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-rw-r--r--Documentation/powerpc/transactional_memory.txt19
-rw-r--r--arch/powerpc/include/asm/processor.h13
-rw-r--r--arch/powerpc/include/asm/signal.h3
-rw-r--r--arch/powerpc/kernel/signal.c40
-rw-r--r--arch/powerpc/kernel/signal.h2
-rw-r--r--arch/powerpc/kernel/signal_32.c10
-rw-r--r--arch/powerpc/kernel/signal_64.c23
7 files changed, 74 insertions, 36 deletions
diff --git a/Documentation/powerpc/transactional_memory.txt b/Documentation/powerpc/transactional_memory.txt
index c54bf312765..dc23e58ae26 100644
--- a/Documentation/powerpc/transactional_memory.txt
+++ b/Documentation/powerpc/transactional_memory.txt
@@ -147,6 +147,25 @@ Example signal handler:
fix_the_problem(ucp->dar);
}
+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.
+
Failure cause codes used by kernel
==================================
diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index 594db6bc093..14a65836369 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -409,21 +409,16 @@ static inline void prefetchw(const void *x)
#endif
#ifdef CONFIG_PPC64
-static inline unsigned long get_clean_sp(struct pt_regs *regs, int is_32)
+static inline unsigned long get_clean_sp(unsigned long sp, int is_32)
{
- unsigned long sp;
-
if (is_32)
- sp = regs->gpr[1] & 0x0ffffffffUL;
- else
- sp = regs->gpr[1];
-
+ return sp & 0x0ffffffffUL;
return sp;
}
#else
-static inline unsigned long get_clean_sp(struct pt_regs *regs, int is_32)
+static inline unsigned long get_clean_sp(unsigned long sp, int is_32)
{
- return regs->gpr[1];
+ return sp;
}
#endif
diff --git a/arch/powerpc/include/asm/signal.h b/arch/powerpc/include/asm/signal.h
index fbe66c46389..9322c28aebd 100644
--- a/arch/powerpc/include/asm/signal.h
+++ b/arch/powerpc/include/asm/signal.h
@@ -3,5 +3,8 @@
#define __ARCH_HAS_SA_RESTORER
#include <uapi/asm/signal.h>
+#include <uapi/asm/ptrace.h>
+
+extern unsigned long get_tm_stackpointer(struct pt_regs *regs);
#endif /* _ASM_POWERPC_SIGNAL_H */
diff --git a/arch/powerpc/kernel/signal.c b/arch/powerpc/kernel/signal.c
index 577a8aa69c6..457e97aa294 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];
+}
diff --git a/arch/powerpc/kernel/signal.h b/arch/powerpc/kernel/signal.h
index ec84c901cea..c69b9aeb9f2 100644
--- a/arch/powerpc/kernel/signal.h
+++ b/arch/powerpc/kernel/signal.h
@@ -12,7 +12,7 @@
extern void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags);
-extern void __user * get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
+extern void __user * get_sigframe(struct k_sigaction *ka, unsigned long sp,
size_t frame_size, int is_32);
extern int handle_signal32(unsigned long sig, struct k_sigaction *ka,
diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
index 95068bf569a..201385c3a1a 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;
diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
index c1794286098..345947367ec 100644
--- a/arch/powerpc/kernel/signal_64.c
+++ b/arch/powerpc/kernel/signal_64.c
@@ -154,11 +154,12 @@ static long setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
* As above, but Transactional Memory is in use, so deliver sigcontexts
* containing checkpointed and transactional register states.
*
- * To do this, we treclaim to gather both sets of registers and set up the
- * 'normal' sigcontext registers with rolled-back register values such that a
- * simple signal handler sees a correct checkpointed register state.
- * If interested, a TM-aware sighandler can examine the transactional registers
- * in the 2nd sigcontext to determine the real origin of the signal.
+ * To do this, we treclaim (done before entering here) to gather both sets of
+ * registers and set up the 'normal' sigcontext registers with rolled-back
+ * register values such that a simple signal handler sees a correct
+ * checkpointed register state. If interested, a TM-aware sighandler can
+ * examine the transactional registers in the 2nd sigcontext to determine the
+ * real origin of the signal.
*/
static long setup_tm_sigcontexts(struct sigcontext __user *sc,
struct sigcontext __user *tm_sc,
@@ -184,16 +185,6 @@ static long setup_tm_sigcontexts(struct sigcontext __user *sc,
BUG_ON(!MSR_TM_ACTIVE(regs->msr));
- /* tm_reclaim rolls back all reg states, saving checkpointed (older)
- * GPRs to thread.ckpt_regs and (if used) FPRs to (newer)
- * thread.transact_fp and/or VRs to (newer) thread.transact_vr.
- * THEN we save out FP/VRs, if necessary, to the checkpointed (older)
- * thread.fr[]/vr[]s. The transactional (newer) GPRs are on the
- * stack, in *regs.
- */
- tm_enable();
- tm_reclaim(&current->thread, msr, TM_CAUSE_SIGNAL);
-
flush_fp_to_thread(current);
#ifdef CONFIG_ALTIVEC
@@ -711,7 +702,7 @@ int handle_rt_signal64(int signr, struct k_sigaction *ka, siginfo_t *info,
unsigned long newsp = 0;
long err = 0;
- frame = get_sigframe(ka, regs, sizeof(*frame), 0);
+ frame = get_sigframe(ka, get_tm_stackpointer(regs), sizeof(*frame), 0);
if (unlikely(frame == NULL))
goto badframe;
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2024-11-16 15:44:07 +0000