Pull novell-bugzilla-156426 into release branch

[pandora-kernel.git] / arch / um / sys-x86_64 / stub_segv.c

diff --git a/arch/um/sys-x86_64/stub_segv.c b/arch/um/sys-x86_64/stub_segv.c
index 161d1fe..1c96702 100644 (file)
--- a/arch/um/sys-x86_64/stub_segv.c
+++ b/arch/um/sys-x86_64/stub_segv.c
@@ -3,29 +3,49 @@
  * Licensed under the GPL
  */
 
+#include <stddef.h>
 #include <signal.h>
 #include <linux/compiler.h>
 #include <asm/unistd.h>
 #include "uml-config.h"
 #include "sysdep/sigcontext.h"
 #include "sysdep/faultinfo.h"
+#include "sysdep/stub.h"
+
+/* Copied from sys-x86_64/signal.c - Can't find an equivalent definition
+ * in the libc headers anywhere.
+ */
+struct rt_sigframe
+{
+       char *pretcode;
+       struct ucontext uc;
+       struct siginfo info;
+};
+
+/* Copied here from <linux/kernel.h> - we're userspace. */
+#define container_of(ptr, type, member) ({                   \
+       const typeof( ((type *)0)->member ) *__mptr = (ptr); \
+       (type *)( (char *)__mptr - offsetof(type,member) );})
 
 void __attribute__ ((__section__ (".__syscall_stub")))
 stub_segv_handler(int sig)
 {
        struct ucontext *uc;
+        int pid;
+
+       __asm__ __volatile__("movq %%rdx, %0" : "=g" (uc) :);
+       GET_FAULTINFO_FROM_SC(*((struct faultinfo *) UML_CONFIG_STUB_DATA),
+                             &uc->uc_mcontext);
 
-       __asm__("movq %%rdx, %0" : "=g" (uc) :);
-        GET_FAULTINFO_FROM_SC(*((struct faultinfo *) UML_CONFIG_STUB_DATA),
-                              &uc->uc_mcontext);
+       pid = stub_syscall0(__NR_getpid);
+       stub_syscall2(__NR_kill, pid, SIGUSR1);
 
-       __asm__("movq %0, %%rax ; syscall": : "g" (__NR_getpid));
-       __asm__("movq %%rax, %%rdi ; movq %0, %%rax ; movq %1, %%rsi ;"
-               "syscall": : "g" (__NR_kill), "g" (SIGUSR1));
-       /* Two popqs to restore the stack to the state just before entering
-        * the handler, one pops the return address, the other pops the frame
-        * pointer.
+       /* sys_sigreturn expects that the stack pointer will be 8 bytes into
+        * the signal frame.  So, we use the ucontext pointer, which we know
+        * already, to get the signal frame pointer, and add 8 to that.
         */
-       __asm__("popq %%rax ; popq %%rax ; movq %0, %%rax ; syscall" : : "g"
-               (__NR_rt_sigreturn));
+       __asm__ __volatile__("movq %0, %%rsp; movq %1, %%rax ; syscall": :
+                             "g" ((unsigned long)
+                                  container_of(uc, struct rt_sigframe, uc) + 8),
+                             "g" (__NR_rt_sigreturn));
 }