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arm64: Kconfig: ptrauth: Add binutils version check to fix mismatch 

Recent addition of ARM64_PTR_AUTH exposed a mismatch issue with binutils.
9.1+ versions of gcc inserts a section note .note.gnu.property but this
can be used properly by binutils version greater than 2.33.1. If older
binutils are used then the following warnings are generated,

aarch64-linux-ld: warning: arch/arm64/kernel/vdso/vgettimeofday.o: unsupported GNU_PROPERTY_TYPE (5) type: 0xc0000000
aarch64-linux-objdump: warning: arch/arm64/lib/csum.o: unsupported GNU_PROPERTY_TYPE (5) type: 0xc0000000
aarch64-linux-nm: warning: .tmp_vmlinux1: unsupported GNU_PROPERTY_TYPE (5) type: 0xc0000000

This patch enables ARM64_PTR_AUTH when gcc and binutils versions are
compatible with each other. Older gcc which do not insert such section
continue to work as before.

This scenario may not occur with clang as a recent commit 3b446c7d27
("arm64: Kconfig: verify binutils support for ARM64_PTR_AUTH") masks
binutils version lesser then 2.34.

Reported-by: kbuild test robot <lkp@intel.com>
Suggested-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com>
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
[catalin.marinas@arm.com: slight adjustment to the comment]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Amit Daniel Kachhap 2020-03-30 17:11:39 +05:30 committed by Catalin Marinas
parent 9553d16fa6
commit 15cd0e675f
1 changed files with 4 additions and 1 deletions
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arch/arm64/Kconfig
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@ -1503,7 +1503,10 @@ 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
depends on CC_IS_GCC || (CC_IS_CLANG && AS_HAS_CFI_NEGATE_RA_STATE)
# GCC 9.1 and later inserts 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 !CC_IS_CLANG || AS_HAS_CFI_NEGATE_RA_STATE
depends on (!FUNCTION_GRAPH_TRACER || DYNAMIC_FTRACE_WITH_REGS)
help
Pointer authentication (part of the ARMv8.3 Extensions) provides