Le 18/09/2014 20:12, Joakim Tjernlund a écrit :
leroy christophe <christophe.le...@c-s.fr> wrote on 2014/09/18 18:42:14:
Le 18/09/2014 17:15, Joakim Tjernlund a écrit :
Christophe Leroy <christophe.le...@c-s.fr> wrote on 2014/09/17
18:36:57:
Exception InstructionAccess does not exist on MPC8xx. No need to
branch
there from somewhere else.
Handling can be done directly in InstructionTLBError Exception.
Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr>
---
Changes in v2:
- None
Changes in v3:
- arch/powerpc/mm/fault.c uses the vector number, so make sure it
understand
the new ones.
arch/powerpc/kernel/head_8xx.S | 17 +++++++----------
arch/powerpc/mm/fault.c | 1 +
2 files changed, 8 insertions(+), 10 deletions(-)
diff --git a/arch/powerpc/kernel/head_8xx.S
b/arch/powerpc/kernel/head_8xx.S
index 3af6db1..fbe5d10 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -234,15 +234,9 @@ DataAccess:
EXC_XFER_LITE(0x300, handle_page_fault)
/* Instruction access exception.
- * This is "never generated" by the MPC8xx. We jump to it for other
- * translation errors.
+ * This is "never generated" by the MPC8xx.
*/
- . = 0x400
-InstructionAccess:
- EXCEPTION_PROLOG
- mr r4,r12
- mr r5,r9
- EXC_XFER_LITE(0x400, handle_page_fault)
+ EXCEPTION(0x400, InstructionAccess, unknown_exception,
EXC_XFER_STD)
/* External interrupt */
EXCEPTION(0x500, HardwareInterrupt, do_IRQ, EXC_XFER_LITE)
@@ -382,7 +376,7 @@ InstructionTLBMiss:
#endif
mfspr r10, SPRN_SPRG_SCRATCH2
EXCEPTION_EPILOG_0
- b InstructionAccess
+ b InstructionTLBError
. = 0x1200
DataStoreTLBMiss:
@@ -477,7 +471,10 @@ DataStoreTLBMiss:
*/
. = 0x1300
InstructionTLBError:
- b InstructionAccess
+ EXCEPTION_PROLOG
+ mr r4,r12
+ mr r5,r9
+ EXC_XFER_LITE(0x1300, handle_page_fault)
Still don't like that you change the vector number, every other ppc
uses
the
standard number.
Can you not just lie here(EXC_XFER_LITE(0x400, handle_page_fault))?
Move the code to InstructionAccess too and let TLBError branch there.
My issue was that if I do EXC_XFER_LITE(0x400, handle_page_fault), I
can't leave the
EXCEPTION(0x400, InstructionAccess, unknown_exception,
EXC_XFER_STD) at address .400
Otherwise, I get twice the same label.
What about the following patch then ? Would this be acceptable ?
@@ -234,15 +234,13 @@ DataAccess:
EXC_XFER_LITE(0x300, handle_page_fault)
/* Instruction access exception.
- * This is "never generated" by the MPC8xx. We jump to it for other
- * translation errors.
+ * This is "never generated" by the MPC8xx.
*/
. = 0x400
InstructionAccess:
EXCEPTION_PROLOG
- mr r4,r12
- mr r5,r9
- EXC_XFER_LITE(0x400, handle_page_fault)
+ addi r3,r1,STACK_FRAME_OVERHEAD
+ EXC_XFER_STD(0x401, unknown_exception)
Since this is never generated I think it is OK. Nedds some more commenst
though, why the 401 etc.
/* External interrupt */
EXCEPTION(0x500, HardwareInterrupt, do_IRQ, EXC_XFER_LITE)
@@ -382,7 +380,7 @@ InstructionTLBMiss:
#endif
mfspr r10, SPRN_SPRG_SCRATCH2
EXCEPTION_EPILOG_0
- b InstructionAccess
+ b InstructionTLBError
. = 0x1200
DataStoreTLBMiss:
@@ -477,7 +475,11 @@ DataStoreTLBMiss:
*/
. = 0x1300
InstructionTLBError:
- b InstructionAccess
+ EXCEPTION_PROLOG
+ mr r4,r12
+ mr r5,r9
+ /* 0x400 is InstructionAccess exception, needed by bad_page_fault()
*/
+ EXC_XFER_LITE(0x400, handle_page_fault)
You should have the code in TLBMiss and have the TLBError branch there as
that is the common case.
As far as I remember, I tried it already but we don't have enough space
in TLBmiss for that. We can only have 40 instructions.
/* This is the data TLB error on the MPC8xx. This could be due to
* many reasons, including a dirty update to a pte. We can catch that
If not I think you should keep the old/current way?
Same for DataTLB Miss/Error
/* This is the data TLB error on the MPC8xx. This could be due to
* many reasons, including a dirty update to a pte. We can catch
that
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 51ab9e7..4d63c96 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -526,6 +526,7 @@ void bad_page_fault(struct pt_regs *regs,
unsigned
long address, int sig)
break;
case 0x400:
case 0x480:
+ case 0x1300:
printk(KERN_ALERT "Unable to handle kernel paging request for
"
"instruction fetch\n");
break;
--
2.1.0
---
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