50f72b5794
UML/x86_64 doesn't run when built with frame pointers disabled. There was an implicit frame pointer assumption in the stub segfault handler. With frame pointers disabled, UML dies on handling its first page fault. The container-of part of this is from Paolo Giarrusso <blaisorblade@yahoo.it>. Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
52 lines
1.5 KiB
C
52 lines
1.5 KiB
C
/*
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* Copyright (C) 2004 Jeff Dike (jdike@addtoit.com)
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* Licensed under the GPL
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*/
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#include <asm/signal.h>
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#include <linux/compiler.h>
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#include <asm/unistd.h>
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#include <asm/ucontext.h>
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#include "uml-config.h"
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#include "sysdep/sigcontext.h"
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#include "sysdep/faultinfo.h"
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#include <stddef.h>
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/* Copied from sys-x86_64/signal.c - Can't find an equivalent definition
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* in the libc headers anywhere.
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*/
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struct rt_sigframe
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{
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char *pretcode;
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struct ucontext uc;
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struct siginfo info;
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};
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/* Copied here from <linux/kernel.h> - we're userspace. */
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#define container_of(ptr, type, member) ({ \
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const typeof( ((type *)0)->member ) *__mptr = (ptr); \
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(type *)( (char *)__mptr - offsetof(type,member) );})
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void __attribute__ ((__section__ (".__syscall_stub")))
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stub_segv_handler(int sig)
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{
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struct ucontext *uc;
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__asm__("movq %%rdx, %0" : "=g" (uc) :);
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GET_FAULTINFO_FROM_SC(*((struct faultinfo *) UML_CONFIG_STUB_DATA),
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&uc->uc_mcontext);
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__asm__("movq %0, %%rax ; syscall": : "g" (__NR_getpid));
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__asm__("movq %%rax, %%rdi ; movq %0, %%rax ; movq %1, %%rsi ;"
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"syscall": : "g" (__NR_kill), "g" (SIGUSR1) :
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"%rdi", "%rax", "%rsi");
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/* sys_sigreturn expects that the stack pointer will be 8 bytes into
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* the signal frame. So, we use the ucontext pointer, which we know
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* already, to get the signal frame pointer, and add 8 to that.
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*/
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__asm__("movq %0, %%rsp": :
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"g" ((unsigned long) container_of(uc, struct rt_sigframe,
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uc) + 8));
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__asm__("movq %0, %%rax ; syscall" : : "g" (__NR_rt_sigreturn));
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}
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