Commit 0fc1e934 authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

powerpc/40x: Prepare for enabling MMU in critical exception prolog 



In order the enable MMU early in exception prolog, implement
CONFIG_VMAP_STACK principles in critical exception prolog.

There is no intention to use CONFIG_VMAP_STACK on 40x,
but related code will be used to enable MMU early in exception
in a later patch.

Also address (critirq_ctx - PAGE_OFFSET) directly instead of
using tophys() in order to win one instruction.

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/3fd75ee54c48307119acdbf66cfea966c1463bbd.1615552866.git.christophe.leroy@csgroup.eu
parent 26c46886

arch/powerpc/kernel/head_40x.S

+37 −3
Original line number Diff line number Diff line
@@ -89,6 +89,12 @@ _ENTRY(crit_srr0) 
	.space	4

_ENTRY(crit_srr1)

	.space	4

_ENTRY(crit_r1)

	.space	4

_ENTRY(crit_dear)

	.space	4

_ENTRY(crit_esr)

	.space	4

_ENTRY(saved_ksp_limit)

	.space	4
@@ -107,32 +113,60 @@ _ENTRY(saved_ksp_limit) 
	mfspr	r11,SPRN_SRR1

	stw	r10,crit_srr0@l(0)

	stw	r11,crit_srr1@l(0)

#ifdef CONFIG_VMAP_STACK

	mfspr	r10,SPRN_DEAR

	mfspr	r11,SPRN_ESR

	stw	r10,crit_dear@l(0)

	stw	r11,crit_esr@l(0)

#endif

	mfcr	r10			/* save CR in r10 for now	   */

	mfspr	r11,SPRN_SRR3		/* check whether user or kernel    */

	andi.	r11,r11,MSR_PR

	lis	r11,critirq_ctx@ha

	tophys(r11,r11)

	lwz	r11,critirq_ctx@l(r11)

	lis	r11,(critirq_ctx-PAGE_OFFSET)@ha

	lwz	r11,(critirq_ctx-PAGE_OFFSET)@l(r11)

	beq	1f

	/* COMING FROM USER MODE */

	mfspr	r11,SPRN_SPRG_THREAD	/* if from user, start at top of   */

	lwz	r11,TASK_STACK-THREAD(r11) /* this thread's kernel stack */

#ifdef CONFIG_VMAP_STACK

1:	stw	r1,crit_r1@l(0)

	addi	r1,r11,THREAD_SIZE-INT_FRAME_SIZE /* Alloc an excpt frm  */

	LOAD_REG_IMMEDIATE(r11,MSR_KERNEL & ~(MSR_IR | MSR_RI))

	mtmsr	r11

	isync

	lwz	r11,crit_r1@l(0)

	stw	r11,GPR1(r1)

	stw	r11,0(r1)

	mr	r11,r1

#else

1:	addi	r11,r11,THREAD_SIZE-INT_FRAME_SIZE /* Alloc an excpt frm  */

	tophys(r11,r11)

	stw	r1,GPR1(r11)

	stw	r1,0(r11)

	tovirt(r1,r11)

#endif

	stw	r10,_CCR(r11)		/* save various registers	   */

	stw	r12,GPR12(r11)

	stw	r9,GPR9(r11)

	mflr	r10

	stw	r10,_LINK(r11)

#ifdef CONFIG_VMAP_STACK

	lis	r9,PAGE_OFFSET@ha

	lwz	r10,crit_r10@l(r9)

	lwz	r12,crit_r11@l(r9)

#else

	lwz	r10,crit_r10@l(0)

	lwz	r12,crit_r11@l(0)

#endif

	stw	r10,GPR10(r11)

	stw	r12,GPR11(r11)

#ifdef CONFIG_VMAP_STACK

	lwz	r12,crit_dear@l(r9)

	lwz	r9,crit_esr@l(r9)

#else

	mfspr	r12,SPRN_DEAR		/* save DEAR and ESR in the frame  */

	mfspr	r9,SPRN_ESR		/* in them at the point where the  */

#endif

	stw	r12,_DEAR(r11)		/* since they may have had stuff   */

	stw	r9,_ESR(r11)		/* exception was taken		   */

	mfspr	r12,SPRN_SRR2