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| author | Mark Brown <broonie@kernel.org> | 2020-05-06 20:51:30 +0100 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2020-05-07 17:53:20 +0100 |
| commit | 714a8d02ca4da1479bf0b778fc1951dc88515c3d (patch) | |
| tree | 052a8bb57dca406062ef023a38d2c3d1fc69c743 | |
| parent | 92e2294d870bc9e77592c2454f565c3bd6bb79ad (diff) | |
| download | linux-714a8d02ca4da1479bf0b778fc1951dc88515c3d.tar.gz | |
arm64: asm: Override SYM_FUNC_START when building the kernel with BTI
When the kernel is built for BTI override SYM_FUNC_START and related macros to add a BTI landing pad to the start of all global functions, ensuring that they are BTI safe. The ; at the end of the BTI_x macros is for the benefit of the macro-generated functions in xen-hypercall.S. Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Link: https://lore.kernel.org/r/20200506195138.22086-4-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
| -rw-r--r-- | arch/arm64/include/asm/linkage.h | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/linkage.h b/arch/arm64/include/asm/linkage.h index ebee3113a62f..b5a7998a6b2a 100644 --- a/arch/arm64/include/asm/linkage.h +++ b/arch/arm64/include/asm/linkage.h @@ -4,6 +4,52 @@ #define __ALIGN .align 2 #define __ALIGN_STR ".align 2" +#if defined(CONFIG_ARM64_BTI_KERNEL) && defined(__aarch64__) + +/* + * Since current versions of gas reject the BTI instruction unless we + * set the architecture version to v8.5 we use the hint instruction + * instead. + */ +#define BTI_C hint 34 ; +#define BTI_J hint 36 ; + +/* + * When using in-kernel BTI we need to ensure that assembly functions + * have suitable annotations. Override SYM_FUNC_START to insert a BTI + * landing pad at the start of everything. + */ +#define SYM_FUNC_START(name) \ + SYM_START(name, SYM_L_GLOBAL, SYM_A_ALIGN) \ + BTI_C + +#define SYM_FUNC_START_NOALIGN(name) \ + SYM_START(name, SYM_L_GLOBAL, SYM_A_NONE) \ + BTI_C + +#define SYM_FUNC_START_LOCAL(name) \ + SYM_START(name, SYM_L_LOCAL, SYM_A_ALIGN) \ + BTI_C + +#define SYM_FUNC_START_LOCAL_NOALIGN(name) \ + SYM_START(name, SYM_L_LOCAL, SYM_A_NONE) \ + BTI_C + +#define SYM_FUNC_START_WEAK(name) \ + SYM_START(name, SYM_L_WEAK, SYM_A_ALIGN) \ + BTI_C + +#define SYM_FUNC_START_WEAK_NOALIGN(name) \ + SYM_START(name, SYM_L_WEAK, SYM_A_NONE) \ + BTI_C + +#define SYM_INNER_LABEL(name, linkage) \ + .type name SYM_T_NONE ASM_NL \ + SYM_ENTRY(name, linkage, SYM_A_NONE) \ + BTI_J + +#endif + /* * Annotate a function as position independent, i.e., safe to be called before * the kernel virtual mapping is activated. |