diff options
Diffstat (limited to 'arch/powerpc/kernel/signal_64.c')
-rw-r--r-- | arch/powerpc/kernel/signal_64.c | 84 |
1 files changed, 56 insertions, 28 deletions
diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c index 83d51bf586c7..bd5e6834ca69 100644 --- a/arch/powerpc/kernel/signal_64.c +++ b/arch/powerpc/kernel/signal_64.c @@ -383,7 +383,7 @@ static long restore_sigcontext(struct task_struct *tsk, sigset_t *set, int sig, err |= __get_user(v_regs, &sc->v_regs); if (err) return err; - if (v_regs && !access_ok(VERIFY_READ, v_regs, 34 * sizeof(vector128))) + if (v_regs && !access_ok(v_regs, 34 * sizeof(vector128))) return -EFAULT; /* Copy 33 vec registers (vr0..31 and vscr) from the stack */ if (v_regs != NULL && (msr & MSR_VEC) != 0) { @@ -467,20 +467,6 @@ static long restore_tm_sigcontexts(struct task_struct *tsk, if (MSR_TM_RESV(msr)) return -EINVAL; - /* pull in MSR TS bits from user context */ - regs->msr = (regs->msr & ~MSR_TS_MASK) | (msr & MSR_TS_MASK); - - /* - * Ensure that TM is enabled in regs->msr before we leave the signal - * handler. It could be the case that (a) user disabled the TM bit - * through the manipulation of the MSR bits in uc_mcontext or (b) the - * TM bit was disabled because a sufficient number of context switches - * happened whilst in the signal handler and load_tm overflowed, - * disabling the TM bit. In either case we can end up with an illegal - * TM state leading to a TM Bad Thing when we return to userspace. - */ - regs->msr |= MSR_TM; - /* pull in MSR LE from user context */ regs->msr = (regs->msr & ~MSR_LE) | (msr & MSR_LE); @@ -516,10 +502,9 @@ static long restore_tm_sigcontexts(struct task_struct *tsk, err |= __get_user(tm_v_regs, &tm_sc->v_regs); if (err) return err; - if (v_regs && !access_ok(VERIFY_READ, v_regs, 34 * sizeof(vector128))) + if (v_regs && !access_ok(v_regs, 34 * sizeof(vector128))) return -EFAULT; - if (tm_v_regs && !access_ok(VERIFY_READ, - tm_v_regs, 34 * sizeof(vector128))) + if (tm_v_regs && !access_ok(tm_v_regs, 34 * sizeof(vector128))) return -EFAULT; /* Copy 33 vec registers (vr0..31 and vscr) from the stack */ if (v_regs != NULL && tm_v_regs != NULL && (msr & MSR_VEC) != 0) { @@ -572,6 +557,34 @@ static long restore_tm_sigcontexts(struct task_struct *tsk, tm_enable(); /* Make sure the transaction is marked as failed */ tsk->thread.tm_texasr |= TEXASR_FS; + + /* + * Disabling preemption, since it is unsafe to be preempted + * with MSR[TS] set without recheckpointing. + */ + preempt_disable(); + + /* pull in MSR TS bits from user context */ + regs->msr = (regs->msr & ~MSR_TS_MASK) | (msr & MSR_TS_MASK); + + /* + * Ensure that TM is enabled in regs->msr before we leave the signal + * handler. It could be the case that (a) user disabled the TM bit + * through the manipulation of the MSR bits in uc_mcontext or (b) the + * TM bit was disabled because a sufficient number of context switches + * happened whilst in the signal handler and load_tm overflowed, + * disabling the TM bit. In either case we can end up with an illegal + * TM state leading to a TM Bad Thing when we return to userspace. + * + * CAUTION: + * After regs->MSR[TS] being updated, make sure that get_user(), + * put_user() or similar functions are *not* called. These + * functions can generate page faults which will cause the process + * to be de-scheduled with MSR[TS] set but without calling + * tm_recheckpoint(). This can cause a bug. + */ + regs->msr |= MSR_TM; + /* This loads the checkpointed FP/VEC state, if used */ tm_recheckpoint(&tsk->thread); @@ -585,6 +598,8 @@ static long restore_tm_sigcontexts(struct task_struct *tsk, regs->msr |= MSR_VEC; } + preempt_enable(); + return err; } #endif @@ -598,11 +613,12 @@ static long setup_trampoline(unsigned int syscall, unsigned int __user *tramp) long err = 0; /* addi r1, r1, __SIGNAL_FRAMESIZE # Pop the dummy stackframe */ - err |= __put_user(0x38210000UL | (__SIGNAL_FRAMESIZE & 0xffff), &tramp[0]); + err |= __put_user(PPC_INST_ADDI | __PPC_RT(R1) | __PPC_RA(R1) | + (__SIGNAL_FRAMESIZE & 0xffff), &tramp[0]); /* li r0, __NR_[rt_]sigreturn| */ - err |= __put_user(0x38000000UL | (syscall & 0xffff), &tramp[1]); + err |= __put_user(PPC_INST_ADDI | (syscall & 0xffff), &tramp[1]); /* sc */ - err |= __put_user(0x44000002UL, &tramp[2]); + err |= __put_user(PPC_INST_SC, &tramp[2]); /* Minimal traceback info */ for (i=TRAMP_TRACEBACK; i < TRAMP_SIZE ;i++) @@ -654,7 +670,7 @@ SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx, ctx_has_vsx_region = 1; if (old_ctx != NULL) { - if (!access_ok(VERIFY_WRITE, old_ctx, ctx_size) + if (!access_ok(old_ctx, ctx_size) || setup_sigcontext(&old_ctx->uc_mcontext, current, 0, NULL, 0, ctx_has_vsx_region) || __copy_to_user(&old_ctx->uc_sigmask, @@ -663,7 +679,7 @@ SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx, } if (new_ctx == NULL) return 0; - if (!access_ok(VERIFY_READ, new_ctx, ctx_size) + if (!access_ok(new_ctx, ctx_size) || __get_user(tmp, (u8 __user *) new_ctx) || __get_user(tmp, (u8 __user *) new_ctx + ctx_size - 1)) return -EFAULT; @@ -708,7 +724,7 @@ SYSCALL_DEFINE0(rt_sigreturn) /* Always make any pending restarted system calls return -EINTR */ current->restart_block.fn = do_no_restart_syscall; - if (!access_ok(VERIFY_READ, uc, sizeof(*uc))) + if (!access_ok(uc, sizeof(*uc))) goto badframe; if (__copy_from_user(&set, &uc->uc_sigmask, sizeof(set))) @@ -740,11 +756,23 @@ SYSCALL_DEFINE0(rt_sigreturn) &uc_transact->uc_mcontext)) goto badframe; } - else - /* Fall through, for non-TM restore */ #endif - if (restore_sigcontext(current, NULL, 1, &uc->uc_mcontext)) - goto badframe; + /* Fall through, for non-TM restore */ + if (!MSR_TM_ACTIVE(msr)) { + /* + * Unset MSR[TS] on the thread regs since MSR from user + * context does not have MSR active, and recheckpoint was + * not called since restore_tm_sigcontexts() was not called + * also. + * + * If not unsetting it, the code can RFID to userspace with + * MSR[TS] set, but without CPU in the proper state, + * causing a TM bad thing. + */ + current->thread.regs->msr &= ~MSR_TS_MASK; + if (restore_sigcontext(current, NULL, 1, &uc->uc_mcontext)) + goto badframe; + } if (restore_altstack(&uc->uc_stack)) goto badframe; |