[PATCH 3.12 136/182] powerpc/tm: Disable IRQ in tm_recheckpoint

From: Jiri Slaby
Date: Tue May 13 2014 - 06:18:18 EST

From: Michael Neuling <mikey@xxxxxxxxxxx>

3.12-stable review patch. If anyone has any objections, please let me know.

===============

commit e6b8fd028b584ffca7a7255b8971f254932c9fce upstream.

We can't take an IRQ when we're about to do a trechkpt as our GPR state is set
to user GPR values.

We've hit this when running some IBM Java stress tests in the lab resulting in
the following dump:

cpu 0x3f: Vector: 700 (Program Check) at [c000000007eb3d40]
pc: c000000000050074: restore_gprs+0xc0/0x148
lr: 00000000b52a8184
sp: ac57d360
msr: 8000000100201030
current = 0xc00000002c500000
paca = 0xc000000007dbfc00 softe: 0 irq_happened: 0x00
pid = 34535, comm = Pooled Thread #
R00 = 00000000b52a8184 R16 = 00000000b3e48fda
R01 = 00000000ac57d360 R17 = 00000000ade79bd8
R02 = 00000000ac586930 R18 = 000000000fac9bcc
R03 = 00000000ade60000 R19 = 00000000ac57f930
R04 = 00000000f6624918 R20 = 00000000ade79be8
R05 = 00000000f663f238 R21 = 00000000ac218a54
R06 = 0000000000000002 R22 = 000000000f956280
R07 = 0000000000000008 R23 = 000000000000007e
R08 = 000000000000000a R24 = 000000000000000c
R09 = 00000000b6e69160 R25 = 00000000b424cf00
R10 = 0000000000000181 R26 = 00000000f66256d4
R11 = 000000000f365ec0 R27 = 00000000b6fdcdd0
R12 = 00000000f66400f0 R28 = 0000000000000001
R13 = 00000000ada71900 R29 = 00000000ade5a300
R14 = 00000000ac2185a8 R30 = 00000000f663f238
R15 = 0000000000000004 R31 = 00000000f6624918
pc = c000000000050074 restore_gprs+0xc0/0x148
cfar= c00000000004fe28 dont_restore_vec+0x1c/0x1a4
lr = 00000000b52a8184
msr = 8000000100201030 cr = 24804888
ctr = 0000000000000000 xer = 0000000000000000 trap = 700

This moves tm_recheckpoint to a C function and moves the tm_restore_sprs into
that function. It then adds IRQ disabling over the trechkpt critical section.
It also sets the TEXASR FS in the signals code to ensure this is never set now
that we explictly write the TM sprs in tm_recheckpoint.

Signed-off-by: Michael Neuling <mikey@xxxxxxxxxxx>
Signed-off-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
arch/powerpc/include/asm/reg.h | 1 +
arch/powerpc/kernel/process.c | 34 ++++++++++++++++++++++++++++------
arch/powerpc/kernel/signal_32.c | 2 ++
arch/powerpc/kernel/signal_64.c | 2 ++
arch/powerpc/kernel/tm.S | 2 +-
5 files changed, 34 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index 7ca729cac073..cb9c1740cee0 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -208,6 +208,7 @@
#define SPRN_ACOP 0x1F /* Available Coprocessor Register */
#define SPRN_TFIAR 0x81 /* Transaction Failure Inst Addr */
#define SPRN_TEXASR 0x82 /* Transaction EXception & Summary */
+#define TEXASR_FS __MASK(63-36) /* Transaction Failure Summary */
#define SPRN_TEXASRU 0x83 /* '' '' '' Upper 32 */
#define SPRN_TFHAR 0x80 /* Transaction Failure Handler Addr */
#define SPRN_CTRLF 0x088
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index aa75b2beba7d..f1106103634b 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -525,6 +525,31 @@ out_and_saveregs:
tm_save_sprs(thr);
}

+extern void __tm_recheckpoint(struct thread_struct *thread,
+ unsigned long orig_msr);
+
+void tm_recheckpoint(struct thread_struct *thread,
+ unsigned long orig_msr)
+{
+ unsigned long flags;
+
+ /* We really can't be interrupted here as the TEXASR registers can't
+ * change and later in the trecheckpoint code, we have a userspace R1.
+ * So let's hard disable over this region.
+ */
+ local_irq_save(flags);
+ hard_irq_disable();
+
+ /* The TM SPRs are restored here, so that TEXASR.FS can be set
+ * before the trecheckpoint and no explosion occurs.
+ */
+ tm_restore_sprs(thread);
+
+ __tm_recheckpoint(thread, orig_msr);
+
+ local_irq_restore(flags);
+}
+
static inline void tm_recheckpoint_new_task(struct task_struct *new)
{
unsigned long msr;
@@ -543,13 +568,10 @@ static inline void tm_recheckpoint_new_task(struct task_struct *new)
if (!new->thread.regs)
return;

- /* The TM SPRs are restored here, so that TEXASR.FS can be set
- * before the trecheckpoint and no explosion occurs.
- */
- tm_restore_sprs(&new->thread);
-
- if (!MSR_TM_ACTIVE(new->thread.regs->msr))
+ if (!MSR_TM_ACTIVE(new->thread.regs->msr)){
+ tm_restore_sprs(&new->thread);
return;
+ }
msr = new->thread.tm_orig_msr;
/* Recheckpoint to restore original checkpointed register state. */
TM_DEBUG("*** tm_recheckpoint of pid %d "
diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
index fea2dba1226c..50606e4261a1 100644
--- a/arch/powerpc/kernel/signal_32.c
+++ b/arch/powerpc/kernel/signal_32.c
@@ -872,6 +872,8 @@ static long restore_tm_user_regs(struct pt_regs *regs,
* transactional versions should be loaded.
*/
tm_enable();
+ /* Make sure the transaction is marked as failed */
+ 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 */
diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
index 36b1d1daa236..4456779dba1c 100644
--- a/arch/powerpc/kernel/signal_64.c
+++ b/arch/powerpc/kernel/signal_64.c
@@ -519,6 +519,8 @@ static long restore_tm_sigcontexts(struct pt_regs *regs,
}
#endif
tm_enable();
+ /* Make sure the transaction is marked as failed */
+ current->thread.tm_texasr |= TEXASR_FS;
/* This loads the checkpointed FP/VEC state, if used */
tm_recheckpoint(&current->thread, msr);

diff --git a/arch/powerpc/kernel/tm.S b/arch/powerpc/kernel/tm.S
index cd809eaa8b5c..8b0518519f9f 100644
--- a/arch/powerpc/kernel/tm.S
+++ b/arch/powerpc/kernel/tm.S
@@ -306,7 +306,7 @@ dont_backup_fp:
* Call with IRQs off, stacks get all out of sync for
* some periods in here!
*/
-_GLOBAL(tm_recheckpoint)
+_GLOBAL(__tm_recheckpoint)
mfcr r5
mflr r0
std r5, 8(r1)
--
1.9.3

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/