powerpc: Fix various syscall/signal/swapcontext bugs
A careful reading of the recent changes to the system call entry/exit
paths revealed several problems, plus some things that could be
simplified and improved:
* 32-bit wasn't testing the _TIF_NOERROR bit in the syscall fast exit
path, so it was only doing anything with it once it saw some other
bit being set. In other words, the noerror behaviour would apply to
the next system call where we had to reschedule or deliver a signal,
which is not necessarily the current system call.
* 32-bit wasn't doing the call to ptrace_notify in the syscall exit
path when the _TIF_SINGLESTEP bit was set.
* _TIF_RESTOREALL was in both _TIF_USER_WORK_MASK and
_TIF_PERSYSCALL_MASK, which is odd since _TIF_RESTOREALL is only set
by system calls. I took it out of _TIF_USER_WORK_MASK.
* On 64-bit, _TIF_RESTOREALL wasn't causing the non-volatile registers
to be restored (unless perhaps a signal was delivered or the syscall
was traced or single-stepped). Thus the non-volatile registers
weren't restored on exit from a signal handler. We probably got
away with it mostly because signal handlers written in C wouldn't
alter the non-volatile registers.
* On 32-bit I simplified the code and made it more like 64-bit by
making the syscall exit path jump to ret_from_except to handle
preemption and signal delivery.
* 32-bit was calling do_signal unnecessarily when _TIF_RESTOREALL was
set - but I think because of that 32-bit was actually restoring the
non-volatile registers on exit from a signal handler.
* I changed the order of enabling interrupts and saving the
non-volatile registers before calling do_syscall_trace_leave; now we
enable interrupts first.
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/include/asm-powerpc/thread_info.h b/include/asm-powerpc/thread_info.h
index 237fc2b..ffc7462 100644
--- a/include/asm-powerpc/thread_info.h
+++ b/include/asm-powerpc/thread_info.h
@@ -37,7 +37,6 @@
int preempt_count; /* 0 => preemptable,
<0 => BUG */
struct restart_block restart_block;
- void __user *nvgprs_frame;
/* low level flags - has atomic operations done on it */
unsigned long flags ____cacheline_aligned_in_smp;
};
@@ -120,7 +119,6 @@
#define TIF_MEMDIE 10
#define TIF_SECCOMP 11 /* secure computing */
#define TIF_RESTOREALL 12 /* Restore all regs (implies NOERROR) */
-#define TIF_SAVE_NVGPRS 13 /* Save r14-r31 in signal frame */
#define TIF_NOERROR 14 /* Force successful syscall return */
#define TIF_RESTORE_SIGMASK 15 /* Restore signal mask in do_signal */
@@ -137,15 +135,13 @@
#define _TIF_SINGLESTEP (1<<TIF_SINGLESTEP)
#define _TIF_SECCOMP (1<<TIF_SECCOMP)
#define _TIF_RESTOREALL (1<<TIF_RESTOREALL)
-#define _TIF_SAVE_NVGPRS (1<<TIF_SAVE_NVGPRS)
#define _TIF_NOERROR (1<<TIF_NOERROR)
#define _TIF_RESTORE_SIGMASK (1<<TIF_RESTORE_SIGMASK)
#define _TIF_SYSCALL_T_OR_A (_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SECCOMP)
#define _TIF_USER_WORK_MASK (_TIF_NOTIFY_RESUME | _TIF_SIGPENDING | \
- _TIF_NEED_RESCHED | _TIF_RESTOREALL | \
- _TIF_RESTORE_SIGMASK)
-#define _TIF_PERSYSCALL_MASK (_TIF_RESTOREALL|_TIF_NOERROR|_TIF_SAVE_NVGPRS)
+ _TIF_NEED_RESCHED | _TIF_RESTORE_SIGMASK)
+#define _TIF_PERSYSCALL_MASK (_TIF_RESTOREALL|_TIF_NOERROR)
#endif /* __KERNEL__ */