diff options
Diffstat (limited to 'arch/um/sys-x86_64/stub_segv.c')
-rw-r--r-- | arch/um/sys-x86_64/stub_segv.c | 43 |
1 files changed, 31 insertions, 12 deletions
diff --git a/arch/um/sys-x86_64/stub_segv.c b/arch/um/sys-x86_64/stub_segv.c index 65a131b362b..a2709953319 100644 --- a/arch/um/sys-x86_64/stub_segv.c +++ b/arch/um/sys-x86_64/stub_segv.c @@ -3,30 +3,49 @@ * Licensed under the GPL */ -#include <asm/signal.h> +#include <stddef.h> +#include <signal.h> #include <linux/compiler.h> #include <asm/unistd.h> -#include <asm/ucontext.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__("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); + + 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__("movq %0, %%rsp; movq %1, %%rax ; syscall": : + "g" ((unsigned long) container_of(uc, struct rt_sigframe, + uc) + 8), + "g" (__NR_rt_sigreturn)); } |