The difference between lite and regular returns is that the lite case
restores all NVGPRs, whereas lite skips that. This is quite clumsy
though, most interrupts want the NVGPRs saved for debugging, not to
modify in the caller, so the NVGPRs restore is not necessary most of
the time. Restore NVGPRs explicitly for one case that requires it,
and move everything else over to avoiding the restore unless the
interrupt return demands it (e.g., handling a signal).
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
v3:
- Add a copule of missing restore cases for instruction emulation
arch/powerpc/kernel/entry_64.S | 6 ------
arch/powerpc/kernel/exceptions-64s.S | 24 ++++++++++++++----------
2 files changed, 14 insertions(+), 16 deletions(-)
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index e13eac968dfc..6d5464f83c05 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -471,12 +471,6 @@ _ASM_NOKPROBE_SYMBOL(fast_interrupt_return)
.globl interrupt_return
interrupt_return:
_ASM_NOKPROBE_SYMBOL(interrupt_return)
- REST_NVGPRS(r1)
-
- .balign IFETCH_ALIGN_BYTES
- .globl interrupt_return_lite
-interrupt_return_lite:
-_ASM_NOKPROBE_SYMBOL(interrupt_return_lite)
ld r4,_MSR(r1)
andi. r0,r4,MSR_PR
beq .Lkernel_interrupt_return
diff --git a/arch/powerpc/kernel/exceptions-64s.S
b/arch/powerpc/kernel/exceptions-64s.S
index d635fd4e40ea..b53e452cbca0 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -1513,7 +1513,7 @@ EXC_COMMON_BEGIN(hardware_interrupt_common)
RUNLATCH_ON
addi r3,r1,STACK_FRAME_OVERHEAD
bl do_IRQ
- b interrupt_return_lite
+ b interrupt_return
GEN_KVM hardware_interrupt
@@ -1541,6 +1541,7 @@ EXC_COMMON_BEGIN(alignment_common)
GEN_COMMON alignment
addi r3,r1,STACK_FRAME_OVERHEAD
bl alignment_exception
+ REST_NVGPRS(r1) /* instruction emulation may change GPRs */
b interrupt_return
GEN_KVM alignment
@@ -1604,6 +1605,7 @@ EXC_COMMON_BEGIN(program_check_common)
3:
addi r3,r1,STACK_FRAME_OVERHEAD
bl program_check_exception
+ REST_NVGPRS(r1) /* instruction emulation may change GPRs */
b interrupt_return
GEN_KVM program_check
@@ -1700,7 +1702,7 @@ EXC_COMMON_BEGIN(decrementer_common)
RUNLATCH_ON
addi r3,r1,STACK_FRAME_OVERHEAD
bl timer_interrupt
- b interrupt_return_lite
+ b interrupt_return
GEN_KVM decrementer
@@ -1791,7 +1793,7 @@ EXC_COMMON_BEGIN(doorbell_super_common)
#else
bl unknown_exception
#endif
- b interrupt_return_lite
+ b interrupt_return
GEN_KVM doorbell_super
@@ -2060,6 +2062,7 @@ EXC_COMMON_BEGIN(emulation_assist_common)
GEN_COMMON emulation_assist
addi r3,r1,STACK_FRAME_OVERHEAD
bl emulation_assist_interrupt
+ REST_NVGPRS(r1) /* instruction emulation may change GPRs */
b interrupt_return
GEN_KVM emulation_assist
@@ -2176,7 +2179,7 @@ EXC_COMMON_BEGIN(h_doorbell_common)
#else
bl unknown_exception
#endif
- b interrupt_return_lite
+ b interrupt_return
GEN_KVM h_doorbell
@@ -2206,7 +2209,7 @@ EXC_COMMON_BEGIN(h_virt_irq_common)
RUNLATCH_ON
addi r3,r1,STACK_FRAME_OVERHEAD
bl do_IRQ
- b interrupt_return_lite
+ b interrupt_return
GEN_KVM h_virt_irq
@@ -2253,7 +2256,7 @@ EXC_COMMON_BEGIN(performance_monitor_common)
RUNLATCH_ON
addi r3,r1,STACK_FRAME_OVERHEAD
bl performance_monitor_exception
- b interrupt_return_lite
+ b interrupt_return
GEN_KVM performance_monitor
@@ -2650,6 +2653,7 @@ EXC_COMMON_BEGIN(altivec_assist_common)
addi r3,r1,STACK_FRAME_OVERHEAD
#ifdef CONFIG_ALTIVEC
bl altivec_assist_exception
+ REST_NVGPRS(r1) /* instruction emulation may change GPRs */
#else
bl unknown_exception
#endif
@@ -3038,7 +3042,7 @@ do_hash_page:
cmpdi r3,0 /* see if __hash_page succeeded */
/* Success */
- beq interrupt_return_lite /* Return from exception on success */
+ beq interrupt_return /* Return from exception on success */
/* Error */
blt- 13f
@@ -3055,7 +3059,7 @@ handle_page_fault:
addi r3,r1,STACK_FRAME_OVERHEAD
bl do_page_fault
cmpdi r3,0
- beq+ interrupt_return_lite
+ beq+ interrupt_return
mr r5,r3
addi r3,r1,STACK_FRAME_OVERHEAD
ld r4,_DAR(r1)
@@ -3070,9 +3074,9 @@ handle_dabr_fault:
bl do_break
/*
* do_break() may have changed the NV GPRS while handling a breakpoint.
- * If so, we need to restore them with their updated values. Don't use
- * interrupt_return_lite here.
+ * If so, we need to restore them with their updated values.
*/
+ REST_NVGPRS(r1)
b interrupt_return
--
2.23.0
