diff options
| -rw-r--r-- | Documentation/powerpc/transactional_memory.txt | 19 | ||||
| -rw-r--r-- | arch/powerpc/include/asm/processor.h | 13 | ||||
| -rw-r--r-- | arch/powerpc/include/asm/signal.h | 3 | ||||
| -rw-r--r-- | arch/powerpc/kernel/signal.c | 40 | ||||
| -rw-r--r-- | arch/powerpc/kernel/signal.h | 2 | ||||
| -rw-r--r-- | arch/powerpc/kernel/signal_32.c | 10 | ||||
| -rw-r--r-- | arch/powerpc/kernel/signal_64.c | 23 |
7 files changed, 74 insertions, 36 deletions
diff --git a/Documentation/powerpc/transactional_memory.txt b/Documentation/powerpc/transactional_memory.txt index c54bf312765..dc23e58ae26 100644 --- a/Documentation/powerpc/transactional_memory.txt +++ b/Documentation/powerpc/transactional_memory.txt @@ -147,6 +147,25 @@ Example signal handler: fix_the_problem(ucp->dar); } +When in an active transaction that takes a signal, we need to be careful with +the stack. It's possible that the stack has moved back up after the tbegin. +The obvious case here is when the tbegin is called inside a function that +returns before a tend. In this case, the stack is part of the checkpointed +transactional memory state. If we write over this non transactionally or in +suspend, we are in trouble because if we get a tm abort, the program counter and +stack pointer will be back at the tbegin but our in memory stack won't be valid +anymore. + +To avoid this, when taking a signal in an active transaction, we need to use +the stack pointer from the checkpointed state, rather than the speculated +state. This ensures that the signal context (written tm suspended) will be +written below the stack required for the rollback. The transaction is aborted +becuase of the treclaim, so any memory written between the tbegin and the +signal will be rolled back anyway. + +For signals taken in non-TM or suspended mode, we use the +normal/non-checkpointed stack pointer. + Failure cause codes used by kernel ================================== diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h index 594db6bc093..14a65836369 100644 --- a/arch/powerpc/include/asm/processor.h +++ b/arch/powerpc/include/asm/processor.h @@ -409,21 +409,16 @@ static inline void prefetchw(const void *x) #endif #ifdef CONFIG_PPC64 -static inline unsigned long get_clean_sp(struct pt_regs *regs, int is_32) +static inline unsigned long get_clean_sp(unsigned long sp, int is_32) { - unsigned long sp; - if (is_32) - sp = regs->gpr[1] & 0x0ffffffffUL; - else - sp = regs->gpr[1]; - + return sp & 0x0ffffffffUL; return sp; } #else -static inline unsigned long get_clean_sp(struct pt_regs *regs, int is_32) +static inline unsigned long get_clean_sp(unsigned long sp, int is_32) { - return regs->gpr[1]; + return sp; } #endif diff --git a/arch/powerpc/include/asm/signal.h b/arch/powerpc/include/asm/signal.h index fbe66c46389..9322c28aebd 100644 --- a/arch/powerpc/include/asm/signal.h +++ b/arch/powerpc/include/asm/signal.h @@ -3,5 +3,8 @@ #define __ARCH_HAS_SA_RESTORER #include <uapi/asm/signal.h> +#include <uapi/asm/ptrace.h> + +extern unsigned long get_tm_stackpointer(struct pt_regs *regs); #endif /* _ASM_POWERPC_SIGNAL_H */ diff --git a/arch/powerpc/kernel/signal.c b/arch/powerpc/kernel/signal.c index 577a8aa69c6..457e97aa294 100644 --- a/arch/powerpc/kernel/signal.c +++ b/arch/powerpc/kernel/signal.c @@ -18,6 +18,7 @@ #include <asm/uaccess.h> #include <asm/unistd.h> #include <asm/debug.h> +#include <asm/tm.h> #include "signal.h" @@ -30,13 +31,13 @@ int show_unhandled_signals = 1; /* * Allocate space for the signal frame */ -void __user * get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, +void __user * get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size, int is_32) { unsigned long oldsp, newsp; /* Default to using normal stack */ - oldsp = get_clean_sp(regs, is_32); + oldsp = get_clean_sp(sp, is_32); /* Check for alt stack */ if ((ka->sa.sa_flags & SA_ONSTACK) && @@ -175,3 +176,38 @@ void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags) user_enter(); } + +unsigned long get_tm_stackpointer(struct pt_regs *regs) +{ + /* When in an active transaction that takes a signal, we need to be + * careful with the stack. It's possible that the stack has moved back + * up after the tbegin. The obvious case here is when the tbegin is + * called inside a function that returns before a tend. In this case, + * the stack is part of the checkpointed transactional memory state. + * If we write over this non transactionally or in suspend, we are in + * trouble because if we get a tm abort, the program counter and stack + * pointer will be back at the tbegin but our in memory stack won't be + * valid anymore. + * + * To avoid this, when taking a signal in an active transaction, we + * need to use the stack pointer from the checkpointed state, rather + * than the speculated state. This ensures that the signal context + * (written tm suspended) will be written below the stack required for + * the rollback. The transaction is aborted becuase of the treclaim, + * so any memory written between the tbegin and the signal will be + * rolled back anyway. + * + * For signals taken in non-TM or suspended mode, we use the + * normal/non-checkpointed stack pointer. + */ + +#ifdef CONFIG_PPC_TRANSACTIONAL_MEM + if (MSR_TM_ACTIVE(regs->msr)) { + tm_enable(); + tm_reclaim(¤t->thread, regs->msr, TM_CAUSE_SIGNAL); + if (MSR_TM_TRANSACTIONAL(regs->msr)) + return current->thread.ckpt_regs.gpr[1]; + } +#endif + return regs->gpr[1]; +} diff --git a/arch/powerpc/kernel/signal.h b/arch/powerpc/kernel/signal.h index ec84c901cea..c69b9aeb9f2 100644 --- a/arch/powerpc/kernel/signal.h +++ b/arch/powerpc/kernel/signal.h @@ -12,7 +12,7 @@ extern void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags); -extern void __user * get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, +extern void __user * get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size, int is_32); extern int handle_signal32(unsigned long sig, struct k_sigaction *ka, diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c index 95068bf569a..201385c3a1a 100644 --- a/arch/powerpc/kernel/signal_32.c +++ b/arch/powerpc/kernel/signal_32.c @@ -503,12 +503,6 @@ static int save_tm_user_regs(struct pt_regs *regs, { unsigned long msr = regs->msr; - /* tm_reclaim rolls back all reg states, updating thread.ckpt_regs, - * thread.transact_fpr[], thread.transact_vr[], etc. - */ - tm_enable(); - tm_reclaim(¤t->thread, msr, TM_CAUSE_SIGNAL); - /* Make sure floating point registers are stored in regs */ flush_fp_to_thread(current); @@ -965,7 +959,7 @@ int handle_rt_signal32(unsigned long sig, struct k_sigaction *ka, /* Set up Signal Frame */ /* Put a Real Time Context onto stack */ - rt_sf = get_sigframe(ka, regs, sizeof(*rt_sf), 1); + rt_sf = get_sigframe(ka, get_tm_stackpointer(regs), sizeof(*rt_sf), 1); addr = rt_sf; if (unlikely(rt_sf == NULL)) goto badframe; @@ -1403,7 +1397,7 @@ int handle_signal32(unsigned long sig, struct k_sigaction *ka, unsigned long tramp; /* Set up Signal Frame */ - frame = get_sigframe(ka, regs, sizeof(*frame), 1); + frame = get_sigframe(ka, get_tm_stackpointer(regs), sizeof(*frame), 1); if (unlikely(frame == NULL)) goto badframe; sc = (struct sigcontext __user *) &frame->sctx; diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c index c1794286098..345947367ec 100644 --- a/arch/powerpc/kernel/signal_64.c +++ b/arch/powerpc/kernel/signal_64.c @@ -154,11 +154,12 @@ static long setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, * As above, but Transactional Memory is in use, so deliver sigcontexts * containing checkpointed and transactional register states. * - * To do this, we treclaim to gather both sets of registers and set up the - * 'normal' sigcontext registers with rolled-back register values such that a - * simple signal handler sees a correct checkpointed register state. - * If interested, a TM-aware sighandler can examine the transactional registers - * in the 2nd sigcontext to determine the real origin of the signal. + * To do this, we treclaim (done before entering here) to gather both sets of + * registers and set up the 'normal' sigcontext registers with rolled-back + * register values such that a simple signal handler sees a correct + * checkpointed register state. If interested, a TM-aware sighandler can + * examine the transactional registers in the 2nd sigcontext to determine the + * real origin of the signal. */ static long setup_tm_sigcontexts(struct sigcontext __user *sc, struct sigcontext __user *tm_sc, @@ -184,16 +185,6 @@ static long setup_tm_sigcontexts(struct sigcontext __user *sc, BUG_ON(!MSR_TM_ACTIVE(regs->msr)); - /* tm_reclaim rolls back all reg states, saving checkpointed (older) - * GPRs to thread.ckpt_regs and (if used) FPRs to (newer) - * thread.transact_fp and/or VRs to (newer) thread.transact_vr. - * THEN we save out FP/VRs, if necessary, to the checkpointed (older) - * thread.fr[]/vr[]s. The transactional (newer) GPRs are on the - * stack, in *regs. - */ - tm_enable(); - tm_reclaim(¤t->thread, msr, TM_CAUSE_SIGNAL); - flush_fp_to_thread(current); #ifdef CONFIG_ALTIVEC @@ -711,7 +702,7 @@ int handle_rt_signal64(int signr, struct k_sigaction *ka, siginfo_t *info, unsigned long newsp = 0; long err = 0; - frame = get_sigframe(ka, regs, sizeof(*frame), 0); + frame = get_sigframe(ka, get_tm_stackpointer(regs), sizeof(*frame), 0); if (unlikely(frame == NULL)) goto badframe; |