diff options
Diffstat (limited to 'arch/powerpc/kernel/signal_32.c')
| -rw-r--r-- | arch/powerpc/kernel/signal_32.c | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c index 27aa913ac91d..2bfa5a7bb672 100644 --- a/arch/powerpc/kernel/signal_32.c +++ b/arch/powerpc/kernel/signal_32.c @@ -866,7 +866,23 @@ static long restore_tm_user_regs(struct pt_regs *regs, /* If TM bits are set to the reserved value, it's an invalid context */ if (MSR_TM_RESV(msr_hi)) return 1; - /* Pull in the MSR TM bits from the user context */ + + /* + * Disabling preemption, since it is unsafe to be preempted + * with MSR[TS] set without recheckpointing. + */ + preempt_disable(); + + /* + * 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. + * + * Pull in the MSR TM bits from the user context + */ regs->msr = (regs->msr & ~MSR_TS_MASK) | (msr_hi & MSR_TS_MASK); /* Now, recheckpoint. This loads up all of the checkpointed (older) * registers, including FP and V[S]Rs. After recheckpointing, the @@ -891,6 +907,8 @@ static long restore_tm_user_regs(struct pt_regs *regs, } #endif + preempt_enable(); + return 0; } #endif |