We also handle fault with proper stack initialized. This enable us to
callout to C in fault handling routines. We don't do this for kernel
mapping, because of the possibility of taking recursive fault if kernel
stack in not yet mapped by an slb entry.
This enable us to handle Power9 slb fault better. We will add bolted
entries for the entire kernel mapping in segment table and user slb
entries we take fault and insert on demand. With translation on, we
should be able to access segment table from fault handler.
Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com>
---
arch/powerpc/kernel/exceptions-64s.S | 55 ++++++++++++++++++++++++++++++++----
arch/powerpc/mm/slb.c | 11 ++++++++
2 files changed, 61 insertions(+), 5 deletions(-)
diff --git a/arch/powerpc/kernel/exceptions-64s.S
b/arch/powerpc/kernel/exceptions-64s.S
index f2bd375b9a4e..2f2c52559ea9 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -794,7 +794,7 @@ data_access_slb_relon_pSeries:
mfspr r3,SPRN_DAR
mfspr r12,SPRN_SRR1
#ifndef CONFIG_RELOCATABLE
- b slb_miss_realmode
+ b handle_slb_miss_relon
#else
/*
* We can't just use a direct branch to slb_miss_realmode
@@ -803,7 +803,7 @@ data_access_slb_relon_pSeries:
*/
mfctr r11
ld r10,PACAKBASE(r13)
- LOAD_HANDLER(r10, slb_miss_realmode)
+ LOAD_HANDLER(r10, handle_slb_miss_relon)
mtctr r10
bctr
#endif
@@ -819,11 +819,11 @@ instruction_access_slb_relon_pSeries:
mfspr r3,SPRN_SRR0 /* SRR0 is faulting address */
mfspr r12,SPRN_SRR1
#ifndef CONFIG_RELOCATABLE
- b slb_miss_realmode
+ b handle_slb_miss_relon
#else
mfctr r11
ld r10,PACAKBASE(r13)
- LOAD_HANDLER(r10, slb_miss_realmode)
+ LOAD_HANDLER(r10, handle_slb_miss_relon)
mtctr r10
bctr
#endif
@@ -961,7 +961,23 @@ h_data_storage_common:
bl unknown_exception
b ret_from_except
+/* r3 point to DAR */
.align 7
+ .globl slb_miss_user
+slb_miss_user:
+ std r3,PACA_EXSLB+EX_DAR(r13)
+ /* Restore r3 as expected by PROLOG_COMMON below */
+ ld r3,PACA_EXSLB+EX_R3(r13)
+ EXCEPTION_PROLOG_COMMON(0x380, PACA_EXSLB)
+ RECONCILE_IRQ_STATE(r10, r11)
+ ld r4,PACA_EXSLB+EX_DAR(r13)
+ li r5,0x380
+ std r4,_DAR(r1)
+ addi r3,r1,STACK_FRAME_OVERHEAD
+ bl handle_slb_miss
+ b ret_from_except_lite
+
+ .align 7
.globl instruction_access_common
instruction_access_common:
EXCEPTION_PROLOG_COMMON(0x400, PACA_EXGEN)
@@ -1379,11 +1395,17 @@ unrecover_mce:
* We assume we aren't going to take any exceptions during this procedure.
*/
slb_miss_realmode:
- mflr r10
#ifdef CONFIG_RELOCATABLE
mtctr r11
#endif
+ /*
+ * Handle user slb miss with translation enabled
+ */
+ cmpdi r3,0
+ bge 3f
+slb_miss_kernel:
+ mflr r10
stw r9,PACA_EXSLB+EX_CCR(r13) /* save CR in exc. frame */
std r10,PACA_EXSLB+EX_LR(r13) /* save LR */
@@ -1428,6 +1450,29 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_TYPE_RADIX)
mtspr SPRN_SRR1,r10
rfid
b .
+3:
+ /*
+ * Enable IR/DR and handle the fault
+ */
+ EXCEPTION_PROLOG_PSERIES_1(slb_miss_user, EXC_STD)
+ /*
+ * handler with relocation on
+ */
+handle_slb_miss_relon:
+#ifdef CONFIG_RELOCATABLE
+ mtctr r11
+#endif
+ /*
+ * Handle user slb miss with stack initialized.
+ */
+ cmpdi r3,0
+ bge 4f
+ /*
+ * go back to slb_miss_realmode
+ */
+ b slb_miss_kernel
+4:
+ EXCEPTION_RELON_PROLOG_PSERIES_1(slb_miss_user, EXC_STD)
unrecov_slb:
EXCEPTION_PROLOG_COMMON(0x4100, PACA_EXSLB)
diff --git a/arch/powerpc/mm/slb.c b/arch/powerpc/mm/slb.c
index 48fc28bab544..b18d7df5601d 100644
--- a/arch/powerpc/mm/slb.c
+++ b/arch/powerpc/mm/slb.c
@@ -25,6 +25,8 @@
#include <asm/udbg.h>
#include <asm/code-patching.h>
+#include <linux/context_tracking.h>
+
enum slb_index {
LINEAR_INDEX = 0, /* Kernel linear map (0xc000000000000000) */
VMALLOC_INDEX = 1, /* Kernel virtual map (0xd000000000000000) */
@@ -346,3 +348,12 @@ void slb_initialize(void)
asm volatile("isync":::"memory");
}
+
+void handle_slb_miss(struct pt_regs *regs,
+ unsigned long address, unsigned long trap)
+{
+ enum ctx_state prev_state = exception_enter();
+
+ slb_allocate(address);
+ exception_exit(prev_state);
+}
--
2.7.4
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