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powerpc/64: Interrupts save PPR on stack rather than thread_struct 

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 <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Nicholas Piggin 2018-10-13 00:15:16 +11:00 committed by Michael Ellerman
parent 3eeacd9f4e
commit 4c2de74cc8
7 changed files with 19 additions and 23 deletions
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9
arch/powerpc/include/asm/exception-64s.h
View File

@ -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

6
arch/powerpc/include/asm/processor.h
View File

@ -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

4
arch/powerpc/include/asm/ptrace.h
View File

@ -51,6 +51,10 @@ struct pt_regs
unsigned long result;
};
};
#ifdef CONFIG_PPC64
unsigned long ppr;
#endif
};
#endif

2
arch/powerpc/kernel/asm-offsets.c
View File

@ -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)

15
arch/powerpc/kernel/entry_64.S
View File

@ -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)

2
arch/powerpc/kernel/process.c
View File

@ -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

4
arch/powerpc/kernel/ptrace.c
View File

@ -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,