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-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 @@
10#include "uml-config.h" 10#include "uml-config.h"
11#include "sysdep/sigcontext.h" 11#include "sysdep/sigcontext.h"
12#include "sysdep/faultinfo.h" 12#include "sysdep/faultinfo.h"
13#include <stddef.h>
14
15/* Copied from sys-x86_64/signal.c - Can't find an equivalent definition
16 * in the libc headers anywhere.
17 */
18struct rt_sigframe
19{
20 char *pretcode;
21 struct ucontext uc;
22 struct siginfo info;
23};
24
25/* Copied here from <linux/kernel.h> - we're userspace. */
26#define container_of(ptr, type, member) ({ \
27 const typeof( ((type *)0)->member ) *__mptr = (ptr); \
28 (type *)( (char *)__mptr - offsetof(type,member) );})
13 29
14void __attribute__ ((__section__ (".__syscall_stub"))) 30void __attribute__ ((__section__ (".__syscall_stub")))
15stub_segv_handler(int sig) 31stub_segv_handler(int sig)
@@ -17,16 +33,19 @@ stub_segv_handler(int sig)
17 struct ucontext *uc; 33 struct ucontext *uc;
18 34
19 __asm__("movq %%rdx, %0" : "=g" (uc) :); 35 __asm__("movq %%rdx, %0" : "=g" (uc) :);
20 GET_FAULTINFO_FROM_SC(*((struct faultinfo *) UML_CONFIG_STUB_DATA), 36 GET_FAULTINFO_FROM_SC(*((struct faultinfo *) UML_CONFIG_STUB_DATA),
21 &uc->uc_mcontext); 37 &uc->uc_mcontext);
22 38
23 __asm__("movq %0, %%rax ; syscall": : "g" (__NR_getpid)); 39 __asm__("movq %0, %%rax ; syscall": : "g" (__NR_getpid));
24 __asm__("movq %%rax, %%rdi ; movq %0, %%rax ; movq %1, %%rsi ;" 40 __asm__("movq %%rax, %%rdi ; movq %0, %%rax ; movq %1, %%rsi ;"
25 "syscall": : "g" (__NR_kill), "g" (SIGUSR1)); 41 "syscall": : "g" (__NR_kill), "g" (SIGUSR1) :
26 /* Two popqs to restore the stack to the state just before entering 42 "%rdi", "%rax", "%rsi");
27 * the handler, one pops the return address, the other pops the frame 43 /* sys_sigreturn expects that the stack pointer will be 8 bytes into
28 * pointer. 44 * the signal frame. So, we use the ucontext pointer, which we know
45 * already, to get the signal frame pointer, and add 8 to that.
29 */ 46 */
30 __asm__("popq %%rax ; popq %%rax ; movq %0, %%rax ; syscall" : : "g" 47 __asm__("movq %0, %%rsp": :
31 (__NR_rt_sigreturn)); 48 "g" ((unsigned long) container_of(uc, struct rt_sigframe,
49 uc) + 8));
50 __asm__("movq %0, %%rax ; syscall" : : "g" (__NR_rt_sigreturn));
32} 51}