sparc: Stash orig_i0 into %g6 instead of %g2
As per the comments added by this commit, %g2 turns out to not be a
usable place to save away orig_i0 for syscall restart handling.
In fact all of %g2, %g3, %g4, and %g5 are assumed to be saved across
a system call by various bits of code in glibc.
%g1 can't be used because that holds the syscall number, which would
need to be saved and restored for syscall restart handling too, and
that would only compound our problems :-)
This leaves us with %g6 and %g7 which are for "system use". %g7 is
used as the "thread register" by glibc, but %g6 is used as a compiler
and assembler temporary scratch register. And in no instance is %g6
used to hold a value across a system call.
Therefore %g6 is safe for storing away orig_i0, at least for now.
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/arch/sparc/kernel/signal32.c b/arch/sparc/kernel/signal32.c
index 2e86fd1..023b886 100644
--- a/arch/sparc/kernel/signal32.c
+++ b/arch/sparc/kernel/signal32.c
@@ -837,7 +837,7 @@
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) {