1 files changed, 226 insertions, 43 deletions

diff --git a/arch/i386/kernel/sysenter.c b/arch/i386/kernel/sysenter.c
index 13ca54a85a1c..ff4ee6f3326b 100644
--- a/arch/i386/kernel/sysenter.c
+++ b/arch/i386/kernel/sysenter.c
@@ -22,16 +22,26 @@
 #include <asm/msr.h>
 #include <asm/pgtable.h>
 #include <asm/unistd.h>
+#include <asm/elf.h>
+#include <asm/tlbflush.h>
+
+enum {
+        VDSO_DISABLED = 0,
+        VDSO_ENABLED = 1,
+        VDSO_COMPAT = 2,
+};
+
+#ifdef CONFIG_COMPAT_VDSO
+#define VDSO_DEFAULT    VDSO_COMPAT
+#else
+#define VDSO_DEFAULT    VDSO_ENABLED
+#endif
 
 /*
  * Should the kernel map a VDSO page into processes and pass its
  * address down to glibc upon exec()?
  */
-#ifdef CONFIG_PARAVIRT
-unsigned int __read_mostly vdso_enabled = 0;
-#else
-unsigned int __read_mostly vdso_enabled = 1;
-#endif
+unsigned int __read_mostly vdso_enabled = VDSO_DEFAULT;
 
 EXPORT_SYMBOL_GPL(vdso_enabled);
 
@@ -46,6 +56,123 @@ __setup("vdso=", vdso_setup);
 
 extern asmlinkage void sysenter_entry(void);
 
+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);
+        }
+}
+
 void enable_sep_cpu(void)
 {
         int cpu = get_cpu();
@@ -56,14 +183,33 @@ void enable_sep_cpu(void)
                 return;
         }
 
-        tss->ss1 = __KERNEL_CS;
-        tss->esp1 = sizeof(struct tss_struct) + (unsigned long) tss;
+        tss->x86_tss.ss1 = __KERNEL_CS;
+        tss->x86_tss.esp1 = sizeof(struct tss_struct) + (unsigned long) tss;
         wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0);
-        wrmsr(MSR_IA32_SYSENTER_ESP, tss->esp1, 0);
+        wrmsr(MSR_IA32_SYSENTER_ESP, tss->x86_tss.esp1, 0);
         wrmsr(MSR_IA32_SYSENTER_EIP, (unsigned long) sysenter_entry, 0);
         put_cpu();      
 }
 
+static struct vm_area_struct gate_vma;
+
+static int __init gate_vma_init(void)
+{
+        gate_vma.vm_mm = NULL;
+        gate_vma.vm_start = FIXADDR_USER_START;
+        gate_vma.vm_end = FIXADDR_USER_END;
+        gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
+        gate_vma.vm_page_prot = __P101;
+        /*
+         * Make sure the vDSO gets into every core dump.
+         * Dumping its contents makes post-mortem fully interpretable later
+         * without matching up the same kernel and hardware config to see
+         * what PC values meant.
+         */
+        gate_vma.vm_flags |= VM_ALWAYSDUMP;
+        return 0;
+}
+
 /*
  * These symbols are defined by vsyscall.o to mark the bounds
  * of the ELF DSO images included therein.
@@ -72,31 +218,48 @@ extern const char vsyscall_int80_start, vsyscall_int80_end;
 extern const char vsyscall_sysenter_start, vsyscall_sysenter_end;
 static struct page *syscall_pages[1];
 
+static void map_compat_vdso(int map)
+{
+        static int vdso_mapped;
+
+        if (map == vdso_mapped)
+                return;
+
+        vdso_mapped = map;
+
+        __set_fixmap(FIX_VDSO, page_to_pfn(syscall_pages[0]) << PAGE_SHIFT,
+                     map ? PAGE_READONLY_EXEC : PAGE_NONE);
+
+        /* flush stray tlbs */
+        flush_tlb_all();
+}
+
 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
-        __set_fixmap(FIX_VDSO, __pa(syscall_page), PAGE_READONLY_EXEC);
+        gate_vma_init();
+
         printk("Compat vDSO mapped to %08lx.\n", __fix_to_virt(FIX_VDSO));
-#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;
 
@@ -105,36 +268,52 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int exstack)
 {
         struct mm_struct *mm = current->mm;
         unsigned long addr;
-        int ret;
+        int ret = 0;
+        bool compat;
 
         down_write(&mm->mmap_sem);
-        addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
-        if (IS_ERR_VALUE(addr)) {
-                ret = addr;
-                goto up_fail;
-        }
 
-        /*
-         * MAYWRITE to allow gdb to COW and set breakpoints
-         *
-         * Make sure the vDSO gets into every core dump.
-         * Dumping its contents makes post-mortem fully interpretable later
-         * without matching up the same kernel and hardware config to see
-         * what PC values meant.
-         */
-        ret = install_special_mapping(mm, addr, PAGE_SIZE,
-                                      VM_READ|VM_EXEC|
-                                      VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
-                                      VM_ALWAYSDUMP,
-                                      syscall_pages);
-        if (ret)
-                goto up_fail;
+        /* Test compat mode once here, in case someone
+           changes it via sysctl */
+        compat = (vdso_enabled == VDSO_COMPAT);
+
+        map_compat_vdso(compat);
+
+        if (compat)
+                addr = VDSO_HIGH_BASE;
+        else {
+                addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
+                if (IS_ERR_VALUE(addr)) {
+                        ret = addr;
+                        goto up_fail;
+                }
+
+                /*
+                 * MAYWRITE to allow gdb to COW and set breakpoints
+                 *
+                 * Make sure the vDSO gets into every core dump.
+                 * Dumping its contents makes post-mortem fully
+                 * interpretable later without matching up the same
+                 * kernel and hardware config to see what PC values
+                 * meant.
+                 */
+                ret = install_special_mapping(mm, addr, PAGE_SIZE,
+                                              VM_READ|VM_EXEC|
+                                              VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
+                                              VM_ALWAYSDUMP,
+                                              syscall_pages);
+
+                if (ret)
+                        goto up_fail;
+        }
 
         current->mm->context.vdso = (void *)addr;
         current_thread_info()->sysenter_return =
-                                    (void *)VDSO_SYM(&SYSENTER_RETURN);
-up_fail:
+                (void *)VDSO_SYM(&SYSENTER_RETURN);
+
+  up_fail:
         up_write(&mm->mmap_sem);
+
         return ret;
 }
 
@@ -147,6 +326,11 @@ const char *arch_vma_name(struct vm_area_struct *vma)
 
 struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
 {
+        struct mm_struct *mm = tsk->mm;
+
+        /* Check to see if this task was created in compat vdso mode */
+        if (mm && mm->context.vdso == (void *)VDSO_HIGH_BASE)
+                return &gate_vma;
         return NULL;
 }
 
@@ -159,4 +343,3 @@ int in_gate_area_no_task(unsigned long addr)
 {
         return 0;
 }
-#endif