Re: [PATCH v4 3/3] arm64: Use BTI C directly and unconditionally
From: Ard Biesheuvel <ardb@kernel.org>
Date: 2021-12-14 15:37:36
On Tue, 14 Dec 2021 at 16:28, Mark Brown [off-list ref] wrote:
Now we have a macro for BTI C that looks like a regular instruction change all the users of the current BTI_C macro to just emit a BTI C directly and remove the macro. This does mean that we now unconditionally BTI annotate all assembly functions, meaning that they are worse in this respect than code generated by the compiler. The overhead should be minimal for implementations with a reasonable HINT implementation. Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
quoted hunk ↗ jump to hunk
--- arch/arm64/include/asm/linkage.h | 22 ++++++---------------- arch/arm64/kernel/entry-ftrace.S | 8 ++------ arch/arm64/lib/kasan_sw_tags.S | 4 +--- 3 files changed, 9 insertions(+), 25 deletions(-)diff --git a/arch/arm64/include/asm/linkage.h b/arch/arm64/include/asm/linkage.h index 1cfa8bb33edd..9065e4749b42 100644 --- a/arch/arm64/include/asm/linkage.h +++ b/arch/arm64/include/asm/linkage.h@@ -4,16 +4,6 @@ #define __ALIGN .align 2 #define __ALIGN_STR ".align 2" -#if defined(CONFIG_ARM64_BTI_KERNEL) && defined(__aarch64__) - -#define BTI_C bti c ; - -#else - -#define BTI_C - -#endif - /* * When using in-kernel BTI we need to ensure that PCS-conformant * assembly functions have suitable annotations. Override@@ -23,27 +13,27 @@ */ #define SYM_FUNC_START(name) \ SYM_START(name, SYM_L_GLOBAL, SYM_A_ALIGN) \ - BTI_C + bti c ; #define SYM_FUNC_START_NOALIGN(name) \ SYM_START(name, SYM_L_GLOBAL, SYM_A_NONE) \ - BTI_C + bti c ; #define SYM_FUNC_START_LOCAL(name) \ SYM_START(name, SYM_L_LOCAL, SYM_A_ALIGN) \ - BTI_C + bti c ; #define SYM_FUNC_START_LOCAL_NOALIGN(name) \ SYM_START(name, SYM_L_LOCAL, SYM_A_NONE) \ - BTI_C + bti c ; #define SYM_FUNC_START_WEAK(name) \ SYM_START(name, SYM_L_WEAK, SYM_A_ALIGN) \ - BTI_C + bti c ; #define SYM_FUNC_START_WEAK_NOALIGN(name) \ SYM_START(name, SYM_L_WEAK, SYM_A_NONE) \ - BTI_C + bti c ; /* * Annotate a function as position independent, i.e., safe to be called beforediff --git a/arch/arm64/kernel/entry-ftrace.S b/arch/arm64/kernel/entry-ftrace.S index 8cf970d219f5..e535480a4069 100644 --- a/arch/arm64/kernel/entry-ftrace.S +++ b/arch/arm64/kernel/entry-ftrace.S@@ -77,17 +77,13 @@ .endm SYM_CODE_START(ftrace_regs_caller) -#ifdef BTI_C - BTI_C -#endif + bti c ftrace_regs_entry 1 b ftrace_common SYM_CODE_END(ftrace_regs_caller) SYM_CODE_START(ftrace_caller) -#ifdef BTI_C - BTI_C -#endif + bti c ftrace_regs_entry 0 b ftrace_common SYM_CODE_END(ftrace_caller)diff --git a/arch/arm64/lib/kasan_sw_tags.S b/arch/arm64/lib/kasan_sw_tags.S index 5b04464c045e..20784ce75def 100644 --- a/arch/arm64/lib/kasan_sw_tags.S +++ b/arch/arm64/lib/kasan_sw_tags.S@@ -38,9 +38,7 @@ * incremented by 256 prior to return). */ SYM_CODE_START(__hwasan_tag_mismatch) -#ifdef BTI_C - BTI_C -#endif + bti c add x29, sp, #232 stp x2, x3, [sp, #8 * 2] stp x4, x5, [sp, #8 * 4] --2.30.2
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