[PATCH] x86_64: Use a VMA for the 32bit vsyscall

Use a real VMA to map the 32bit vsyscall page

This interacts better with Hugh's upcomming VMA walk optimization
Also removes some ugly special cases.

Code roughly modelled after the ppc64 vdso version from Ben Herrenschmidt.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/arch/x86_64/ia32/ia32_binfmt.c b/arch/x86_64/ia32/ia32_binfmt.c
index 93d568dfa762168c2baf2b391e7fe255beff77e1..99b522052d16d9cae2f3c07f11afd9c3cdfb59e9 100644 (file)
--- a/arch/x86_64/ia32/ia32_binfmt.c
+++ b/arch/x86_64/ia32/ia32_binfmt.c
@@ -312,6 +312,10 @@ MODULE_AUTHOR("Eric Youngdale, Andi Kleen");
 
 static void elf32_init(struct pt_regs *);
 
+#define ARCH_HAS_SETUP_ADDITIONAL_PAGES 1
+#define arch_setup_additional_pages syscall32_setup_pages
+extern int syscall32_setup_pages(struct linux_binprm *, int exstack);
+
 #include "../../../fs/binfmt_elf.c" 
 
 static void elf32_init(struct pt_regs *regs)

diff --git a/arch/x86_64/ia32/syscall32.c b/arch/x86_64/ia32/syscall32.c
index 399ff498509978c834420c82bc539ed4bfe6b268..01d8db1a1c09c7bff982a740bf5222735e996893 100644 (file)
--- a/arch/x86_64/ia32/syscall32.c
+++ b/arch/x86_64/ia32/syscall32.c
@@ -9,6 +9,7 @@
 #include <linux/gfp.h>
 #include <linux/init.h>
 #include <linux/stringify.h>
+#include <linux/security.h>
 #include <asm/proto.h>
 #include <asm/tlbflush.h>
 #include <asm/ia32_unistd.h>
@@ -30,51 +31,57 @@ extern int sysctl_vsyscall32;
 char *syscall32_page; 
 static int use_sysenter = -1;
 
-/*
- * Map the 32bit vsyscall page on demand.
- *
- * RED-PEN: This knows too much about high level VM.
- *
- * Alternative would be to generate a vma with appropriate backing options
- * and let it be handled by generic VM.
- */
-int __map_syscall32(struct mm_struct *mm, unsigned long address)
-{ 
-       pgd_t *pgd;
-       pud_t *pud;
-       pte_t *pte;
-       pmd_t *pmd;
-       int err = -ENOMEM;
-
-       spin_lock(&mm->page_table_lock); 
-       pgd = pgd_offset(mm, address);
-       pud = pud_alloc(mm, pgd, address);
-       if (pud) {
-               pmd = pmd_alloc(mm, pud, address);
-               if (pmd && (pte = pte_alloc_map(mm, pmd, address)) != NULL) {
-                       if (pte_none(*pte)) {
-                               set_pte(pte,
-                                       mk_pte(virt_to_page(syscall32_page),
-                                              PAGE_KERNEL_VSYSCALL32));
-                       }
-                       /* Flush only the local CPU. Other CPUs taking a fault
-                          will just end up here again
-                          This probably not needed and just paranoia. */
-                       __flush_tlb_one(address);
-                       err = 0;
-               }
-       }
-       spin_unlock(&mm->page_table_lock);
-       return err;
+static struct page *
+syscall32_nopage(struct vm_area_struct *vma, unsigned long adr, int *type)
+{
+       struct page *p = virt_to_page(adr - vma->vm_start + syscall32_page);
+       get_page(p);
+       return p;
 }
 
-int map_syscall32(struct mm_struct *mm, unsigned long address)
+/* Prevent VMA merging */
+static void syscall32_vma_close(struct vm_area_struct *vma)
 {
-       int err;
-       down_read(&mm->mmap_sem);
-       err = __map_syscall32(mm, address);
-       up_read(&mm->mmap_sem);
-       return err;
+}
+
+static struct vm_operations_struct syscall32_vm_ops = {
+       .close = syscall32_vma_close,
+       .nopage = syscall32_nopage,
+};
+
+struct linux_binprm;
+
+/* Setup a VMA at program startup for the vsyscall page */
+int syscall32_setup_pages(struct linux_binprm *bprm, int exstack)
+{
+       int npages = (VSYSCALL32_END - VSYSCALL32_BASE) >> PAGE_SHIFT;
+       struct vm_area_struct *vma;
+       struct mm_struct *mm = current->mm;
+
+       vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
+       if (!vma)
+               return -ENOMEM;
+       if (security_vm_enough_memory(npages)) {
+               kmem_cache_free(vm_area_cachep, vma);
+               return -ENOMEM;
+       }
+
+       memset(vma, 0, sizeof(struct vm_area_struct));
+       /* Could randomize here */
+       vma->vm_start = VSYSCALL32_BASE;
+       vma->vm_end = VSYSCALL32_END;
+       /* MAYWRITE to allow gdb to COW and set breakpoints */
+       vma->vm_flags = VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC|VM_MAYEXEC|VM_MAYWRITE;
+       vma->vm_flags |= mm->def_flags;
+       vma->vm_page_prot = protection_map[vma->vm_flags & 7];
+       vma->vm_ops = &syscall32_vm_ops;
+       vma->vm_mm = mm;
+
+       down_write(&mm->mmap_sem);
+       insert_vm_struct(mm, vma);
+       mm->total_vm += npages;
+       up_write(&mm->mmap_sem);
+       return 0;
 }
 
 static int __init init_syscall32(void)
@@ -82,7 +89,6 @@ static int __init init_syscall32(void)
        syscall32_page = (void *)get_zeroed_page(GFP_KERNEL); 
        if (!syscall32_page) 
                panic("Cannot allocate syscall32 page"); 
-       SetPageReserved(virt_to_page(syscall32_page));
        if (use_sysenter > 0) {
                memcpy(syscall32_page, syscall32_sysenter,
                       syscall32_sysenter_end - syscall32_sysenter);

diff --git a/arch/x86_64/mm/fault.c b/arch/x86_64/mm/fault.c
index 5724370475cc10816730aeb7375e4193206f36fc..d4676ca091449bd87c075956057716f57decd406 100644 (file)
--- a/arch/x86_64/mm/fault.c
+++ b/arch/x86_64/mm/fault.c
@@ -458,17 +458,6 @@ bad_area:
        up_read(&mm->mmap_sem);
 
 bad_area_nosemaphore:
-
-#ifdef CONFIG_IA32_EMULATION
-       /* 32bit vsyscall. map on demand. */
-       if (test_thread_flag(TIF_IA32) &&
-           address >= VSYSCALL32_BASE && address < VSYSCALL32_END) {
-               if (map_syscall32(mm, address) < 0)
-                       goto out_of_memory2;
-               return;
-       }
-#endif
-
        /* User mode accesses just cause a SIGSEGV */
        if (error_code & 4) {
                if (is_prefetch(regs, address, error_code))
@@ -550,7 +539,6 @@ no_context:
  */
 out_of_memory:
        up_read(&mm->mmap_sem);
-out_of_memory2:
        if (current->pid == 1) { 
                yield();
                goto again;

diff --git a/arch/x86_64/mm/init.c b/arch/x86_64/mm/init.c
index b0d604551d862ad474d6e49670cbc11a371a7f96..dbe53b4c7e66c0c0f75fbccfb8d404961d7eb10d 100644 (file)
--- a/arch/x86_64/mm/init.c
+++ b/arch/x86_64/mm/init.c
@@ -583,9 +583,9 @@ static __init int x8664_sysctl_init(void)
 __initcall(x8664_sysctl_init);
 #endif
 
-/* Pseudo VMAs to allow ptrace access for the vsyscall pages.  x86-64 has two
-   different ones: one for 32bit and one for 64bit. Use the appropiate
-   for the target task. */
+/* A pseudo VMAs to allow ptrace access for the vsyscall page.   This only
+   covers the 64bit vsyscall page now. 32bit has a real VMA now and does
+   not need special handling anymore. */
 
 static struct vm_area_struct gate_vma = {
        .vm_start = VSYSCALL_START,
@@ -593,22 +593,11 @@ static struct vm_area_struct gate_vma = {
        .vm_page_prot = PAGE_READONLY
 };
 
-static struct vm_area_struct gate32_vma = {
-       .vm_start = VSYSCALL32_BASE,
-       .vm_end = VSYSCALL32_END,
-       .vm_page_prot = PAGE_READONLY
-};
-
 struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
 {
 #ifdef CONFIG_IA32_EMULATION
-       if (test_tsk_thread_flag(tsk, TIF_IA32)) {
-               /* lookup code assumes the pages are present. set them up
-                  now */
-               if (__map_syscall32(tsk->mm, VSYSCALL32_BASE) < 0)
-                       return NULL;
-               return &gate32_vma;
-       }
+       if (test_tsk_thread_flag(tsk, TIF_IA32))
+               return NULL;
 #endif
        return &gate_vma;
 }
@@ -616,6 +605,8 @@ struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
 int in_gate_area(struct task_struct *task, unsigned long addr)
 {
        struct vm_area_struct *vma = get_gate_vma(task);
+       if (!vma)
+               return 0;
        return (addr >= vma->vm_start) && (addr < vma->vm_end);
 }
 
@@ -625,6 +616,5 @@ int in_gate_area(struct task_struct *task, unsigned long addr)
  */
 int in_gate_area_no_task(unsigned long addr)
 {
-       return (((addr >= VSYSCALL_START) && (addr < VSYSCALL_END)) ||
-               ((addr >= VSYSCALL32_BASE) && (addr < VSYSCALL32_END)));
+       return (addr >= VSYSCALL_START) && (addr < VSYSCALL_END);
 }

diff --git a/include/asm-x86_64/proto.h b/include/asm-x86_64/proto.h
index c59526ee54da668b388597892c03c914abe13968..217bd9ace69b7b56a83ca0f556f043df29c6b7f1 100644 (file)
--- a/include/asm-x86_64/proto.h
+++ b/include/asm-x86_64/proto.h
@@ -69,8 +69,6 @@ extern void __die(const char * str, struct pt_regs * regs, long err);
 extern void __show_regs(struct pt_regs * regs);
 extern void show_regs(struct pt_regs * regs);
 
-extern int map_syscall32(struct mm_struct *mm, unsigned long address);
-extern int __map_syscall32(struct mm_struct *mm, unsigned long address);
 extern char *syscall32_page;
 extern void syscall32_cpu_init(void);