3 files changed, 46 insertions, 36 deletions

diff --git a/arch/um/include/sysdep-i386/stub.h b/arch/um/include/sysdep-i386/stub.h
index 6ba8cbbe0d36..b492b12b4a10 100644
--- a/arch/um/include/sysdep-i386/stub.h
+++ b/arch/um/include/sysdep-i386/stub.h
@@ -6,8 +6,12 @@
 #ifndef __SYSDEP_STUB_H
 #define __SYSDEP_STUB_H
 
+#include <sys/mman.h>
 #include <asm/ptrace.h>
 #include <asm/unistd.h>
+#include "stub-data.h"
+#include "kern_constants.h"
+#include "uml-config.h"
 
 extern void stub_segv_handler(int sig);
 extern void stub_clone_handler(void);
@@ -76,23 +80,22 @@ static inline long stub_syscall5(long syscall, long arg1, long arg2, long arg3,
         return ret;
 }
 
-static inline long stub_syscall6(long syscall, long arg1, long arg2, long arg3,
-                                 long arg4, long arg5, long arg6)
+static inline void trap_myself(void)
 {
-        long ret;
-
-        __asm__ volatile ("push %%ebp ; movl %%eax,%%ebp ; movl %1,%%eax ; "
-                        "int $0x80 ; pop %%ebp"
-                        : "=a" (ret)
-                        : "g" (syscall), "b" (arg1), "c" (arg2), "d" (arg3),
-                          "S" (arg4), "D" (arg5), "0" (arg6));
-
-        return ret;
+        __asm("int3");
 }
 
-static inline void trap_myself(void)
+static inline void remap_stack(int fd, unsigned long offset)
 {
-        __asm("int3");
+        __asm__ volatile ("movl %%eax,%%ebp ; movl %0,%%eax ; int $0x80 ;"
+                          "movl %7, %%ebx ; movl %%eax, (%%ebx)"
+                          : : "g" (STUB_MMAP_NR), "b" (UML_CONFIG_STUB_DATA), 
+                            "c" (UM_KERN_PAGE_SIZE), 
+                            "d" (PROT_READ | PROT_WRITE),
+                            "S" (MAP_FIXED | MAP_SHARED), "D" (fd), 
+                            "a" (offset), 
+                            "i" (&((struct stub_data *) UML_CONFIG_STUB_DATA)->err) 
+                          : "memory");
 }
 
 #endif
diff --git a/arch/um/include/sysdep-x86_64/stub.h b/arch/um/include/sysdep-x86_64/stub.h
index c41689c13dc9..92e989f81761 100644
--- a/arch/um/include/sysdep-x86_64/stub.h
+++ b/arch/um/include/sysdep-x86_64/stub.h
@@ -6,8 +6,12 @@
 #ifndef __SYSDEP_STUB_H
 #define __SYSDEP_STUB_H
 
+#include <sys/mman.h>
 #include <asm/unistd.h>
 #include <sysdep/ptrace_user.h>
+#include "stub-data.h"
+#include "kern_constants.h"
+#include "uml-config.h"
 
 extern void stub_segv_handler(int sig);
 extern void stub_clone_handler(void);
@@ -81,23 +85,23 @@ static inline long stub_syscall5(long syscall, long arg1, long arg2, long arg3,
         return ret;
 }
 
-static inline long stub_syscall6(long syscall, long arg1, long arg2, long arg3,
-                                 long arg4, long arg5, long arg6)
+static inline void trap_myself(void)
 {
-        long ret;
-
-        __asm__ volatile ("movq %5,%%r10 ; movq %6,%%r8 ; "
-                "movq %7, %%r9; " __syscall : "=a" (ret)
-                : "0" (syscall), "D" (arg1), "S" (arg2), "d" (arg3),
-                  "g" (arg4), "g" (arg5), "g" (arg6)
-                : __syscall_clobber, "r10", "r8", "r9" );
-
-        return ret;
+        __asm("int3");
 }
 
-static inline void trap_myself(void)
+static inline void remap_stack(long fd, unsigned long offset)
 {
-        __asm("int3");
+        __asm__ volatile ("movq %4,%%r10 ; movq %5,%%r8 ; "
+                          "movq %6, %%r9; " __syscall "; movq %7, %%rbx ; "
+                          "movq %%rax, (%%rbx)": 
+                          : "a" (STUB_MMAP_NR), "D" (UML_CONFIG_STUB_DATA), 
+                            "S" (UM_KERN_PAGE_SIZE), 
+                            "d" (PROT_READ | PROT_WRITE), 
+                            "g" (MAP_FIXED | MAP_SHARED), "g" (fd), 
+                            "g" (offset),
+                            "i" (&((struct stub_data *) UML_CONFIG_STUB_DATA)->err)
+                          : __syscall_clobber, "r10", "r8", "r9" );
 }
 
 #endif
diff --git a/arch/um/kernel/skas/clone.c b/arch/um/kernel/skas/clone.c
index cb37ce9124a6..47b812b3bca8 100644
--- a/arch/um/kernel/skas/clone.c
+++ b/arch/um/kernel/skas/clone.c
@@ -18,11 +18,10 @@
  * on some systems.
  */
 
-#define STUB_DATA(field) (((struct stub_data *) UML_CONFIG_STUB_DATA)->field)
-
 void __attribute__ ((__section__ (".__syscall_stub")))
 stub_clone_handler(void)
 {
+        struct stub_data *data = (struct stub_data *) UML_CONFIG_STUB_DATA;
         long err;
 
         err = stub_syscall2(__NR_clone, CLONE_PARENT | CLONE_FILES | SIGCHLD,
@@ -35,17 +34,21 @@ stub_clone_handler(void)
         if(err)
                 goto out;
 
-        err = stub_syscall3(__NR_setitimer, ITIMER_VIRTUAL,
-                            (long) &STUB_DATA(timer), 0);
+        err = stub_syscall3(__NR_setitimer, ITIMER_VIRTUAL, 
+                            (long) &data->timer, 0);
         if(err)
                 goto out;
 
-        err = stub_syscall6(STUB_MMAP_NR, UML_CONFIG_STUB_DATA,
-                            UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE,
-                            MAP_FIXED | MAP_SHARED, STUB_DATA(fd),
-                            STUB_DATA(offset));
+        remap_stack(data->fd, data->offset);
+        goto done;
+
  out:
-        /* save current result. Parent: pid; child: retcode of mmap */
-        STUB_DATA(err) = err;
+        /* save current result. 
+         * Parent: pid; 
+         * child: retcode of mmap already saved and it jumps around this 
+         * assignment
+         */
+        data->err = err;
+ done:
         trap_myself();
 }