sparc: Allow handling signals when stack is corrupted.

If we can't push the pending register windows onto the user's stack,
we disallow signal delivery even if the signal would be delivered on a
valid seperate signal stack.

Add a register window save area in the signal frame, and store any
unsavable windows there.

On sigreturn, if any windows are still queued up in the signal frame,
try to push them back onto the stack and if that fails we kill the
process immediately.

This allows the debug/tst-longjmp_chk2 glibc test case to pass.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 14 insertions, 0 deletions

diff --git a/arch/sparc/include/asm/sigcontext.h b/arch/sparc/include/asm/sigcontext.h
index a1607d18..69914d7 100644
--- a/arch/sparc/include/asm/sigcontext.h
+++ b/arch/sparc/include/asm/sigcontext.h
@@ -45,6 +45,19 @@ typedef struct {
 	int			si_mask;
 } __siginfo32_t;
 
+#define __SIGC_MAXWIN	7
+
+typedef struct {
+	unsigned long locals[8];
+	unsigned long ins[8];
+} __siginfo_reg_window;
+
+typedef struct {
+	int			wsaved;
+	__siginfo_reg_window	reg_window[__SIGC_MAXWIN];
+	unsigned long		rwbuf_stkptrs[__SIGC_MAXWIN];
+} __siginfo_rwin_t;
+
 #ifdef CONFIG_SPARC64
 typedef struct {
 	unsigned   int si_float_regs [64];
@@ -73,6 +86,7 @@ struct sigcontext {
 		unsigned long	ss_size;
 	}			sigc_stack;
 	unsigned long		sigc_mask;
+	__siginfo_rwin_t *	sigc_rwin_save;
 };
 
 #else