Commit 02847487 authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

powerpc/32: prepare for CONFIG_VMAP_STACK 



To support CONFIG_VMAP_STACK, the kernel has to activate Data MMU
Translation for accessing the stack. Before doing that it must save
SRR0, SRR1 and also DAR and DSISR when relevant, in order to not
loose them in case there is a Data TLB Miss once the translation is
reactivated.

This patch adds fields in thread struct for saving those registers.
It prepares entry_32.S to handle exception entry with
Data MMU Translation enabled and alters EXCEPTION_PROLOG macros to
save SRR0, SRR1, DAR and DSISR then reenables Data MMU.

Signed-off-by: default avatarChristophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/a775a1fea60f190e0f63503463fb775310a2009b.1576916812.git.christophe.leroy@c-s.fr
parent c9c84fd9

arch/powerpc/include/asm/processor.h

+6 −0
Original line number Diff line number Diff line
@@ -162,6 +162,12 @@ struct thread_struct { 
#endif

#if defined(CONFIG_PPC_BOOK3S_32) && defined(CONFIG_PPC_KUAP)

	unsigned long	kuap;		/* opened segments for user access */

#endif

#ifdef CONFIG_VMAP_STACK

	unsigned long	srr0;

	unsigned long	srr1;

	unsigned long	dar;

	unsigned long	dsisr;

#endif

	/* Debug Registers */

	struct debug_reg debug;

arch/powerpc/include/asm/thread_info.h

+5 −0
Original line number Diff line number Diff line
@@ -10,10 +10,15 @@ 
#define _ASM_POWERPC_THREAD_INFO_H



#include <asm/asm-const.h>

#include <asm/page.h>



#ifdef __KERNEL__



#if defined(CONFIG_VMAP_STACK) && CONFIG_THREAD_SHIFT < PAGE_SHIFT

#define THREAD_SHIFT		PAGE_SHIFT

#else

#define THREAD_SHIFT		CONFIG_THREAD_SHIFT

#endif



#define THREAD_SIZE		(1 << THREAD_SHIFT)

arch/powerpc/kernel/asm-offsets.c

+6 −0
Original line number Diff line number Diff line
@@ -127,6 +127,12 @@ int main(void) 
	OFFSET(KSP_VSID, thread_struct, ksp_vsid);

#else /* CONFIG_PPC64 */

	OFFSET(PGDIR, thread_struct, pgdir);

#ifdef CONFIG_VMAP_STACK

	OFFSET(SRR0, thread_struct, srr0);

	OFFSET(SRR1, thread_struct, srr1);

	OFFSET(DAR, thread_struct, dar);

	OFFSET(DSISR, thread_struct, dsisr);

#endif

#ifdef CONFIG_SPE

	OFFSET(THREAD_EVR0, thread_struct, evr[0]);

	OFFSET(THREAD_ACC, thread_struct, acc);

arch/powerpc/kernel/entry_32.S

+3 −1
Original line number Diff line number Diff line
@@ -140,6 +140,7 @@ transfer_to_handler: 
	stw	r12,_CTR(r11)

	stw	r2,_XER(r11)

	mfspr	r12,SPRN_SPRG_THREAD

	tovirt_vmstack r12, r12

	beq	2f			/* if from user, fix up THREAD.regs */

	addi	r2, r12, -THREAD

	addi	r11,r1,STACK_FRAME_OVERHEAD
@@ -195,7 +196,8 @@ transfer_to_handler: 
transfer_to_handler_cont:

3:

	mflr	r9

	tovirt(r2, r2)			/* set r2 to current */

	tovirt_novmstack r2, r2 	/* set r2 to current */

	tovirt_vmstack r9, r9

	lwz	r11,0(r9)		/* virtual address of handler */

	lwz	r9,4(r9)		/* where to go when done */

#if defined(CONFIG_PPC_8xx) && defined(CONFIG_PERF_EVENTS)

arch/powerpc/kernel/head_32.h

+113 −15
Original line number Diff line number Diff line
@@ -10,31 +10,54 @@ 
 * We assume sprg3 has the physical address of the current

 * task's thread_struct.

 */

.macro EXCEPTION_PROLOG

	EXCEPTION_PROLOG_0

.macro EXCEPTION_PROLOG handle_dar_dsisr=0

	EXCEPTION_PROLOG_0	handle_dar_dsisr=\handle_dar_dsisr

	EXCEPTION_PROLOG_1

	EXCEPTION_PROLOG_2

	EXCEPTION_PROLOG_2	handle_dar_dsisr=\handle_dar_dsisr

.endm



.macro EXCEPTION_PROLOG_0

.macro EXCEPTION_PROLOG_0 handle_dar_dsisr=0

	mtspr	SPRN_SPRG_SCRATCH0,r10

	mtspr	SPRN_SPRG_SCRATCH1,r11

#ifdef CONFIG_VMAP_STACK

	mfspr	r10, SPRN_SPRG_THREAD

	.if	\handle_dar_dsisr

	mfspr	r11, SPRN_DAR

	stw	r11, DAR(r10)

	mfspr	r11, SPRN_DSISR

	stw	r11, DSISR(r10)

	.endif

	mfspr	r11, SPRN_SRR0

	stw	r11, SRR0(r10)

#endif

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

#ifdef CONFIG_VMAP_STACK

	stw	r11, SRR1(r10)

#endif

	mfcr	r10

	andi.	r11, r11, MSR_PR

.endm



.macro EXCEPTION_PROLOG_1

#ifdef CONFIG_VMAP_STACK

	li	r11, MSR_KERNEL & ~(MSR_IR | MSR_RI) /* can take DTLB miss */

	mtmsr	r11

	isync

	subi	r11, r1, INT_FRAME_SIZE		/* use r1 if kernel */

#else

	tophys(r11,r1)			/* use tophys(r1) if kernel */

	subi	r11, r11, INT_FRAME_SIZE	/* alloc exc. frame */

#endif

	beq	1f

	mfspr	r11,SPRN_SPRG_THREAD

	tovirt_vmstack r11, r11

	lwz	r11,TASK_STACK-THREAD(r11)

	addi	r11,r11,THREAD_SIZE

	tophys(r11,r11)

1:	subi	r11,r11,INT_FRAME_SIZE	/* alloc exc. frame */

	addi	r11, r11, THREAD_SIZE - INT_FRAME_SIZE

	tophys_novmstack r11, r11

1:

.endm



.macro EXCEPTION_PROLOG_2

.macro EXCEPTION_PROLOG_2 handle_dar_dsisr=0

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

	stw	r12,GPR12(r11)

	stw	r9,GPR9(r11)
@@ -44,15 +67,32 @@ 
	stw	r12,GPR11(r11)

	mflr	r10

	stw	r10,_LINK(r11)

#ifdef CONFIG_VMAP_STACK

	mfspr	r12, SPRN_SPRG_THREAD

	tovirt(r12, r12)

	.if	\handle_dar_dsisr

	lwz	r10, DAR(r12)

	stw	r10, _DAR(r11)

	lwz	r10, DSISR(r12)

	stw	r10, _DSISR(r11)

	.endif

	lwz	r9, SRR1(r12)

	lwz	r12, SRR0(r12)

#else

	mfspr	r12,SPRN_SRR0

	mfspr	r9,SPRN_SRR1

#endif

	stw	r1,GPR1(r11)

	stw	r1,0(r11)

	tovirt(r1,r11)			/* set new kernel sp */

	tovirt_novmstack r1, r11	/* set new kernel sp */

#ifdef CONFIG_40x

	rlwinm	r9,r9,0,14,12		/* clear MSR_WE (necessary?) */

#else

#ifdef CONFIG_VMAP_STACK

	li	r10, MSR_KERNEL & ~MSR_IR /* can take exceptions */

#else

	li	r10,MSR_KERNEL & ~(MSR_IR|MSR_DR) /* can take exceptions */

#endif

	mtmsr	r10			/* (except for mach check in rtas) */

#endif

	stw	r0,GPR0(r11)
@@ -65,24 +105,45 @@ 


.macro SYSCALL_ENTRY trapno

	mfspr	r12,SPRN_SPRG_THREAD

#ifdef CONFIG_VMAP_STACK

	mfspr	r9, SPRN_SRR0

	mfspr	r11, SPRN_SRR1

	stw	r9, SRR0(r12)

	stw	r11, SRR1(r12)

#endif

	mfcr	r10

	lwz	r11,TASK_STACK-THREAD(r12)

	mflr	r9

	addi	r11,r11,THREAD_SIZE - INT_FRAME_SIZE

	rlwinm	r10,r10,0,4,2	/* Clear SO bit in CR */

	tophys(r11,r11)

	addi	r11, r11, THREAD_SIZE - INT_FRAME_SIZE

#ifdef CONFIG_VMAP_STACK

	li	r9, MSR_KERNEL & ~(MSR_IR | MSR_RI) /* can take DTLB miss */

	mtmsr	r9

	isync

#endif

	tovirt_vmstack r12, r12

	tophys_novmstack r11, r11

	mflr	r9

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

	mfspr	r10,SPRN_SRR0

	stw	r9, _LINK(r11)

#ifdef CONFIG_VMAP_STACK

	lwz	r10, SRR0(r12)

	lwz	r9, SRR1(r12)

#else

	mfspr	r10,SPRN_SRR0

	mfspr	r9,SPRN_SRR1

#endif

	stw	r1,GPR1(r11)

	stw	r1,0(r11)

	tovirt(r1,r11)			/* set new kernel sp */

	tovirt_novmstack r1, r11	/* set new kernel sp */

	stw	r10,_NIP(r11)

#ifdef CONFIG_40x

	rlwinm	r9,r9,0,14,12		/* clear MSR_WE (necessary?) */

#else

#ifdef CONFIG_VMAP_STACK

	LOAD_REG_IMMEDIATE(r10, MSR_KERNEL & ~MSR_IR) /* can take exceptions */

#else

	LOAD_REG_IMMEDIATE(r10, MSR_KERNEL & ~(MSR_IR|MSR_DR)) /* can take exceptions */

#endif

	mtmsr	r10			/* (except for mach check in rtas) */

#endif

	lis	r10,STACK_FRAME_REGS_MARKER@ha /* exception frame marker */
@@ -121,7 +182,7 @@ 
#endif



3:

	tovirt(r2, r2)			/* set r2 to current */

	tovirt_novmstack r2, r2 	/* set r2 to current */

	lis	r11, transfer_to_syscall@h

	ori	r11, r11, transfer_to_syscall@l

#ifdef CONFIG_TRACE_IRQFLAGS
@@ -145,14 +206,51 @@ 
.endm



.macro save_dar_dsisr_on_stack reg1, reg2, sp

#ifndef CONFIG_VMAP_STACK

	mfspr	\reg1, SPRN_DAR

	mfspr	\reg2, SPRN_DSISR

	stw	\reg1, _DAR(\sp)

	stw	\reg2, _DSISR(\sp)

#endif

.endm



.macro get_and_save_dar_dsisr_on_stack reg1, reg2, sp

#ifdef CONFIG_VMAP_STACK

	lwz	\reg1, _DAR(\sp)

	lwz	\reg2, _DSISR(\sp)

#else

	save_dar_dsisr_on_stack \reg1, \reg2, \sp

#endif

.endm



.macro tovirt_vmstack dst, src

#ifdef CONFIG_VMAP_STACK

	tovirt(\dst, \src)

#else

	.ifnc	\dst, \src

	mr	\dst, \src

	.endif

#endif

.endm



.macro tovirt_novmstack dst, src

#ifndef CONFIG_VMAP_STACK

	tovirt(\dst, \src)

#else

	.ifnc	\dst, \src

	mr	\dst, \src

	.endif

#endif

.endm



.macro tophys_novmstack dst, src

#ifndef CONFIG_VMAP_STACK

	tophys(\dst, \src)

#else

	.ifnc	\dst, \src

	mr	\dst, \src

	.endif

#endif

.endm



/*

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