[PATCH] uml: move LDT creation

s390 doesn't have a LDT.  So MM_COPY_SEGMENTS will not be supported on s390.

The only user of MM_COPY_SEGMENTS is new_mm(), but that's no longer useful, as
arch/sys-i386/ldt.c defines init_new_ldt(), which is called immediately after
new_mm().  So we should copy host's LDT in init_new_ldt(), if /proc/mm is
available, to have this subarch specific call in subarch code.

Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 24 insertions, 2 deletions

diff --git a/arch/um/sys-i386/ldt.c b/arch/um/sys-i386/ldt.c
index 17746b4c08ff..0cdfd4481d5e 100644
--- a/arch/um/sys-i386/ldt.c
+++ b/arch/um/sys-i386/ldt.c
@@ -16,6 +16,8 @@
 #include "choose-mode.h"
 #include "kern.h"
 #include "mode_kern.h"
+#include "proc_mm.h"
+#include "os.h"
 
 extern int modify_ldt(int func, void *ptr, unsigned long bytecount);
 
@@ -456,13 +458,14 @@ long init_new_ldt(struct mmu_context_skas * new_mm,
         int i;
         long page, err=0;
         void *addr = NULL;
+        struct proc_mm_op copy;
 
-        memset(&desc, 0, sizeof(desc));
 
         if(!ptrace_ldt)
                 init_MUTEX(&new_mm->ldt.semaphore);
 
         if(!from_mm){
+                memset(&desc, 0, sizeof(desc));
                 /*
                  * We have to initialize a clean ldt.
                  */
@@ -494,8 +497,26 @@ long init_new_ldt(struct mmu_context_skas * new_mm,
                         }
                 }
                 new_mm->ldt.entry_count = 0;
+
+                goto out;
         }
-        else if (!ptrace_ldt) {
+
+        if(proc_mm){
+                /* We have a valid from_mm, so we now have to copy the LDT of
+                 * from_mm to new_mm, because using proc_mm an new mm with
+                 * an empty/default LDT was created in new_mm()
+                 */
+                copy = ((struct proc_mm_op) { .op       = MM_COPY_SEGMENTS,
+                                              .u        =
+                                              { .copy_segments =
+                                                        from_mm->id.u.mm_fd } } );
+                i = os_write_file(new_mm->id.u.mm_fd, &copy, sizeof(copy));
+                if(i != sizeof(copy))
+                        printk("new_mm : /proc/mm copy_segments failed, "
+                               "err = %d\n", -i);
+        }
+
+        if(!ptrace_ldt) {
                 /* Our local LDT is used to supply the data for
                  * modify_ldt(READLDT), if PTRACE_LDT isn't available,
                  * i.e., we have to use the stub for modify_ldt, which
@@ -524,6 +545,7 @@ long init_new_ldt(struct mmu_context_skas * new_mm,
                 up(&from_mm->ldt.semaphore);
         }
 
+    out:
         return err;
 }