Commit 711e8b0d authored by Will Deacon's avatar Will Deacon
Browse files

arm64: scs: Use 'scs_sp' register alias for x18 



x18 holds the SCS stack pointer value, so introduce a register alias to
make this easier to read in assembly code.

Tested-by: default avatarSami Tolvanen <samitolvanen@google.com>
Reviewed-by: default avatarMark Rutland <mark.rutland@arm.com>
Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent bee348fa

arch/arm64/include/asm/scs.h

+4 −2
Original line number Diff line number Diff line
@@ -7,12 +7,14 @@ 
#include <asm/asm-offsets.h>



#ifdef CONFIG_SHADOW_CALL_STACK

	scs_sp	.req	x18



	.macro scs_load tsk, tmp

	ldr	x18, [\tsk, #TSK_TI_SCS_SP]

	ldr	scs_sp, [\tsk, #TSK_TI_SCS_SP]

	.endm



	.macro scs_save tsk, tmp

	str	x18, [\tsk, #TSK_TI_SCS_SP]

	str	scs_sp, [\tsk, #TSK_TI_SCS_SP]

	.endm

#else

	.macro scs_load tsk, tmp

arch/arm64/kernel/entry.S

+5 −5
Original line number Diff line number Diff line
@@ -394,7 +394,7 @@ alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0 
	.macro	irq_stack_entry

	mov	x19, sp			// preserve the original sp

#ifdef CONFIG_SHADOW_CALL_STACK

	mov	x24, x18		// preserve the original shadow stack

	mov	x24, scs_sp		// preserve the original shadow stack

#endif



	/*
@@ -416,7 +416,7 @@ alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0 


#ifdef CONFIG_SHADOW_CALL_STACK

	/* also switch to the irq shadow stack */

	adr_this_cpu x18, irq_shadow_call_stack, x26

	adr_this_cpu scs_sp, irq_shadow_call_stack, x26

#endif



9998:
@@ -430,7 +430,7 @@ alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0 
	.macro	irq_stack_exit

	mov	sp, x19

#ifdef CONFIG_SHADOW_CALL_STACK

	mov	x18, x24

	mov	scs_sp, x24

#endif

	.endm
@@ -1071,9 +1071,9 @@ SYM_CODE_START(__sdei_asm_handler) 
#ifdef CONFIG_SHADOW_CALL_STACK

	/* Use a separate shadow call stack for normal and critical events */

	cbnz	w4, 3f

	adr_this_cpu dst=x18, sym=sdei_shadow_call_stack_normal, tmp=x6

	adr_this_cpu dst=scs_sp, sym=sdei_shadow_call_stack_normal, tmp=x6

	b	4f

3:	adr_this_cpu dst=x18, sym=sdei_shadow_call_stack_critical, tmp=x6

3:	adr_this_cpu dst=scs_sp, sym=sdei_shadow_call_stack_critical, tmp=x6

4:

#endif

arch/arm64/kernel/head.S

+1 −1
Original line number Diff line number Diff line
@@ -426,7 +426,7 @@ SYM_FUNC_START_LOCAL(__primary_switched) 
	mov	x29, sp



#ifdef CONFIG_SHADOW_CALL_STACK

	adr_l	x18, init_shadow_call_stack	// Set shadow call stack

	adr_l	scs_sp, init_shadow_call_stack	// Set shadow call stack

#endif



	str_l	x21, __fdt_pointer, x5		// Save FDT pointer

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