From 702f0980522239bc7fd1360b24f722a90b6b4418 Mon Sep 17 00:00:00 2001
From: Nicholas Piggin <npiggin@gmail.com>
Date: Wed, 26 Feb 2020 03:35:38 +1000
Subject: [PATCH] powerpc/64s/exception: Remove lite interrupt return
References: jsc#SLE-9246
Patch-mainline: v5.7-rc1
Git-commit: 702f0980522239bc7fd1360b24f722a90b6b4418
Regular interrupt return restores NVGPRS whereas lite returns do not.
This is clumsy: most interrupts can return without restoring NVGPRS in
most of the time, but there are special cases that require it (when
registers have been modified by the kernel). So change interrupt
return to not restore NVGPRS, and have interrupt handlers restore them
explicitly in the cases that requires it.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200225173541.1549955-30-npiggin@gmail.com
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
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 5d782acb86d4..95905ed3d86e 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -479,12 +479,6 @@ _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 11244031adc5..18bbce143084 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -1529,7 +1529,7 @@ 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
@@ -1557,6 +1557,7 @@ 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
@@ -1620,6 +1621,7 @@ 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
@@ -1716,7 +1718,7 @@ 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
@@ -1807,7 +1809,7 @@ EXC_COMMON_BEGIN(doorbell_super_common)
#else
bl unknown_exception
#endif
- b interrupt_return_lite
+ b interrupt_return
GEN_KVM doorbell_super
@@ -2076,6 +2078,7 @@ 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
@@ -2194,7 +2197,7 @@ EXC_COMMON_BEGIN(h_doorbell_common)
#else
bl unknown_exception
#endif
- b interrupt_return_lite
+ b interrupt_return
GEN_KVM h_doorbell
@@ -2224,7 +2227,7 @@ 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
@@ -2271,7 +2274,7 @@ 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
@@ -2668,6 +2671,7 @@ 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
@@ -3057,7 +3061,7 @@ 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
@@ -3074,7 +3078,7 @@ 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)
@@ -3089,9 +3093,9 @@ 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
--
2.28.0