Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=d4f7a2c18e59e0304a1c733589ce14fc02fec1bd
Commit:     d4f7a2c18e59e0304a1c733589ce14fc02fec1bd
Parent:     a6c4e076ee4c1ea670e4faa55814e63dd08e3f29
Author:     Jeremy Fitzhardinge <[EMAIL PROTECTED]>
AuthorDate: Wed May 2 19:27:12 2007 +0200
Committer:  Andi Kleen <[EMAIL PROTECTED]>
CommitDate: Wed May 2 19:27:12 2007 +0200

    [PATCH] i386: Relocate VDSO ELF headers to match mapped location with 
COMPAT_VDSO
    
    Some versions of libc can't deal with a VDSO which doesn't have its
    ELF headers matching its mapped address.  COMPAT_VDSO maps the VDSO at
    a specific system-wide fixed address.  Previously this was all done at
    build time, on the grounds that the fixed VDSO address is always at
    the top of the address space.  However, a hypervisor may reserve some
    of that address space, pushing the fixmap address down.
    
    This patch does the adjustment dynamically at runtime, depending on
    the runtime location of the VDSO fixmap.
    
    [ Patch has been through several hands: Jan Beulich wrote the orignal
      version; Zach reworked it, and Jeremy converted it to relocate phdrs
      as well as sections. ]
    
    Signed-off-by: Jeremy Fitzhardinge <[EMAIL PROTECTED]>
    Signed-off-by: Andi Kleen <[EMAIL PROTECTED]>
    Cc: Zachary Amsden <[EMAIL PROTECTED]>
    Cc: "Jan Beulich" <[EMAIL PROTECTED]>
    Cc: Eric W. Biederman <[EMAIL PROTECTED]>
    Cc: Andi Kleen <[EMAIL PROTECTED]>
    Cc: Ingo Molnar <[EMAIL PROTECTED]>
    Cc: Roland McGrath <[EMAIL PROTECTED]>
---
 arch/i386/kernel/entry.S    |    4 -
 arch/i386/kernel/sysenter.c |  158 ++++++++++++++++++++++++++++++++++++++++---
 arch/i386/mm/pgtable.c      |    6 --
 include/asm-i386/elf.h      |   28 +++-----
 include/asm-i386/fixmap.h   |    8 +--
 include/linux/elf.h         |   17 +++++
 6 files changed, 178 insertions(+), 43 deletions(-)

diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S
index c61c6b6..e901952 100644
--- a/arch/i386/kernel/entry.S
+++ b/arch/i386/kernel/entry.S
@@ -305,16 +305,12 @@ sysenter_past_esp:
        pushl $(__USER_CS)
        CFI_ADJUST_CFA_OFFSET 4
        /*CFI_REL_OFFSET cs, 0*/
-#ifndef CONFIG_COMPAT_VDSO
        /*
         * Push current_thread_info()->sysenter_return to the stack.
         * A tiny bit of offset fixup is necessary - 4*4 means the 4 words
         * pushed above; +8 corresponds to copy_thread's esp0 setting.
         */
        pushl (TI_sysenter_return-THREAD_SIZE+8+4*4)(%esp)
-#else
-       pushl $SYSENTER_RETURN
-#endif
        CFI_ADJUST_CFA_OFFSET 4
        CFI_REL_OFFSET eip, 0
 
diff --git a/arch/i386/kernel/sysenter.c b/arch/i386/kernel/sysenter.c
index 13ca54a..e5a9583 100644
--- a/arch/i386/kernel/sysenter.c
+++ b/arch/i386/kernel/sysenter.c
@@ -22,6 +22,7 @@
 #include <asm/msr.h>
 #include <asm/pgtable.h>
 #include <asm/unistd.h>
+#include <asm/elf.h>
 
 /*
  * Should the kernel map a VDSO page into processes and pass its
@@ -46,6 +47,129 @@ __setup("vdso=", vdso_setup);
 
 extern asmlinkage void sysenter_entry(void);
 
+#ifdef CONFIG_COMPAT_VDSO
+static __init void reloc_symtab(Elf32_Ehdr *ehdr,
+                               unsigned offset, unsigned size)
+{
+       Elf32_Sym *sym = (void *)ehdr + offset;
+       unsigned nsym = size / sizeof(*sym);
+       unsigned i;
+
+       for(i = 0; i < nsym; i++, sym++) {
+               if (sym->st_shndx == SHN_UNDEF ||
+                   sym->st_shndx == SHN_ABS)
+                       continue;  /* skip */
+
+               if (sym->st_shndx > SHN_LORESERVE) {
+                       printk(KERN_INFO "VDSO: unexpected st_shndx %x\n",
+                              sym->st_shndx);
+                       continue;
+               }
+
+               switch(ELF_ST_TYPE(sym->st_info)) {
+               case STT_OBJECT:
+               case STT_FUNC:
+               case STT_SECTION:
+               case STT_FILE:
+                       sym->st_value += VDSO_HIGH_BASE;
+               }
+       }
+}
+
+static __init void reloc_dyn(Elf32_Ehdr *ehdr, unsigned offset)
+{
+       Elf32_Dyn *dyn = (void *)ehdr + offset;
+
+       for(; dyn->d_tag != DT_NULL; dyn++)
+               switch(dyn->d_tag) {
+               case DT_PLTGOT:
+               case DT_HASH:
+               case DT_STRTAB:
+               case DT_SYMTAB:
+               case DT_RELA:
+               case DT_INIT:
+               case DT_FINI:
+               case DT_REL:
+               case DT_DEBUG:
+               case DT_JMPREL:
+               case DT_VERSYM:
+               case DT_VERDEF:
+               case DT_VERNEED:
+               case DT_ADDRRNGLO ... DT_ADDRRNGHI:
+                       /* definitely pointers needing relocation */
+                       dyn->d_un.d_ptr += VDSO_HIGH_BASE;
+                       break;
+
+               case DT_ENCODING ... OLD_DT_LOOS-1:
+               case DT_LOOS ... DT_HIOS-1:
+                       /* Tags above DT_ENCODING are pointers if
+                          they're even */
+                       if (dyn->d_tag >= DT_ENCODING &&
+                           (dyn->d_tag & 1) == 0)
+                               dyn->d_un.d_ptr += VDSO_HIGH_BASE;
+                       break;
+
+               case DT_VERDEFNUM:
+               case DT_VERNEEDNUM:
+               case DT_FLAGS_1:
+               case DT_RELACOUNT:
+               case DT_RELCOUNT:
+               case DT_VALRNGLO ... DT_VALRNGHI:
+                       /* definitely not pointers */
+                       break;
+
+               case OLD_DT_LOOS ... DT_LOOS-1:
+               case DT_HIOS ... DT_VALRNGLO-1:
+               default:
+                       if (dyn->d_tag > DT_ENCODING)
+                               printk(KERN_INFO "VDSO: unexpected DT_tag %x\n",
+                                      dyn->d_tag);
+                       break;
+               }
+}
+
+static __init void relocate_vdso(Elf32_Ehdr *ehdr)
+{
+       Elf32_Phdr *phdr;
+       Elf32_Shdr *shdr;
+       int i;
+
+       BUG_ON(memcmp(ehdr->e_ident, ELFMAG, 4) != 0 ||
+              !elf_check_arch(ehdr) ||
+              ehdr->e_type != ET_DYN);
+
+       ehdr->e_entry += VDSO_HIGH_BASE;
+
+       /* rebase phdrs */
+       phdr = (void *)ehdr + ehdr->e_phoff;
+       for (i = 0; i < ehdr->e_phnum; i++) {
+               phdr[i].p_vaddr += VDSO_HIGH_BASE;
+
+               /* relocate dynamic stuff */
+               if (phdr[i].p_type == PT_DYNAMIC)
+                       reloc_dyn(ehdr, phdr[i].p_offset);
+       }
+
+       /* rebase sections */
+       shdr = (void *)ehdr + ehdr->e_shoff;
+       for(i = 0; i < ehdr->e_shnum; i++) {
+               if (!(shdr[i].sh_flags & SHF_ALLOC))
+                       continue;
+
+               shdr[i].sh_addr += VDSO_HIGH_BASE;
+
+               if (shdr[i].sh_type == SHT_SYMTAB ||
+                   shdr[i].sh_type == SHT_DYNSYM)
+                       reloc_symtab(ehdr, shdr[i].sh_offset,
+                                    shdr[i].sh_size);
+       }
+}
+#else
+static inline void relocate_vdso(Elf32_Ehdr *ehdr)
+{
+}
+#endif /* COMPAT_VDSO */
+
 void enable_sep_cpu(void)
 {
        int cpu = get_cpu();
@@ -75,6 +199,9 @@ static struct page *syscall_pages[1];
 int __init sysenter_setup(void)
 {
        void *syscall_page = (void *)get_zeroed_page(GFP_ATOMIC);
+       const void *vsyscall;
+       size_t vsyscall_len;
+
        syscall_pages[0] = virt_to_page(syscall_page);
 
 #ifdef CONFIG_COMPAT_VDSO
@@ -83,23 +210,23 @@ int __init sysenter_setup(void)
 #endif
 
        if (!boot_cpu_has(X86_FEATURE_SEP)) {
-               memcpy(syscall_page,
-                      &vsyscall_int80_start,
-                      &vsyscall_int80_end - &vsyscall_int80_start);
-               return 0;
+               vsyscall = &vsyscall_int80_start;
+               vsyscall_len = &vsyscall_int80_end - &vsyscall_int80_start;
+       } else {
+               vsyscall = &vsyscall_sysenter_start;
+               vsyscall_len = &vsyscall_sysenter_end - 
&vsyscall_sysenter_start;
        }
 
-       memcpy(syscall_page,
-              &vsyscall_sysenter_start,
-              &vsyscall_sysenter_end - &vsyscall_sysenter_start);
+       memcpy(syscall_page, vsyscall, vsyscall_len);
+       relocate_vdso(syscall_page);
 
        return 0;
 }
 
-#ifndef CONFIG_COMPAT_VDSO
 /* Defined in vsyscall-sysenter.S */
 extern void SYSENTER_RETURN;
 
+#ifdef __HAVE_ARCH_GATE_AREA
 /* Setup a VMA at program startup for the vsyscall page */
 int arch_setup_additional_pages(struct linux_binprm *bprm, int exstack)
 {
@@ -159,4 +286,17 @@ int in_gate_area_no_task(unsigned long addr)
 {
        return 0;
 }
-#endif
+#else  /* !__HAVE_ARCH_GATE_AREA */
+int arch_setup_additional_pages(struct linux_binprm *bprm, int exstack)
+{
+       /*
+        * If not creating userspace VMA, simply set vdso to point to
+        * fixmap page.
+        */
+       current->mm->context.vdso = (void *)VDSO_HIGH_BASE;
+       current_thread_info()->sysenter_return =
+               (void *)VDSO_SYM(&SYSENTER_RETURN);
+
+       return 0;
+}
+#endif /* __HAVE_ARCH_GATE_AREA */
diff --git a/arch/i386/mm/pgtable.c b/arch/i386/mm/pgtable.c
index fa0cfbd..99c09ed 100644
--- a/arch/i386/mm/pgtable.c
+++ b/arch/i386/mm/pgtable.c
@@ -144,10 +144,8 @@ void set_pmd_pfn(unsigned long vaddr, unsigned long pfn, 
pgprot_t flags)
 }
 
 static int fixmaps;
-#ifndef CONFIG_COMPAT_VDSO
 unsigned long __FIXADDR_TOP = 0xfffff000;
 EXPORT_SYMBOL(__FIXADDR_TOP);
-#endif
 
 void __set_fixmap (enum fixed_addresses idx, unsigned long phys, pgprot_t 
flags)
 {
@@ -173,12 +171,8 @@ void reserve_top_address(unsigned long reserve)
        BUG_ON(fixmaps > 0);
        printk(KERN_INFO "Reserving virtual address space above 0x%08x\n",
               (int)-reserve);
-#ifdef CONFIG_COMPAT_VDSO
-       BUG_ON(reserve != 0);
-#else
        __FIXADDR_TOP = -reserve - PAGE_SIZE;
        __VMALLOC_RESERVE += reserve;
-#endif
 }
 
 pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
diff --git a/include/asm-i386/elf.h b/include/asm-i386/elf.h
index 952b3ee..d304ab4 100644
--- a/include/asm-i386/elf.h
+++ b/include/asm-i386/elf.h
@@ -133,39 +133,31 @@ extern int dump_task_extended_fpu (struct task_struct *, 
struct user_fxsr_struct
 #define ELF_CORE_COPY_XFPREGS(tsk, elf_xfpregs) dump_task_extended_fpu(tsk, 
elf_xfpregs)
 
 #define VDSO_HIGH_BASE         (__fix_to_virt(FIX_VDSO))
-#define VDSO_BASE              ((unsigned long)current->mm->context.vdso)
-
-#ifdef CONFIG_COMPAT_VDSO
-# define VDSO_COMPAT_BASE      VDSO_HIGH_BASE
-# define VDSO_PRELINK          VDSO_HIGH_BASE
-#else
-# define VDSO_COMPAT_BASE      VDSO_BASE
-# define VDSO_PRELINK          0
-#endif
+#define VDSO_CURRENT_BASE      ((unsigned long)current->mm->context.vdso)
+#define VDSO_PRELINK           0
 
 #define VDSO_SYM(x) \
-               (VDSO_COMPAT_BASE + (unsigned long)(x) - VDSO_PRELINK)
+               (VDSO_CURRENT_BASE + (unsigned long)(x) - VDSO_PRELINK)
 
 #define VDSO_HIGH_EHDR         ((const struct elfhdr *) VDSO_HIGH_BASE)
-#define VDSO_EHDR              ((const struct elfhdr *) VDSO_COMPAT_BASE)
+#define VDSO_EHDR              ((const struct elfhdr *) VDSO_CURRENT_BASE)
 
 extern void __kernel_vsyscall;
 
 #define VDSO_ENTRY             VDSO_SYM(&__kernel_vsyscall)
 
-#ifndef CONFIG_COMPAT_VDSO
-#define ARCH_HAS_SETUP_ADDITIONAL_PAGES
 struct linux_binprm;
+
+#define ARCH_HAS_SETUP_ADDITIONAL_PAGES
 extern int arch_setup_additional_pages(struct linux_binprm *bprm,
                                        int executable_stack);
-#endif
 
 extern unsigned int vdso_enabled;
 
-#define ARCH_DLINFO                                            \
-do if (vdso_enabled) {                                         \
-               NEW_AUX_ENT(AT_SYSINFO, VDSO_ENTRY);            \
-               NEW_AUX_ENT(AT_SYSINFO_EHDR, VDSO_COMPAT_BASE); \
+#define ARCH_DLINFO                                                    \
+do if (vdso_enabled) {                                                 \
+               NEW_AUX_ENT(AT_SYSINFO, VDSO_ENTRY);                    \
+               NEW_AUX_ENT(AT_SYSINFO_EHDR, VDSO_CURRENT_BASE);        \
 } while (0)
 
 #endif
diff --git a/include/asm-i386/fixmap.h b/include/asm-i386/fixmap.h
index 3e9f610..e5651b2 100644
--- a/include/asm-i386/fixmap.h
+++ b/include/asm-i386/fixmap.h
@@ -19,13 +19,9 @@
  * Leave one empty page between vmalloc'ed areas and
  * the start of the fixmap.
  */
-#ifndef CONFIG_COMPAT_VDSO
 extern unsigned long __FIXADDR_TOP;
-#else
-#define __FIXADDR_TOP  0xfffff000
-#define FIXADDR_USER_START     __fix_to_virt(FIX_VDSO)
-#define FIXADDR_USER_END       __fix_to_virt(FIX_VDSO - 1)
-#endif
+#define FIXADDR_USER_START     __fix_to_virt(FIX_VDSO)
+#define FIXADDR_USER_END       __fix_to_virt(FIX_VDSO - 1)
 
 #ifndef __ASSEMBLY__
 #include <linux/kernel.h>
diff --git a/include/linux/elf.h b/include/linux/elf.h
index 60713e6..8b17ffe 100644
--- a/include/linux/elf.h
+++ b/include/linux/elf.h
@@ -83,6 +83,23 @@ typedef __s64        Elf64_Sxword;
 #define DT_DEBUG       21
 #define DT_TEXTREL     22
 #define DT_JMPREL      23
+#define DT_ENCODING    32
+#define OLD_DT_LOOS    0x60000000
+#define DT_LOOS                0x6000000d
+#define DT_HIOS                0x6ffff000
+#define DT_VALRNGLO    0x6ffffd00
+#define DT_VALRNGHI    0x6ffffdff
+#define DT_ADDRRNGLO   0x6ffffe00
+#define DT_ADDRRNGHI   0x6ffffeff
+#define DT_VERSYM      0x6ffffff0
+#define DT_RELACOUNT   0x6ffffff9
+#define DT_RELCOUNT    0x6ffffffa
+#define DT_FLAGS_1     0x6ffffffb
+#define DT_VERDEF      0x6ffffffc
+#define        DT_VERDEFNUM    0x6ffffffd
+#define DT_VERNEED     0x6ffffffe
+#define        DT_VERNEEDNUM   0x6fffffff
+#define OLD_DT_HIOS     0x6fffffff
 #define DT_LOPROC      0x70000000
 #define DT_HIPROC      0x7fffffff
 
-
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