3 files changed, 48 insertions, 2 deletions

diff --git a/arch/um/sys-i386/Makefile b/arch/um/sys-i386/Makefile
index 095bcdb0b9cc..77c3c4d29f55 100644
--- a/arch/um/sys-i386/Makefile
+++ b/arch/um/sys-i386/Makefile
@@ -1,6 +1,6 @@
 obj-y = bitops.o bugs.o checksum.o delay.o fault.o ksyms.o ldt.o ptrace.o \
-        ptrace_user.o semaphore.o signal.o sigcontext.o syscalls.o sysrq.o \
-        sys_call_table.o
+        ptrace_user.o semaphore.o signal.o sigcontext.o stub.o stub_segv.o \
+        syscalls.o sysrq.o sys_call_table.o
 
 obj-$(CONFIG_HIGHMEM) += highmem.o
 obj-$(CONFIG_MODULES) += module.o
@@ -16,6 +16,14 @@ semaphore.c-dir = kernel
 highmem.c-dir = mm
 module.c-dir = kernel
 
+STUB_CFLAGS = -Wp,-MD,$(depfile) $(call unprofile,$(USER_CFLAGS))
+
+# _cflags works with kernel files, not with userspace ones, but c_flags does,
+# why ask why?
+$(obj)/stub_segv.o : c_flags = $(STUB_CFLAGS)
+
+$(obj)/stub.o : a_flags = $(STUB_CFLAGS)
+
 subdir- := util
 
 include arch/um/scripts/Makefile.unmap
diff --git a/arch/um/sys-i386/stub.S b/arch/um/sys-i386/stub.S
new file mode 100644
index 000000000000..2f2c70a8f043
--- /dev/null
+++ b/arch/um/sys-i386/stub.S
@@ -0,0 +1,8 @@
+#include "uml-config.h"
+
+        .globl syscall_stub
+.section .__syscall_stub, "x"
+syscall_stub:
+        int     $0x80
+        mov     %eax, UML_CONFIG_STUB_DATA
+        int3
diff --git a/arch/um/sys-i386/stub_segv.c b/arch/um/sys-i386/stub_segv.c
new file mode 100644
index 000000000000..b251442ad0b1
--- /dev/null
+++ b/arch/um/sys-i386/stub_segv.c
@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) 2004 Jeff Dike (jdike@addtoit.com)
+ * Licensed under the GPL
+ */
+
+#include <signal.h>
+#include <asm/sigcontext.h>
+#include <asm/unistd.h>
+#include "uml-config.h"
+#include "sysdep/sigcontext.h"
+#include "sysdep/faultinfo.h"
+
+void __attribute__ ((__section__ (".__syscall_stub")))
+stub_segv_handler(int sig)
+{
+        struct sigcontext *sc = (struct sigcontext *) (&sig + 1);
+
+        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));
+        /* Pop the frame pointer and return address since we need to leave
+         * the stack in its original form when we do the sigreturn here, by
+         * hand.
+         */
+        __asm__("popl %%eax ; popl %%eax ; popl %%eax ; movl %0, %%eax ; "
+                "int $0x80" : : "g" (__NR_sigreturn));
+}