[PATCH v2 3/9] powerpc/64: interrupts save PPR on stack rather than thread_struct
Nicholas Piggin
npiggin at gmail.com
Wed Oct 3 00:27:53 AEST 2018
PPR is the odd register out when it comes to interrupt handling,
it is saved in current->thread.ppr while all others are saved on
the stack.
The difficulty with this is that accessing thread.ppr can cause a
SLB fault, but the SLB fault handler implementation in C change had
assumed the normal exception entry handlers would not cause an SLB
fault.
Fix this by allocating room in the interrupt stack to save PPR.
Fixes: 5e46e29e6a97 ("powerpc/64s/hash: convert SLB miss handlers to C")
Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
---
arch/powerpc/include/asm/exception-64s.h | 9 ++++-----
arch/powerpc/include/asm/processor.h | 12 +++++++-----
arch/powerpc/include/asm/ptrace.h | 1 +
arch/powerpc/kernel/asm-offsets.c | 2 +-
arch/powerpc/kernel/entry_64.S | 15 +++++----------
arch/powerpc/kernel/process.c | 2 +-
arch/powerpc/kernel/ptrace.c | 4 ++--
7 files changed, 21 insertions(+), 24 deletions(-)
diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h
index 47578b79f0fb..3b4767ed3ec5 100644
--- a/arch/powerpc/include/asm/exception-64s.h
+++ b/arch/powerpc/include/asm/exception-64s.h
@@ -228,11 +228,10 @@
* PPR save/restore macros used in exceptions_64s.S
* Used for P7 or later processors
*/
-#define SAVE_PPR(area, ra, rb) \
+#define SAVE_PPR(area, ra) \
BEGIN_FTR_SECTION_NESTED(940) \
- ld ra,PACACURRENT(r13); \
- ld rb,area+EX_PPR(r13); /* Read PPR from paca */ \
- std rb,TASKTHREADPPR(ra); \
+ ld ra,area+EX_PPR(r13); /* Read PPR from paca */ \
+ std ra,_PPR(r1); \
END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,940)
#define RESTORE_PPR_PACA(area, ra) \
@@ -500,7 +499,7 @@ END_FTR_SECTION_NESTED(ftr,ftr,943)
3: EXCEPTION_PROLOG_COMMON_1(); \
beq 4f; /* if from kernel mode */ \
ACCOUNT_CPU_USER_ENTRY(r13, r9, r10); \
- SAVE_PPR(area, r9, r10); \
+ SAVE_PPR(area, r9); \
4: EXCEPTION_PROLOG_COMMON_2(area) \
EXCEPTION_PROLOG_COMMON_3(n) \
ACCOUNT_STOLEN_TIME
diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index 350c584ca179..07251598056c 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -32,9 +32,9 @@
/* Default SMT priority is set to 3. Use 11- 13bits to save priority. */
#define PPR_PRIORITY 3
#ifdef __ASSEMBLY__
-#define INIT_PPR (PPR_PRIORITY << 50)
+#define DEFAULT_PPR (PPR_PRIORITY << 50)
#else
-#define INIT_PPR ((u64)PPR_PRIORITY << 50)
+#define DEFAULT_PPR ((u64)PPR_PRIORITY << 50)
#endif /* __ASSEMBLY__ */
#endif /* CONFIG_PPC64 */
@@ -247,7 +247,11 @@ struct thread_struct {
#ifdef CONFIG_PPC64
unsigned long ksp_vsid;
#endif
- struct pt_regs *regs; /* Pointer to saved register state */
+ union {
+ struct int_regs *iregs; /* Pointer to saved register state */
+ struct pt_regs *regs; /* Pointer to saved register state */
+ };
+
mm_segment_t addr_limit; /* for get_fs() validation */
#ifdef CONFIG_BOOKE
/* BookE base exception scratch space; align on cacheline */
@@ -342,7 +346,6 @@ struct thread_struct {
* onwards.
*/
int dscr_inherit;
- unsigned long ppr; /* used to save/restore SMT priority */
unsigned long tidr;
#endif
#ifdef CONFIG_PPC_BOOK3S_64
@@ -390,7 +393,6 @@ struct thread_struct {
.regs = (struct pt_regs *)INIT_SP - 1, /* XXX bogus, I think */ \
.addr_limit = KERNEL_DS, \
.fpexc_mode = 0, \
- .ppr = INIT_PPR, \
.fscr = FSCR_TAR | FSCR_EBB \
}
#endif
diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h
index 1a98cd8c49f6..9a5a1cc85bd0 100644
--- a/arch/powerpc/include/asm/ptrace.h
+++ b/arch/powerpc/include/asm/ptrace.h
@@ -78,6 +78,7 @@
struct int_regs {
/* pt_regs must be offset 0 so r1 + STACK_FRAME_OVERHEAD points to it */
struct pt_regs pt_regs;
+ unsigned long ppr;
};
#define GET_IP(regs) ((regs)->nip)
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 509a113f97dc..56241174ea94 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -88,7 +88,6 @@ int main(void)
#ifdef CONFIG_PPC64
DEFINE(SIGSEGV, SIGSEGV);
DEFINE(NMI_MASK, NMI_MASK);
- OFFSET(TASKTHREADPPR, task_struct, thread.ppr);
#else
OFFSET(THREAD_INFO, task_struct, stack);
DEFINE(THREAD_INFO_GAP, _ALIGN_UP(sizeof(struct thread_info), 16));
@@ -283,6 +282,7 @@ int main(void)
/* Create extra stack space for SRR0 and SRR1 when calling prom/rtas. */
DEFINE(PROM_FRAME_SIZE, STACK_FRAME_OVERHEAD + sizeof(struct int_regs) + 16);
DEFINE(RTAS_FRAME_SIZE, STACK_FRAME_OVERHEAD + sizeof(struct int_regs) + 16);
+ STACK_INT_REGS_OFFSET(_PPR, ppr);
#endif /* CONFIG_PPC64 */
STACK_PT_REGS_OFFSET(GPR0, gpr[0]);
STACK_PT_REGS_OFFSET(GPR1, gpr[1]);
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 77a888bfcb53..ce448f753d2e 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -386,10 +386,9 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
4: /* Anything else left to do? */
BEGIN_FTR_SECTION
- lis r3,INIT_PPR at highest /* Set thread.ppr = 3 */
- ld r10,PACACURRENT(r13)
+ lis r3,DEFAULT_PPR at highest /* Set default PPR */
sldi r3,r3,32 /* bits 11-13 are used for ppr */
- std r3,TASKTHREADPPR(r10)
+ std r3,_PPR(r1)
END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
andi. r0,r9,(_TIF_SYSCALL_DOTRACE|_TIF_SINGLESTEP)
@@ -938,12 +937,6 @@ fast_exception_return:
andi. r0,r3,MSR_RI
beq- .Lunrecov_restore
- /* Load PPR from thread struct before we clear MSR:RI */
-BEGIN_FTR_SECTION
- ld r2,PACACURRENT(r13)
- ld r2,TASKTHREADPPR(r2)
-END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
-
/*
* Clear RI before restoring r13. If we are returning to
* userspace and we take an exception after restoring r13,
@@ -964,7 +957,9 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
andi. r0,r3,MSR_PR
beq 1f
BEGIN_FTR_SECTION
- mtspr SPRN_PPR,r2 /* Restore PPR */
+ /* Restore PPR */
+ ld r2,_PPR(r1)
+ mtspr SPRN_PPR,r2
END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
ACCOUNT_CPU_USER_EXIT(r13, r2, r4)
REST_GPR(13, r1)
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 532e9a83e526..18a14fb8f759 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1711,7 +1711,7 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
p->thread.dscr = mfspr(SPRN_DSCR);
}
if (cpu_has_feature(CPU_FTR_HAS_PPR))
- p->thread.ppr = INIT_PPR;
+ childregs->ppr = DEFAULT_PPR;
p->thread.tidr = 0;
#endif
diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index 9667666eb18e..57c04176f686 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -1609,7 +1609,7 @@ static int ppr_get(struct task_struct *target,
void *kbuf, void __user *ubuf)
{
return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
- &target->thread.ppr, 0, sizeof(u64));
+ &target->thread.iregs->ppr, 0, sizeof(u64));
}
static int ppr_set(struct task_struct *target,
@@ -1618,7 +1618,7 @@ static int ppr_set(struct task_struct *target,
const void *kbuf, const void __user *ubuf)
{
return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
- &target->thread.ppr, 0, sizeof(u64));
+ &target->thread.iregs->ppr, 0, sizeof(u64));
}
static int dscr_get(struct task_struct *target,
--
2.18.0
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