Commit 742a15b1 authored by Mark Brown's avatar Mark Brown Committed by Catalin Marinas
Browse files

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: default avatarMark Brown <broonie@kernel.org>
Reviewed-by: default avatarArd Biesheuvel <ardb@kernel.org>
Acked-by: default avatarMark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20211214152714.2380849-4-broonie@kernel.org


Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 481ee45c

arch/arm64/include/asm/linkage.h

+6 −16
Original line number Diff line number Diff line
@@ -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

arch/arm64/kernel/entry-ftrace.S

+2 −6
Original line number Diff line number Diff line
@@ -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)

arch/arm64/lib/kasan_sw_tags.S

+1 −3
Original line number Diff line number Diff line
@@ -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]