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arm64: Use BTI C directly and unconditionally 

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>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20211214152714.2380849-4-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Mark Brown 2021-12-14 15:27:14 +00:00 committed by Catalin Marinas
parent 481ee45ce9
commit 742a15b1a2
3 changed files with 9 additions and 25 deletions
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22
arch/arm64/include/asm/linkage.h
View File

@ -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 before

8
arch/arm64/kernel/entry-ftrace.S
View File

@ -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)

4
arch/arm64/lib/kasan_sw_tags.S
View File

@ -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]