diff mbox series

[04/23] powerpc/64s: Use {ZEROIZE,SAVE,REST}_GPRS macros in sc, scv 0 handlers

Message ID 20220916053300.786330-5-rmclure@linux.ibm.com (mailing list archive)
State Superseded
Headers show
Series powerpc: Syscall wrapper and register clearing | expand

Commit Message

Rohan McLure Sept. 16, 2022, 5:32 a.m. UTC 
Use the convenience macros for saving/clearing/restoring gprs in keeping
with syscall calling conventions. The plural variants of these macros
can store a range of registers for concision.

This works well when the user gpr value we are hoping to save is still
live. In the syscall interrupt handlers, user register state is
sometimes juggled between registers. Hold-off from issuing the SAVE_GPR
macro for applicable neighbouring lines to highlight the delicate
register save logic.

Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
---
V1 -> V2: Update summary
V2 -> V3: Update summary regarding exclusions for the SAVE_GPR marco.
Acknowledge new name for ZEROIZE_GPR{,S} macros.
V4 -> V5: Move to beginning of series
---
 arch/powerpc/kernel/interrupt_64.S | 43 ++++++----------------------
 1 file changed, 9 insertions(+), 34 deletions(-)
diff mbox series

Patch

diff --git a/arch/powerpc/kernel/interrupt_64.S b/arch/powerpc/kernel/interrupt_64.S
index 71d2d9497283..7d92a7a54727 100644
--- a/arch/powerpc/kernel/interrupt_64.S
+++ b/arch/powerpc/kernel/interrupt_64.S
@@ -71,12 +71,7 @@  _ASM_NOKPROBE_SYMBOL(system_call_vectored_\name)
 	mfcr	r12
 	li	r11,0
 	/* Can we avoid saving r3-r8 in common case? */
-	std	r3,GPR3(r1)
-	std	r4,GPR4(r1)
-	std	r5,GPR5(r1)
-	std	r6,GPR6(r1)
-	std	r7,GPR7(r1)
-	std	r8,GPR8(r1)
+	SAVE_GPRS(3, 8, r1)
 	/* Zero r9-r12, this should only be required when restoring all GPRs */
 	std	r11,GPR9(r1)
 	std	r11,GPR10(r1)
@@ -149,17 +144,10 @@  END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
 	/* Could zero these as per ABI, but we may consider a stricter ABI
 	 * which preserves these if libc implementations can benefit, so
 	 * restore them for now until further measurement is done. */
-	ld	r0,GPR0(r1)
-	ld	r4,GPR4(r1)
-	ld	r5,GPR5(r1)
-	ld	r6,GPR6(r1)
-	ld	r7,GPR7(r1)
-	ld	r8,GPR8(r1)
+	REST_GPR(0, r1)
+	REST_GPRS(4, 8, r1)
 	/* Zero volatile regs that may contain sensitive kernel data */
-	li	r9,0
-	li	r10,0
-	li	r11,0
-	li	r12,0
+	ZEROIZE_GPRS(9, 12)
 	mtspr	SPRN_XER,r0
 
 	/*
@@ -182,7 +170,7 @@  END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
 	ld	r5,_XER(r1)
 
 	REST_NVGPRS(r1)
-	ld	r0,GPR0(r1)
+	REST_GPR(0, r1)
 	mtcr	r2
 	mtctr	r3
 	mtlr	r4
@@ -250,12 +238,7 @@  END_BTB_FLUSH_SECTION
 	mfcr	r12
 	li	r11,0
 	/* Can we avoid saving r3-r8 in common case? */
-	std	r3,GPR3(r1)
-	std	r4,GPR4(r1)
-	std	r5,GPR5(r1)
-	std	r6,GPR6(r1)
-	std	r7,GPR7(r1)
-	std	r8,GPR8(r1)
+	SAVE_GPRS(3, 8, r1)
 	/* Zero r9-r12, this should only be required when restoring all GPRs */
 	std	r11,GPR9(r1)
 	std	r11,GPR10(r1)
@@ -345,16 +328,8 @@  END_FTR_SECTION_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
 	cmpdi	r3,0
 	bne	.Lsyscall_restore_regs
 	/* Zero volatile regs that may contain sensitive kernel data */
-	li	r0,0
-	li	r4,0
-	li	r5,0
-	li	r6,0
-	li	r7,0
-	li	r8,0
-	li	r9,0
-	li	r10,0
-	li	r11,0
-	li	r12,0
+	ZEROIZE_GPR(0)
+	ZEROIZE_GPRS(4, 12)
 	mtctr	r0
 	mtspr	SPRN_XER,r0
 .Lsyscall_restore_regs_cont:
@@ -380,7 +355,7 @@  END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
 	REST_NVGPRS(r1)
 	mtctr	r3
 	mtspr	SPRN_XER,r4
-	ld	r0,GPR0(r1)
+	REST_GPR(0, r1)
 	REST_GPRS(4, 12, r1)
 	b	.Lsyscall_restore_regs_cont
 .Lsyscall_rst_end: