diff options
author | Marcel Ziswiler <marcel.ziswiler@toradex.com> | 2019-03-28 16:27:49 +0100 |
---|---|---|
committer | Marcel Ziswiler <marcel.ziswiler@toradex.com> | 2019-03-28 16:27:49 +0100 |
commit | d899927728beca8357a5b4120b690cb3c1d80844 (patch) | |
tree | ccb170439cc8638d71f6120ae08a6faded46db98 /arch/powerpc/kernel/signal_64.c | |
parent | 8d60367808c45e33c0a9127621f4e5fc34914f6b (diff) | |
parent | 0a8ab17689e628c84a666195bfc6ab85d11cf057 (diff) |
Merge remote-tracking branch 'remotes/fslc/4.9-2.3.x-imx' into toradex_4.9-2.3.x-imx-nextColibri-iMX7_LXDE-Image_2.8b6.184-20190401Colibri-iMX6_LXDE-Image_2.8b6.184-20190401Colibri-iMX6ULL_LXDE-Image_2.8b6.184-20190401Apalis-iMX6_LXDE-Image_2.8b6.184-20190401
Diffstat (limited to 'arch/powerpc/kernel/signal_64.c')
-rw-r--r-- | arch/powerpc/kernel/signal_64.c | 44 |
1 files changed, 30 insertions, 14 deletions
diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c index 04e92257fd69..d929afab7b24 100644 --- a/arch/powerpc/kernel/signal_64.c +++ b/arch/powerpc/kernel/signal_64.c @@ -452,20 +452,6 @@ 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); @@ -557,6 +543,34 @@ 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, msr); @@ -570,6 +584,8 @@ static long restore_tm_sigcontexts(struct task_struct *tsk, regs->msr |= MSR_VEC; } + preempt_enable(); + return err; } #endif |