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120dc60d |
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25-Aug-2020 |
Ard Biesheuvel <ardb@kernel.org> |
arm64: get rid of TEXT_OFFSET TEXT_OFFSET serves no purpose, and for this reason, it was redefined as 0x0 in the v5.8 timeframe. Since this does not appear to have caused any issues that require us to revisit that decision, let's get rid of the macro entirely, along with any references to it. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Link: https://lore.kernel.org/r/20200825135440.11288-1-ardb@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
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90776dd1 |
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13-Aug-2019 |
Kees Cook <keescook@chromium.org> |
arm64/efi: Move variable assignments after SECTIONS It seems that LLVM's linker does not correctly handle variable assignments involving section positions that are updated during the SECTIONS parsing. Commit aa69fb62bea1 ("arm64/efi: Mark __efistub_stext_offset as an absolute symbol explicitly") ran into this too, but found a different workaround. However, this was not enough, as other variables were also miscalculated which manifested as boot failures under UEFI where __efistub__end was not taking the correct _end value (they should be the same): $ ld.lld -EL -maarch64elf --no-undefined -X -shared \ -Bsymbolic -z notext -z norelro --no-apply-dynamic-relocs \ -o vmlinux.lld -T poc.lds --whole-archive vmlinux.o && \ readelf -Ws vmlinux.lld | egrep '\b(__efistub_|)_end\b' 368272: ffff000002218000 0 NOTYPE LOCAL HIDDEN 38 __efistub__end 368322: ffff000012318000 0 NOTYPE GLOBAL DEFAULT 38 _end $ aarch64-linux-gnu-ld.bfd -EL -maarch64elf --no-undefined -X -shared \ -Bsymbolic -z notext -z norelro --no-apply-dynamic-relocs \ -o vmlinux.bfd -T poc.lds --whole-archive vmlinux.o && \ readelf -Ws vmlinux.bfd | egrep '\b(__efistub_|)_end\b' 338124: ffff000012318000 0 NOTYPE LOCAL DEFAULT ABS __efistub__end 383812: ffff000012318000 0 NOTYPE GLOBAL DEFAULT 15325 _end To work around this, all of the __efistub_-prefixed variable assignments need to be moved after the linker script's SECTIONS entry. As it turns out, this also solves the problem fixed in commit aa69fb62bea1, so those changes are reverted here. Link: https://github.com/ClangBuiltLinux/linux/issues/634 Link: https://bugs.llvm.org/show_bug.cgi?id=42990 Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Will Deacon <will@kernel.org>
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aa69fb62 |
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25-Jun-2019 |
Nathan Chancellor <nathan@kernel.org> |
arm64/efi: Mark __efistub_stext_offset as an absolute symbol explicitly After r363059 and r363928 in LLVM, a build using ld.lld as the linker with CONFIG_RANDOMIZE_BASE enabled fails like so: ld.lld: error: relocation R_AARCH64_ABS32 cannot be used against symbol __efistub_stext_offset; recompile with -fPIC Fangrui and Peter figured out that ld.lld is incorrectly considering __efistub_stext_offset as a relative symbol because of the order in which symbols are evaluated. _text is treated as an absolute symbol and stext is a relative symbol, making __efistub_stext_offset a relative symbol. Adding ABSOLUTE will force ld.lld to evalute this expression in the right context and does not change ld.bfd's behavior. ld.lld will need to be fixed but the developers do not see a quick or simple fix without some research (see the linked issue for further explanation). Add this simple workaround so that ld.lld can continue to link kernels. Link: https://github.com/ClangBuiltLinux/linux/issues/561 Link: https://github.com/llvm/llvm-project/commit/025a815d75d2356f2944136269aa5874721ec236 Link: https://github.com/llvm/llvm-project/commit/249fde85832c33f8b06c6b4ac65d1c4b96d23b83 Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Debugged-by: Fangrui Song <maskray@google.com> Debugged-by: Peter Smith <peter.smith@linaro.org> Suggested-by: Fangrui Song <maskray@google.com> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> [will: add comment] Signed-off-by: Will Deacon <will@kernel.org>
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#
caab277b |
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02-Jun-2019 |
Thomas Gleixner <tglx@linutronix.de> |
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 234 Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details you should have received a copy of the gnu general public license along with this program if not see http www gnu org licenses extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 503 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexios Zavras <alexios.zavras@intel.com> Reviewed-by: Allison Randal <allison@lohutok.net> Reviewed-by: Enrico Weigelt <info@metux.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190602204653.811534538@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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f56063c5 |
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14-Nov-2018 |
AKASHI Takahiro <takahiro.akashi@linaro.org> |
arm64: add image head flag definitions Those image head's flags will be used later by kexec_file loader. Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Acked-by: James Morse <james.morse@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
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dd6846d7 |
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29-Nov-2018 |
Ard Biesheuvel <ardb@kernel.org> |
arm64: drop linker script hack to hide __efistub_ symbols Commit 1212f7a16af4 ("scripts/kallsyms: filter arm64's __efistub_ symbols") updated the kallsyms code to filter out symbols with the __efistub_ prefix explicitly, so we no longer require the hack in our linker script to emit them as absolute symbols. Cc: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
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fdfb69a7 |
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01-Mar-2018 |
Rob Herring <robh@kernel.org> |
arm64/efi: Make strrchr() available to the EFI namespace libfdt gained a new dependency on strrchr, so make it available to the EFI namespace before we update libfdt. Thanks to Ard for providing this fix. Cc: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Rob Herring <robh@kernel.org>
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57fdb89a |
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25-Apr-2016 |
Ard Biesheuvel <ardb@kernel.org> |
arm64/efi/libstub: Make screen_info accessible to the UEFI stub Unlike on 32-bit ARM, where we need to pass the stub's version of struct screen_info to the kernel proper via a configuration table, on 64-bit ARM it simply involves making the core kernel's copy of struct screen_info visible to the stub by exposing an __efistub_ alias for it. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk> Acked-by: Will Deacon <will.deacon@arm.com> Cc: Borislav Petkov <bp@alien8.de> Cc: David Herrmann <dh.herrmann@gmail.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Peter Jones <pjones@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/1461614832-17633-21-git-send-email-matt@codeblueprint.co.uk Signed-off-by: Ingo Molnar <mingo@kernel.org>
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18b9c0d6 |
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18-Apr-2016 |
Ard Biesheuvel <ardb@kernel.org> |
arm64: don't map TEXT_OFFSET bytes below the kernel if we can avoid it For historical reasons, the kernel Image must be loaded into physical memory at a 512 KB offset above a 2 MB aligned base address. The region between the base address and the start of the kernel Image has no significance to the kernel itself, but it is currently mapped explicitly into the early kernel VMA range for all translation granules. In some cases (i.e., 4 KB granule), this is unavoidable, due to the 2 MB granularity of the early kernel mappings. However, in other cases, e.g., when running with larger page sizes, or in the future, with more granular KASLR, there is no reason to map it explicitly like we do currently. So update the logic so that the region is mapped only if that happens as a side effect of rounding the start address of the kernel to swapper block size, and leave it unmapped otherwise. Since the symbol kernel_img_size now simply resolves to the memory footprint of the kernel Image, we can drop its definition from image.h and opencode its calculation. Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
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546c8c44 |
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30-Mar-2016 |
Ard Biesheuvel <ardb@kernel.org> |
arm64: move early boot code to the .init segment Apart from the arm64/linux and EFI header data structures, there is nothing in the .head.text section that must reside at the beginning of the Image. So let's move it to the .init section where it belongs. Note that this involves some minor tweaking of the EFI header, primarily because the address of 'stext' no longer coincides with the start of the .text section. It also requires a couple of relocated symbol references to be slightly rewritten or their definition moved to the linker script. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
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6ad1fe5d |
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26-Dec-2015 |
Ard Biesheuvel <ardb@kernel.org> |
arm64: avoid R_AARCH64_ABS64 relocations for Image header fields Unfortunately, the current way of using the linker to emit build time constants into the Image header will no longer work once we switch to the use of PIE executables. The reason is that such constants are emitted into the binary using R_AARCH64_ABS64 relocations, which are resolved at runtime, not at build time, and the places targeted by those relocations will contain zeroes before that. So refactor the endian swapping linker script constant generation code so that it emits the upper and lower 32-bit words separately. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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a7f8de16 |
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16-Feb-2016 |
Ard Biesheuvel <ardb@kernel.org> |
arm64: allow kernel Image to be loaded anywhere in physical memory This relaxes the kernel Image placement requirements, so that it may be placed at any 2 MB aligned offset in physical memory. This is accomplished by ignoring PHYS_OFFSET when installing memblocks, and accounting for the apparent virtual offset of the kernel Image. As a result, virtual address references below PAGE_OFFSET are correctly mapped onto physical references into the kernel Image regardless of where it sits in memory. Special care needs to be taken for dealing with memory limits passed via mem=, since the generic implementation clips memory top down, which may clip the kernel image itself if it is loaded high up in memory. To deal with this case, we simply add back the memory covering the kernel image, which may result in more memory to be retained than was passed as a mem= parameter. Since mem= should not be considered a production feature, a panic notifier handler is installed that dumps the memory limit at panic time if one was set. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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7f4e3462 |
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16-Feb-2016 |
Thierry Reding <treding@nvidia.com> |
arm64/efi: Make strnlen() available to the EFI namespace Changes introduced in the upstream version of libfdt pulled in by commit 91feabc2e224 ("scripts/dtc: Update to upstream commit b06e55c88b9b") use the strnlen() function, which isn't currently available to the EFI name- space. Add it to the EFI namespace to avoid a linker error. Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Rob Herring <robh@kernel.org> Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Thierry Reding <treding@nvidia.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
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75feee3d |
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15-Jan-2016 |
Ard Biesheuvel <ardb@kernel.org> |
arm64: hide __efistub_ aliases from kallsyms Commit e8f3010f7326 ("arm64/efi: isolate EFI stub from the kernel proper") isolated the EFI stub code from the kernel proper by prefixing all of its symbols with __efistub_, and selectively allowing access to core kernel symbols from the stub by emitting __efistub_ aliases for functions and variables that the stub can access legally. As an unintended side effect, these aliases are emitted into the kallsyms symbol table, which means they may turn up in backtraces, e.g., ... PC is at __efistub_memset+0x108/0x200 LR is at fixup_init+0x3c/0x48 ... [<ffffff8008328608>] __efistub_memset+0x108/0x200 [<ffffff8008094dcc>] free_initmem+0x2c/0x40 [<ffffff8008645198>] kernel_init+0x20/0xe0 [<ffffff8008085cd0>] ret_from_fork+0x10/0x40 The backtrace in question has nothing to do with the EFI stub, but simply returns one of the several aliases of memset() that have been recorded in the kallsyms table. This is undesirable, since it may suggest to people who are not aware of this that the issue they are seeing is somehow EFI related. So hide the __efistub_ aliases from kallsyms, by emitting them as absolute linker symbols explicitly. The distinction between those and section relative symbols is completely irrelevant to these definitions, and to the final link we are performing when these definitions are being taken into account (the distinction is only relevant to symbols defined inside a section definition when performing a partial link), and so the resulting values are identical to the original ones. Since absolute symbols are ignored by kallsyms, this will result in these values to be omitted from its symbol table. After this patch, the backtrace generated from the same address looks like this: ... PC is at __memset+0x108/0x200 LR is at fixup_init+0x3c/0x48 ... [<ffffff8008328608>] __memset+0x108/0x200 [<ffffff8008094dcc>] free_initmem+0x2c/0x40 [<ffffff8008645198>] kernel_init+0x20/0xe0 [<ffffff8008085cd0>] ret_from_fork+0x10/0x40 Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
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9d372c9f |
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19-Oct-2015 |
Ard Biesheuvel <ardb@kernel.org> |
arm64: Add page size to the kernel image header This patch adds the page size to the arm64 kernel image header so that one can infer the PAGESIZE used by the kernel. This will be helpful to diagnose failures to boot the kernel with page size not supported by the CPU. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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39d114dd |
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12-Oct-2015 |
Andrey Ryabinin <ryabinin.a.a@gmail.com> |
arm64: add KASAN support This patch adds arch specific code for kernel address sanitizer (see Documentation/kasan.txt). 1/8 of kernel addresses reserved for shadow memory. There was no big enough hole for this, so virtual addresses for shadow were stolen from vmalloc area. At early boot stage the whole shadow region populated with just one physical page (kasan_zero_page). Later, this page reused as readonly zero shadow for some memory that KASan currently don't track (vmalloc). After mapping the physical memory, pages for shadow memory are allocated and mapped. Functions like memset/memmove/memcpy do a lot of memory accesses. If bad pointer passed to one of these function it is important to catch this. Compiler's instrumentation cannot do this since these functions are written in assembly. KASan replaces memory functions with manually instrumented variants. Original functions declared as weak symbols so strong definitions in mm/kasan/kasan.c could replace them. Original functions have aliases with '__' prefix in name, so we could call non-instrumented variant if needed. Some files built without kasan instrumentation (e.g. mm/slub.c). Original mem* function replaced (via #define) with prefixed variants to disable memory access checks for such files. Signed-off-by: Andrey Ryabinin <ryabinin.a.a@gmail.com> Tested-by: Linus Walleij <linus.walleij@linaro.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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#
e8f3010f |
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08-Oct-2015 |
Ard Biesheuvel <ardb@kernel.org> |
arm64/efi: isolate EFI stub from the kernel proper Since arm64 does not use a builtin decompressor, the EFI stub is built into the kernel proper. So far, this has been working fine, but actually, since the stub is in fact a PE/COFF relocatable binary that is executed at an unknown offset in the 1:1 mapping provided by the UEFI firmware, we should not be seamlessly sharing code with the kernel proper, which is a position dependent executable linked at a high virtual offset. So instead, separate the contents of libstub and its dependencies, by putting them into their own namespace by prefixing all of its symbols with __efistub. This way, we have tight control over what parts of the kernel proper are referenced by the stub. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Matt Fleming <matt.fleming@intel.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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a2c1d73b |
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24-Jun-2014 |
Mark Rutland <mark.rutland@arm.com> |
arm64: Update the Image header Currently the kernel Image is stripped of everything past the initial stack, and at runtime the memory is initialised and used by the kernel. This makes the effective minimum memory footprint of the kernel larger than the size of the loaded binary, though bootloaders have no mechanism to identify how large this minimum memory footprint is. This makes it difficult to choose safe locations to place both the kernel and other binaries required at boot (DTB, initrd, etc), such that the kernel won't clobber said binaries or other reserved memory during initialisation. Additionally when big endian support was added the image load offset was overlooked, and is currently of an arbitrary endianness, which makes it difficult for bootloaders to make use of it. It seems that bootloaders aren't respecting the image load offset at present anyway, and are assuming that offset 0x80000 will always be correct. This patch adds an effective image size to the kernel header which describes the amount of memory from the start of the kernel Image binary which the kernel expects to use before detecting memory and handling any memory reservations. This can be used by bootloaders to choose suitable locations to load the kernel and/or other binaries such that the kernel will not clobber any memory unexpectedly. As before, memory reservations are required to prevent the kernel from clobbering these locations later. Both the image load offset and the effective image size are forced to be little-endian regardless of the native endianness of the kernel to enable bootloaders to load a kernel of arbitrary endianness. Bootloaders which wish to make use of the load offset can inspect the effective image size field for a non-zero value to determine if the offset is of a known endianness. To enable software to determine the endinanness of the kernel as may be required for certain use-cases, a new flags field (also little-endian) is added to the kernel header to export this information. The documentation is updated to clarify these details. To discourage future assumptions regarding the value of text_offset, the value at this point in time is removed from the main flow of the documentation (though kept as a compatibility note). Some minor formatting issues in the documentation are also corrected. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Tom Rini <trini@ti.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Kevin Hilman <kevin.hilman@linaro.org> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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