diff options
Diffstat (limited to 'arch/x86/vdso')
| -rw-r--r-- | arch/x86/vdso/Makefile | 2 | ||||
| -rw-r--r-- | arch/x86/vdso/vdso32-setup.c | 344 |
2 files changed, 345 insertions, 1 deletions
diff --git a/arch/x86/vdso/Makefile b/arch/x86/vdso/Makefile index ca2aabf8ed39..1efe785979a2 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 000000000000..85c52d23ee40 --- /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; +} |