diff options
Diffstat (limited to 'arch/sparc/kernel/signal_64.c')
| -rw-r--r-- | arch/sparc/kernel/signal_64.c | 20 |
1 files changed, 15 insertions, 5 deletions
diff --git a/arch/sparc/kernel/signal_64.c b/arch/sparc/kernel/signal_64.c index 1ddf0dedb92..f0836cd0e2f 100644 --- a/arch/sparc/kernel/signal_64.c +++ b/arch/sparc/kernel/signal_64.c @@ -533,13 +533,23 @@ static void do_signal(struct pt_regs *regs, unsigned long orig_i0) * register for GDB to save and restore in order to get * orig_i0 correct for syscall restarts when debugging. * - * However, we luckily can use the fact that several registers - * are volatile across system calls. One such register is - * %g2, so use that as a place to save away orig_i0. + * 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))) - regs->u_regs[UREG_G2] = orig_i0; + regs->u_regs[UREG_G6] = orig_i0; if (current_thread_info()->status & TS_RESTORE_SIGMASK) oldset = ¤t->saved_sigmask; @@ -560,7 +570,7 @@ static void do_signal(struct pt_regs *regs, unsigned long orig_i0) if (pt_regs_is_syscall(regs) && (regs->tstate & (TSTATE_XCARRY | TSTATE_ICARRY))) { restart_syscall = 1; - orig_i0 = regs->u_regs[UREG_G2]; + orig_i0 = regs->u_regs[UREG_G6]; } if (signr > 0) { |