Commit 4dc9b282 authored by Mark Brown's avatar Mark Brown Committed by Will Deacon

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 15cd0e67 (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: default avatarKernelCI <bot@kernelci.org>
Reported-by: default avatarNick Desaulniers <ndesaulniers@google.com>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
Reviewed-by: default avatarNick Desaulniers <ndesaulniers@google.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/1054
Link: https://lore.kernel.org/r/20200619123550.48098-1-broonie@kernel.orgSigned-off-by: default avatarWill Deacon <will@kernel.org>
parent 2d071968
...@@ -1518,9 +1518,9 @@ config ARM64_PTR_AUTH ...@@ -1518,9 +1518,9 @@ config ARM64_PTR_AUTH
default y default y
depends on !KVM || ARM64_VHE depends on !KVM || ARM64_VHE
depends on (CC_HAS_SIGN_RETURN_ADDRESS || CC_HAS_BRANCH_PROT_PAC_RET) && AS_HAS_PAC 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. # 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 !CC_IS_CLANG || AS_HAS_CFI_NEGATE_RA_STATE
depends on (!FUNCTION_GRAPH_TRACER || DYNAMIC_FTRACE_WITH_REGS) depends on (!FUNCTION_GRAPH_TRACER || DYNAMIC_FTRACE_WITH_REGS)
help help
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment