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powerpc/64: use 32-bit immediate for STACK_FRAME_REGS_MARKER

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Using a 32-bit constant for this marker allows it to be loaded with
two ALU instructions, like 32-bit. This avoids a TOC entry and a
TOC load that depends on the r2 value that has just been loaded from
the PACA.

This changes the value for 32-bit as well, so both have the same
value in the low 4 bytes and 64-bit has 0 in the top bytes.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220926034057.2360083-2-npiggin@gmail.com
This commit is contained in:
Nicholas Piggin 2022-09-26 13:40:53 +10:00 committed by Michael Ellerman
parent 4b2a9315f2
commit 17773afdcd
6 changed files with 10 additions and 23 deletions
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4
arch/powerpc/include/asm/ptrace.h
View File

@ -99,6 +99,8 @@ struct pt_regs
#define STACK_FRAME_WITH_PT_REGS (STACK_FRAME_OVERHEAD + sizeof(struct pt_regs))
#define STACK_FRAME_REGS_MARKER ASM_CONST(0x72656773)
#ifdef __powerpc64__
/*
@ -115,7 +117,6 @@ struct pt_regs
#define STACK_FRAME_OVERHEAD 112 /* size of minimum stack frame */
#define STACK_FRAME_LR_SAVE 2 /* Location of LR in stack frame */
#define STACK_FRAME_REGS_MARKER ASM_CONST(0x7265677368657265)
#define STACK_INT_FRAME_SIZE (sizeof(struct pt_regs) + \
STACK_FRAME_OVERHEAD + KERNEL_REDZONE_SIZE)
#define STACK_FRAME_MARKER 12
@ -136,7 +137,6 @@ struct pt_regs
#define KERNEL_REDZONE_SIZE 0
#define STACK_FRAME_OVERHEAD 16 /* size of minimum stack frame */
#define STACK_FRAME_LR_SAVE 1 /* Location of LR in stack frame */
#define STACK_FRAME_REGS_MARKER ASM_CONST(0x72656773)
#define STACK_INT_FRAME_SIZE (sizeof(struct pt_regs) + STACK_FRAME_OVERHEAD)
#define STACK_FRAME_MARKER 2
#define STACK_FRAME_MIN_SIZE STACK_FRAME_OVERHEAD

6
arch/powerpc/kernel/entry_32.S
View File

@ -263,7 +263,7 @@ fast_exception_return:
mtcr r10
lwz r10,_LINK(r11)
mtlr r10
/* Clear the exception_marker on the stack to avoid confusing stacktrace */
/* Clear the exception marker on the stack to avoid confusing stacktrace */
li r10, 0
stw r10, 8(r11)
REST_GPR(10, r11)
@ -320,7 +320,7 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
li r0,0
/*
* Leaving a stale exception_marker on the stack can confuse
* Leaving a stale exception marker on the stack can confuse
* the reliable stack unwinder later on. Clear it.
*/
stw r0,8(r1)
@ -372,7 +372,7 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
mtspr SPRN_XER,r5
/*
* Leaving a stale exception_marker on the stack can confuse
* Leaving a stale exception marker on the stack can confuse
* the reliable stack unwinder later on. Clear it.
*/
stw r0,8(r1)

8
arch/powerpc/kernel/exceptions-64e.S
View File

@ -378,7 +378,7 @@ exc_##n##_common: \
ld r9,excf+EX_R1(r13); /* load orig r1 back from PACA */ \
lwz r10,excf+EX_CR(r13); /* load orig CR back from PACA */ \
lbz r11,PACAIRQSOFTMASK(r13); /* get current IRQ softe */ \
ld r12,exception_marker@toc(r2); \
LOAD_REG_IMMEDIATE(r12, STACK_FRAME_REGS_MARKER); \
ZEROIZE_GPR(0); \
std r3,GPR10(r1); /* save r10 to stackframe */ \
std r4,GPR11(r1); /* save r11 to stackframe */ \
@ -459,12 +459,6 @@ exc_##n##_bad_stack: \
bl hdlr; \
b interrupt_return
/* This value is used to mark exception frames on the stack. */
.section ".toc","aw"
exception_marker:
.tc ID_EXC_MARKER[TC],STACK_FRAME_REGS_MARKER
/*
* And here we have the exception vectors !
*/

2
arch/powerpc/kernel/exceptions-64s.S
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@ -589,7 +589,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_CFAR)
li r9,IVEC
std r9,_TRAP(r1) /* set trap number */
li r10,0
ld r11,exception_marker@toc(r2)
LOAD_REG_IMMEDIATE(r11, STACK_FRAME_REGS_MARKER)
std r10,RESULT(r1) /* clear regs->result */
std r11,STACK_FRAME_OVERHEAD-16(r1) /* mark the frame */
.endm

7
arch/powerpc/kernel/head_64.S
View File

@ -192,13 +192,6 @@ __secondary_hold:
#endif
CLOSE_FIXED_SECTION(first_256B)
/* This value is used to mark exception frames on the stack. */
.section ".toc","aw"
/* This value is used to mark exception frames on the stack. */
exception_marker:
.tc ID_EXC_MARKER[TC],STACK_FRAME_REGS_MARKER
.previous
/*
* On server, we include the exception vectors code here as it
* relies on absolute addressing which is only possible within

6
arch/powerpc/kernel/interrupt_64.S
View File

@ -80,7 +80,7 @@ _ASM_NOKPROBE_SYMBOL(system_call_vectored_\name)
/* Calling convention has r3 = regs, r4 = orig r0 */
addi r3,r1,STACK_FRAME_OVERHEAD
mr r4,r0
ld r11,exception_marker@toc(r2)
LOAD_REG_IMMEDIATE(r11, STACK_FRAME_REGS_MARKER)
std r11,-16(r3) /* "regshere" marker */
BEGIN_FTR_SECTION
@ -253,7 +253,7 @@ END_BTB_FLUSH_SECTION
/* Calling convention has r3 = regs, r4 = orig r0 */
addi r3,r1,STACK_FRAME_OVERHEAD
mr r4,r0
ld r11,exception_marker@toc(r2)
LOAD_REG_IMMEDIATE(r11, STACK_FRAME_REGS_MARKER)
std r11,-16(r3) /* "regshere" marker */
#ifdef CONFIG_PPC_BOOK3S
@ -614,7 +614,7 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
mtspr SPRN_XER,r5
/*
* Leaving a stale exception_marker on the stack can confuse
* Leaving a stale STACK_FRAME_REGS_MARKER on the stack can confuse
* the reliable stack unwinder later on. Clear it.
*/
std r0,STACK_FRAME_OVERHEAD-16(r1)