summaryrefslogtreecommitdiffstats
path: root/arch/powerpc/kernel/signal.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/powerpc/kernel/signal.c')
-rw-r--r--arch/powerpc/kernel/signal.c40
1 files changed, 38 insertions, 2 deletions
diff --git a/arch/powerpc/kernel/signal.c b/arch/powerpc/kernel/signal.c
index 577a8aa69c6e..457e97aa2945 100644
--- a/arch/powerpc/kernel/signal.c
+++ b/arch/powerpc/kernel/signal.c
@@ -18,6 +18,7 @@
#include <asm/uaccess.h>
#include <asm/unistd.h>
#include <asm/debug.h>
+#include <asm/tm.h>
#include "signal.h"
@@ -30,13 +31,13 @@ int show_unhandled_signals = 1;
/*
* Allocate space for the signal frame
*/
-void __user * get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
+void __user * get_sigframe(struct k_sigaction *ka, unsigned long sp,
size_t frame_size, int is_32)
{
unsigned long oldsp, newsp;
/* Default to using normal stack */
- oldsp = get_clean_sp(regs, is_32);
+ oldsp = get_clean_sp(sp, is_32);
/* Check for alt stack */
if ((ka->sa.sa_flags & SA_ONSTACK) &&
@@ -175,3 +176,38 @@ void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
user_enter();
}
+
+unsigned long get_tm_stackpointer(struct pt_regs *regs)
+{
+ /* 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.
+ */
+
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+ if (MSR_TM_ACTIVE(regs->msr)) {
+ tm_enable();
+ tm_reclaim(&current->thread, regs->msr, TM_CAUSE_SIGNAL);
+ if (MSR_TM_TRANSACTIONAL(regs->msr))
+ return current->thread.ckpt_regs.gpr[1];
+ }
+#endif
+ return regs->gpr[1];
+}