[PATCH 3/4] UML - Properly invoke x86_64 system calls
From: Jeff Dike
Date: Thu Nov 17 2005 - 15:18:28 EST
This patch makes stub_segv use the stub_syscall macros. This was
needed anyway, but the bug that prompted this was the discovery that
gcc was storing stuff in RCX, which is trashed across a system
call. This is exactly the sort of problem that the new macros fix.
There is a stub_syscall0 for getpid.
stub_segv was changed to be a libc file, and that caused some
include changes.
Signed-off-by: Jeff Dike <jdike@xxxxxxxxxxx>
Index: linux-2.6.15/arch/um/include/sysdep-i386/stub.h
===================================================================
--- linux-2.6.15.orig/arch/um/include/sysdep-i386/stub.h 2005-11-17 14:59:30.000000000 -0500
+++ linux-2.6.15/arch/um/include/sysdep-i386/stub.h 2005-11-17 14:59:55.000000000 -0500
@@ -16,6 +16,15 @@
#define STUB_MMAP_NR __NR_mmap2
#define MMAP_OFFSET(o) ((o) >> PAGE_SHIFT)
+static inline long stub_syscall0(long syscall)
+{
+ long ret;
+
+ __asm__ volatile ("int $0x80" : "=a" (ret) : "0" (syscall));
+
+ return ret;
+}
+
static inline long stub_syscall1(long syscall, long arg1)
{
long ret;
Index: linux-2.6.15/arch/um/include/sysdep-x86_64/stub.h
===================================================================
--- linux-2.6.15.orig/arch/um/include/sysdep-x86_64/stub.h 2005-11-17 14:59:30.000000000 -0500
+++ linux-2.6.15/arch/um/include/sysdep-x86_64/stub.h 2005-11-17 14:59:55.000000000 -0500
@@ -6,7 +6,6 @@
#ifndef __SYSDEP_STUB_H
#define __SYSDEP_STUB_H
-#include <asm/ptrace.h>
#include <asm/unistd.h>
#include <sysdep/ptrace_user.h>
@@ -20,6 +19,17 @@
#define __syscall_clobber "r11","rcx","memory"
#define __syscall "syscall"
+static inline long stub_syscall0(long syscall)
+{
+ long ret;
+
+ __asm__ volatile (__syscall
+ : "=a" (ret)
+ : "0" (syscall) : __syscall_clobber );
+
+ return ret;
+}
+
static inline long stub_syscall2(long syscall, long arg1, long arg2)
{
long ret;
Index: linux-2.6.15/arch/um/sys-i386/Makefile
===================================================================
--- linux-2.6.15.orig/arch/um/sys-i386/Makefile 2005-11-17 14:59:30.000000000 -0500
+++ linux-2.6.15/arch/um/sys-i386/Makefile 2005-11-17 14:59:55.000000000 -0500
@@ -5,7 +5,7 @@
obj-$(CONFIG_HIGHMEM) += highmem.o
obj-$(CONFIG_MODULES) += module.o
-USER_OBJS := bugs.o ptrace_user.o sigcontext.o fault.o
+USER_OBJS := bugs.o ptrace_user.o sigcontext.o fault.o stub_segv.o
SYMLINKS = bitops.c semaphore.c highmem.c module.c
Index: linux-2.6.15/arch/um/sys-i386/stub_segv.c
===================================================================
--- linux-2.6.15.orig/arch/um/sys-i386/stub_segv.c 2005-11-17 14:59:30.000000000 -0500
+++ linux-2.6.15/arch/um/sys-i386/stub_segv.c 2005-11-17 14:59:55.000000000 -0500
@@ -3,9 +3,11 @@
* Licensed under the GPL
*/
-#include <asm/signal.h>
+#include <signal.h>
+#include <sys/select.h> /* The only way I can see to get sigset_t */
#include <asm/unistd.h>
#include "uml-config.h"
+#include "sysdep/stub.h"
#include "sysdep/sigcontext.h"
#include "sysdep/faultinfo.h"
@@ -13,13 +15,14 @@
stub_segv_handler(int sig)
{
struct sigcontext *sc = (struct sigcontext *) (&sig + 1);
+ int pid;
GET_FAULTINFO_FROM_SC(*((struct faultinfo *) UML_CONFIG_STUB_DATA),
sc);
- __asm__("movl %0, %%eax ; int $0x80": : "g" (__NR_getpid));
- __asm__("movl %%eax, %%ebx ; movl %0, %%eax ; movl %1, %%ecx ;"
- "int $0x80": : "g" (__NR_kill), "g" (SIGUSR1));
+ pid = stub_syscall0(__NR_getpid);
+ stub_syscall2(__NR_kill, pid, SIGUSR1);
+
/* Load pointer to sigcontext into esp, since we need to leave
* the stack in its original form when we do the sigreturn here, by
* hand.
Index: linux-2.6.15/arch/um/sys-x86_64/Makefile
===================================================================
--- linux-2.6.15.orig/arch/um/sys-x86_64/Makefile 2005-11-17 14:59:30.000000000 -0500
+++ linux-2.6.15/arch/um/sys-x86_64/Makefile 2005-11-17 14:59:55.000000000 -0500
@@ -12,7 +12,7 @@
obj-y := ksyms.o
obj-$(CONFIG_MODULES) += module.o um_module.o
-USER_OBJS := ptrace_user.o sigcontext.o
+USER_OBJS := ptrace_user.o sigcontext.o stub_segv.o
SYMLINKS = bitops.c csum-copy.S csum-partial.c csum-wrappers.c ldt.c memcpy.S \
thunk.S module.c
Index: linux-2.6.15/arch/um/sys-x86_64/stub_segv.c
===================================================================
--- linux-2.6.15.orig/arch/um/sys-x86_64/stub_segv.c 2005-11-17 14:59:30.000000000 -0500
+++ linux-2.6.15/arch/um/sys-x86_64/stub_segv.c 2005-11-17 15:12:23.000000000 -0500
@@ -3,14 +3,14 @@
* 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 <stddef.h>
+#include "sysdep/stub.h"
/* Copied from sys-x86_64/signal.c - Can't find an equivalent definition
* in the libc headers anywhere.
@@ -31,21 +31,21 @@
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);
- __asm__("movq %0, %%rax ; syscall": : "g" (__NR_getpid));
- __asm__("movq %%rax, %%rdi ; movq %0, %%rax ; movq %1, %%rsi ;"
- "syscall": : "g" (__NR_kill), "g" (SIGUSR1) :
- "%rdi", "%rax", "%rsi");
+ pid = stub_syscall0(__NR_getpid);
+ stub_syscall2(__NR_kill, pid, SIGUSR1);
+
/* 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__("movq %0, %%rsp": :
+ __asm__("movq %0, %%rsp; movq %1, %%rax ; syscall": :
"g" ((unsigned long) container_of(uc, struct rt_sigframe,
- uc) + 8));
- __asm__("movq %0, %%rax ; syscall" : : "g" (__NR_rt_sigreturn));
+ uc) + 8),
+ "g" (__NR_rt_sigreturn));
}
-
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