1 files changed, 28 insertions, 9 deletions

diff --git a/arch/um/sys-x86_64/stub_segv.c b/arch/um/sys-x86_64/stub_segv.c
index 65a131b362b6..d1e53bdf2e85 100644
--- a/arch/um/sys-x86_64/stub_segv.c
+++ b/arch/um/sys-x86_64/stub_segv.c
@@ -10,6 +10,22 @@
 #include "uml-config.h"
 #include "sysdep/sigcontext.h"
 #include "sysdep/faultinfo.h"
+#include <stddef.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)
@@ -17,16 +33,19 @@ stub_segv_handler(int sig)
         struct ucontext *uc;
 
         __asm__("movq %%rdx, %0" : "=g" (uc) :);
-        GET_FAULTINFO_FROM_SC(*((struct faultinfo *) UML_CONFIG_STUB_DATA),
-                              &uc->uc_mcontext);
+        GET_FAULTINFO_FROM_SC(*((struct faultinfo *) UML_CONFIG_STUB_DATA),
+                              &uc->uc_mcontext);
 
-        __asm__("movq %0, %%rax ; syscall": : "g" (__NR_getpid));
+        __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.
+                "syscall": : "g" (__NR_kill), "g" (SIGUSR1) : 
+                "%rdi", "%rax", "%rsi");
+        /* 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__("movq %0, %%rsp": : 
+                "g" ((unsigned long) container_of(uc, struct rt_sigframe, 
+                                                  uc) + 8));
+        __asm__("movq %0, %%rax ; syscall" : : "g" (__NR_rt_sigreturn));
 }