[PATCH] uml: maintain own LDT entries
Patch imlements full LDT handling in SKAS:
* UML holds it's own LDT table, used to deliver data on
modify_ldt(READ)
* UML disables the default_ldt, inherited from the host (SKAS3)
or resets LDT entries, set by host's clib and inherited in
SKAS0
* A new global variable skas_needs_stub is inserted, that
can be used to decide, whether stub-pages must be supported
or not.
* Uses the syscall-stub to replace missing PTRACE_LDT (therefore,
write_ldt_entry needs to be modified)
Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/um/kernel/skas/include/mmu-skas.h b/arch/um/kernel/skas/include/mmu-skas.h
index 09536f8..44110c5 100644
--- a/arch/um/kernel/skas/include/mmu-skas.h
+++ b/arch/um/kernel/skas/include/mmu-skas.h
@@ -8,6 +8,7 @@
#include "linux/config.h"
#include "mm_id.h"
+#include "asm/ldt.h"
struct mmu_context_skas {
struct mm_id id;
@@ -15,6 +16,7 @@
#ifdef CONFIG_3_LEVEL_PGTABLES
unsigned long last_pmd;
#endif
+ uml_ldt_t ldt;
};
extern void switch_mm_skas(struct mm_id * mm_idp);
diff --git a/arch/um/kernel/skas/include/skas.h b/arch/um/kernel/skas/include/skas.h
index 0609347..daa2f85 100644
--- a/arch/um/kernel/skas/include/skas.h
+++ b/arch/um/kernel/skas/include/skas.h
@@ -10,7 +10,8 @@
#include "sysdep/ptrace.h"
extern int userspace_pid[];
-extern int proc_mm, ptrace_faultinfo;
+extern int proc_mm, ptrace_faultinfo, ptrace_ldt;
+extern int skas_needs_stub;
extern void switch_threads(void *me, void *next);
extern void thread_wait(void *sw, void *fb);
diff --git a/arch/um/kernel/skas/mem.c b/arch/um/kernel/skas/mem.c
index 147466d..88ab96c 100644
--- a/arch/um/kernel/skas/mem.c
+++ b/arch/um/kernel/skas/mem.c
@@ -20,7 +20,7 @@
*task_size_out = CONFIG_HOST_TASK_SIZE;
#else
*host_size_out = top;
- if (proc_mm && ptrace_faultinfo)
+ if (!skas_needs_stub)
*task_size_out = top;
else *task_size_out = CONFIG_STUB_START & PGDIR_MASK;
#endif
diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c
index 9e5e39c..677871f 100644
--- a/arch/um/kernel/skas/mmu.c
+++ b/arch/um/kernel/skas/mmu.c
@@ -15,6 +15,7 @@
#include "asm/mmu.h"
#include "asm/pgalloc.h"
#include "asm/pgtable.h"
+#include "asm/ldt.h"
#include "os.h"
#include "skas.h"
@@ -74,13 +75,12 @@
int init_new_context_skas(struct task_struct *task, struct mm_struct *mm)
{
- struct mm_struct *cur_mm = current->mm;
- struct mm_id *cur_mm_id = &cur_mm->context.skas.id;
- struct mm_id *mm_id = &mm->context.skas.id;
+ struct mmu_context_skas *from_mm = NULL;
+ struct mmu_context_skas *to_mm = &mm->context.skas;
unsigned long stack = 0;
- int from, ret = -ENOMEM;
+ int from_fd, ret = -ENOMEM;
- if(!proc_mm || !ptrace_faultinfo){
+ if(skas_needs_stub){
stack = get_zeroed_page(GFP_KERNEL);
if(stack == 0)
goto out;
@@ -102,33 +102,43 @@
mm->nr_ptes--;
}
- mm_id->stack = stack;
+
+ to_mm->id.stack = stack;
+ if(current->mm != NULL && current->mm != &init_mm)
+ from_mm = ¤t->mm->context.skas;
if(proc_mm){
- if((cur_mm != NULL) && (cur_mm != &init_mm))
- from = cur_mm_id->u.mm_fd;
- else from = -1;
+ if(from_mm)
+ from_fd = from_mm->id.u.mm_fd;
+ else from_fd = -1;
- ret = new_mm(from, stack);
+ ret = new_mm(from_fd, stack);
if(ret < 0){
printk("init_new_context_skas - new_mm failed, "
"errno = %d\n", ret);
goto out_free;
}
- mm_id->u.mm_fd = ret;
+ to_mm->id.u.mm_fd = ret;
}
else {
- if((cur_mm != NULL) && (cur_mm != &init_mm))
- mm_id->u.pid = copy_context_skas0(stack,
- cur_mm_id->u.pid);
- else mm_id->u.pid = start_userspace(stack);
+ if(from_mm)
+ to_mm->id.u.pid = copy_context_skas0(stack,
+ from_mm->id.u.pid);
+ else to_mm->id.u.pid = start_userspace(stack);
+ }
+
+ ret = init_new_ldt(to_mm, from_mm);
+ if(ret < 0){
+ printk("init_new_context_skas - init_ldt"
+ " failed, errno = %d\n", ret);
+ goto out_free;
}
return 0;
out_free:
- if(mm_id->stack != 0)
- free_page(mm_id->stack);
+ if(to_mm->id.stack != 0)
+ free_page(to_mm->id.stack);
out:
return ret;
}
diff --git a/arch/um/kernel/skas/process.c b/arch/um/kernel/skas/process.c
index 42f2da6..599d679 100644
--- a/arch/um/kernel/skas/process.c
+++ b/arch/um/kernel/skas/process.c
@@ -381,9 +381,9 @@
}
/*
- * This is used only, if proc_mm is available, while PTRACE_FAULTINFO
- * isn't. Opening /proc/mm creates a new mm_context, which lacks the stub-pages
- * Thus, we map them using /proc/mm-fd
+ * This is used only, if stub pages are needed, while proc_mm is
+ * availabl. Opening /proc/mm creates a new mm_context, which lacks
+ * the stub-pages. Thus, we map them using /proc/mm-fd
*/
void map_stub_pages(int fd, unsigned long code,
unsigned long data, unsigned long stack)
diff --git a/arch/um/kernel/skas/process_kern.c b/arch/um/kernel/skas/process_kern.c
index efe92e8..9c99025 100644
--- a/arch/um/kernel/skas/process_kern.c
+++ b/arch/um/kernel/skas/process_kern.c
@@ -145,7 +145,7 @@
"err = %d\n", -n);
}
- if(!ptrace_faultinfo)
+ if(skas_needs_stub)
map_stub_pages(fd, CONFIG_STUB_CODE, CONFIG_STUB_DATA, stack);
return(fd);