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authorDave Martin <Dave.Martin@arm.com>2020-03-16 16:50:45 +0000
committerCatalin Marinas <catalin.marinas@arm.com>2020-03-16 17:19:48 +0000
commit8ef8f360cf30be12382f89ff48a57fbbd9b31c14 (patch)
tree6060caf0bfe50a4c370c86625b7325f6199b746a /arch/arm64/include/asm/cpucaps.h
parent00e19ceec80b03a43f626f891fcc53e57919f1b3 (diff)
downloadlinux-8ef8f360cf30be12382f89ff48a57fbbd9b31c14.tar.bz2
arm64: Basic Branch Target Identification support
This patch adds the bare minimum required to expose the ARMv8.5 Branch Target Identification feature to userspace. By itself, this does _not_ automatically enable BTI for any initial executable pages mapped by execve(). This will come later, but for now it should be possible to enable BTI manually on those pages by using mprotect() from within the target process. Other arches already using the generic mman.h are already using 0x10 for arch-specific prot flags, so we use that for PROT_BTI here. For consistency, signal handler entry points in BTI guarded pages are required to be annotated as such, just like any other function. This blocks a relatively minor attack vector, but comforming userspace will have the annotations anyway, so we may as well enforce them. Signed-off-by: Mark Brown <broonie@kernel.org> Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/include/asm/cpucaps.h')
-rw-r--r--arch/arm64/include/asm/cpucaps.h3
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
index 865e0253fc1e..58e776c22aab 100644
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -58,7 +58,8 @@
#define ARM64_WORKAROUND_SPECULATIVE_AT_NVHE 48
#define ARM64_HAS_E0PD 49
#define ARM64_HAS_RNG 50
+#define ARM64_BTI 51
-#define ARM64_NCAPS 51
+#define ARM64_NCAPS 52
#endif /* __ASM_CPUCAPS_H */