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Diffstat (limited to 'arch/sparc/kernel/signal_64.c')
-rw-r--r--arch/sparc/kernel/signal_64.c42
1 files changed, 28 insertions, 14 deletions
diff --git a/arch/sparc/kernel/signal_64.c b/arch/sparc/kernel/signal_64.c
index a2b81598d905..f0836cd0e2f2 100644
--- a/arch/sparc/kernel/signal_64.c
+++ b/arch/sparc/kernel/signal_64.c
@@ -529,11 +529,27 @@ static void do_signal(struct pt_regs *regs, unsigned long orig_i0)
siginfo_t info;
int signr;
+ /* It's a lot of work and synchronization to add a new ptrace
+ * register for GDB to save and restore in order to get
+ * orig_i0 correct for syscall restarts when debugging.
+ *
+ * Although it should be the case that most of the global
+ * registers are volatile across a system call, glibc already
+ * depends upon that fact that we preserve them. So we can't
+ * just use any global register to save away the orig_i0 value.
+ *
+ * In particular %g2, %g3, %g4, and %g5 are all assumed to be
+ * preserved across a system call trap by various pieces of
+ * code in glibc.
+ *
+ * %g7 is used as the "thread register". %g6 is not used in
+ * any fixed manner. %g6 is used as a scratch register and
+ * a compiler temporary, but it's value is never used across
+ * a system call. Therefore %g6 is usable for orig_i0 storage.
+ */
if (pt_regs_is_syscall(regs) &&
- (regs->tstate & (TSTATE_XCARRY | TSTATE_ICARRY))) {
- restart_syscall = 1;
- } else
- restart_syscall = 0;
+ (regs->tstate & (TSTATE_XCARRY | TSTATE_ICARRY)))
+ regs->u_regs[UREG_G6] = orig_i0;
if (current_thread_info()->status & TS_RESTORE_SIGMASK)
oldset = &current->saved_sigmask;
@@ -542,22 +558,20 @@ static void do_signal(struct pt_regs *regs, unsigned long orig_i0)
#ifdef CONFIG_COMPAT
if (test_thread_flag(TIF_32BIT)) {
- extern void do_signal32(sigset_t *, struct pt_regs *,
- int restart_syscall,
- unsigned long orig_i0);
- do_signal32(oldset, regs, restart_syscall, orig_i0);
+ extern void do_signal32(sigset_t *, struct pt_regs *);
+ do_signal32(oldset, regs);
return;
}
#endif
signr = get_signal_to_deliver(&info, &ka, regs, NULL);
- /* If the debugger messes with the program counter, it clears
- * the software "in syscall" bit, directing us to not perform
- * a syscall restart.
- */
- if (restart_syscall && !pt_regs_is_syscall(regs))
- restart_syscall = 0;
+ restart_syscall = 0;
+ if (pt_regs_is_syscall(regs) &&
+ (regs->tstate & (TSTATE_XCARRY | TSTATE_ICARRY))) {
+ restart_syscall = 1;
+ orig_i0 = regs->u_regs[UREG_G6];
+ }
if (signr > 0) {
if (restart_syscall)