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

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

Tested-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Will Deacon 2020-05-15 14:46:46 +01:00
parent bee348fab0
commit 711e8b0de0
3 changed files with 10 additions and 8 deletions
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6
arch/arm64/include/asm/scs.h
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@ -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

10
arch/arm64/kernel/entry.S
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@ -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

2
arch/arm64/kernel/head.S
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@ -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