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authorMark Brown <broonie@kernel.org>2020-06-19 13:35:50 +0100
committerWill Deacon <will@kernel.org>2020-06-23 16:18:17 +0100
commit4dc9b282bf5fc80b1761bac467adf78cd417b777 (patch)
tree14c0917de8a7511e90987f2534870e9e4bea9654 /arch
parent2d071968a4052e58681ace6488e2625b2a30a7f7 (diff)
arm64: Depend on newer binutils when building PAC
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 15cd0e675f3f76b (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: https://github.com/ClangBuiltLinux/linux/issues/1054 Link: https://lore.kernel.org/r/20200619123550.48098-1-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm64/Kconfig4
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 4ae2419c14a8..e391e6580bf7 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1518,9 +1518,9 @@ config ARM64_PTR_AUTH
default y
depends on !KVM || ARM64_VHE
depends on (CC_HAS_SIGN_RETURN_ADDRESS || CC_HAS_BRANCH_PROT_PAC_RET) && AS_HAS_PAC
- # GCC 9.1 and later inserts a .note.gnu.property section note for PAC
+ # Modern compilers insert a .note.gnu.property section note for PAC
# which is only understood by binutils starting with version 2.33.1.
- depends on !CC_IS_GCC || GCC_VERSION < 90100 || LD_VERSION >= 233010000
+ depends on LD_IS_LLD || LD_VERSION >= 233010000 || (CC_IS_GCC && GCC_VERSION < 90100)
depends on !CC_IS_CLANG || AS_HAS_CFI_NEGATE_RA_STATE
depends on (!FUNCTION_GRAPH_TRACER || DYNAMIC_FTRACE_WITH_REGS)
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