unsupported GNU_PROPERTY_TYPE (5) type: 0xc0000000 via aarch64 #1054
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[ARCH] arm64
This bug impacts ARCH=arm64
[FEATURE] PAC
Related to building the kernel with ARM v8.3 Pointer Authentication Code support
[Reported-by] KernelCI
Reported-by: kernelci.org bot <bot@kernelci.org>
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nickdesaulniers
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[ARCH] arm64
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0xc0000000 looks like a magic constant from https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=a6aadc28278a05f394c9353460ec74610ddf7ac6&id=3a9b136c998fc990cbde1a3cbc343050de704d6b |
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Since the warning appears to be coming from aarch64-linux-gnu-ar, I would have guessed that $ aarch64-linux-gnu-as foo.s -o foo.o
$ aarch64-linux-gnu-ar cDPrsT foo.a foo.owould've reproduced. I tested with binutils 2.27, but couldn't reproduce with that. |
nvm, the log has warnings from:
So it seems that for some version of binutils, none of the utilities understand this note. For the assembler file not reproducing, I wonder if Clang is emitting these notes? |
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0xc0000000 shows up in https://github.com/llvm/llvm-project/blob/55d53d4f5448db87ab0bec903be94b696c8ed3e8/llvm/include/llvm/BinaryFormat/ELF.h#L1446 and is used in |
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This warning is caused by the .note.gnu.property. [1] The above reproducer works with binutils 2.30 for me. Maybe that check should be there globally if the gnu-binutils are used. [1] Special Sections at |
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#844 is a similar issue. |
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I've done a patch adding the check for binutils - will put it on the list shortly. These binutils version checks will need revisiting for lld support. I've not made the check global since some versions of GCC don't emit the note and therefore don't need the newer binutils. |
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Versions of binutils prior to 2.33.1 don't understand the ELF notes that are added by modern compilers to indicate the PAC and BTI options used to build the code. This causes them to emit large numbers of warnings in the form: aarch64-linux-gnu-nm: warning: .tmp_vmlinux.kallsyms2: unsupported GNU_PROPERTY_TYPE (5) type: 0xc0000000 during the kernel build. In commit 15cd0e6 (arm64: Kconfig: ptrauth: Add binutils version check to fix mismatch) we added a dependency on binutils to avoid this issue when building with versions of GCC that emit the notes but did not do so for clang as it was believed that the existing check for .cfi_negate_ra_state was already requiring a new enough binutils. This does not appear to be the case for some versions of binutils (eg, the binutils in Debian 10) so add an explicit binutils version check for clang too. Link: ClangBuiltLinux#1054 Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Mark Brown <broonie@kernel.org>
fengguang
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Versions of binutils prior to 2.33.1 don't understand the ELF notes that are added by modern compilers to indicate the PAC and BTI options used to build the code. This causes them to emit large numbers of warnings in the form: aarch64-linux-gnu-nm: warning: .tmp_vmlinux.kallsyms2: unsupported GNU_PROPERTY_TYPE (5) type: 0xc0000000 during the kernel build which is currently causing quite a bit of disruption for automated build testing using clang. In commit 15cd0e6 (arm64: Kconfig: ptrauth: Add binutils version check to fix mismatch) we added a dependency on binutils to avoid this issue when building with versions of GCC that emit the notes but did not do so for clang as it was believed that the existing check for .cfi_negate_ra_state was already requiring a new enough binutils. This does not appear to be the case for some versions of binutils (eg, the binutils in Debian 10) so instead refactor so we require a new enough GNU binutils in all cases other than when we are using an old GCC version that does not emit notes. Other, more exotic, combinations of tools are possible such as using clang, lld and gas together are possible and may have further problems but rather than adding further version checks it looks like the most robust thing will be to just test that we can build cleanly with the configured tools but that will require more review and discussion so do this for now to address the immediate problem disrupting build testing. Link: ClangBuiltLinux#1054 Reported-by: KernelCI <bot@kernelci.org> Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Mark Brown <broonie@kernel.org>
nickdesaulniers
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ruscur
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Versions of binutils prior to 2.33.1 don't understand the ELF notes that are added by modern compilers to indicate the PAC and BTI options used to build the code. This causes them to emit large numbers of warnings in the form: aarch64-linux-gnu-nm: warning: .tmp_vmlinux.kallsyms2: unsupported GNU_PROPERTY_TYPE (5) type: 0xc0000000 during the kernel build which is currently causing quite a bit of disruption for automated build testing using clang. In commit 15cd0e6 (arm64: Kconfig: ptrauth: Add binutils version check to fix mismatch) we added a dependency on binutils to avoid this issue when building with versions of GCC that emit the notes but did not do so for clang as it was believed that the existing check for .cfi_negate_ra_state was already requiring a new enough binutils. This does not appear to be the case for some versions of binutils (eg, the binutils in Debian 10) so instead refactor so we require a new enough GNU binutils in all cases other than when we are using an old GCC version that does not emit notes. Other, more exotic, combinations of tools are possible such as using clang, lld and gas together are possible and may have further problems but rather than adding further version checks it looks like the most robust thing will be to just test that we can build cleanly with the configured tools but that will require more review and discussion so do this for now to address the immediate problem disrupting build testing. Reported-by: KernelCI <bot@kernelci.org> Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Link: ClangBuiltLinux#1054 Link: https://lore.kernel.org/r/20200619123550.48098-1-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
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Cool, that dropped our number of warnings down from >29k to 149. It looks like we might still have an issue in EFI libstub: I didn't see any PAC related CFLAGS in drivers/firmware/efi/libstub/Makefile. IIUC, drivers/firmware/efi/libstub/lib-ctype.o comes from lib/ctype.o? I don't see any modifications to CFLAGS_ctype.o in lib/Makefile that might accidentally modify any flags. Maybe there's a missing preprocessor guard on |
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Yeah, I think that's the same problem as #1068 : non-code object files are getting GNU_PROPERTY_TYPEs emitted. |
9034725985
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Versions of binutils prior to 2.33.1 don't understand the ELF notes that are added by modern compilers to indicate the PAC and BTI options used to build the code. This causes them to emit large numbers of warnings in the form: aarch64-linux-gnu-nm: warning: .tmp_vmlinux.kallsyms2: unsupported GNU_PROPERTY_TYPE (5) type: 0xc0000000 during the kernel build which is currently causing quite a bit of disruption for automated build testing using clang. In commit 15cd0e6 (arm64: Kconfig: ptrauth: Add binutils version check to fix mismatch) we added a dependency on binutils to avoid this issue when building with versions of GCC that emit the notes but did not do so for clang as it was believed that the existing check for .cfi_negate_ra_state was already requiring a new enough binutils. This does not appear to be the case for some versions of binutils (eg, the binutils in Debian 10) so instead refactor so we require a new enough GNU binutils in all cases other than when we are using an old GCC version that does not emit notes. Other, more exotic, combinations of tools are possible such as using clang, lld and gas together are possible and may have further problems but rather than adding further version checks it looks like the most robust thing will be to just test that we can build cleanly with the configured tools but that will require more review and discussion so do this for now to address the immediate problem disrupting build testing. Reported-by: KernelCI <bot@kernelci.org> Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Link: ClangBuiltLinux/linux#1054 Link: https://lore.kernel.org/r/20200619123550.48098-1-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
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The Clang-10 release has finished, and I wouldn't consider this a blocker. Clang-10 will ship with this known issue. We can either choose to disable PAC w/ clang-10 (@broonie notes that there's no codegen bugs per se, just annoying build warnings), or move kernel CI builds to I'd still like to land the LLVM patches for clang-11 before closing this; just noting this will be a known issue w/ Clang 10. |
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The kernel already disables PAC on these systems - the bug is that clang emits the PAC/BTI notes unconditionally for some input files, regardless of what it's been asked to produce or what the linker on the system can cope sensibly with. |
fifteenhex
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Versions of binutils prior to 2.33.1 don't understand the ELF notes that are added by modern compilers to indicate the PAC and BTI options used to build the code. This causes them to emit large numbers of warnings in the form: aarch64-linux-gnu-nm: warning: .tmp_vmlinux.kallsyms2: unsupported GNU_PROPERTY_TYPE (5) type: 0xc0000000 during the kernel build which is currently causing quite a bit of disruption for automated build testing using clang. In commit 15cd0e6 (arm64: Kconfig: ptrauth: Add binutils version check to fix mismatch) we added a dependency on binutils to avoid this issue when building with versions of GCC that emit the notes but did not do so for clang as it was believed that the existing check for .cfi_negate_ra_state was already requiring a new enough binutils. This does not appear to be the case for some versions of binutils (eg, the binutils in Debian 10) so instead refactor so we require a new enough GNU binutils in all cases other than when we are using an old GCC version that does not emit notes. Other, more exotic, combinations of tools are possible such as using clang, lld and gas together are possible and may have further problems but rather than adding further version checks it looks like the most robust thing will be to just test that we can build cleanly with the configured tools but that will require more review and discussion so do this for now to address the immediate problem disrupting build testing. Reported-by: KernelCI <bot@kernelci.org> Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Link: ClangBuiltLinux#1054 Link: https://lore.kernel.org/r/20200619123550.48098-1-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
fifteenhex
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Versions of binutils prior to 2.33.1 don't understand the ELF notes that are added by modern compilers to indicate the PAC and BTI options used to build the code. This causes them to emit large numbers of warnings in the form: aarch64-linux-gnu-nm: warning: .tmp_vmlinux.kallsyms2: unsupported GNU_PROPERTY_TYPE (5) type: 0xc0000000 during the kernel build which is currently causing quite a bit of disruption for automated build testing using clang. In commit 15cd0e6 (arm64: Kconfig: ptrauth: Add binutils version check to fix mismatch) we added a dependency on binutils to avoid this issue when building with versions of GCC that emit the notes but did not do so for clang as it was believed that the existing check for .cfi_negate_ra_state was already requiring a new enough binutils. This does not appear to be the case for some versions of binutils (eg, the binutils in Debian 10) so instead refactor so we require a new enough GNU binutils in all cases other than when we are using an old GCC version that does not emit notes. Other, more exotic, combinations of tools are possible such as using clang, lld and gas together are possible and may have further problems but rather than adding further version checks it looks like the most robust thing will be to just test that we can build cleanly with the configured tools but that will require more review and discussion so do this for now to address the immediate problem disrupting build testing. Reported-by: KernelCI <bot@kernelci.org> Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Link: ClangBuiltLinux#1054 Link: https://lore.kernel.org/r/20200619123550.48098-1-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
fifteenhex
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Versions of binutils prior to 2.33.1 don't understand the ELF notes that are added by modern compilers to indicate the PAC and BTI options used to build the code. This causes them to emit large numbers of warnings in the form: aarch64-linux-gnu-nm: warning: .tmp_vmlinux.kallsyms2: unsupported GNU_PROPERTY_TYPE (5) type: 0xc0000000 during the kernel build which is currently causing quite a bit of disruption for automated build testing using clang. In commit 15cd0e6 (arm64: Kconfig: ptrauth: Add binutils version check to fix mismatch) we added a dependency on binutils to avoid this issue when building with versions of GCC that emit the notes but did not do so for clang as it was believed that the existing check for .cfi_negate_ra_state was already requiring a new enough binutils. This does not appear to be the case for some versions of binutils (eg, the binutils in Debian 10) so instead refactor so we require a new enough GNU binutils in all cases other than when we are using an old GCC version that does not emit notes. Other, more exotic, combinations of tools are possible such as using clang, lld and gas together are possible and may have further problems but rather than adding further version checks it looks like the most robust thing will be to just test that we can build cleanly with the configured tools but that will require more review and discussion so do this for now to address the immediate problem disrupting build testing. Reported-by: KernelCI <bot@kernelci.org> Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Link: ClangBuiltLinux#1054 Link: https://lore.kernel.org/r/20200619123550.48098-1-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
fifteenhex
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Versions of binutils prior to 2.33.1 don't understand the ELF notes that are added by modern compilers to indicate the PAC and BTI options used to build the code. This causes them to emit large numbers of warnings in the form: aarch64-linux-gnu-nm: warning: .tmp_vmlinux.kallsyms2: unsupported GNU_PROPERTY_TYPE (5) type: 0xc0000000 during the kernel build which is currently causing quite a bit of disruption for automated build testing using clang. In commit 15cd0e6 (arm64: Kconfig: ptrauth: Add binutils version check to fix mismatch) we added a dependency on binutils to avoid this issue when building with versions of GCC that emit the notes but did not do so for clang as it was believed that the existing check for .cfi_negate_ra_state was already requiring a new enough binutils. This does not appear to be the case for some versions of binutils (eg, the binutils in Debian 10) so instead refactor so we require a new enough GNU binutils in all cases other than when we are using an old GCC version that does not emit notes. Other, more exotic, combinations of tools are possible such as using clang, lld and gas together are possible and may have further problems but rather than adding further version checks it looks like the most robust thing will be to just test that we can build cleanly with the configured tools but that will require more review and discussion so do this for now to address the immediate problem disrupting build testing. Reported-by: KernelCI <bot@kernelci.org> Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Link: ClangBuiltLinux#1054 Link: https://lore.kernel.org/r/20200619123550.48098-1-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
fifteenhex
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Aug 1, 2020
Versions of binutils prior to 2.33.1 don't understand the ELF notes that are added by modern compilers to indicate the PAC and BTI options used to build the code. This causes them to emit large numbers of warnings in the form: aarch64-linux-gnu-nm: warning: .tmp_vmlinux.kallsyms2: unsupported GNU_PROPERTY_TYPE (5) type: 0xc0000000 during the kernel build which is currently causing quite a bit of disruption for automated build testing using clang. In commit 15cd0e6 (arm64: Kconfig: ptrauth: Add binutils version check to fix mismatch) we added a dependency on binutils to avoid this issue when building with versions of GCC that emit the notes but did not do so for clang as it was believed that the existing check for .cfi_negate_ra_state was already requiring a new enough binutils. This does not appear to be the case for some versions of binutils (eg, the binutils in Debian 10) so instead refactor so we require a new enough GNU binutils in all cases other than when we are using an old GCC version that does not emit notes. Other, more exotic, combinations of tools are possible such as using clang, lld and gas together are possible and may have further problems but rather than adding further version checks it looks like the most robust thing will be to just test that we can build cleanly with the configured tools but that will require more review and discussion so do this for now to address the immediate problem disrupting build testing. Reported-by: KernelCI <bot@kernelci.org> Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Link: ClangBuiltLinux#1054 Link: https://lore.kernel.org/r/20200619123550.48098-1-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
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@nickdesaulniers you mentioned there was some follow up that was needed for clang-11 with this? Otherwise, are we good to close this up? |
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A fix hasn't landed in LLVM yet. #1068 . Let's close this and follow up there. |
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Versions of binutils prior to 2.33.1 don't understand the ELF notes that are added by modern compilers to indicate the PAC and BTI options used to build the code. This causes them to emit large numbers of warnings in the form: aarch64-linux-gnu-nm: warning: .tmp_vmlinux.kallsyms2: unsupported GNU_PROPERTY_TYPE (5) type: 0xc0000000 during the kernel build which is currently causing quite a bit of disruption for automated build testing using clang. In commit 9778538e45dd794 (arm64: Kconfig: ptrauth: Add binutils version check to fix mismatch) we added a dependency on binutils to avoid this issue when building with versions of GCC that emit the notes but did not do so for clang as it was believed that the existing check for .cfi_negate_ra_state was already requiring a new enough binutils. This does not appear to be the case for some versions of binutils (eg, the binutils in Debian 10) so instead refactor so we require a new enough GNU binutils in all cases other than when we are using an old GCC version that does not emit notes. Other, more exotic, combinations of tools are possible such as using clang, lld and gas together are possible and may have further problems but rather than adding further version checks it looks like the most robust thing will be to just test that we can build cleanly with the configured tools but that will require more review and discussion so do this for now to address the immediate problem disrupting build testing. Reported-by: KernelCI <bot@kernelci.org> Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Link: ClangBuiltLinux/linux#1054 Link: https://lore.kernel.org/r/20200619123550.48098-1-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
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Versions of binutils prior to 2.33.1 don't understand the ELF notes that are added by modern compilers to indicate the PAC and BTI options used to build the code. This causes them to emit large numbers of warnings in the form: aarch64-linux-gnu-nm: warning: .tmp_vmlinux.kallsyms2: unsupported GNU_PROPERTY_TYPE (5) type: 0xc0000000 during the kernel build which is currently causing quite a bit of disruption for automated build testing using clang. In commit 9778538e45dd794 (arm64: Kconfig: ptrauth: Add binutils version check to fix mismatch) we added a dependency on binutils to avoid this issue when building with versions of GCC that emit the notes but did not do so for clang as it was believed that the existing check for .cfi_negate_ra_state was already requiring a new enough binutils. This does not appear to be the case for some versions of binutils (eg, the binutils in Debian 10) so instead refactor so we require a new enough GNU binutils in all cases other than when we are using an old GCC version that does not emit notes. Other, more exotic, combinations of tools are possible such as using clang, lld and gas together are possible and may have further problems but rather than adding further version checks it looks like the most robust thing will be to just test that we can build cleanly with the configured tools but that will require more review and discussion so do this for now to address the immediate problem disrupting build testing. Reported-by: KernelCI <bot@kernelci.org> Reported-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Link: ClangBuiltLinux/linux#1054 Link: https://lore.kernel.org/r/20200619123550.48098-1-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
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cc @DanielKristofKiss @broonie @kbeyls
our clang-10 arm64 builds on kernel CI are getting flooded with
I also noticed the warning from gdb:
I assume we just need to refine our test in Kconfig for whether the tools support this note property? @DanielKristofKiss mentioned being familiar with the note; can you help recommend a way to feature test support?
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