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authorLinus Torvalds <torvalds@linux-foundation.org>2015-11-26 11:19:59 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-11-26 11:19:59 -0800
commit02a5fec18297bb6991f5bc5ebc7e73fa6810809d (patch)
tree6976eb940b5f0e37083366f0140525deef9c2925
parent78c4a49a69e910a162b05e4e8727b9bdbf948f13 (diff)
parent7f821fc9c77a9b01fe7b1d6e72717b33d8d64142 (diff)
downloadlwn-02a5fec18297bb6991f5bc5ebc7e73fa6810809d.tar.gz
lwn-02a5fec18297bb6991f5bc5ebc7e73fa6810809d.zip
Merge tag 'powerpc-4.4-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc fixes from Michael Ellerman: - tm: Block signal return from setting invalid MSR state from Michael Neuling - tm: Check for already reclaimed tasks from Michael Neuling * tag 'powerpc-4.4-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: powerpc/tm: Check for already reclaimed tasks powerpc/tm: Block signal return setting invalid MSR state
-rw-r--r--arch/powerpc/include/asm/reg.h1
-rw-r--r--arch/powerpc/kernel/process.c18
-rw-r--r--arch/powerpc/kernel/signal_32.c14
-rw-r--r--arch/powerpc/kernel/signal_64.c4
4 files changed, 32 insertions, 5 deletions
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index a908ada8e0a5..2220f7a60def 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -108,6 +108,7 @@
#define MSR_TS_T __MASK(MSR_TS_T_LG) /* Transaction Transactional */
#define MSR_TS_MASK (MSR_TS_T | MSR_TS_S) /* Transaction State bits */
#define MSR_TM_ACTIVE(x) (((x) & MSR_TS_MASK) != 0) /* Transaction active? */
+#define MSR_TM_RESV(x) (((x) & MSR_TS_MASK) == MSR_TS_MASK) /* Reserved */
#define MSR_TM_TRANSACTIONAL(x) (((x) & MSR_TS_MASK) == MSR_TS_T)
#define MSR_TM_SUSPENDED(x) (((x) & MSR_TS_MASK) == MSR_TS_S)
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 75b6676c1a0b..646bf4d222c1 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -551,6 +551,24 @@ static void tm_reclaim_thread(struct thread_struct *thr,
msr_diff &= MSR_FP | MSR_VEC | MSR_VSX | MSR_FE0 | MSR_FE1;
}
+ /*
+ * Use the current MSR TM suspended bit to track if we have
+ * checkpointed state outstanding.
+ * On signal delivery, we'd normally reclaim the checkpointed
+ * state to obtain stack pointer (see:get_tm_stackpointer()).
+ * This will then directly return to userspace without going
+ * through __switch_to(). However, if the stack frame is bad,
+ * we need to exit this thread which calls __switch_to() which
+ * will again attempt to reclaim the already saved tm state.
+ * Hence we need to check that we've not already reclaimed
+ * this state.
+ * We do this using the current MSR, rather tracking it in
+ * some specific thread_struct bit, as it has the additional
+ * benifit of checking for a potential TM bad thing exception.
+ */
+ if (!MSR_TM_SUSPENDED(mfmsr()))
+ return;
+
tm_reclaim(thr, thr->regs->msr, cause);
/* Having done the reclaim, we now have the checkpointed
diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
index 0dbee465af7a..ef7c24e84a62 100644
--- a/arch/powerpc/kernel/signal_32.c
+++ b/arch/powerpc/kernel/signal_32.c
@@ -875,6 +875,15 @@ static long restore_tm_user_regs(struct pt_regs *regs,
return 1;
#endif /* CONFIG_SPE */
+ /* Get the top half of the MSR from the user context */
+ if (__get_user(msr_hi, &tm_sr->mc_gregs[PT_MSR]))
+ return 1;
+ msr_hi <<= 32;
+ /* 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 */
+ 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
* transactional versions should be loaded.
@@ -884,11 +893,6 @@ static long restore_tm_user_regs(struct pt_regs *regs,
current->thread.tm_texasr |= TEXASR_FS;
/* This loads the checkpointed FP/VEC state, if used */
tm_recheckpoint(&current->thread, msr);
- /* Get the top half of the MSR */
- if (__get_user(msr_hi, &tm_sr->mc_gregs[PT_MSR]))
- return 1;
- /* Pull in MSR TM from user context */
- regs->msr = (regs->msr & ~MSR_TS_MASK) | ((msr_hi<<32) & MSR_TS_MASK);
/* This loads the speculative FP/VEC state, if used */
if (msr & MSR_FP) {
diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
index 20756dfb9f34..c676ecec0869 100644
--- a/arch/powerpc/kernel/signal_64.c
+++ b/arch/powerpc/kernel/signal_64.c
@@ -438,6 +438,10 @@ static long restore_tm_sigcontexts(struct pt_regs *regs,
/* get MSR separately, transfer the LE bit if doing signal return */
err |= __get_user(msr, &sc->gp_regs[PT_MSR]);
+ /* Don't allow reserved mode. */
+ if (MSR_TM_RESV(msr))
+ return -EINVAL;
+
/* pull in MSR TM from user context */
regs->msr = (regs->msr & ~MSR_TS_MASK) | (msr & MSR_TS_MASK);