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Subject[RFC PATCH v1 07/41] powerpc/40x: Prepare normal exception handler for enabling MMU early
Date
Ensure normal exception handler are able to manage stuff with
MMU enabled. For that we use CONFIG_VMAP_STACK related code
allthough there is no intention to really activate CONFIG_VMAP_STACK
on powerpc 40x for the moment.

40x uses SPRN_DEAR instead of SPRN_DAR and SPRN_ESR instead of
SPRN_DSISR. Take it into account in common macros.

40x MSR value doesn't fit on 15 bits, use LOAD_REG_IMMEDIATE() in
common macros that will be used also with 40x.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
arch/powerpc/kernel/entry_32.S | 2 +-
arch/powerpc/kernel/head_32.h | 15 ++++++++++++++-
arch/powerpc/kernel/head_40x.S | 17 ++++++-----------
3 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 1e59d0bb1a6f..9312634085ba 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -162,7 +162,7 @@ transfer_to_handler:
li r12,-1 /* clear all pending debug events */
mtspr SPRN_DBSR,r12
lis r11,global_dbcr0@ha
- tophys(r11,r11)
+ tophys_novmstack r11,r11
addi r11,r11,global_dbcr0@l
#ifdef CONFIG_SMP
lwz r9,TASK_CPU(r2)
diff --git a/arch/powerpc/kernel/head_32.h b/arch/powerpc/kernel/head_32.h
index 5d4706c14572..ac6b391f1493 100644
--- a/arch/powerpc/kernel/head_32.h
+++ b/arch/powerpc/kernel/head_32.h
@@ -22,9 +22,17 @@
#ifdef CONFIG_VMAP_STACK
mfspr r10, SPRN_SPRG_THREAD
.if \handle_dar_dsisr
+#ifdef CONFIG_40x
+ mfspr r11, SPRN_DEAR
+#else
mfspr r11, SPRN_DAR
+#endif
stw r11, DAR(r10)
+#ifdef CONFIG_40x
+ mfspr r11, SPRN_ESR
+#else
mfspr r11, SPRN_DSISR
+#endif
stw r11, DSISR(r10)
.endif
mfspr r11, SPRN_SRR0
@@ -61,7 +69,7 @@

.macro EXCEPTION_PROLOG_2 handle_dar_dsisr=0
#ifdef CONFIG_VMAP_STACK
- li r11, MSR_KERNEL & ~(MSR_IR | MSR_RI) /* can take DTLB miss */
+ LOAD_REG_IMMEDIATE(r11, MSR_KERNEL & ~(MSR_IR | MSR_RI)) /* can take DTLB miss */
mtmsr r11
isync
mfspr r11, SPRN_SPRG_SCRATCH2
@@ -158,8 +166,13 @@

.macro save_dar_dsisr_on_stack reg1, reg2, sp
#ifndef CONFIG_VMAP_STACK
+#ifdef CONFIG_40x
+ mfspr \reg1, SPRN_DEAR
+ mfspr \reg2, SPRN_ESR
+#else
mfspr \reg1, SPRN_DAR
mfspr \reg2, SPRN_DSISR
+#endif
stw \reg1, _DAR(\sp)
stw \reg2, _DSISR(\sp)
#endif
diff --git a/arch/powerpc/kernel/head_40x.S b/arch/powerpc/kernel/head_40x.S
index 1468f38c3860..4bf0aee858eb 100644
--- a/arch/powerpc/kernel/head_40x.S
+++ b/arch/powerpc/kernel/head_40x.S
@@ -221,11 +221,8 @@ _ENTRY(saved_ksp_limit)
* if they can't resolve the lightweight TLB fault.
*/
START_EXCEPTION(0x0300, DataStorage)
- EXCEPTION_PROLOG
- mfspr r5, SPRN_ESR /* Grab the ESR, save it */
- stw r5, _ESR(r11)
- mfspr r4, SPRN_DEAR /* Grab the DEAR, save it */
- stw r4, _DEAR(r11)
+ EXCEPTION_PROLOG handle_dar_dsisr=1
+ save_dar_dsisr_on_stack r4, r5, r11
EXC_XFER_LITE(0x300, handle_page_fault)

/*
@@ -244,17 +241,15 @@ _ENTRY(saved_ksp_limit)

/* 0x0600 - Alignment Exception */
START_EXCEPTION(0x0600, Alignment)
- EXCEPTION_PROLOG
- mfspr r4,SPRN_DEAR /* Grab the DEAR and save it */
- stw r4,_DEAR(r11)
+ EXCEPTION_PROLOG handle_dar_dsisr=1
+ save_dar_dsisr_on_stack r4, r5, r11
addi r3,r1,STACK_FRAME_OVERHEAD
EXC_XFER_STD(0x600, alignment_exception)

/* 0x0700 - Program Exception */
START_EXCEPTION(0x0700, ProgramCheck)
- EXCEPTION_PROLOG
- mfspr r4,SPRN_ESR /* Grab the ESR and save it */
- stw r4,_ESR(r11)
+ EXCEPTION_PROLOG handle_dar_dsisr=1
+ save_dar_dsisr_on_stack r4, r5, r11
addi r3,r1,STACK_FRAME_OVERHEAD
EXC_XFER_STD(0x700, program_check_exception)

--
2.25.0
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