| Message ID | 1489167858-24867-1-git-send-email-mark.rutland@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h index 05310ad..f31c48d 100644 --- a/arch/arm64/include/asm/cpufeature.h +++ b/arch/arm64/include/asm/cpufeature.h @@ -251,7 +251,7 @@ static inline bool system_supports_fpsimd(void) static inline bool system_uses_ttbr0_pan(void) { return IS_ENABLED(CONFIG_ARM64_SW_TTBR0_PAN) && - !cpus_have_cap(ARM64_HAS_PAN); + !cpus_have_const_cap(ARM64_HAS_PAN); } #endif /* __ASSEMBLY__ */
Since commit 4b65a5db362783ab ("arm64: Introduce uaccess_{disable,enable} functionality based on TTBR0_EL1"), system_uses_ttbr0_pan() has used cpus_have_cap() to determine whether PAN is present. Since commit a4023f682739439b ("arm64: Add hypervisor safe helper for checking constant capabilities"), which was introduced around the same time, cpus_have_cap() doesn't try to use a static key, and must always perform a load, test, and consitional branch (likely a tbnz for the latter two). Elsewhere, we moved to using cpus_have_const_cap(), which can use a static key (i.e. a non-conditional branch), which is patched at runtime when the feature is detected. This patch makes system_uses_ttbr0_pan() use cpus_have_const_cap(). The static key is likely a win for hot-paths like the uacccess primitives, and this makes our usage consistent regardless. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> --- arch/arm64/include/asm/cpufeature.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)