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-rw-r--r--arch/x86/vdso/Makefile2
-rw-r--r--arch/x86/vdso/vdso32-setup.c344
2 files changed, 345 insertions, 1 deletions
diff --git a/arch/x86/vdso/Makefile b/arch/x86/vdso/Makefile
index ca2aabf8ed3..1efe785979a 100644
--- a/arch/x86/vdso/Makefile
+++ b/arch/x86/vdso/Makefile
@@ -15,7 +15,7 @@ vobjs-y := vdso-note.o vclock_gettime.o vgetcpu.o vvar.o
# files to link into kernel
obj-$(VDSO64-y) += vma.o vdso.o
-obj-$(CONFIG_X86_32) += vdso32.o
+obj-$(CONFIG_X86_32) += vdso32.o vdso32-setup.o
vobjs := $(foreach F,$(vobjs-y),$(obj)/$F)
diff --git a/arch/x86/vdso/vdso32-setup.c b/arch/x86/vdso/vdso32-setup.c
new file mode 100644
index 00000000000..85c52d23ee4
--- /dev/null
+++ b/arch/x86/vdso/vdso32-setup.c
@@ -0,0 +1,344 @@
+/*
+ * (C) Copyright 2002 Linus Torvalds
+ * Portions based on the vdso-randomization code from exec-shield:
+ * Copyright(C) 2005-2006, Red Hat, Inc., Ingo Molnar
+ *
+ * This file contains the needed initializations to support sysenter.
+ */
+
+#include <linux/init.h>
+#include <linux/smp.h>
+#include <linux/thread_info.h>
+#include <linux/sched.h>
+#include <linux/gfp.h>
+#include <linux/string.h>
+#include <linux/elf.h>
+#include <linux/mm.h>
+#include <linux/err.h>
+#include <linux/module.h>
+
+#include <asm/cpufeature.h>
+#include <asm/msr.h>
+#include <asm/pgtable.h>
+#include <asm/unistd.h>
+#include <asm/elf.h>
+#include <asm/tlbflush.h>
+#include <asm/vdso.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()?
+ */
+unsigned int __read_mostly vdso_enabled = VDSO_DEFAULT;
+
+EXPORT_SYMBOL_GPL(vdso_enabled);
+
+static int __init vdso_setup(char *s)
+{
+ vdso_enabled = simple_strtoul(s, NULL, 0);
+
+ return 1;
+}
+
+__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();
+ struct tss_struct *tss = &per_cpu(init_tss, cpu);
+
+ if (!boot_cpu_has(X86_FEATURE_SEP)) {
+ put_cpu();
+ return;
+ }
+
+ 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->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.
+ */
+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);
+
+ gate_vma_init();
+
+ printk("Compat vDSO mapped to %08lx.\n", __fix_to_virt(FIX_VDSO));
+
+ if (!boot_cpu_has(X86_FEATURE_SEP)) {
+ 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, vsyscall_len);
+ relocate_vdso(syscall_page);
+
+ return 0;
+}
+
+/* Setup a VMA at program startup for the vsyscall page */
+int arch_setup_additional_pages(struct linux_binprm *bprm, int exstack)
+{
+ struct mm_struct *mm = current->mm;
+ unsigned long addr;
+ int ret = 0;
+ bool compat;
+
+ down_write(&mm->mmap_sem);
+
+ /* 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 =
+ VDSO32_SYMBOL(addr, SYSENTER_RETURN);
+
+ up_fail:
+ up_write(&mm->mmap_sem);
+
+ return ret;
+}
+
+const char *arch_vma_name(struct vm_area_struct *vma)
+{
+ if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso)
+ return "[vdso]";
+ return NULL;
+}
+
+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;
+}
+
+int in_gate_area(struct task_struct *task, unsigned long addr)
+{
+ const struct vm_area_struct *vma = get_gate_vma(task);
+
+ return vma && addr >= vma->vm_start && addr < vma->vm_end;
+}
+
+int in_gate_area_no_task(unsigned long addr)
+{
+ return 0;
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-19 04:06:46 +0000