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Subject[PATCH] ARC: Machine Check Exception: enable MMU in single place
Date
Machine check Exception is handled in distinc ways depending on cause
- Duplicate TLB Entry (relevent mostly for ARC700)
- everything else

Currently we re-enable MMU seperately for each of these cases, which can
be consolidated by dign this before we fork off the handling in low
level handler.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
arch/arc/kernel/entry.S | 6 ++++++
arch/arc/kernel/traps.c | 6 ------
arch/arc/mm/tlb.c | 3 ---
3 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/arch/arc/kernel/entry.S b/arch/arc/kernel/entry.S
index 1eea99beecc3..85d9ea4a0acc 100644
--- a/arch/arc/kernel/entry.S
+++ b/arch/arc/kernel/entry.S
@@ -92,6 +92,12 @@ ENTRY(EV_MachineCheck)
lr r0, [efa]
mov r1, sp

+ ; hardware auto-disables MMU, re-enable it to allow kernel vaddr
+ ; access for say stack unwinding of modules for crash dumps
+ lr r3, [ARC_REG_PID]
+ or r3, r3, MMU_ENABLE
+ sr r3, [ARC_REG_PID]
+
lsr r3, r2, 8
bmsk r3, r3, 7
brne r3, ECR_C_MCHK_DUP_TLB, 1f
diff --git a/arch/arc/kernel/traps.c b/arch/arc/kernel/traps.c
index b636dfe8ee9e..b03daa7a9a2b 100644
--- a/arch/arc/kernel/traps.c
+++ b/arch/arc/kernel/traps.c
@@ -105,12 +105,6 @@ int do_misaligned_access(unsigned long address, struct pt_regs *regs,
*/
void do_machine_check_fault(unsigned long address, struct pt_regs *regs)
{
- /*
- * Hardware auto-disables MMU upon this exception hence re-enabled
- * for ksym lookup in modules to work (in kernel vaddr space)
- */
- write_aux_reg(ARC_REG_PID, MMU_ENABLE | read_aux_reg(ARC_REG_PID));
-
die("Unhandled Machine Check Exception", regs, address);
}

diff --git a/arch/arc/mm/tlb.c b/arch/arc/mm/tlb.c
index edc59a0a9c9b..8ceefbf72fb0 100644
--- a/arch/arc/mm/tlb.c
+++ b/arch/arc/mm/tlb.c
@@ -908,9 +908,6 @@ void do_tlb_overlap_fault(unsigned long cause, unsigned long address,

local_irq_save(flags);

- /* re-enable the MMU */
- write_aux_reg(ARC_REG_PID, MMU_ENABLE | read_aux_reg(ARC_REG_PID));
-
/* loop thru all sets of TLB */
for (set = 0; set < mmu->sets; set++) {

--
2.7.4
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