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Subject[PATCH 8/10] UML - Maintain own LDT entries
Date
From
From: Bodo Stroesser <bstroesser@fujitsu-siemens.com>

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>

Index: 2.6.14-akpm/arch/um/kernel/skas/include/mmu-skas.h
===================================================================
--- 2.6.14-akpm.orig/arch/um/kernel/skas/include/mmu-skas.h 2005-10-28 12:58:12.000000000 -0400
+++ 2.6.14-akpm/arch/um/kernel/skas/include/mmu-skas.h 2005-10-28 16:09:59.000000000 -0400
@@ -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 @@ struct mmu_context_skas {
#ifdef CONFIG_3_LEVEL_PGTABLES
unsigned long last_pmd;
#endif
+ uml_ldt_t ldt;
};

extern void switch_mm_skas(struct mm_id * mm_idp);
Index: 2.6.14-akpm/arch/um/kernel/skas/include/skas.h
===================================================================
--- 2.6.14-akpm.orig/arch/um/kernel/skas/include/skas.h 2005-10-28 12:58:12.000000000 -0400
+++ 2.6.14-akpm/arch/um/kernel/skas/include/skas.h 2005-10-28 16:09:59.000000000 -0400
@@ -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);
Index: 2.6.14-akpm/arch/um/kernel/skas/mem.c
===================================================================
--- 2.6.14-akpm.orig/arch/um/kernel/skas/mem.c 2005-08-28 19:41:01.000000000 -0400
+++ 2.6.14-akpm/arch/um/kernel/skas/mem.c 2005-10-28 16:09:59.000000000 -0400
@@ -20,7 +20,7 @@ unsigned long set_task_sizes_skas(int ar
*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
Index: 2.6.14-akpm/arch/um/kernel/skas/mmu.c
===================================================================
--- 2.6.14-akpm.orig/arch/um/kernel/skas/mmu.c 2005-10-28 12:58:12.000000000 -0400
+++ 2.6.14-akpm/arch/um/kernel/skas/mmu.c 2005-10-28 16:09:59.000000000 -0400
@@ -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"

@@ -77,13 +78,12 @@ static int init_stub_pte(struct mm_struc

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;
@@ -105,33 +105,43 @@ int init_new_context_skas(struct task_st

mm->nr_ptes--;
}
- mm_id->stack = stack;
+
+ to_mm->id.stack = stack;
+ if(current->mm != NULL && current->mm != &init_mm)
+ from_mm = &current->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;
}
Index: 2.6.14-akpm/arch/um/kernel/skas/process.c
===================================================================
--- 2.6.14-akpm.orig/arch/um/kernel/skas/process.c 2005-10-28 15:47:24.000000000 -0400
+++ 2.6.14-akpm/arch/um/kernel/skas/process.c 2005-10-28 16:09:59.000000000 -0400
@@ -381,9 +381,9 @@ int copy_context_skas0(unsigned long new
}

/*
- * 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)
Index: 2.6.14-akpm/arch/um/kernel/skas/process_kern.c
===================================================================
--- 2.6.14-akpm.orig/arch/um/kernel/skas/process_kern.c 2005-10-28 12:58:12.000000000 -0400
+++ 2.6.14-akpm/arch/um/kernel/skas/process_kern.c 2005-10-28 17:31:08.000000000 -0400
@@ -145,7 +145,7 @@ int new_mm(int from, unsigned long stack
"err = %d\n", -n);
}

- if(!ptrace_faultinfo)
+ if(skas_needs_stub)
map_stub_pages(fd, CONFIG_STUB_CODE, CONFIG_STUB_DATA, stack);

return(fd);
Index: 2.6.14-akpm/arch/um/os-Linux/start_up.c
===================================================================
--- 2.6.14-akpm.orig/arch/um/os-Linux/start_up.c 2005-10-28 12:58:12.000000000 -0400
+++ 2.6.14-akpm/arch/um/os-Linux/start_up.c 2005-10-28 17:31:08.000000000 -0400
@@ -135,7 +135,9 @@ static int stop_ptraced_child(int pid, v
}

int ptrace_faultinfo = 1;
+int ptrace_ldt = 1;
int proc_mm = 1;
+int skas_needs_stub = 0;

static int __init skas0_cmd_param(char *str, int* add)
{
@@ -352,14 +354,26 @@ __uml_setup("noptracefaultinfo", noptrac
" it. To support PTRACE_FAULTINFO, the host needs to be patched\n"
" using the current skas3 patch.\n\n");

+static int __init noptraceldt_cmd_param(char *str, int* add)
+{
+ ptrace_ldt = 0;
+ return 0;
+}
+
+__uml_setup("noptraceldt", noptraceldt_cmd_param,
+"noptraceldt\n"
+" Turns off usage of PTRACE_LDT, even if host supports it.\n"
+" To support PTRACE_LDT, the host needs to be patched using\n"
+" the current skas3 patch.\n\n");
+
#ifdef UML_CONFIG_MODE_SKAS
-static inline void check_skas3_ptrace_support(void)
+static inline void check_skas3_ptrace_faultinfo(void)
{
struct ptrace_faultinfo fi;
void *stack;
int pid, n;

- printf("Checking for the skas3 patch in the host...");
+ printf(" - PTRACE_FAULTINFO...");
pid = start_ptraced_child(&stack);

n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi);
@@ -381,9 +395,49 @@ static inline void check_skas3_ptrace_su
stop_ptraced_child(pid, stack, 1, 1);
}

-int can_do_skas(void)
+static inline void check_skas3_ptrace_ldt(void)
+{
+#ifdef PTRACE_LDT
+ void *stack;
+ int pid, n;
+ unsigned char ldtbuf[40];
+ struct ptrace_ldt ldt_op = (struct ptrace_ldt) {
+ .func = 2, /* read default ldt */
+ .ptr = ldtbuf,
+ .bytecount = sizeof(ldtbuf)};
+
+ printf(" - PTRACE_LDT...");
+ pid = start_ptraced_child(&stack);
+
+ n = ptrace(PTRACE_LDT, pid, 0, (unsigned long) &ldt_op);
+ if (n < 0) {
+ if(errno == EIO)
+ printf("not found\n");
+ else {
+ perror("not found");
+ }
+ ptrace_ldt = 0;
+ }
+ else {
+ if(ptrace_ldt)
+ printf("found\n");
+ else
+ printf("found, but use is disabled\n");
+ }
+
+ stop_ptraced_child(pid, stack, 1, 1);
+#else
+ /* PTRACE_LDT might be disabled via cmdline option.
+ * We want to override this, else we might use the stub
+ * without real need
+ */
+ ptrace_ldt = 1;
+#endif
+}
+
+static inline void check_skas3_proc_mm(void)
{
- printf("Checking for /proc/mm...");
+ printf(" - /proc/mm...");
if (os_access("/proc/mm", OS_ACC_W_OK) < 0) {
proc_mm = 0;
printf("not found\n");
@@ -394,8 +448,19 @@ int can_do_skas(void)
else
printf("found\n");
}
+}
+
+int can_do_skas(void)
+{
+ printf("Checking for the skas3 patch in the host:\n");
+
+ check_skas3_proc_mm();
+ check_skas3_ptrace_faultinfo();
+ check_skas3_ptrace_ldt();
+
+ if(!proc_mm || !ptrace_faultinfo || !ptrace_ldt)
+ skas_needs_stub = 1;

- check_skas3_ptrace_support();
return 1;
}
#else
Index: 2.6.14-akpm/arch/um/scripts/Makefile.rules
===================================================================
--- 2.6.14-akpm.orig/arch/um/scripts/Makefile.rules 2005-10-28 12:58:12.000000000 -0400
+++ 2.6.14-akpm/arch/um/scripts/Makefile.rules 2005-10-28 16:09:59.000000000 -0400
@@ -26,8 +26,13 @@ define unprofile
$(patsubst -pg,,$(patsubst -fprofile-arcs -ftest-coverage,,$(1)))
endef

+# cmd_make_link checks to see if the $(foo-dir) variable starts with a /. If
+# so, it's considered to be a path relative to $(srcdir) rather than
+# $(srcdir)/arch/$(SUBARCH). This is because x86_64 wants to get ldt.c from
+# arch/um/sys-i386 rather than arch/i386 like the other borrowed files. So,
+# it sets $(ldt.c-dir) to /arch/um/sys-i386.
quiet_cmd_make_link = SYMLINK $@
-cmd_make_link = ln -sf $(srctree)/arch/$(SUBARCH)/$($(notdir $@)-dir)/$(notdir $@) $@
+cmd_make_link = rm -f $@; ln -sf $(srctree)$(if $(filter-out /%,$($(notdir $@)-dir)),/arch/$(SUBARCH))/$($(notdir $@)-dir)/$(notdir $@) $@

# this needs to be before the foreach, because targets does not accept
# complete paths like $(obj)/$(f). To make sure this works, use a := assignment
Index: 2.6.14-akpm/arch/um/sys-i386/ldt.c
===================================================================
--- 2.6.14-akpm.orig/arch/um/sys-i386/ldt.c 2005-10-28 12:58:12.000000000 -0400
+++ 2.6.14-akpm/arch/um/sys-i386/ldt.c 2005-10-28 17:31:07.000000000 -0400
@@ -3,53 +3,26 @@
* Licensed under the GPL
*/

+#include "linux/stddef.h"
#include "linux/config.h"
#include "linux/sched.h"
#include "linux/slab.h"
#include "linux/types.h"
+#include "linux/errno.h"
#include "asm/uaccess.h"
-#include "asm/ptrace.h"
#include "asm/smp.h"
#include "asm/ldt.h"
+#include "asm/unistd.h"
#include "choose-mode.h"
#include "kern.h"
#include "mode_kern.h"

-#ifdef CONFIG_MODE_TT
-
extern int modify_ldt(int func, void *ptr, unsigned long bytecount);

-static int do_modify_ldt_tt(int func, void *ptr, unsigned long bytecount)
-{
- return modify_ldt(func, ptr, bytecount);
-}
-
-#endif
-
-#ifdef CONFIG_MODE_SKAS
-
-#include "skas.h"
-#include "skas_ptrace.h"
-
-static int do_modify_ldt_skas(int func, void *ptr, unsigned long bytecount)
-{
- struct ptrace_ldt ldt;
- u32 cpu;
- int res;
-
- ldt = ((struct ptrace_ldt) { .func = func,
- .ptr = ptr,
- .bytecount = bytecount });
-
- cpu = get_cpu();
- res = ptrace(PTRACE_LDT, userspace_pid[cpu], 0, (unsigned long) &ldt);
- put_cpu();
-
- return res;
-}
-#endif
+#ifdef CONFIG_MODE_TT

-int sys_modify_ldt(int func, void __user *ptr, unsigned long bytecount)
+static long do_modify_ldt_tt(int func, void __user *ptr,
+ unsigned long bytecount)
{
struct user_desc info;
int res = 0;
@@ -89,8 +62,7 @@ int sys_modify_ldt(int func, void __user
goto out;
}

- res = CHOOSE_MODE_PROC(do_modify_ldt_tt, do_modify_ldt_skas, func,
- p, bytecount);
+ res = modify_ldt(func, p, bytecount);
if(res < 0)
goto out;

@@ -108,3 +80,467 @@ out:
kfree(buf);
return res;
}
+
+#endif
+
+#ifdef CONFIG_MODE_SKAS
+
+#include "skas.h"
+#include "skas_ptrace.h"
+#include "asm/mmu_context.h"
+
+long write_ldt_entry(struct mm_id * mm_idp, int func, struct user_desc * desc,
+ void **addr, int done)
+{
+ long res;
+
+ if(proc_mm){
+ /* This is a special handling for the case, that the mm to
+ * modify isn't current->active_mm.
+ * If this is called directly by modify_ldt,
+ * (current->active_mm->context.skas.u == mm_idp)
+ * will be true. So no call to switch_mm_skas(mm_idp) is done.
+ * If this is called in case of init_new_ldt or PTRACE_LDT,
+ * mm_idp won't belong to current->active_mm, but child->mm.
+ * So we need to switch child's mm into our userspace, then
+ * later switch back.
+ *
+ * Note: I'm unshure: should interrupts be disabled here?
+ */
+ if(!current->active_mm || current->active_mm == &init_mm ||
+ mm_idp != &current->active_mm->context.skas.id)
+ switch_mm_skas(mm_idp);
+ }
+
+ if(ptrace_ldt) {
+ struct ptrace_ldt ldt_op = (struct ptrace_ldt) {
+ .func = func,
+ .ptr = desc,
+ .bytecount = sizeof(*desc)};
+ u32 cpu;
+ int pid;
+
+ if(!proc_mm)
+ pid = mm_idp->u.pid;
+ else {
+ cpu = get_cpu();
+ pid = userspace_pid[cpu];
+ }
+
+ res = ptrace(PTRACE_LDT, pid, 0, (unsigned long) &ldt_op);
+ if(res)
+ res = errno;
+
+ if(proc_mm)
+ put_cpu();
+ }
+ else {
+ void *stub_addr;
+ res = syscall_stub_data(mm_idp, (unsigned long *)desc,
+ (sizeof(*desc) + sizeof(long) - 1) &
+ ~(sizeof(long) - 1),
+ addr, &stub_addr);
+ if(!res){
+ unsigned long args[] = { func,
+ (unsigned long)stub_addr,
+ sizeof(*desc),
+ 0, 0, 0 };
+ res = run_syscall_stub(mm_idp, __NR_modify_ldt, args,
+ 0, addr, done);
+ }
+ }
+
+ if(proc_mm){
+ /* This is the second part of special handling, that makes
+ * PTRACE_LDT possible to implement.
+ */
+ if(current->active_mm && current->active_mm != &init_mm &&
+ mm_idp != &current->active_mm->context.skas.id)
+ switch_mm_skas(&current->active_mm->context.skas.id);
+ }
+
+ return res;
+}
+
+static long read_ldt_from_host(void __user * ptr, unsigned long bytecount)
+{
+ int res, n;
+ struct ptrace_ldt ptrace_ldt = (struct ptrace_ldt) {
+ .func = 0,
+ .bytecount = bytecount,
+ .ptr = (void *)kmalloc(bytecount, GFP_KERNEL)};
+ u32 cpu;
+
+ if(ptrace_ldt.ptr == NULL)
+ return -ENOMEM;
+
+ /* This is called from sys_modify_ldt only, so userspace_pid gives
+ * us the right number
+ */
+
+ cpu = get_cpu();
+ res = ptrace(PTRACE_LDT, userspace_pid[cpu], 0,
+ (unsigned long) &ptrace_ldt);
+ put_cpu();
+ if(res < 0)
+ goto out;
+
+ n = copy_to_user(ptr, ptrace_ldt.ptr, res);
+ if(n != 0)
+ res = -EFAULT;
+
+ out:
+ kfree(ptrace_ldt.ptr);
+
+ return res;
+}
+
+/*
+ * In skas mode, we hold our own ldt data in UML.
+ * Thus, the code implementing sys_modify_ldt_skas
+ * is very similar to (and mostly stolen from) sys_modify_ldt
+ * for arch/i386/kernel/ldt.c
+ * The routines copied and modified in part are:
+ * - read_ldt
+ * - read_default_ldt
+ * - write_ldt
+ * - sys_modify_ldt_skas
+ */
+
+static int read_ldt(void __user * ptr, unsigned long bytecount)
+{
+ int i, err = 0;
+ unsigned long size;
+ uml_ldt_t * ldt = &current->mm->context.skas.ldt;
+
+ if(!ldt->entry_count)
+ goto out;
+ if(bytecount > LDT_ENTRY_SIZE*LDT_ENTRIES)
+ bytecount = LDT_ENTRY_SIZE*LDT_ENTRIES;
+ err = bytecount;
+
+ if(ptrace_ldt){
+ return read_ldt_from_host(ptr, bytecount);
+ }
+
+ down(&ldt->semaphore);
+ if(ldt->entry_count <= LDT_DIRECT_ENTRIES){
+ size = LDT_ENTRY_SIZE*LDT_DIRECT_ENTRIES;
+ if(size > bytecount)
+ size = bytecount;
+ if(copy_to_user(ptr, ldt->entries, size))
+ err = -EFAULT;
+ bytecount -= size;
+ ptr += size;
+ }
+ else {
+ for(i=0; i<ldt->entry_count/LDT_ENTRIES_PER_PAGE && bytecount;
+ i++){
+ size = PAGE_SIZE;
+ if(size > bytecount)
+ size = bytecount;
+ if(copy_to_user(ptr, ldt->pages[i], size)){
+ err = -EFAULT;
+ break;
+ }
+ bytecount -= size;
+ ptr += size;
+ }
+ }
+ up(&ldt->semaphore);
+
+ if(bytecount == 0 || err == -EFAULT)
+ goto out;
+
+ if(clear_user(ptr, bytecount))
+ err = -EFAULT;
+
+out:
+ return err;
+}
+
+static int read_default_ldt(void __user * ptr, unsigned long bytecount)
+{
+ int err;
+
+ if(bytecount > 5*LDT_ENTRY_SIZE)
+ bytecount = 5*LDT_ENTRY_SIZE;
+
+ err = bytecount;
+ /* UML doesn't support lcall7 and lcall27.
+ * So, we don't really have a default ldt, but emulate
+ * an empty ldt of common host default ldt size.
+ */
+ if(clear_user(ptr, bytecount))
+ err = -EFAULT;
+
+ return err;
+}
+
+static int write_ldt(void __user * ptr, unsigned long bytecount, int func)
+{
+ uml_ldt_t * ldt = &current->mm->context.skas.ldt;
+ struct mm_id * mm_idp = &current->mm->context.skas.id;
+ int i, err;
+ struct user_desc ldt_info;
+ struct ldt_entry entry0, *ldt_p;
+ void *addr = NULL;
+
+ err = -EINVAL;
+ if(bytecount != sizeof(ldt_info))
+ goto out;
+ err = -EFAULT;
+ if(copy_from_user(&ldt_info, ptr, sizeof(ldt_info)))
+ goto out;
+
+ err = -EINVAL;
+ if(ldt_info.entry_number >= LDT_ENTRIES)
+ goto out;
+ if(ldt_info.contents == 3){
+ if (func == 1)
+ goto out;
+ if (ldt_info.seg_not_present == 0)
+ goto out;
+ }
+
+ if(!ptrace_ldt)
+ down(&ldt->semaphore);
+
+ err = write_ldt_entry(mm_idp, func, &ldt_info, &addr, 1);
+ if(err)
+ goto out_unlock;
+ else if(ptrace_ldt) {
+ /* With PTRACE_LDT available, this is used as a flag only */
+ ldt->entry_count = 1;
+ goto out;
+ }
+
+ if(ldt_info.entry_number >= ldt->entry_count &&
+ ldt_info.entry_number >= LDT_DIRECT_ENTRIES){
+ for(i=ldt->entry_count/LDT_ENTRIES_PER_PAGE;
+ i*LDT_ENTRIES_PER_PAGE <= ldt_info.entry_number;
+ i++){
+ if(i == 0)
+ memcpy(&entry0, ldt->entries, sizeof(entry0));
+ ldt->pages[i] = (struct ldt_entry *)
+ __get_free_page(GFP_KERNEL|__GFP_ZERO);
+ if(!ldt->pages[i]){
+ err = -ENOMEM;
+ /* Undo the change in host */
+ memset(&ldt_info, 0, sizeof(ldt_info));
+ write_ldt_entry(mm_idp, 1, &ldt_info, &addr, 1);
+ goto out_unlock;
+ }
+ if(i == 0) {
+ memcpy(ldt->pages[0], &entry0, sizeof(entry0));
+ memcpy(ldt->pages[0]+1, ldt->entries+1,
+ sizeof(entry0)*(LDT_DIRECT_ENTRIES-1));
+ }
+ ldt->entry_count = (i + 1) * LDT_ENTRIES_PER_PAGE;
+ }
+ }
+ if(ldt->entry_count <= ldt_info.entry_number)
+ ldt->entry_count = ldt_info.entry_number + 1;
+
+ if(ldt->entry_count <= LDT_DIRECT_ENTRIES)
+ ldt_p = ldt->entries + ldt_info.entry_number;
+ else
+ ldt_p = ldt->pages[ldt_info.entry_number/LDT_ENTRIES_PER_PAGE] +
+ ldt_info.entry_number%LDT_ENTRIES_PER_PAGE;
+
+ if(ldt_info.base_addr == 0 && ldt_info.limit == 0 &&
+ (func == 1 || LDT_empty(&ldt_info))){
+ ldt_p->a = 0;
+ ldt_p->b = 0;
+ }
+ else{
+ if (func == 1)
+ ldt_info.useable = 0;
+ ldt_p->a = LDT_entry_a(&ldt_info);
+ ldt_p->b = LDT_entry_b(&ldt_info);
+ }
+ err = 0;
+
+out_unlock:
+ up(&ldt->semaphore);
+out:
+ return err;
+}
+
+static long do_modify_ldt_skas(int func, void __user *ptr,
+ unsigned long bytecount)
+{
+ int ret = -ENOSYS;
+
+ switch (func) {
+ case 0:
+ ret = read_ldt(ptr, bytecount);
+ break;
+ case 1:
+ case 0x11:
+ ret = write_ldt(ptr, bytecount, func);
+ break;
+ case 2:
+ ret = read_default_ldt(ptr, bytecount);
+ break;
+ }
+ return ret;
+}
+
+short dummy_list[9] = {0, -1};
+short * host_ldt_entries = NULL;
+
+void ldt_get_host_info(void)
+{
+ long ret;
+ struct ldt_entry * ldt;
+ int i, size, k, order;
+
+ host_ldt_entries = dummy_list+1;
+
+ for(i = LDT_PAGES_MAX-1, order=0; i; i>>=1, order++);
+
+ ldt = (struct ldt_entry *)
+ __get_free_pages(GFP_KERNEL|__GFP_ZERO, order);
+ if(ldt == NULL) {
+ printk("ldt_get_host_info: couldn't allocate buffer for host ldt\n");
+ return;
+ }
+
+ ret = modify_ldt(0, ldt, (1<<order)*PAGE_SIZE);
+ if(ret < 0) {
+ printk("ldt_get_host_info: couldn't read host ldt\n");
+ goto out_free;
+ }
+ if(ret == 0) {
+ /* default_ldt is active, simply write an empty entry 0 */
+ host_ldt_entries = dummy_list;
+ goto out_free;
+ }
+
+ for(i=0, size=0; i<ret/LDT_ENTRY_SIZE; i++){
+ if(ldt[i].a != 0 || ldt[i].b != 0)
+ size++;
+ }
+
+ if(size < sizeof(dummy_list)/sizeof(dummy_list[0])) {
+ host_ldt_entries = dummy_list;
+ }
+ else {
+ size = (size + 1) * sizeof(dummy_list[0]);
+ host_ldt_entries = (short *)kmalloc(size, GFP_KERNEL);
+ if(host_ldt_entries == NULL) {
+ printk("ldt_get_host_info: couldn't allocate host ldt list\n");
+ goto out_free;
+ }
+ }
+
+ for(i=0, k=0; i<ret/LDT_ENTRY_SIZE; i++){
+ if(ldt[i].a != 0 || ldt[i].b != 0) {
+ host_ldt_entries[k++] = i;
+ }
+ }
+ host_ldt_entries[k] = -1;
+
+out_free:
+ free_pages((unsigned long)ldt, order);
+}
+
+long init_new_ldt(struct mmu_context_skas * new_mm,
+ struct mmu_context_skas * from_mm)
+{
+ struct user_desc desc;
+ short * num_p;
+ int i;
+ long page, err=0;
+ void *addr = NULL;
+
+ memset(&desc, 0, sizeof(desc));
+
+ if(!ptrace_ldt)
+ init_MUTEX(&new_mm->ldt.semaphore);
+
+ if(!from_mm){
+ /*
+ * We have to initialize a clean ldt.
+ */
+ if(proc_mm) {
+ /*
+ * If the new mm was created using proc_mm, host's
+ * default-ldt currently is assigned, which normally
+ * contains the call-gates for lcall7 and lcall27.
+ * To remove these gates, we simply write an empty
+ * entry as number 0 to the host.
+ */
+ err = write_ldt_entry(&new_mm->id, 1, &desc,
+ &addr, 1);
+ }
+ else{
+ /*
+ * Now we try to retrieve info about the ldt, we
+ * inherited from the host. All ldt-entries found
+ * will be reset in the following loop
+ */
+ if(host_ldt_entries == NULL)
+ ldt_get_host_info();
+ for(num_p=host_ldt_entries; *num_p != -1; num_p++){
+ desc.entry_number = *num_p;
+ err = write_ldt_entry(&new_mm->id, 1, &desc,
+ &addr, *(num_p + 1) == -1);
+ if(err)
+ break;
+ }
+ }
+ new_mm->ldt.entry_count = 0;
+ }
+ else 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
+ * can't handle the big read buffer of up to 64kB.
+ */
+ down(&from_mm->ldt.semaphore);
+ if(from_mm->ldt.entry_count <= LDT_DIRECT_ENTRIES){
+ memcpy(new_mm->ldt.entries, from_mm->ldt.entries,
+ sizeof(new_mm->ldt.entries));
+ }
+ else{
+ i = from_mm->ldt.entry_count / LDT_ENTRIES_PER_PAGE;
+ while(i-->0){
+ page = __get_free_page(GFP_KERNEL|__GFP_ZERO);
+ if (!page){
+ err = -ENOMEM;
+ break;
+ }
+ new_mm->ldt.pages[i] = (struct ldt_entry*)page;
+ memcpy(new_mm->ldt.pages[i],
+ from_mm->ldt.pages[i], PAGE_SIZE);
+ }
+ }
+ new_mm->ldt.entry_count = from_mm->ldt.entry_count;
+ up(&from_mm->ldt.semaphore);
+ }
+
+ return err;
+}
+
+
+void free_ldt(struct mmu_context_skas * mm)
+{
+ int i;
+
+ if(!ptrace_ldt && mm->ldt.entry_count > LDT_DIRECT_ENTRIES){
+ i = mm->ldt.entry_count / LDT_ENTRIES_PER_PAGE;
+ while(i-- > 0){
+ free_page((long )mm->ldt.pages[i]);
+ }
+ }
+ mm->ldt.entry_count = 0;
+}
+#endif
+
+int sys_modify_ldt(int func, void __user *ptr, unsigned long bytecount)
+{
+ return(CHOOSE_MODE_PROC(do_modify_ldt_tt, do_modify_ldt_skas, func,
+ ptr, bytecount));
+}
Index: 2.6.14-akpm/arch/um/sys-x86_64/Makefile
===================================================================
--- 2.6.14-akpm.orig/arch/um/sys-x86_64/Makefile 2005-10-28 12:58:12.000000000 -0400
+++ 2.6.14-akpm/arch/um/sys-x86_64/Makefile 2005-10-28 16:09:59.000000000 -0400
@@ -5,7 +5,7 @@
#

#XXX: why into lib-y?
-lib-y = bitops.o bugs.o csum-partial.o delay.o fault.o mem.o memcpy.o \
+lib-y = bitops.o bugs.o csum-partial.o delay.o fault.o ldt.o mem.o memcpy.o \
ptrace.o ptrace_user.o sigcontext.o signal.o stub.o \
stub_segv.o syscalls.o syscall_table.o sysrq.o thunk.o

@@ -14,7 +14,7 @@ obj-$(CONFIG_MODULES) += module.o um_mod

USER_OBJS := ptrace_user.o sigcontext.o

-SYMLINKS = bitops.c csum-copy.S csum-partial.c csum-wrappers.c memcpy.S \
+SYMLINKS = bitops.c csum-copy.S csum-partial.c csum-wrappers.c ldt.c memcpy.S \
thunk.S module.c

include arch/um/scripts/Makefile.rules
@@ -23,6 +23,7 @@ bitops.c-dir = lib
csum-copy.S-dir = lib
csum-partial.c-dir = lib
csum-wrappers.c-dir = lib
+ldt.c-dir = /arch/um/sys-i386
memcpy.S-dir = lib
thunk.S-dir = lib
module.c-dir = kernel
Index: 2.6.14-akpm/arch/um/sys-x86_64/syscalls.c
===================================================================
--- 2.6.14-akpm.orig/arch/um/sys-x86_64/syscalls.c 2005-08-28 19:41:01.000000000 -0400
+++ 2.6.14-akpm/arch/um/sys-x86_64/syscalls.c 2005-10-28 16:09:59.000000000 -0400
@@ -29,81 +29,6 @@ asmlinkage long sys_uname64(struct new_u
}

#ifdef CONFIG_MODE_TT
-extern int modify_ldt(int func, void *ptr, unsigned long bytecount);
-
-long sys_modify_ldt_tt(int func, void *ptr, unsigned long bytecount)
-{
- /* XXX This should check VERIFY_WRITE depending on func, check this
- * in i386 as well.
- */
- if (!access_ok(VERIFY_READ, ptr, bytecount))
- return -EFAULT;
- return(modify_ldt(func, ptr, bytecount));
-}
-#endif
-
-#ifdef CONFIG_MODE_SKAS
-extern int userspace_pid[];
-
-#include "skas_ptrace.h"
-
-long sys_modify_ldt_skas(int func, void *ptr, unsigned long bytecount)
-{
- struct ptrace_ldt ldt;
- void *buf;
- int res, n;
-
- buf = kmalloc(bytecount, GFP_KERNEL);
- if(buf == NULL)
- return(-ENOMEM);
-
- res = 0;
-
- switch(func){
- case 1:
- case 0x11:
- res = copy_from_user(buf, ptr, bytecount);
- break;
- }
-
- if(res != 0){
- res = -EFAULT;
- goto out;
- }
-
- ldt = ((struct ptrace_ldt) { .func = func,
- .ptr = buf,
- .bytecount = bytecount });
-#warning Need to look up userspace_pid by cpu
- res = ptrace(PTRACE_LDT, userspace_pid[0], 0, (unsigned long) &ldt);
- if(res < 0)
- goto out;
-
- switch(func){
- case 0:
- case 2:
- n = res;
- res = copy_to_user(ptr, buf, n);
- if(res != 0)
- res = -EFAULT;
- else
- res = n;
- break;
- }
-
- out:
- kfree(buf);
- return(res);
-}
-#endif
-
-long sys_modify_ldt(int func, void *ptr, unsigned long bytecount)
-{
- return(CHOOSE_MODE_PROC(sys_modify_ldt_tt, sys_modify_ldt_skas, func,
- ptr, bytecount));
-}
-
-#ifdef CONFIG_MODE_TT
extern long arch_prctl(int code, unsigned long addr);

static long arch_prctl_tt(int code, unsigned long addr)
Index: 2.6.14-akpm/include/asm-um/ldt-i386.h
===================================================================
--- 2.6.14-akpm.orig/include/asm-um/ldt-i386.h 2005-10-28 06:47:18.772411750 -0400
+++ 2.6.14-akpm/include/asm-um/ldt-i386.h 2005-10-28 17:31:07.000000000 -0400
@@ -0,0 +1,69 @@
+/*
+ * Copyright (C) 2004 Fujitsu Siemens Computers GmbH
+ * Licensed under the GPL
+ *
+ * Author: Bodo Stroesser <bstroesser@fujitsu-siemens.com>
+ */
+
+#ifndef __ASM_LDT_I386_H
+#define __ASM_LDT_I386_H
+
+#include "asm/semaphore.h"
+#include "asm/arch/ldt.h"
+
+struct mmu_context_skas;
+extern void ldt_host_info(void);
+extern long init_new_ldt(struct mmu_context_skas * to_mm,
+ struct mmu_context_skas * from_mm);
+extern void free_ldt(struct mmu_context_skas * mm);
+
+#define LDT_PAGES_MAX \
+ ((LDT_ENTRIES * LDT_ENTRY_SIZE)/PAGE_SIZE)
+#define LDT_ENTRIES_PER_PAGE \
+ (PAGE_SIZE/LDT_ENTRY_SIZE)
+#define LDT_DIRECT_ENTRIES \
+ ((LDT_PAGES_MAX*sizeof(void *))/LDT_ENTRY_SIZE)
+
+struct ldt_entry {
+ __u32 a;
+ __u32 b;
+};
+
+typedef struct uml_ldt {
+ int entry_count;
+ struct semaphore semaphore;
+ union {
+ struct ldt_entry * pages[LDT_PAGES_MAX];
+ struct ldt_entry entries[LDT_DIRECT_ENTRIES];
+ };
+} uml_ldt_t;
+
+/*
+ * macros stolen from include/asm-i386/desc.h
+ */
+#define LDT_entry_a(info) \
+ ((((info)->base_addr & 0x0000ffff) << 16) | ((info)->limit & 0x0ffff))
+
+#define LDT_entry_b(info) \
+ (((info)->base_addr & 0xff000000) | \
+ (((info)->base_addr & 0x00ff0000) >> 16) | \
+ ((info)->limit & 0xf0000) | \
+ (((info)->read_exec_only ^ 1) << 9) | \
+ ((info)->contents << 10) | \
+ (((info)->seg_not_present ^ 1) << 15) | \
+ ((info)->seg_32bit << 22) | \
+ ((info)->limit_in_pages << 23) | \
+ ((info)->useable << 20) | \
+ 0x7000)
+
+#define LDT_empty(info) (\
+ (info)->base_addr == 0 && \
+ (info)->limit == 0 && \
+ (info)->contents == 0 && \
+ (info)->read_exec_only == 1 && \
+ (info)->seg_32bit == 0 && \
+ (info)->limit_in_pages == 0 && \
+ (info)->seg_not_present == 1 && \
+ (info)->useable == 0 )
+
+#endif
Index: 2.6.14-akpm/include/asm-um/ldt.h
===================================================================
--- 2.6.14-akpm.orig/include/asm-um/ldt.h 2005-08-28 19:41:01.000000000 -0400
+++ 2.6.14-akpm/include/asm-um/ldt.h 2005-10-28 17:31:07.000000000 -0400
@@ -1,3 +1,72 @@
+/*
+ * Copyright (C) 2004 Fujitsu Siemens Computers GmbH
+ * Licensed under the GPL
+ *
+ * Author: Bodo Stroesser <bstroesser@fujitsu-siemens.com>
+ */
+
+#ifndef __ASM_LDT_I386_H
+#define __ASM_LDT_I386_H
+
+#include "asm/semaphore.h"
+#include "asm/arch/ldt.h"
+
+struct mmu_context_skas;
+extern void ldt_host_info(void);
+extern long init_new_ldt(struct mmu_context_skas * to_mm,
+ struct mmu_context_skas * from_mm);
+extern void free_ldt(struct mmu_context_skas * mm);
+
+#define LDT_PAGES_MAX \
+ ((LDT_ENTRIES * LDT_ENTRY_SIZE)/PAGE_SIZE)
+#define LDT_ENTRIES_PER_PAGE \
+ (PAGE_SIZE/LDT_ENTRY_SIZE)
+#define LDT_DIRECT_ENTRIES \
+ ((LDT_PAGES_MAX*sizeof(void *))/LDT_ENTRY_SIZE)
+
+struct ldt_entry {
+ __u32 a;
+ __u32 b;
+};
+
+typedef struct uml_ldt {
+ int entry_count;
+ struct semaphore semaphore;
+ union {
+ struct ldt_entry * pages[LDT_PAGES_MAX];
+ struct ldt_entry entries[LDT_DIRECT_ENTRIES];
+ };
+} uml_ldt_t;
+
+/*
+ * macros stolen from include/asm-i386/desc.h
+ */
+#define LDT_entry_a(info) \
+ ((((info)->base_addr & 0x0000ffff) << 16) | ((info)->limit & 0x0ffff))
+
+#define LDT_entry_b(info) \
+ (((info)->base_addr & 0xff000000) | \
+ (((info)->base_addr & 0x00ff0000) >> 16) | \
+ ((info)->limit & 0xf0000) | \
+ (((info)->read_exec_only ^ 1) << 9) | \
+ ((info)->contents << 10) | \
+ (((info)->seg_not_present ^ 1) << 15) | \
+ ((info)->seg_32bit << 22) | \
+ ((info)->limit_in_pages << 23) | \
+ ((info)->useable << 20) | \
+ 0x7000)
+
+#define LDT_empty(info) (\
+ (info)->base_addr == 0 && \
+ (info)->limit == 0 && \
+ (info)->contents == 0 && \
+ (info)->read_exec_only == 1 && \
+ (info)->seg_32bit == 0 && \
+ (info)->limit_in_pages == 0 && \
+ (info)->seg_not_present == 1 && \
+ (info)->useable == 0 )
+
+#endif
#ifndef __UM_LDT_H
#define __UM_LDT_H

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