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arm64: scs: Drop unused 'tmp' argument to scs_{load, save} asm macros

PATCH In review Will Deacon 3 participants 3 messages May 27, 2021 arm64

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Will Deacon

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PATCH 1/1 arm64: scs: Drop unused 'tmp' argument to scs_{load, save} asm macros

The scs_load and scs_save asm macros don't make use of the mandatory 'tmp' register argument, so drop it and fix up the callers.

Cc Sami Tolvanen <[email protected]>
Cc Mark Rutland <[email protected]>
Signed-off-by Will Deacon <[email protected]>

---

Applies against for-next/boot

 arch/arm64/include/asm/scs.h | 8 ++++----
 arch/arm64/kernel/entry.S    | 8 ++++----
 arch/arm64/kernel/head.S     | 2 +-
 3 files changed, 9 insertions(+), 9 deletions(-)
arch/arm64/include/asm/scs.h +4 -4
index eaa2cd92e4c1..8297bccf0784 100644
@@ -9,18 +9,18 @@
 #ifdef CONFIG_SHADOW_CALL_STACK
 	scs_sp	.req	x18
 
-	.macro scs_load tsk, tmp
+	.macro scs_load tsk
 	ldr	scs_sp, [\tsk, #TSK_TI_SCS_SP]
 	.endm
 
-	.macro scs_save tsk, tmp
+	.macro scs_save tsk
 	str	scs_sp, [\tsk, #TSK_TI_SCS_SP]
 	.endm
 #else
-	.macro scs_load tsk, tmp
+	.macro scs_load tsk
 	.endm
 
-	.macro scs_save tsk, tmp
+	.macro scs_save tsk
 	.endm
 #endif /* CONFIG_SHADOW_CALL_STACK */
arch/arm64/kernel/entry.S +4 -4
index 294f24e16fee..3153f1448cdb 100644
@@ -275,7 +275,7 @@ alternative_else_nop_endif
 
 	mte_set_kernel_gcr x22, x23
 
-	scs_load tsk, x20
+	scs_load tsk
 	.else
 	add	x21, sp, #PT_REGS_SIZE
 	get_current_task tsk

@@ -375,7 +375,7 @@ alternative_if ARM64_WORKAROUND_845719
 alternative_else_nop_endif
 #endif
 3:
-	scs_save tsk, x0
+	scs_save tsk
 
 #ifdef CONFIG_ARM64_PTR_AUTH
 alternative_if ARM64_HAS_ADDRESS_AUTH

@@ -979,8 +979,8 @@ SYM_FUNC_START(cpu_switch_to)
 	mov	sp, x9
 	msr	sp_el0, x1
 	ptrauth_keys_install_kernel x1, x8, x9, x10
-	scs_save x0, x8
-	scs_load x1, x8
+	scs_save x0
+	scs_load x1
 	ret
 SYM_FUNC_END(cpu_switch_to)
 NOKPROBE(cpu_switch_to)
arch/arm64/kernel/head.S +1 -1
index 070ed53c049d..6a700526b117 100644
@@ -412,7 +412,7 @@ SYM_FUNC_END(__create_page_tables)
 	stp	xzr, xzr, [sp, #S_STACKFRAME]
 	add	x29, sp, #S_STACKFRAME
 
-	scs_load \tsk, \tmp1
+	scs_load \tsk
 
 	adr_l	\tmp1, __per_cpu_offset
 	ldr	w\tmp2, [\tsk, #TSK_CPU]
Signature · 7 lines
2.31.1.818.g46aad6cb9e-goog


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reviewer Acked-by on v1 1/1
#1 lore raw

Re: [PATCH] arm64: scs: Drop unused 'tmp' argument to scs_{load,save} asm macros

Quoted 6 lines · Will Deacon

The scs_load and scs_save asm macros don't make use of the mandatory 'tmp' register argument, so drop it and fix up the callers.

Cc Sami Tolvanen <[email protected]>
Cc Mark Rutland <[email protected]>
Signed-off-by Will Deacon <[email protected]>

I see this has been the case since commit:

51189c7a7ed1b4ed ("arm64: scs: Store absolute SCS stack pointer value in thread_info")

... so this looks good to me:

Acked-by Mark Rutland <[email protected]>

Mark.

Quoted 85 lines

---

Applies against for-next/boot

 arch/arm64/include/asm/scs.h | 8 ++++----
 arch/arm64/kernel/entry.S    | 8 ++++----
 arch/arm64/kernel/head.S     | 2 +-
 3 files changed, 9 insertions(+), 9 deletions(-)
arch/arm64/include/asm/scs.h +4 -4
index eaa2cd92e4c1..8297bccf0784 100644
@@ -9,18 +9,18 @@
 #ifdef CONFIG_SHADOW_CALL_STACK
 	scs_sp	.req	x18
 
-	.macro scs_load tsk, tmp
+	.macro scs_load tsk
 	ldr	scs_sp, [\tsk, #TSK_TI_SCS_SP]
 	.endm
 
-	.macro scs_save tsk, tmp
+	.macro scs_save tsk
 	str	scs_sp, [\tsk, #TSK_TI_SCS_SP]
 	.endm
 #else
-	.macro scs_load tsk, tmp
+	.macro scs_load tsk
 	.endm
 
-	.macro scs_save tsk, tmp
+	.macro scs_save tsk
 	.endm
 #endif /* CONFIG_SHADOW_CALL_STACK */
arch/arm64/kernel/entry.S +4 -4
index 294f24e16fee..3153f1448cdb 100644
@@ -275,7 +275,7 @@ alternative_else_nop_endif
 
 	mte_set_kernel_gcr x22, x23
 
-	scs_load tsk, x20
+	scs_load tsk
 	.else
 	add	x21, sp, #PT_REGS_SIZE
 	get_current_task tsk

@@ -375,7 +375,7 @@ alternative_if ARM64_WORKAROUND_845719
 alternative_else_nop_endif
 #endif
 3:
-	scs_save tsk, x0
+	scs_save tsk
 
 #ifdef CONFIG_ARM64_PTR_AUTH
 alternative_if ARM64_HAS_ADDRESS_AUTH

@@ -979,8 +979,8 @@ SYM_FUNC_START(cpu_switch_to)
 	mov	sp, x9
 	msr	sp_el0, x1
 	ptrauth_keys_install_kernel x1, x8, x9, x10
-	scs_save x0, x8
-	scs_load x1, x8
+	scs_save x0
+	scs_load x1
 	ret
 SYM_FUNC_END(cpu_switch_to)
 NOKPROBE(cpu_switch_to)
arch/arm64/kernel/head.S +1 -1
index 070ed53c049d..6a700526b117 100644
@@ -412,7 +412,7 @@ SYM_FUNC_END(__create_page_tables)
 	stp	xzr, xzr, [sp, #S_STACKFRAME]
 	add	x29, sp, #S_STACKFRAME
 
-	scs_load \tsk, \tmp1
+	scs_load \tsk
 
 	adr_l	\tmp1, __per_cpu_offset
 	ldr	w\tmp2, [\tsk, #TSK_CPU]
Signature · 1 line
2.31.1.818.g46aad6cb9e-goog

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Reviewed-by on v1 1/1
#2 lore raw
In reply to Will Deacon

Hi Will,

Quoted 81 lines · Will Deacon

The scs_load and scs_save asm macros don't make use of the mandatory 'tmp' register argument, so drop it and fix up the callers.

Cc Sami Tolvanen <[email protected]>
Cc Mark Rutland <[email protected]>
Signed-off-by Will Deacon <[email protected]>

---

Applies against for-next/boot

 arch/arm64/include/asm/scs.h | 8 ++++----
 arch/arm64/kernel/entry.S    | 8 ++++----
 arch/arm64/kernel/head.S     | 2 +-
 3 files changed, 9 insertions(+), 9 deletions(-)
arch/arm64/include/asm/scs.h +4 -4
index eaa2cd92e4c1..8297bccf0784 100644
@@ -9,18 +9,18 @@
 #ifdef CONFIG_SHADOW_CALL_STACK
        scs_sp  .req    x18
 
-       .macro scs_load tsk, tmp
+       .macro scs_load tsk
        ldr     scs_sp, [\tsk, #TSK_TI_SCS_SP]
        .endm
 
-       .macro scs_save tsk, tmp
+       .macro scs_save tsk
        str     scs_sp, [\tsk, #TSK_TI_SCS_SP]
        .endm
 #else
-       .macro scs_load tsk, tmp
+       .macro scs_load tsk
        .endm
 
-       .macro scs_save tsk, tmp
+       .macro scs_save tsk
        .endm
 #endif /* CONFIG_SHADOW_CALL_STACK */
arch/arm64/kernel/entry.S +4 -4
index 294f24e16fee..3153f1448cdb 100644
@@ -275,7 +275,7 @@ alternative_else_nop_endif
 
        mte_set_kernel_gcr x22, x23
 
-       scs_load tsk, x20
+       scs_load tsk
        .else
        add     x21, sp, #PT_REGS_SIZE
        get_current_task tsk

@@ -375,7 +375,7 @@ alternative_if ARM64_WORKAROUND_845719
 alternative_else_nop_endif
 #endif
 3:
-       scs_save tsk, x0
+       scs_save tsk
 
 #ifdef CONFIG_ARM64_PTR_AUTH
 alternative_if ARM64_HAS_ADDRESS_AUTH

@@ -979,8 +979,8 @@ SYM_FUNC_START(cpu_switch_to)
        mov     sp, x9
        msr     sp_el0, x1
        ptrauth_keys_install_kernel x1, x8, x9, x10
-       scs_save x0, x8
-       scs_load x1, x8
+       scs_save x0
+       scs_load x1
        ret
 SYM_FUNC_END(cpu_switch_to)
 NOKPROBE(cpu_switch_to)
arch/arm64/kernel/head.S +0 -0
index 070ed53c049d..6a700526b117 100644

arch/arm64/kernel/head.S SYM_FUNC_END(__create_page_tables) · line 418

Quoted 8 lines
arch/arm64/kernel/head.S +1 -1
@@ -412,7 +412,7 @@ SYM_FUNC_END(__create_page_tables)
        stp     xzr, xzr, [sp, #S_STACKFRAME]
        add     x29, sp, #S_STACKFRAME
 
-       scs_load \tsk, \tmp1
+       scs_load \tsk
 
        adr_l   \tmp1, __per_cpu_offset
        ldr     w\tmp2, [\tsk, #TSK_CPU]

Looks good to me, thanks for cleaning this up!

Reviewed-by Sami Tolvanen <[email protected]>

Sami

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