From: Nicholas Piggin <npig...@gmail.com>
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.
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
Signed-off-by: Michael Ellerman <m...@ellerman.id.au>
---
arch/powerpc/include/asm/exception-64s.h | 9 ++++-----
arch/powerpc/include/asm/processor.h | 6 ++----
arch/powerpc/include/asm/ptrace.h | 4 ++++
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, 19 insertions(+), 23 deletions(-)
diff --git a/arch/powerpc/include/asm/exception-64s.h
b/arch/powerpc/include/asm/exception-64s.h
index a86feddddad0..403d73898a9a 100644
--- a/arch/powerpc/include/asm/exception-64s.h
+++ b/arch/powerpc/include/asm/exception-64s.h
@@ -236,11 +236,10 @@
* 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) \
@@ -508,7 +507,7 @@ 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 52fadded5c1e..3fefb8a65b17 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 */
@@ -341,7 +341,6 @@ 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
@@ -389,7 +388,6 @@ 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 3dd15024db93..2ba2a1e52291 100644
--- a/arch/powerpc/include/asm/ptrace.h
+++ b/arch/powerpc/include/asm/ptrace.h
@@ -51,6 +51,10 @@ struct pt_regs
unsigned long result;
};
};
+
+#ifdef CONFIG_PPC64
+ unsigned long ppr;
+#endif
};
#endif
diff --git a/arch/powerpc/kernel/asm-offsets.c
b/arch/powerpc/kernel/asm-offsets.c
index 2eb4923f8468..92156c61d21c 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -89,7 +89,6 @@ 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));
@@ -323,6 +322,7 @@ int main(void)
STACK_PT_REGS_OFFSET(_ESR, dsisr);
#else /* CONFIG_PPC64 */
STACK_PT_REGS_OFFSET(SOFTE, softe);
+ STACK_PT_REGS_OFFSET(_PPR, ppr);
#endif /* CONFIG_PPC64 */
#if defined(CONFIG_PPC32)
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 7db00ee6be48..7b1693adff2a 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@highest /* Set thread.ppr = 3 */
- ld r10,PACACURRENT(r13)
+ lis r3,DEFAULT_PPR@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)
@@ -942,12 +941,6 @@ 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,
@@ -968,7 +961,9 @@ 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 0ed8d0968515..f9d1cca28cce 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1710,7 +1710,7 @@ 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 c7d0d0c1e34d..afb819f4ca68 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.regs->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.regs->ppr, 0, sizeof(u64));
}
static int dscr_get(struct task_struct *target,
--
2.17.1
