* [PATCH] powerpc/64e/interrupt: fix nvgprs being clobbered
@ 2021-05-14 4:40 Nicholas Piggin
2021-05-15 22:43 ` Michael Ellerman
0 siblings, 1 reply; 2+ messages in thread
From: Nicholas Piggin @ 2021-05-14 4:40 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Nicholas Piggin, Christian Zigotzky
Some interrupt handlers have an "extra" that saves 1 or 2 registers
(r14, r15) in the paca save area and makes them available to use by the
handler.
The change to always save nvgprs in exception handlers lead to some
interrupt handlers saving those scratch r14 / r15 registers into the
interrupt frame's GPR saves, which get restored on interrupt exit.
Fix this by always reloading those scratch registers from paca before the
EXCEPTION_COMMON that saves nvgprs.
Fixes: 4228b2c3d20e ("powerpc/64e/interrupt: always save nvgprs on interrupt")
Tested-by: Christian Zigotzky <chzigotzky@xenosoft.de>
Reported-by: Christian Zigotzky <chzigotzky@xenosoft.de>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/kernel/exceptions-64e.S | 38 ++++++++++++++++++----------
1 file changed, 24 insertions(+), 14 deletions(-)
diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S
index 7c3654b0d0f4..f1ae710274bc 100644
--- a/arch/powerpc/kernel/exceptions-64e.S
+++ b/arch/powerpc/kernel/exceptions-64e.S
@@ -340,6 +340,12 @@ ret_from_mc_except:
andi. r10,r10,IRQS_DISABLED; /* yes -> go out of line */ \
bne masked_interrupt_book3e_##n
+/*
+ * Additional regs must be re-loaded from paca before EXCEPTION_COMMON* is
+ * called, because that does SAVE_NVGPRS which must see the original register
+ * values, otherwise the scratch values might be restored when exiting the
+ * interrupt.
+ */
#define PROLOG_ADDITION_2REGS_GEN(n) \
std r14,PACA_EXGEN+EX_R14(r13); \
std r15,PACA_EXGEN+EX_R15(r13)
@@ -535,6 +541,10 @@ __end_interrupts:
PROLOG_ADDITION_2REGS)
mfspr r14,SPRN_DEAR
mfspr r15,SPRN_ESR
+ std r14,_DAR(r1)
+ std r15,_DSISR(r1)
+ ld r14,PACA_EXGEN+EX_R14(r13)
+ ld r15,PACA_EXGEN+EX_R15(r13)
EXCEPTION_COMMON(0x300)
b storage_fault_common
@@ -544,6 +554,10 @@ __end_interrupts:
PROLOG_ADDITION_2REGS)
li r15,0
mr r14,r10
+ std r14,_DAR(r1)
+ std r15,_DSISR(r1)
+ ld r14,PACA_EXGEN+EX_R14(r13)
+ ld r15,PACA_EXGEN+EX_R15(r13)
EXCEPTION_COMMON(0x400)
b storage_fault_common
@@ -557,6 +571,10 @@ __end_interrupts:
PROLOG_ADDITION_2REGS)
mfspr r14,SPRN_DEAR
mfspr r15,SPRN_ESR
+ std r14,_DAR(r1)
+ std r15,_DSISR(r1)
+ ld r14,PACA_EXGEN+EX_R14(r13)
+ ld r15,PACA_EXGEN+EX_R15(r13)
EXCEPTION_COMMON(0x600)
b alignment_more /* no room, go out of line */
@@ -565,10 +583,10 @@ __end_interrupts:
NORMAL_EXCEPTION_PROLOG(0x700, BOOKE_INTERRUPT_PROGRAM,
PROLOG_ADDITION_1REG)
mfspr r14,SPRN_ESR
- EXCEPTION_COMMON(0x700)
std r14,_DSISR(r1)
- addi r3,r1,STACK_FRAME_OVERHEAD
ld r14,PACA_EXGEN+EX_R14(r13)
+ EXCEPTION_COMMON(0x700)
+ addi r3,r1,STACK_FRAME_OVERHEAD
bl program_check_exception
REST_NVGPRS(r1)
b interrupt_return
@@ -725,11 +743,11 @@ END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
* normal exception
*/
mfspr r14,SPRN_DBSR
- EXCEPTION_COMMON_CRIT(0xd00)
std r14,_DSISR(r1)
- addi r3,r1,STACK_FRAME_OVERHEAD
ld r14,PACA_EXCRIT+EX_R14(r13)
ld r15,PACA_EXCRIT+EX_R15(r13)
+ EXCEPTION_COMMON_CRIT(0xd00)
+ addi r3,r1,STACK_FRAME_OVERHEAD
bl DebugException
REST_NVGPRS(r1)
b interrupt_return
@@ -796,11 +814,11 @@ kernel_dbg_exc:
* normal exception
*/
mfspr r14,SPRN_DBSR
- EXCEPTION_COMMON_DBG(0xd08)
std r14,_DSISR(r1)
- addi r3,r1,STACK_FRAME_OVERHEAD
ld r14,PACA_EXDBG+EX_R14(r13)
ld r15,PACA_EXDBG+EX_R15(r13)
+ EXCEPTION_COMMON_DBG(0xd08)
+ addi r3,r1,STACK_FRAME_OVERHEAD
bl DebugException
REST_NVGPRS(r1)
b interrupt_return
@@ -931,11 +949,7 @@ masked_interrupt_book3e_0x2c0:
* original values stashed away in the PACA
*/
storage_fault_common:
- std r14,_DAR(r1)
- std r15,_DSISR(r1)
addi r3,r1,STACK_FRAME_OVERHEAD
- ld r14,PACA_EXGEN+EX_R14(r13)
- ld r15,PACA_EXGEN+EX_R15(r13)
bl do_page_fault
b interrupt_return
@@ -944,11 +958,7 @@ storage_fault_common:
* continues here.
*/
alignment_more:
- std r14,_DAR(r1)
- std r15,_DSISR(r1)
addi r3,r1,STACK_FRAME_OVERHEAD
- ld r14,PACA_EXGEN+EX_R14(r13)
- ld r15,PACA_EXGEN+EX_R15(r13)
bl alignment_exception
REST_NVGPRS(r1)
b interrupt_return
--
2.23.0
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