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Commit ed9e84a4 authored by Joel Stanley's avatar Joel Stanley Committed by Michael Ellerman
Browse files

powerpc: Use SWITCH_FRAME_SIZE for prom and rtas entry 

Commit 6c171994 ("powerpc/of: Remove useless register save/restore
when calling OF back") removed the saving of srr0 and srr1 when calling
into OpenFirmware. Commit e31aa453 ("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: default avatarJoel Stanley <joel@jms.id.au>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 65b9fdad

arch/powerpc/kernel/asm-offsets.c

+0 −9
Original line number Diff line number Diff line
@@ -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)

arch/powerpc/kernel/entry_64.S

+5 −5
Original line number Diff line number Diff line
@@ -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
@@ -1325,7 +1325,7 @@ _GLOBAL(enter_prom) 
	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