diff options
| -rw-r--r-- | arch/um/sys-x86_64/stub_segv.c | 37 |
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)); } |