To support CONFIG_VMAP_STACK, the kernel must be able to activate
Data MMU Translation for accessing the stack. Before doing that
it must save SRR0, SRR1 and DAR in order to not loose them in
case there is a Data TLB Miss once the translation is reactivated.
This patch defines fields in the thread struct for saving those
registers. It also prepares entry_32.S to handle exception entry
with Data MMU Translation enabled.
Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr>
---
arch/powerpc/include/asm/processor.h | 5 +++++
arch/powerpc/include/asm/thread_info.h | 5 +++++
arch/powerpc/kernel/asm-offsets.c | 5 +++++
arch/powerpc/kernel/entry_32.S | 16 ++++++++++++++++
4 files changed, 31 insertions(+)
diff --git a/arch/powerpc/include/asm/processor.h
b/arch/powerpc/include/asm/processor.h
index 8179b64871ed..e839a1231b17 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -218,6 +218,11 @@ struct thread_struct {
#ifdef CONFIG_PPC32
void *pgdir; /* root of page-table tree */
unsigned long ksp_limit; /* if ksp <= ksp_limit stack overflow */
+#ifdef CONFIG_VMAP_STACK
+ unsigned long dar;
+ unsigned long srr0;
+ unsigned long srr1;
+#endif
#endif
/* Debug Registers */
struct debug_reg debug;
diff --git a/arch/powerpc/include/asm/thread_info.h
b/arch/powerpc/include/asm/thread_info.h
index 8e1d0195ac36..488d5c4670ff 100644
--- a/arch/powerpc/include/asm/thread_info.h
+++ b/arch/powerpc/include/asm/thread_info.h
@@ -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)
diff --git a/arch/powerpc/kernel/asm-offsets.c
b/arch/powerpc/kernel/asm-offsets.c
index 03439785c2ea..985523ef23e8 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -128,6 +128,11 @@ 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);
+#endif
#ifdef CONFIG_SPE
OFFSET(THREAD_EVR0, thread_struct, evr[0]);
OFFSET(THREAD_ACC, thread_struct, acc);
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 52a061f14c7d..6e2c45fdd2c0 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -150,8 +150,13 @@ transfer_to_handler:
stw r12,_CTR(r11)
stw r2,_XER(r11)
mfspr r12,SPRN_SPRG_THREAD
+#ifdef CONFIG_VMAP_STACK
+ tovirt(r12, r12)
+#endif
addi r2,r12,-THREAD
+#ifndef CONFIG_VMAP_STACK
tovirt(r2,r2) /* set r2 to current */
+#endif
beq 2f /* if from user, fix up THREAD.regs */
addi r11,r1,STACK_FRAME_OVERHEAD
stw r11,PT_REGS(r12)
@@ -179,9 +184,13 @@ transfer_to_handler:
stw r12,4(r11)
#endif
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
+#ifdef CONFIG_VMAP_STACK
+ ACCOUNT_CPU_USER_ENTRY(r2, r11, r12)
+#else
tophys(r9, r2)
ACCOUNT_CPU_USER_ENTRY(r9, r11, r12)
#endif
+#endif
b 3f
@@ -193,8 +202,12 @@ transfer_to_handler:
ble- stack_ovf /* then the kernel stack overflowed */
5:
#if defined(CONFIG_PPC_BOOK3S_32) || defined(CONFIG_E500)
+#ifdef CONFIG_VMAP_STACK
+ lwz r12, TI_LOCAL_FLAGS(r2)
+#else
tophys(r9,r2) /* check local flags */
lwz r12,TI_LOCAL_FLAGS(r9)
+#endif
mtcrf 0x01,r12
bt- 31-TLF_NAPPING,4f
bt- 31-TLF_SLEEPING,7f
@@ -203,6 +216,9 @@ transfer_to_handler:
transfer_to_handler_cont:
3:
mflr r9
+#ifdef CONFIG_VMAP_STACK
+ tovirt(r9,r9)
+#endif
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)
--
2.13.3
