Commit de1cd079 authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

powerpc/32s: Use SPRN_SPRG_SCRATCH2 in DSI prolog 



Use SPRN_SPRG_SCRATCH2 as an alternative scratch register in
the early part of DSI prolog in order to avoid clobbering
SPRN_SPRG_SCRATCH0/1 used by other prologs.

The 603 doesn't like a jump from DataLoadTLBMiss to the 10 nops
that are now in the beginning of DSI exception as a result of
the feature section. To workaround this, add a jump as alternative.
It also avoids fetching 10 nops for nothing.

Signed-off-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/f9f8df2a2be93568768ef1ac793639f7914cf103.1606285014.git.christophe.leroy@csgroup.eu
parent 6285f9cf

arch/powerpc/include/asm/reg.h

+1 −0
Original line number Diff line number Diff line
@@ -1204,6 +1204,7 @@ 
#ifdef CONFIG_PPC_BOOK3S_32

#define SPRN_SPRG_SCRATCH0	SPRN_SPRG0

#define SPRN_SPRG_SCRATCH1	SPRN_SPRG1

#define SPRN_SPRG_SCRATCH2	SPRN_SPRG2

#define SPRN_SPRG_603_LRU	SPRN_SPRG4

#endif

arch/powerpc/kernel/head_book3s_32.S

+8 −16
Original line number Diff line number Diff line
@@ -288,9 +288,9 @@ MachineCheck: 
	DO_KVM  0x300

DataAccess:

#ifdef CONFIG_VMAP_STACK

	mtspr	SPRN_SPRG_SCRATCH0,r10

	mfspr	r10, SPRN_SPRG_THREAD

BEGIN_MMU_FTR_SECTION

	mtspr	SPRN_SPRG_SCRATCH2,r10

	mfspr	r10, SPRN_SPRG_THREAD

	stw	r11, THR11(r10)

	mfspr	r10, SPRN_DSISR

	mfcr	r11
@@ -304,19 +304,11 @@ BEGIN_MMU_FTR_SECTION 
.Lhash_page_dsi_cont:

	mtcr	r11

	lwz	r11, THR11(r10)

END_MMU_FTR_SECTION_IFSET(MMU_FTR_HPTE_TABLE)

	mtspr	SPRN_SPRG_SCRATCH1,r11

	mfspr	r11, SPRN_DAR

	stw	r11, DAR(r10)

	mfspr	r11, SPRN_DSISR

	stw	r11, DSISR(r10)

	mfspr	r11, SPRN_SRR0

	stw	r11, SRR0(r10)

	mfspr	r11, SPRN_SRR1		/* check whether user or kernel */

	stw	r11, SRR1(r10)

	mfcr	r10

	andi.	r11, r11, MSR_PR



	mfspr	r10, SPRN_SPRG_SCRATCH2

MMU_FTR_SECTION_ELSE

	b	1f

ALT_MMU_FTR_SECTION_END_IFSET(MMU_FTR_HPTE_TABLE)

1:	EXCEPTION_PROLOG_0 handle_dar_dsisr=1

	EXCEPTION_PROLOG_1

	b	handle_page_fault_tramp_1

#else	/* CONFIG_VMAP_STACK */
@@ -764,7 +756,7 @@ fast_hash_page_return: 
	/* DSI */

	mtcr	r11

	lwz	r11, THR11(r10)

	mfspr	r10, SPRN_SPRG_SCRATCH0

	mfspr	r10, SPRN_SPRG_SCRATCH2

	rfi



1:	/* ISI */