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authorMichael Neuling <mikey@neuling.org>2013-05-26 18:09:41 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2013-06-01 08:29:23 +1000
commit2b3f8e87cf99a33fb6faf5026d7147748bbd77b6 (patch)
treedfeb4cb63821ec34279d26b0ac7a35d96316b648 /arch/powerpc/kernel/signal_32.c
parentb75c100ef24894bd2c8b52e123bcc5f191c5d9fd (diff)
downloadlinux-2b3f8e87cf99a33fb6faf5026d7147748bbd77b6.tar.bz2
powerpc/tm: Fix userspace stack corruption on signal delivery for active transactions
When in an active transaction that takes a signal, we need to be careful with the stack. It's possible that the stack has moved back up after the tbegin. The obvious case here is when the tbegin is called inside a function that returns before a tend. In this case, the stack is part of the checkpointed transactional memory state. If we write over this non transactionally or in suspend, we are in trouble because if we get a tm abort, the program counter and stack pointer will be back at the tbegin but our in memory stack won't be valid anymore. To avoid this, when taking a signal in an active transaction, we need to use the stack pointer from the checkpointed state, rather than the speculated state. This ensures that the signal context (written tm suspended) will be written below the stack required for the rollback. The transaction is aborted becuase of the treclaim, so any memory written between the tbegin and the signal will be rolled back anyway. For signals taken in non-TM or suspended mode, we use the normal/non-checkpointed stack pointer. Tested with 64 and 32 bit signals Signed-off-by: Michael Neuling <mikey@neuling.org> Cc: <stable@vger.kernel.org> # v3.9 Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/kernel/signal_32.c')
-rw-r--r--arch/powerpc/kernel/signal_32.c10
1 files changed, 2 insertions, 8 deletions
diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
index 95068bf569ad..201385c3a1ae 100644
--- a/arch/powerpc/kernel/signal_32.c
+++ b/arch/powerpc/kernel/signal_32.c
@@ -503,12 +503,6 @@ static int save_tm_user_regs(struct pt_regs *regs,
{
unsigned long msr = regs->msr;
- /* tm_reclaim rolls back all reg states, updating thread.ckpt_regs,
- * thread.transact_fpr[], thread.transact_vr[], etc.
- */
- tm_enable();
- tm_reclaim(&current->thread, msr, TM_CAUSE_SIGNAL);
-
/* Make sure floating point registers are stored in regs */
flush_fp_to_thread(current);
@@ -965,7 +959,7 @@ int handle_rt_signal32(unsigned long sig, struct k_sigaction *ka,
/* Set up Signal Frame */
/* Put a Real Time Context onto stack */
- rt_sf = get_sigframe(ka, regs, sizeof(*rt_sf), 1);
+ rt_sf = get_sigframe(ka, get_tm_stackpointer(regs), sizeof(*rt_sf), 1);
addr = rt_sf;
if (unlikely(rt_sf == NULL))
goto badframe;
@@ -1403,7 +1397,7 @@ int handle_signal32(unsigned long sig, struct k_sigaction *ka,
unsigned long tramp;
/* Set up Signal Frame */
- frame = get_sigframe(ka, regs, sizeof(*frame), 1);
+ frame = get_sigframe(ka, get_tm_stackpointer(regs), sizeof(*frame), 1);
if (unlikely(frame == NULL))
goto badframe;
sc = (struct sigcontext __user *) &frame->sctx;