on ARMv6+, which generates binaries with mixed code vs data endianness (little endian code, big endian data). Else mismatch between code endianness for the generated signatures and data endianness for the RSEQ_SIG parameter passed to the rseq registration will trigger application segmentation faults when the kernel try to abort rseq critical sections. Prior to ARMv6, -mbig-endian generates big-endian code and data, so endianness should not be reversed in that case. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> CC: Peter Zijlstra <peterz@infradead.org> CC: Thomas Gleixner <tglx@linutronix.de> CC: Joel Fernandes <joelaf@google.com> CC: Catalin Marinas <catalin.marinas@arm.com> CC: Dave Watson <davejwatson@fb.com> CC: Will Deacon <will.deacon@arm.com> CC: Shuah Khan <shuah@kernel.org> CC: Andi Kleen <andi@firstfloor.org> CC: linux-kselftest@vger.kernel.org CC: "H . Peter Anvin" <hpa@zytor.com> CC: Chris Lameter <cl@linux.com> CC: Russell King <linux@arm.linux.org.uk> CC: Michael Kerrisk <mtk.manpages@gmail.com> CC: "Paul E . McKenney" <paulmck@linux.vnet.ibm.com> CC: Paul Turner <pjt@google.com> CC: Boqun Feng <boqun.feng@gmail.com> CC: Josh Triplett <josh@joshtriplett.org> CC: Steven Rostedt <rostedt@goodmis.org> CC: Ben Maurer <bmaurer@fb.com> CC: linux-api@vger.kernel.org CC: Andy Lutomirski <luto@amacapital.net> CC: Andrew Morton <akpm@linux-foundation.org> CC: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
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a3e3131f |
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29-Apr-2019 |
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
rseq/selftests: Introduce __rseq_cs_ptr_array, rename __rseq_table to __rseq_cs The entries within __rseq_table are aligned on 32 bytes due to linux/rseq.h struct rseq_cs uapi requirements, but the start of the __rseq_table section is not guaranteed to be 32-byte aligned. It can cause padding to be added at the start of the section, which makes it hard to use as an array of items by debuggers. Considering that __rseq_table does not really consist of a table due to the presence of padding, rename this section to __rseq_cs. Create a new __rseq_cs_ptr_array section which contains 64-bit packed pointers to entries within the __rseq_cs section. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> CC: Thomas Gleixner <tglx@linutronix.de> CC: Joel Fernandes <joelaf@google.com> CC: Peter Zijlstra <peterz@infradead.org> CC: Catalin Marinas <catalin.marinas@arm.com> CC: Dave Watson <davejwatson@fb.com> CC: Will Deacon <will.deacon@arm.com> CC: Shuah Khan <shuah@kernel.org> CC: Andi Kleen <andi@firstfloor.org> CC: linux-kselftest@vger.kernel.org CC: "H . Peter Anvin" <hpa@zytor.com> CC: Chris Lameter <cl@linux.com> CC: Russell King <linux@arm.linux.org.uk> CC: Michael Kerrisk <mtk.manpages@gmail.com> CC: "Paul E . McKenney" <paulmck@linux.vnet.ibm.com> CC: Paul Turner <pjt@google.com> CC: Boqun Feng <boqun.feng@gmail.com> CC: Josh Triplett <josh@joshtriplett.org> CC: Steven Rostedt <rostedt@goodmis.org> CC: Ben Maurer <bmaurer@fb.com> CC: linux-api@vger.kernel.org CC: Andy Lutomirski <luto@amacapital.net> CC: Andrew Morton <akpm@linux-foundation.org> CC: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
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4fe2088e |
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29-Apr-2019 |
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
rseq/selftests: Add __rseq_exit_point_array section for debuggers Knowing all exit points is useful to assist debuggers stepping over the rseq critical sections without requiring them to disassemble the content of the critical section to figure out the exit points. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> CC: Thomas Gleixner <tglx@linutronix.de> CC: Joel Fernandes <joelaf@google.com> CC: Peter Zijlstra <peterz@infradead.org> CC: Catalin Marinas <catalin.marinas@arm.com> CC: Dave Watson <davejwatson@fb.com> CC: Will Deacon <will.deacon@arm.com> CC: Shuah Khan <shuah@kernel.org> CC: Andi Kleen <andi@firstfloor.org> CC: linux-kselftest@vger.kernel.org CC: "H . Peter Anvin" <hpa@zytor.com> CC: Chris Lameter <cl@linux.com> CC: Russell King <linux@arm.linux.org.uk> CC: Michael Kerrisk <mtk.manpages@gmail.com> CC: "Paul E . McKenney" <paulmck@linux.vnet.ibm.com> CC: Paul Turner <pjt@google.com> CC: Boqun Feng <boqun.feng@gmail.com> CC: Josh Triplett <josh@joshtriplett.org> CC: Steven Rostedt <rostedt@goodmis.org> CC: Ben Maurer <bmaurer@fb.com> CC: linux-api@vger.kernel.org CC: Andy Lutomirski <luto@amacapital.net> CC: Andrew Morton <akpm@linux-foundation.org> CC: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
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0ea73d5e |
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19-Jun-2018 |
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
rseq/selftests/arm: Align 'struct rseq_cs' on 32 bytes uapi/linux/rseq.h aligns 'struct rseq_cs' on 32 bytes. Satisfy this alignment requirement in its definition within the rseq-arm.h inline assembly as well. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Andrew Hunter <ahh@google.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Ben Maurer <bmaurer@fb.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chris Lameter <cl@linux.com> Cc: Dave Watson <davejwatson@fb.com> Cc: Joel Fernandes <joelaf@google.com> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Russell King <linux@arm.linux.org.uk> Cc: Shuah Khan <shuahkh@osg.samsung.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Cc: linux-api@vger.kernel.org Cc: linux-kselftest@vger.kernel.org Link: https://lore.kernel.org/lkml/20180619133230.4087-3-mathieu.desnoyers@efficios.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
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2e155fb7 |
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02-Jun-2018 |
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
rseq/selftests: Provide rseq library This rseq helper library provides a user-space API to the rseq() system call. The rseq fast-path exposes the instruction pointer addresses where the rseq assembly blocks begin and end, as well as the associated abort instruction pointer, in the __rseq_table section. This section allows debuggers may know where to place breakpoints when single-stepping through assembly blocks which may be aborted at any point by the kernel. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Joel Fernandes <joelaf@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Watson <davejwatson@fb.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Shuah Khan <shuahkh@osg.samsung.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: linux-kselftest@vger.kernel.org Cc: "H . Peter Anvin" <hpa@zytor.com> Cc: Chris Lameter <cl@linux.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: Andrew Hunter <ahh@google.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: "Paul E . McKenney" <paulmck@linux.vnet.ibm.com> Cc: Paul Turner <pjt@google.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Ben Maurer <bmaurer@fb.com> Cc: linux-api@vger.kernel.org Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lkml.kernel.org/r/20180602124408.8430-13-mathieu.desnoyers@efficios.com
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