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

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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>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220921065605.1051927-5-rmclure@linux.ibm.com
This commit is contained in:
Rohan McLure
2022-09-21 16:55:44 +10:00
committed by Michael Ellerman
parent 9d54a5ce3a
commit 2b1dac4b5f
1 changed files with 9 additions and 34 deletions
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arch/powerpc/kernel/interrupt_64.S
+9 -34
View File
@@ -61,12 +61,7 @@ _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)
@@ -139,17 +134,10 @@ 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
/*
@@ -172,7 +160,7 @@ 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
@@ -240,12 +228,7 @@ 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)
@@ -335,16 +318,8 @@ 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:
@@ -370,7 +345,7 @@ 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: