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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: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/a775a1fea60f190e0f63503463fb775310a2009b.1576916812.git.christophe.leroy@c-s.fr
This commit is contained in:
Christophe Leroy 2019-12-21 08:32:27 +00:00 committed by Michael Ellerman
parent c9c84fd945
commit 028474876f
5 changed files with 133 additions and 16 deletions
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6
arch/powerpc/include/asm/processor.h
View File

@ -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;

5
arch/powerpc/include/asm/thread_info.h
View File

@ -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)

6
arch/powerpc/kernel/asm-offsets.c
View File

@ -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);

4
arch/powerpc/kernel/entry_32.S
View File

@ -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)

128
arch/powerpc/kernel/head_32.h
View File

@ -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 */
stw r9, _LINK(r11)
#ifdef CONFIG_VMAP_STACK
lwz r10, SRR0(r12)
lwz r9, SRR1(r12)
#else
mfspr r10,SPRN_SRR0
stw r9,_LINK(r11)
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
/*