[PATCH] uml: Fix skas0 stub return

It's wrong to pop a fixed number of words from stack before calling sigreturn,
as the number depends on what code is generated by the compiler for the start
of stub_segv_handler().  What we need is esp containing the address of
sigcontext.  So we explicitly load that pointer into esp.

Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/um/sys-i386/stub_segv.c

@@ -21,10 +21,10 @@ stub_segv_handler(int sig)
 	__asm__("movl %0, %%eax ; int $0x80": : "g" (__NR_getpid));
 	__asm__("movl %%eax, %%ebx ; movl %0, %%eax ; movl %1, %%ecx ;"
 		"int $0x80": : "g" (__NR_kill), "g" (SIGUSR1));
-	/* Pop the frame pointer and return address since we need to leave
+	/* Load pointer to sigcontext into esp, since we need to leave
 	 * the stack in its original form when we do the sigreturn here, by
 	 * hand.
 	 */
-	__asm__("popl %%eax ; popl %%eax ; popl %%eax ; movl %0, %%eax ; "
-		"int $0x80" : : "g" (__NR_sigreturn));
+	__asm__("mov %0,%%esp ; movl %1, %%eax ; "
+		"int $0x80" : : "a" (sc), "g" (__NR_sigreturn));
 }