From 4c2de74cc8696154b283f241d74ec0bb24438e22 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Sat, 13 Oct 2018 00:15:16 +1100 Subject: [PATCH] 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 Signed-off-by: Michael Ellerman --- 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,