[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>

4 files changed, 29 insertions, 23 deletions

diff --git a/arch/um/kernel/skas/include/skas.h b/arch/um/kernel/skas/include/skas.h
index 01d489de3986..a7f7cd556f1f 100644
--- a/arch/um/kernel/skas/include/skas.h
+++ b/arch/um/kernel/skas/include/skas.h
@@ -33,7 +33,7 @@ extern int protect(struct mm_id * mm_idp, unsigned long addr,
                    unsigned long len, int r, int w, int x, int done,
                    void **data);
 extern void user_signal(int sig, union uml_pt_regs *regs, int pid);
-extern int new_mm(int from, unsigned long stack);
+extern int new_mm(unsigned long stack);
 extern int start_userspace(unsigned long stub_stack);
 extern int copy_context_skas0(unsigned long stack, int pid);
 extern void get_skas_faultinfo(int pid, struct faultinfo * fi);
diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c
index 677871f1b37c..c5c9885a8297 100644
--- a/arch/um/kernel/skas/mmu.c
+++ b/arch/um/kernel/skas/mmu.c
@@ -78,7 +78,7 @@ int init_new_context_skas(struct task_struct *task, struct mm_struct *mm)
         struct mmu_context_skas *from_mm = NULL;
         struct mmu_context_skas *to_mm = &mm->context.skas;
         unsigned long stack = 0;
-        int from_fd, ret = -ENOMEM;
+        int ret = -ENOMEM;
 
         if(skas_needs_stub){
                 stack = get_zeroed_page(GFP_KERNEL);
@@ -108,11 +108,7 @@ int init_new_context_skas(struct task_struct *task, struct mm_struct *mm)
                 from_mm = &current->mm->context.skas;
 
         if(proc_mm){
-                if(from_mm)
-                        from_fd = from_mm->id.u.mm_fd;
-                else from_fd = -1;
-
-                ret = new_mm(from_fd, stack);
+                ret = new_mm(stack);
                 if(ret < 0){
                         printk("init_new_context_skas - new_mm failed, "
                                "errno = %d\n", ret);
diff --git a/arch/um/kernel/skas/process_kern.c b/arch/um/kernel/skas/process_kern.c
index dc41c6dc2f34..fcddee76c7c0 100644
--- a/arch/um/kernel/skas/process_kern.c
+++ b/arch/um/kernel/skas/process_kern.c
@@ -20,7 +20,6 @@
 #include "tlb.h"
 #include "kern.h"
 #include "mode.h"
-#include "proc_mm.h"
 #include "registers.h"
 
 void switch_to_skas(void *prev, void *next)
@@ -125,25 +124,14 @@ int copy_thread_skas(int nr, unsigned long clone_flags, unsigned long sp,
 
 extern void map_stub_pages(int fd, unsigned long code,
                            unsigned long data, unsigned long stack);
-int new_mm(int from, unsigned long stack)
+int new_mm(unsigned long stack)
 {
-        struct proc_mm_op copy;
-        int n, fd;
+        int fd;
 
         fd = os_open_file("/proc/mm", of_cloexec(of_write(OPENFLAGS())), 0);
         if(fd < 0)
                 return(fd);
 
-        if(from != -1){
-                copy = ((struct proc_mm_op) { .op       = MM_COPY_SEGMENTS,
-                                              .u        =
-                                              { .copy_segments  = from } } );
-                n = os_write_file(fd, &copy, sizeof(copy));
-                if(n != sizeof(copy))
-                        printk("new_mm : /proc/mm copy_segments failed, "
-                               "err = %d\n", -n);
-        }
-
         if(skas_needs_stub)
                 map_stub_pages(fd, CONFIG_STUB_CODE, CONFIG_STUB_DATA, stack);
 
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;
 }