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powerpc: Use SWITCH_FRAME_SIZE for prom and rtas entry 

Commit 6c1719942e ("powerpc/of: Remove useless register save/restore
when calling OF back") removed the saving of srr0 and srr1 when calling
into OpenFirmware. Commit e31aa453bb ("powerpc: Use LOAD_REG_IMMEDIATE
only for constants on 64-bit") did the same for rtas.

This means we don't need to save the extra stack space and can use
the common SWITCH_FRAME_SIZE.

There were already no users of _SRR0 and _SRR1 so we can remove them
too.

Link: https://github.com/linuxppc/linux/issues/83
Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Joel Stanley 2018-10-12 13:14:06 +10:30 committed by Michael Ellerman
parent 65b9fdadfc
commit ed9e84a4d7
2 changed files with 5 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
arch/powerpc/kernel/asm-offsets.c
View File

@ -280,11 +280,6 @@ int main(void)
/* Interrupt register frame */
DEFINE(INT_FRAME_SIZE, STACK_INT_FRAME_SIZE);
DEFINE(SWITCH_FRAME_SIZE, STACK_FRAME_OVERHEAD + sizeof(struct pt_regs));
#ifdef CONFIG_PPC64
/* Create extra stack space for SRR0 and SRR1 when calling prom/rtas. */
DEFINE(PROM_FRAME_SIZE, STACK_FRAME_OVERHEAD + sizeof(struct pt_regs) + 16);
DEFINE(RTAS_FRAME_SIZE, STACK_FRAME_OVERHEAD + sizeof(struct pt_regs) + 16);
#endif /* CONFIG_PPC64 */
STACK_PT_REGS_OFFSET(GPR0, gpr[0]);
STACK_PT_REGS_OFFSET(GPR1, gpr[1]);
STACK_PT_REGS_OFFSET(GPR2, gpr[2]);
@ -328,10 +323,6 @@ int main(void)
STACK_PT_REGS_OFFSET(_ESR, dsisr);
#else /* CONFIG_PPC64 */
STACK_PT_REGS_OFFSET(SOFTE, softe);
/* These _only_ to be used with {PROM,RTAS}_FRAME_SIZE!!! */
DEFINE(_SRR0, STACK_FRAME_OVERHEAD+sizeof(struct pt_regs));
DEFINE(_SRR1, STACK_FRAME_OVERHEAD+sizeof(struct pt_regs)+8);
#endif /* CONFIG_PPC64 */
#if defined(CONFIG_PPC32)

10
arch/powerpc/kernel/entry_64.S
View File

@ -1124,7 +1124,7 @@ _ASM_NOKPROBE_SYMBOL(fast_exception_return);
_GLOBAL(enter_rtas)
mflr r0
std r0,16(r1)
stdu r1,-RTAS_FRAME_SIZE(r1) /* Save SP and create stack space. */
stdu r1,-SWITCH_FRAME_SIZE(r1) /* Save SP and create stack space. */
/* Because RTAS is running in 32b mode, it clobbers the high order half
* of all registers that it saves. We therefore save those registers
@ -1256,7 +1256,7 @@ rtas_restore_regs:
ld r8,_DSISR(r1)
mtdsisr r8
addi r1,r1,RTAS_FRAME_SIZE /* Unstack our frame */
addi r1,r1,SWITCH_FRAME_SIZE /* Unstack our frame */
ld r0,16(r1) /* get return address */
mtlr r0
@ -1267,7 +1267,7 @@ rtas_restore_regs:
_GLOBAL(enter_prom)
mflr r0
std r0,16(r1)
stdu r1,-PROM_FRAME_SIZE(r1) /* Save SP and create stack space */
stdu r1,-SWITCH_FRAME_SIZE(r1) /* Save SP and create stack space */
/* Because PROM is running in 32b mode, it clobbers the high order half
* of all registers that it saves. We therefore save those registers
@ -1324,8 +1324,8 @@ _GLOBAL(enter_prom)
REST_10GPRS(22, r1)
ld r4,_CCR(r1)
mtcr r4
addi r1,r1,PROM_FRAME_SIZE
addi r1,r1,SWITCH_FRAME_SIZE
ld r0,16(r1)
mtlr r0
blr