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Subject[RFC PATCH v1 14/41] powerpc/32: Tag DAR in EXCEPTION_PROLOG_2 for the 8xx
Date
8xx requires to tag the DAR with a magic value in order to
detect fixup DAR on faults generated by 'dcbX', as the 8xx
forgets to update the DAR for those faults.

Do the tagging as early as possible, that is before enabling MMU.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
arch/powerpc/kernel/head_32.h | 6 ++++++
arch/powerpc/kernel/head_8xx.S | 18 ++++++------------
2 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/arch/powerpc/kernel/head_32.h b/arch/powerpc/kernel/head_32.h
index 1b707755c68e..910f86642eec 100644
--- a/arch/powerpc/kernel/head_32.h
+++ b/arch/powerpc/kernel/head_32.h
@@ -57,6 +57,12 @@
.endm

.macro EXCEPTION_PROLOG_2 handle_dar_dsisr=0
+#ifdef CONFIG_PPC_8xx
+ .if \handle_dar_dsisr
+ li r11, RPN_PATTERN
+ mtspr SPRN_DAR, r11 /* Tag DAR, to be used in DTLB Error */
+ .endif
+#endif
LOAD_REG_IMMEDIATE(r11, MSR_KERNEL & ~(MSR_IR | MSR_RI)) /* can take DTLB miss */
mtmsr r11
isync
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 792e2fd86479..cdbfa9d41353 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -30,6 +30,12 @@
#include <asm/export.h>
#include <asm/code-patching-asm.h>

+/*
+ * Value for the bits that have fixed value in RPN entries.
+ * Also used for tagging DAR for DTLBerror.
+ */
+#define RPN_PATTERN 0x00f0
+
#include "head_32.h"

.macro compare_to_kernel_boundary scratch, addr
@@ -42,12 +48,6 @@
#endif
.endm

-/*
- * Value for the bits that have fixed value in RPN entries.
- * Also used for tagging DAR for DTLBerror.
- */
-#define RPN_PATTERN 0x00f0
-
#define PAGE_SHIFT_512K 19
#define PAGE_SHIFT_8M 23

@@ -124,8 +124,6 @@ instruction_counter:
. = 0x200
MachineCheck:
EXCEPTION_PROLOG handle_dar_dsisr=1
- li r6, RPN_PATTERN
- mtspr SPRN_DAR, r6 /* Tag DAR, to be used in DTLB Error */
addi r3,r1,STACK_FRAME_OVERHEAD
EXC_XFER_STD(0x200, machine_check_exception)

@@ -136,8 +134,6 @@ MachineCheck:
. = 0x600
Alignment:
EXCEPTION_PROLOG handle_dar_dsisr=1
- li r6, RPN_PATTERN
- mtspr SPRN_DAR, r6 /* Tag DAR, to be used in DTLB Error */
addi r3,r1,STACK_FRAME_OVERHEAD
b .Lalignment_exception_ool

@@ -331,8 +327,6 @@ DataTLBError:
cmpwi cr1, r11, RPN_PATTERN
beq- cr1, FixupDAR /* must be a buggy dcbX, icbi insn. */
DARFixed:/* Return from dcbx instruction bug workaround */
- li r11, RPN_PATTERN
- mtspr SPRN_DAR, r11 /* Tag DAR, to be used in DTLB Error */
EXCEPTION_PROLOG_1
EXCEPTION_PROLOG_2 handle_dar_dsisr=1
lwz r4, _DAR(r11)
--
2.25.0
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