bitkeeper revision 1.165.1.1 (3e9c3ccaCJe7Z8jxplsENPEQ5oFIFw)

Many files:
  Partial checkin of virtualised LDT support.

13 files changed, 373 insertions, 56 deletions

diff --git a/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/entry.S b/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/entry.S
index 0a6a5374d1..0525e2976e 100644
--- a/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/entry.S
+++ b/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/entry.S
@@ -133,6 +133,55 @@ ENOSYS = 38
 	movl $-8192, reg; \
 	andl %esp, reg
 
+ENTRY(lcall7)
+	pushfl			# We get a different stack layout with call
+	pushl %eax		# gates, which has to be cleaned up later..
+	SAVE_ALL
+	movl EIP(%esp),%eax	# due to call gates, this is eflags, not eip..
+	movl CS(%esp),%edx	# this is eip..
+	movl EFLAGS(%esp),%ecx	# and this is cs..
+	movl %eax,EFLAGS(%esp)	#
+	andl $~(NT_MASK|TF_MASK|DF_MASK), %eax
+	pushl %eax
+	popfl
+	movl %edx,EIP(%esp)	# Now we move them to their "normal" places
+	movl %ecx,CS(%esp)	#
+	movl %esp,%ebx
+	pushl %ebx
+	andl $-8192,%ebx	# GET_CURRENT
+	movl exec_domain(%ebx),%edx	# Get the execution domain
+	movl 4(%edx),%edx	# Get the lcall7 handler for the domain
+	pushl $0x7
+	call *%edx
+	addl $4, %esp
+	popl %eax
+	jmp ret_from_sys_call
+
+ENTRY(lcall27)
+	pushfl			# We get a different stack layout with call
+	pushl %eax		# gates, which has to be cleaned up later..
+	SAVE_ALL
+	movl EIP(%esp),%eax	# due to call gates, this is eflags, not eip..
+	movl CS(%esp),%edx	# this is eip..
+	movl EFLAGS(%esp),%ecx	# and this is cs..
+	movl %eax,EFLAGS(%esp)	#
+	andl $~(NT_MASK|TF_MASK|DF_MASK), %eax
+	pushl %eax
+	popfl
+	movl %edx,EIP(%esp)	# Now we move them to their "normal" places
+	movl %ecx,CS(%esp)	#
+	movl %esp,%ebx
+	pushl %ebx
+	andl $-8192,%ebx	# GET_CURRENT
+	movl exec_domain(%ebx),%edx	# Get the execution domain
+	movl 4(%edx),%edx	# Get the lcall7 handler for the domain
+	pushl $0x27
+	call *%edx
+	addl $4, %esp
+	popl %eax
+	jmp ret_from_sys_call
+
+        
 ENTRY(ret_from_fork)
 	pushl %ebx
 	call SYMBOL_NAME(schedule_tail)
diff --git a/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/head.S b/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/head.S
index 86a82b13dc..a89fd8eda4 100644
--- a/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/head.S
+++ b/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/head.S
@@ -57,11 +57,14 @@ ENTRY(stack_start)
 ENTRY(empty_zero_page)
 
 .org 0x2000
+ENTRY(default_ldt)
+
+.org 0x3000
 ENTRY(cpu0_pte_quicklist)
 
-.org 0x2400
+.org 0x3400
 ENTRY(cpu0_pgd_quicklist)
         
-.org 0x2800
+.org 0x3800
 ENTRY(stext)
 ENTRY(_stext)
diff --git a/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/ldt.c b/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/ldt.c
index 6c93943036..ca89b694bd 100644
--- a/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/ldt.c
+++ b/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/ldt.c
@@ -9,18 +9,161 @@
 #include <linux/sched.h>
 #include <linux/string.h>
 #include <linux/mm.h>
+#include <linux/smp.h>
+#include <linux/smp_lock.h>
+#include <linux/vmalloc.h>
+
+#include <asm/uaccess.h>
+#include <asm/system.h>
+#include <asm/ldt.h>
+#include <asm/desc.h>
 
 /*
- * XXX KAF (28/7/02): This stuff is only used for DOS emulation, and is
- * the default way of finding current TCB in linuxthreads. Supporting
- * table update svia the hypervisor is feasible, but a hassle: for now,
- * recompiling linuxthreads is the most sensible option.
- * 
- * Oh, this may become an issue depending on what JVM we use for
- * running the xeno-daemon.
+ * read_ldt() is not really atomic - this is not a problem since
+ * synchronization of reads and writes done to the LDT has to be
+ * assured by user-space anyway. Writes are atomic, to protect
+ * the security checks done on new descriptors.
  */
+static int read_ldt(void * ptr, unsigned long bytecount)
+{
+    int err;
+    unsigned long size;
+    struct mm_struct * mm = current->mm;
+
+    err = 0;
+    if (!mm->context.segments)
+        goto out;
+
+    size = LDT_ENTRIES*LDT_ENTRY_SIZE;
+    if (size > bytecount)
+        size = bytecount;
+
+    err = size;
+    if (copy_to_user(ptr, mm->context.segments, size))
+        err = -EFAULT;
+ out:
+    return err;
+}
+
+static int read_default_ldt(void * ptr, unsigned long bytecount)
+{
+    int err;
+    unsigned long size;
+    void *address;
+
+    err = 0;
+    address = &default_ldt[0];
+    size = sizeof(struct desc_struct);
+    if (size > bytecount)
+        size = bytecount;
+
+    err = size;
+    if (copy_to_user(ptr, address, size))
+        err = -EFAULT;
+
+    return err;
+}
+
+static int write_ldt(void * ptr, unsigned long bytecount, int oldmode)
+{
+    struct mm_struct * mm = current->mm;
+    __u32 entry_1, entry_2, *lp;
+    unsigned long phys_lp;
+    int error;
+    struct modify_ldt_ldt_s ldt_info;
+
+    error = -EINVAL;
+    if (bytecount != sizeof(ldt_info))
+        goto out;
+    error = -EFAULT; 	
+    if (copy_from_user(&ldt_info, ptr, sizeof(ldt_info)))
+        goto out;
+
+    error = -EINVAL;
+    if (ldt_info.entry_number >= LDT_ENTRIES)
+        goto out;
+    if (ldt_info.contents == 3) {
+        if (oldmode)
+            goto out;
+        if (ldt_info.seg_not_present == 0)
+            goto out;
+    }
+
+    down_write(&mm->mmap_sem);
+    if (!mm->context.segments) {
+        void * segments = vmalloc(LDT_ENTRIES*LDT_ENTRY_SIZE);
+        error = -ENOMEM;
+        if (!segments)
+            goto out_unlock;
+        memset(segments, 0, LDT_ENTRIES*LDT_ENTRY_SIZE);
+        make_pages_readonly(segments, (LDT_ENTRIES*LDT_ENTRY_SIZE)/PAGE_SIZE);
+        wmb();
+        mm->context.segments = segments;
+        mm->context.cpuvalid = 1UL << smp_processor_id();
+        load_LDT(mm);
+        flush_page_update_queue();
+    }
+
+    lp = (__u32 *)((ldt_info.entry_number<<3) + (char *)mm->context.segments);
+    phys_lp = arbitrary_virt_to_phys(lp);
+
+    /* Allow LDTs to be cleared by the user. */
+    if (ldt_info.base_addr == 0 && ldt_info.limit == 0) {
+        if (oldmode ||
+            (ldt_info.contents == 0		&&
+             ldt_info.read_exec_only == 1	&&
+             ldt_info.seg_32bit == 0		&&
+             ldt_info.limit_in_pages == 0	&&
+             ldt_info.seg_not_present == 1	&&
+             ldt_info.useable == 0 )) {
+            entry_1 = 0;
+            entry_2 = 0;
+            goto install;
+        }
+    }
+
+    entry_1 = ((ldt_info.base_addr & 0x0000ffff) << 16) |
+        (ldt_info.limit & 0x0ffff);
+    entry_2 = (ldt_info.base_addr & 0xff000000) |
+        ((ldt_info.base_addr & 0x00ff0000) >> 16) |
+        (ldt_info.limit & 0xf0000) |
+        ((ldt_info.read_exec_only ^ 1) << 9) |
+        (ldt_info.contents << 10) |
+        ((ldt_info.seg_not_present ^ 1) << 15) |
+        (ldt_info.seg_32bit << 22) |
+        (ldt_info.limit_in_pages << 23) |
+        0x7000;
+    if (!oldmode)
+        entry_2 |= (ldt_info.useable << 20);
+
+    /* Install the new entry ...  */
+ install:
+    HYPERVISOR_update_descriptor(phys_lp, entry_1, entry_2);
+    error = 0;
+
+ out_unlock:
+    up_write(&mm->mmap_sem);
+ out:
+    return error;
+}
 
 asmlinkage int sys_modify_ldt(int func, void *ptr, unsigned long bytecount)
 {
-    return -ENOSYS;
+    int ret = -ENOSYS;
+
+    switch (func) {
+    case 0:
+        ret = read_ldt(ptr, bytecount);
+        break;
+    case 1:
+        ret = write_ldt(ptr, bytecount, 1);
+        break;
+    case 2:
+        ret = read_default_ldt(ptr, bytecount);
+        break;
+    case 0x11:
+        ret = write_ldt(ptr, bytecount, 0);
+        break;
+    }
+    return ret;
 }
diff --git a/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/process.c b/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/process.c
index 32ce1a66ab..4dc1273c7b 100644
--- a/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/process.c
+++ b/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/process.c
@@ -140,6 +140,8 @@ void release_segments(struct mm_struct *mm)
     if (ldt) {
         mm->context.segments = NULL;
         clear_LDT();
+        make_pages_writeable(ldt, (LDT_ENTRIES*LDT_ENTRY_SIZE)/PAGE_SIZE);
+        flush_page_update_queue();
         vfree(ldt);
     }
 }
@@ -225,10 +227,15 @@ void copy_segments(struct task_struct *p, struct mm_struct *new_mm)
          * Completely new LDT, we initialize it from the parent:
          */
         ldt = vmalloc(LDT_ENTRIES*LDT_ENTRY_SIZE);
-        if (!ldt)
+        if ( ldt == NULL )
+        {
             printk(KERN_WARNING "ldt allocation failed\n");
+        }
         else
+        {
             memcpy(ldt, old_ldt, LDT_ENTRIES*LDT_ENTRY_SIZE);
+            make_pages_readonly(ldt, (LDT_ENTRIES*LDT_ENTRY_SIZE)/PAGE_SIZE);
+        }
     }
     new_mm->context.segments = ldt;
     new_mm->context.cpuvalid = ~0UL;	/* valid on all CPU's - they can't have stale data */
@@ -335,6 +342,10 @@ void __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
     struct thread_struct *prev = &prev_p->thread,
         *next = &next_p->thread;
 
+    __cli();
+
+    MULTICALL_flush_page_update_queue();
+
     /*
      * This is basically 'unlazy_fpu', except that we queue a multicall to 
      * indicate FPU task switch, rather than synchronously trapping to Xen.
@@ -356,7 +367,7 @@ void __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 
     /* EXECUTE ALL TASK SWITCH XEN SYSCALLS AT THIS POINT. */
     execute_multicall_list();
-    sti(); /* matches 'cli' in switch_mm() */
+    __sti();
 
     /*
      * Save away %fs and %gs. No need to save %es and %ds, as
diff --git a/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/setup.c b/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/setup.c
index 6ac4ff242e..b3fa27fb11 100644
--- a/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/setup.c
+++ b/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/setup.c
@@ -968,6 +968,9 @@ void __init cpu_init (void)
 
     HYPERVISOR_stack_switch(__KERNEL_DS, current->thread.esp0);
 
+    load_LDT(&init_mm);
+    flush_page_update_queue();
+
     /* Force FPU initialization. */
     current->flags &= ~PF_USEDFPU;
     current->used_math = 0;
diff --git a/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/traps.c b/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/traps.c
index da7cd7413e..a10c07a0ae 100644
--- a/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/traps.c
+++ b/xenolinux-2.4.21-pre4-sparse/arch/xeno/kernel/traps.c
@@ -42,6 +42,8 @@
 #include <linux/module.h>
 
 asmlinkage int system_call(void);
+asmlinkage void lcall7(void);
+asmlinkage void lcall27(void);
 
 asmlinkage void divide_error(void);
 asmlinkage void debug(void);
@@ -530,6 +532,26 @@ asmlinkage void math_state_restore(struct pt_regs regs)
 	current->flags |= PF_USEDFPU;	/* So we fnsave on switch_to() */
 }
 
+
+#define _set_gate(gate_addr,type,dpl,addr) \
+do { \
+  int __d0, __d1; \
+  __asm__ __volatile__ ("movw %%dx,%%ax\n\t" \
+	"movw %4,%%dx\n\t" \
+	"movl %%eax,%0\n\t" \
+	"movl %%edx,%1" \
+	:"=m" (*((long *) (gate_addr))), \
+	 "=m" (*(1+(long *) (gate_addr))), "=&a" (__d0), "=&d" (__d1) \
+	:"i" ((short) (0x8000+(dpl<<13)+(type<<8))), \
+	 "3" ((char *) (addr)),"2" (__KERNEL_CS << 16)); \
+} while (0)
+
+static void __init set_call_gate(void *a, void *addr)
+{
+	_set_gate(a,12,3,addr);
+}
+
+
 static trap_info_t trap_table[] = {
     {  0, 0, __KERNEL_CS, (unsigned long)divide_error                },
     {  1, 0, __KERNEL_CS, (unsigned long)debug                       },
@@ -561,5 +583,15 @@ void __init trap_init(void)
 {
     HYPERVISOR_set_trap_table(trap_table);    
     HYPERVISOR_set_fast_trap(SYSCALL_VECTOR);
+
+    /*
+     * The default LDT is a single-entry callgate to lcall7 for iBCS and a
+     * callgate to lcall27 for Solaris/x86 binaries.
+     */
+    clear_page(&default_ldt[0]);
+    set_call_gate(&default_ldt[0],lcall7);
+    set_call_gate(&default_ldt[4],lcall27);
+    __make_page_readonly(&default_ldt[0]);
+
     cpu_init();
 }
diff --git a/xenolinux-2.4.21-pre4-sparse/arch/xeno/mm/hypervisor.c b/xenolinux-2.4.21-pre4-sparse/arch/xeno/mm/hypervisor.c
index 93554c3420..d67ad51dc5 100644
--- a/xenolinux-2.4.21-pre4-sparse/arch/xeno/mm/hypervisor.c
+++ b/xenolinux-2.4.21-pre4-sparse/arch/xeno/mm/hypervisor.c
@@ -81,12 +81,6 @@ static void DEBUG_disallow_pt_read(unsigned long pa)
 
 
 /*
- * This is the current pagetable base pointer, which is updated
- * on context switch.
- */
-unsigned long pt_baseptr;
-
-/*
  * MULTICALL_flush_page_update_queue:
  *   This is a version of the flush which queues as part of a multicall.
  */
@@ -232,3 +226,13 @@ void queue_pte_unpin(unsigned long ptr)
     increment_index();
     spin_unlock_irqrestore(&update_lock, flags);
 }
+
+void queue_set_ldt(unsigned long ptr, unsigned long len)
+{
+    unsigned long flags;
+    spin_lock_irqsave(&update_lock, flags);
+    update_queue[idx].ptr  = PGREQ_EXTENDED_COMMAND | ptr;
+    update_queue[idx].val  = PGEXT_SET_LDT | (len << PGEXT_CMD_SHIFT);
+    increment_index();
+    spin_unlock_irqrestore(&update_lock, flags);
+}
diff --git a/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/desc.h b/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/desc.h
index 1920de026a..c417cbe807 100644
--- a/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/desc.h
+++ b/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/desc.h
@@ -3,9 +3,37 @@
 
 #include <asm/ldt.h>
 
-#define __LDT(_X)     (0)
+#ifndef __ASSEMBLY__
 
-#define clear_LDT()   ((void)0)
-#define load_LDT(_mm) ((void)0)
+struct desc_struct {
+	unsigned long a,b;
+};
 
-#endif
+struct Xgt_desc_struct {
+	unsigned short size;
+	unsigned long address __attribute__((packed));
+};
+
+extern struct desc_struct default_ldt[];
+
+static inline void clear_LDT(void)
+{
+    queue_set_ldt((unsigned long)&default_ldt[0], 5);
+}
+
+static inline void load_LDT(struct mm_struct *mm)
+{
+    void *segments = mm->context.segments;
+    int count = LDT_ENTRIES;
+
+    if (!segments) {
+        segments = &default_ldt[0];
+        count = 5;
+    }
+         
+    queue_set_ldt((unsigned long)segments, count);
+}
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* __ARCH_DESC_H__ */
diff --git a/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/hypervisor.h b/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/hypervisor.h
index 35de4c20eb..b7dfb52e20 100644
--- a/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/hypervisor.h
+++ b/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/hypervisor.h
@@ -11,6 +11,7 @@
 
 #include <asm/hypervisor-ifs/hypervisor-if.h>
 #include <asm/ptrace.h>
+#include <asm/page.h>
 
 /* arch/xeno/kernel/setup.c */
 union start_info_union
@@ -42,7 +43,7 @@ void queue_pgd_pin(unsigned long ptr);
 void queue_pgd_unpin(unsigned long ptr);
 void queue_pte_pin(unsigned long ptr);
 void queue_pte_unpin(unsigned long ptr);
-
+void queue_set_ldt(unsigned long ptr, unsigned long bytes);
 #define PT_UPDATE_DEBUG 0
 
 #if PT_UPDATE_DEBUG > 0
@@ -119,6 +120,10 @@ extern page_update_debug_t update_debug_queue[];
  printk("PTE UNPIN %s %d: %08lx\n", __FILE__, __LINE__, (_p));    \
  queue_pte_unpin(_p);                                             \
 })   
+#define queue_set_ldt(_p,_l) ({                                        \
+ printk("SETL LDT %s %d: %08lx %d\n", __FILE__, __LINE__, (_p), (_l)); \
+ queue_set_ldt((_p), (_l));                                            \
+})   
 #endif
 
 void _flush_page_update_queue(void);
diff --git a/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/mmu_context.h b/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/mmu_context.h
index ad07796f95..cdf5319f48 100644
--- a/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/mmu_context.h
+++ b/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/mmu_context.h
@@ -34,7 +34,6 @@ extern pgd_t *cur_pgd;
 
 static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, struct task_struct *tsk, unsigned cpu)
 {
-	cli(); /* protect flush_update_queue multicall */
 	if (prev != next) {
 		/* stop flush ipis for the previous mm */
 		clear_bit(cpu, &prev->cpu_vm_mask);
@@ -52,7 +51,6 @@ static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, str
 		/* Re-load page tables */
 		cur_pgd = next->pgd;
 		queue_pt_switch(__pa(cur_pgd));
-		MULTICALL_flush_page_update_queue();
 	}
 #ifdef CONFIG_SMP
 	else {
@@ -74,8 +72,7 @@ static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, str
 #define activate_mm(prev, next) \
 do { \
 	switch_mm((prev),(next),NULL,smp_processor_id()); \
-	execute_multicall_list(); \
-	sti(); /* matches 'cli' in switch_mm() */ \
+	flush_page_update_queue(); \
 } while ( 0 )
 
 #endif
diff --git a/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/pgalloc.h b/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/pgalloc.h
index 6dec534017..49d6e30b2a 100644
--- a/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/pgalloc.h
+++ b/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/pgalloc.h
@@ -73,19 +73,13 @@ out_oom:
 static inline pgd_t *get_pgd_slow(void)
 {
 	pgd_t *pgd = (pgd_t *)__get_free_page(GFP_KERNEL);
-	pgd_t *kpgd;
-	pmd_t *kpmd;
-	pte_t *kpte;
 
 	if (pgd) {
 		memset(pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
 		memcpy(pgd + USER_PTRS_PER_PGD,
 			init_mm.pgd + USER_PTRS_PER_PGD,
 			(PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
-		kpgd = pgd_offset_k((unsigned long)pgd);
-		kpmd = pmd_offset(kpgd, (unsigned long)pgd);
-		kpte = pte_offset(kpmd, (unsigned long)pgd);
-		queue_l1_entry_update(__pa(kpte), (*(unsigned long *)kpte)&~_PAGE_RW);
+                __make_page_readonly(pgd);
 		queue_pgd_pin(__pa(pgd));
 
 	}
@@ -117,14 +111,8 @@ static inline void free_pgd_slow(pgd_t *pgd)
 		free_page((unsigned long)__va(pgd_val(pgd[i])-1));
 	kmem_cache_free(pae_pgd_cachep, pgd);
 #else
-	pgd_t *kpgd;
-	pmd_t *kpmd;
-	pte_t *kpte;
 	queue_pgd_unpin(__pa(pgd));
-	kpgd = pgd_offset_k((unsigned long)pgd);
-	kpmd = pmd_offset(kpgd, (unsigned long)pgd);
-	kpte = pte_offset(kpmd, (unsigned long)pgd);
-	queue_l1_entry_update(__pa(kpte), (*(unsigned long *)kpte)|_PAGE_RW);
+        __make_page_writeable(pgd);
 	free_page((unsigned long)pgd);
 #endif
 }
@@ -141,18 +129,12 @@ static inline void free_pgd_fast(pgd_t *pgd)
 static inline pte_t *pte_alloc_one(struct mm_struct *mm, unsigned long address)
 {
     pte_t *pte;
-    pgd_t *kpgd;
-    pmd_t *kpmd;
-    pte_t *kpte;
 
     pte = (pte_t *) __get_free_page(GFP_KERNEL);
     if (pte)
     {
         clear_page(pte);
-        kpgd = pgd_offset_k((unsigned long)pte);
-        kpmd = pmd_offset(kpgd, (unsigned long)pte);
-        kpte = pte_offset(kpmd, (unsigned long)pte);
-        queue_l1_entry_update(__pa(kpte), (*(unsigned long *)kpte)&~_PAGE_RW);
+        __make_page_readonly(pte);
         queue_pte_pin(__pa(pte));
     }
     return pte;
@@ -172,14 +154,8 @@ static inline pte_t *pte_alloc_one_fast(struct mm_struct *mm,
 
 static __inline__ void pte_free_slow(pte_t *pte)
 {
-    pgd_t *kpgd;
-    pmd_t *kpmd;
-    pte_t *kpte;
     queue_pte_unpin(__pa(pte));
-    kpgd = pgd_offset_k((unsigned long)pte);
-    kpmd = pmd_offset(kpgd, (unsigned long)pte);
-    kpte = pte_offset(kpmd, (unsigned long)pte);
-    queue_l1_entry_update(__pa(kpte), (*(unsigned long *)kpte)|_PAGE_RW);
+    __make_page_writeable(pte);
     free_page((unsigned long)pte);
 }
 
diff --git a/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/pgtable.h b/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/pgtable.h
index 3cc0e90ae5..0f914c7c42 100644
--- a/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/pgtable.h
+++ b/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/pgtable.h
@@ -99,6 +99,7 @@ extern void pgtable_cache_init(void);
 #ifndef __ASSEMBLY__
 /* 4MB is just a nice "safety zone". Also, we align to a fresh pde. */
 #define VMALLOC_OFFSET	(4*1024*1024)
+extern void * high_memory;
 #define VMALLOC_START	(((unsigned long) high_memory + 2*VMALLOC_OFFSET-1) & \
 						~(VMALLOC_OFFSET-1))
 #define VMALLOC_VMADDR(x) ((unsigned long)(x))
@@ -291,6 +292,71 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
 struct page;
 int change_page_attr(struct page *, int, pgprot_t prot);
 
+static inline void __make_page_readonly(void *va)
+{
+    pgd_t *pgd = pgd_offset_k((unsigned long)va);
+    pmd_t *pmd = pmd_offset(pgd, (unsigned long)va);
+    pte_t *pte = pte_offset(pmd, (unsigned long)va);
+    queue_l1_entry_update(__pa(pte), (*(unsigned long *)pte)&~_PAGE_RW);
+}
+
+static inline void __make_page_writeable(void *va)
+{
+    pgd_t *pgd = pgd_offset_k((unsigned long)va);
+    pmd_t *pmd = pmd_offset(pgd, (unsigned long)va);
+    pte_t *pte = pte_offset(pmd, (unsigned long)va);
+    queue_l1_entry_update(__pa(pte), (*(unsigned long *)pte)|_PAGE_RW);
+}
+
+static inline void make_page_readonly(void *va)
+{
+    pgd_t *pgd = pgd_offset_k((unsigned long)va);
+    pmd_t *pmd = pmd_offset(pgd, (unsigned long)va);
+    pte_t *pte = pte_offset(pmd, (unsigned long)va);
+    queue_l1_entry_update(__pa(pte), (*(unsigned long *)pte)&~_PAGE_RW);
+    if ( (unsigned long)va >= VMALLOC_START )
+        __make_page_readonly(machine_to_virt(
+            *(unsigned long *)pte&PAGE_MASK));
+}
+
+static inline void make_page_writeable(void *va)
+{
+    pgd_t *pgd = pgd_offset_k((unsigned long)va);
+    pmd_t *pmd = pmd_offset(pgd, (unsigned long)va);
+    pte_t *pte = pte_offset(pmd, (unsigned long)va);
+    queue_l1_entry_update(__pa(pte), (*(unsigned long *)pte)|_PAGE_RW);
+    if ( (unsigned long)va >= VMALLOC_START )
+        __make_page_writeable(machine_to_virt(
+            *(unsigned long *)pte&PAGE_MASK));
+}
+
+static inline void make_pages_readonly(void *va, unsigned int nr)
+{
+    while ( nr-- != 0 )
+    {
+        make_page_readonly(va);
+        va = (void *)((unsigned long)va + PAGE_SIZE);
+    }
+}
+
+static inline void make_pages_writeable(void *va, unsigned int nr)
+{
+    while ( nr-- != 0 )
+    {
+        make_page_writeable(va);
+        va = (void *)((unsigned long)va + PAGE_SIZE);
+    }
+}
+
+static inline unsigned long arbitrary_virt_to_phys(void *va)
+{
+    pgd_t *pgd = pgd_offset_k((unsigned long)va);
+    pmd_t *pmd = pmd_offset(pgd, (unsigned long)va);
+    pte_t *pte = pte_offset(pmd, (unsigned long)va);
+    unsigned long pa = (*(unsigned long *)pte) & PAGE_MASK;
+    return pa | ((unsigned long)va & (PAGE_SIZE-1));
+}
+
 #endif /* !__ASSEMBLY__ */
 
 /* Needs to be defined here and not in linux/mm.h, as it is arch dependent */
diff --git a/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/processor.h b/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/processor.h
index f21e0d7f2d..86b0020c23 100644
--- a/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/processor.h
+++ b/xenolinux-2.4.21-pre4-sparse/include/asm-xeno/processor.h
@@ -381,7 +381,7 @@ struct thread_struct {
 	0,0,0,0, /* esp,ebp,esi,edi */				\
 	0,0,0,0,0,0, /* es,cs,ss */				\
 	0,0,0,0,0,0, /* ds,fs,gs */				\
-	__LDT(0),0, /* ldt */					\
+	0,0, /* ldt */						\
 	0, INVALID_IO_BITMAP_OFFSET, /* tace, bitmap */		\
 	{~0, } /* ioperm */					\
 }