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authorPaul Mackerras <paulus@samba.org>2014-01-13 04:56:30 (GMT)
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2014-01-15 02:59:14 (GMT)
commit3ac8ff1c475bda7174fce63230c0932454287cd5 (patch)
tree080d06818982dfad75939133faa4ac34be6f348d /arch/powerpc
parentd31626f70b6103f4d9153b75d07e0e8795728cc9 (diff)
powerpc: Fix transactional FP/VMX/VSX unavailable handlers
Currently, if a process starts a transaction and then takes an exception because the FPU, VMX or VSX unit is unavailable to it, we end up corrupting any FP/VMX/VSX state that was valid before the interrupt. For example, if the process starts a transaction with the FPU available to it but VMX unavailable, and then does a VMX instruction inside the transaction, the FP state gets corrupted. Loading up the desired state generally involves doing a reclaim and a recheckpoint. To avoid corrupting already-valid state, we have to be careful not to reload that state from the thread_struct between the reclaim and the recheckpoint (since the thread_struct values are stale by now), and we have to reload that state from the transact_fp/vr arrays after the recheckpoint to get back the current transactional values saved there by the reclaim. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc')
-rw-r--r--arch/powerpc/kernel/traps.c45
1 files changed, 36 insertions, 9 deletions
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 26e1358..33cd7a0 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -1416,11 +1416,19 @@ void fp_unavailable_tm(struct pt_regs *regs)
/* This loads and recheckpoints the FP registers from
* thread.fpr[]. They will remain in registers after the
* checkpoint so we don't need to reload them after.
+ * If VMX is in use, the VRs now hold checkpointed values,
+ * so we don't want to load the VRs from the thread_struct.
*/
- tm_recheckpoint(&current->thread, regs->msr);
+ tm_recheckpoint(&current->thread, MSR_FP);
+
+ /* If VMX is in use, get the transactional values back */
+ if (regs->msr & MSR_VEC) {
+ do_load_up_transact_altivec(&current->thread);
+ /* At this point all the VSX state is loaded, so enable it */
+ regs->msr |= MSR_VSX;
+ }
}
-#ifdef CONFIG_ALTIVEC
void altivec_unavailable_tm(struct pt_regs *regs)
{
/* See the comments in fp_unavailable_tm(). This function operates
@@ -1432,14 +1440,19 @@ void altivec_unavailable_tm(struct pt_regs *regs)
regs->nip, regs->msr);
tm_reclaim_current(TM_CAUSE_FAC_UNAV);
regs->msr |= MSR_VEC;
- tm_recheckpoint(&current->thread, regs->msr);
+ tm_recheckpoint(&current->thread, MSR_VEC);
current->thread.used_vr = 1;
+
+ if (regs->msr & MSR_FP) {
+ do_load_up_transact_fpu(&current->thread);
+ regs->msr |= MSR_VSX;
+ }
}
-#endif
-#ifdef CONFIG_VSX
void vsx_unavailable_tm(struct pt_regs *regs)
{
+ unsigned long orig_msr = regs->msr;
+
/* See the comments in fp_unavailable_tm(). This works similarly,
* though we're loading both FP and VEC registers in here.
*
@@ -1451,16 +1464,30 @@ void vsx_unavailable_tm(struct pt_regs *regs)
"MSR=%lx\n",
regs->nip, regs->msr);
+ current->thread.used_vsr = 1;
+
+ /* If FP and VMX are already loaded, we have all the state we need */
+ if ((orig_msr & (MSR_FP | MSR_VEC)) == (MSR_FP | MSR_VEC)) {
+ regs->msr |= MSR_VSX;
+ return;
+ }
+
/* This reclaims FP and/or VR regs if they're already enabled */
tm_reclaim_current(TM_CAUSE_FAC_UNAV);
regs->msr |= MSR_VEC | MSR_FP | current->thread.fpexc_mode |
MSR_VSX;
- /* This loads & recheckpoints FP and VRs. */
- tm_recheckpoint(&current->thread, regs->msr);
- current->thread.used_vsr = 1;
+
+ /* This loads & recheckpoints FP and VRs; but we have
+ * to be sure not to overwrite previously-valid state.
+ */
+ tm_recheckpoint(&current->thread, regs->msr & ~orig_msr);
+
+ if (orig_msr & MSR_FP)
+ do_load_up_transact_fpu(&current->thread);
+ if (orig_msr & MSR_VEC)
+ do_load_up_transact_altivec(&current->thread);
}
-#endif
#endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
void performance_monitor_exception(struct pt_regs *regs)

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