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Diffstat (limited to 'arch')
-rw-r--r--arch/um/sys-x86_64/stub_segv.c37
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));
}