440 lines
9.7 KiB
C
440 lines
9.7 KiB
C
/*
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* (C) Copyright 2002 Linus Torvalds
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* Portions based on the vdso-randomization code from exec-shield:
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* Copyright(C) 2005-2006, Red Hat, Inc., Ingo Molnar
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*
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* This file contains the needed initializations to support sysenter.
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*/
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#include <linux/init.h>
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#include <linux/smp.h>
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#include <linux/thread_info.h>
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#include <linux/sched.h>
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#include <linux/gfp.h>
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#include <linux/string.h>
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#include <linux/elf.h>
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#include <linux/mm.h>
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#include <linux/err.h>
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#include <linux/module.h>
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#include <asm/cpufeature.h>
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#include <asm/msr.h>
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#include <asm/pgtable.h>
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#include <asm/unistd.h>
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#include <asm/elf.h>
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#include <asm/tlbflush.h>
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#include <asm/vdso.h>
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#include <asm/proto.h>
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enum {
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VDSO_DISABLED = 0,
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VDSO_ENABLED = 1,
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VDSO_COMPAT = 2,
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};
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#ifdef CONFIG_COMPAT_VDSO
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#define VDSO_DEFAULT VDSO_COMPAT
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#else
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#define VDSO_DEFAULT VDSO_ENABLED
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#endif
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#ifdef CONFIG_X86_64
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#define vdso_enabled sysctl_vsyscall32
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#define arch_setup_additional_pages syscall32_setup_pages
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#endif
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/*
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* This is the difference between the prelinked addresses in the vDSO images
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* and the VDSO_HIGH_BASE address where CONFIG_COMPAT_VDSO places the vDSO
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* in the user address space.
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*/
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#define VDSO_ADDR_ADJUST (VDSO_HIGH_BASE - (unsigned long)VDSO32_PRELINK)
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/*
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* Should the kernel map a VDSO page into processes and pass its
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* address down to glibc upon exec()?
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*/
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unsigned int __read_mostly vdso_enabled = VDSO_DEFAULT;
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static int __init vdso_setup(char *s)
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{
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vdso_enabled = simple_strtoul(s, NULL, 0);
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return 1;
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}
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/*
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* For consistency, the argument vdso32=[012] affects the 32-bit vDSO
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* behavior on both 64-bit and 32-bit kernels.
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* On 32-bit kernels, vdso=[012] means the same thing.
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*/
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__setup("vdso32=", vdso_setup);
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#ifdef CONFIG_X86_32
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__setup_param("vdso=", vdso32_setup, vdso_setup, 0);
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EXPORT_SYMBOL_GPL(vdso_enabled);
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#endif
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static __init void reloc_symtab(Elf32_Ehdr *ehdr,
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unsigned offset, unsigned size)
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{
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Elf32_Sym *sym = (void *)ehdr + offset;
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unsigned nsym = size / sizeof(*sym);
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unsigned i;
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for(i = 0; i < nsym; i++, sym++) {
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if (sym->st_shndx == SHN_UNDEF ||
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sym->st_shndx == SHN_ABS)
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continue; /* skip */
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if (sym->st_shndx > SHN_LORESERVE) {
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printk(KERN_INFO "VDSO: unexpected st_shndx %x\n",
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sym->st_shndx);
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continue;
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}
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switch(ELF_ST_TYPE(sym->st_info)) {
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case STT_OBJECT:
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case STT_FUNC:
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case STT_SECTION:
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case STT_FILE:
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sym->st_value += VDSO_ADDR_ADJUST;
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}
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}
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}
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static __init void reloc_dyn(Elf32_Ehdr *ehdr, unsigned offset)
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{
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Elf32_Dyn *dyn = (void *)ehdr + offset;
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for(; dyn->d_tag != DT_NULL; dyn++)
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switch(dyn->d_tag) {
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case DT_PLTGOT:
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case DT_HASH:
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case DT_STRTAB:
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case DT_SYMTAB:
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case DT_RELA:
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case DT_INIT:
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case DT_FINI:
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case DT_REL:
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case DT_DEBUG:
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case DT_JMPREL:
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case DT_VERSYM:
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case DT_VERDEF:
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case DT_VERNEED:
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case DT_ADDRRNGLO ... DT_ADDRRNGHI:
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/* definitely pointers needing relocation */
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dyn->d_un.d_ptr += VDSO_ADDR_ADJUST;
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break;
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case DT_ENCODING ... OLD_DT_LOOS-1:
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case DT_LOOS ... DT_HIOS-1:
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/* Tags above DT_ENCODING are pointers if
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they're even */
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if (dyn->d_tag >= DT_ENCODING &&
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(dyn->d_tag & 1) == 0)
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dyn->d_un.d_ptr += VDSO_ADDR_ADJUST;
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break;
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case DT_VERDEFNUM:
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case DT_VERNEEDNUM:
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case DT_FLAGS_1:
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case DT_RELACOUNT:
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case DT_RELCOUNT:
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case DT_VALRNGLO ... DT_VALRNGHI:
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/* definitely not pointers */
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break;
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case OLD_DT_LOOS ... DT_LOOS-1:
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case DT_HIOS ... DT_VALRNGLO-1:
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default:
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if (dyn->d_tag > DT_ENCODING)
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printk(KERN_INFO "VDSO: unexpected DT_tag %x\n",
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dyn->d_tag);
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break;
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}
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}
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static __init void relocate_vdso(Elf32_Ehdr *ehdr)
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{
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Elf32_Phdr *phdr;
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Elf32_Shdr *shdr;
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int i;
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BUG_ON(memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0 ||
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!elf_check_arch_ia32(ehdr) ||
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ehdr->e_type != ET_DYN);
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ehdr->e_entry += VDSO_ADDR_ADJUST;
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/* rebase phdrs */
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phdr = (void *)ehdr + ehdr->e_phoff;
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for (i = 0; i < ehdr->e_phnum; i++) {
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phdr[i].p_vaddr += VDSO_ADDR_ADJUST;
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/* relocate dynamic stuff */
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if (phdr[i].p_type == PT_DYNAMIC)
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reloc_dyn(ehdr, phdr[i].p_offset);
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}
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/* rebase sections */
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shdr = (void *)ehdr + ehdr->e_shoff;
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for(i = 0; i < ehdr->e_shnum; i++) {
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if (!(shdr[i].sh_flags & SHF_ALLOC))
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continue;
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shdr[i].sh_addr += VDSO_ADDR_ADJUST;
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if (shdr[i].sh_type == SHT_SYMTAB ||
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shdr[i].sh_type == SHT_DYNSYM)
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reloc_symtab(ehdr, shdr[i].sh_offset,
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shdr[i].sh_size);
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}
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}
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static struct page *vdso32_pages[1];
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#ifdef CONFIG_X86_64
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#define vdso32_sysenter() (boot_cpu_has(X86_FEATURE_SYSENTER32))
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#define vdso32_syscall() (boot_cpu_has(X86_FEATURE_SYSCALL32))
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/* May not be __init: called during resume */
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void syscall32_cpu_init(void)
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{
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/* Load these always in case some future AMD CPU supports
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SYSENTER from compat mode too. */
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checking_wrmsrl(MSR_IA32_SYSENTER_CS, (u64)__KERNEL_CS);
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checking_wrmsrl(MSR_IA32_SYSENTER_ESP, 0ULL);
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checking_wrmsrl(MSR_IA32_SYSENTER_EIP, (u64)ia32_sysenter_target);
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wrmsrl(MSR_CSTAR, ia32_cstar_target);
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}
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#define compat_uses_vma 1
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static inline void map_compat_vdso(int map)
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{
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}
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#else /* CONFIG_X86_32 */
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#define vdso32_sysenter() (boot_cpu_has(X86_FEATURE_SEP))
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#define vdso32_syscall() (0)
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void enable_sep_cpu(void)
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{
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int cpu = get_cpu();
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struct tss_struct *tss = &per_cpu(init_tss, cpu);
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if (!boot_cpu_has(X86_FEATURE_SEP)) {
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put_cpu();
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return;
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}
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tss->x86_tss.ss1 = __KERNEL_CS;
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tss->x86_tss.sp1 = sizeof(struct tss_struct) + (unsigned long) tss;
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wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0);
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wrmsr(MSR_IA32_SYSENTER_ESP, tss->x86_tss.sp1, 0);
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wrmsr(MSR_IA32_SYSENTER_EIP, (unsigned long) ia32_sysenter_target, 0);
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put_cpu();
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}
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static struct vm_area_struct gate_vma;
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static int __init gate_vma_init(void)
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{
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gate_vma.vm_mm = NULL;
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gate_vma.vm_start = FIXADDR_USER_START;
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gate_vma.vm_end = FIXADDR_USER_END;
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gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
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gate_vma.vm_page_prot = __P101;
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/*
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* Make sure the vDSO gets into every core dump.
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* Dumping its contents makes post-mortem fully interpretable later
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* without matching up the same kernel and hardware config to see
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* what PC values meant.
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*/
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gate_vma.vm_flags |= VM_ALWAYSDUMP;
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return 0;
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}
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#define compat_uses_vma 0
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static void map_compat_vdso(int map)
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{
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static int vdso_mapped;
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if (map == vdso_mapped)
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return;
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vdso_mapped = map;
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__set_fixmap(FIX_VDSO, page_to_pfn(vdso32_pages[0]) << PAGE_SHIFT,
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map ? PAGE_READONLY_EXEC : PAGE_NONE);
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/* flush stray tlbs */
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flush_tlb_all();
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}
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#endif /* CONFIG_X86_64 */
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int __init sysenter_setup(void)
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{
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void *syscall_page = (void *)get_zeroed_page(GFP_ATOMIC);
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const void *vsyscall;
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size_t vsyscall_len;
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vdso32_pages[0] = virt_to_page(syscall_page);
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#ifdef CONFIG_X86_32
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gate_vma_init();
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#endif
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if (vdso32_syscall()) {
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vsyscall = &vdso32_syscall_start;
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vsyscall_len = &vdso32_syscall_end - &vdso32_syscall_start;
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} else if (vdso32_sysenter()){
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vsyscall = &vdso32_sysenter_start;
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vsyscall_len = &vdso32_sysenter_end - &vdso32_sysenter_start;
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} else {
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vsyscall = &vdso32_int80_start;
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vsyscall_len = &vdso32_int80_end - &vdso32_int80_start;
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}
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memcpy(syscall_page, vsyscall, vsyscall_len);
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relocate_vdso(syscall_page);
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return 0;
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}
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/* Setup a VMA at program startup for the vsyscall page */
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int arch_setup_additional_pages(struct linux_binprm *bprm, int exstack)
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{
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struct mm_struct *mm = current->mm;
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unsigned long addr;
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int ret = 0;
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bool compat;
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if (vdso_enabled == VDSO_DISABLED)
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return 0;
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down_write(&mm->mmap_sem);
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/* Test compat mode once here, in case someone
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changes it via sysctl */
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compat = (vdso_enabled == VDSO_COMPAT);
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map_compat_vdso(compat);
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if (compat)
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addr = VDSO_HIGH_BASE;
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else {
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addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
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if (IS_ERR_VALUE(addr)) {
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ret = addr;
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goto up_fail;
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}
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}
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if (compat_uses_vma || !compat) {
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/*
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* MAYWRITE to allow gdb to COW and set breakpoints
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*
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* Make sure the vDSO gets into every core dump.
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* Dumping its contents makes post-mortem fully
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* interpretable later without matching up the same
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* kernel and hardware config to see what PC values
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* meant.
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*/
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ret = install_special_mapping(mm, addr, PAGE_SIZE,
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VM_READ|VM_EXEC|
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VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
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VM_ALWAYSDUMP,
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vdso32_pages);
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if (ret)
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goto up_fail;
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}
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current->mm->context.vdso = (void *)addr;
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current_thread_info()->sysenter_return =
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VDSO32_SYMBOL(addr, SYSENTER_RETURN);
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up_fail:
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up_write(&mm->mmap_sem);
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return ret;
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}
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#ifdef CONFIG_X86_64
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__initcall(sysenter_setup);
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#ifdef CONFIG_SYSCTL
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/* Register vsyscall32 into the ABI table */
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#include <linux/sysctl.h>
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static ctl_table abi_table2[] = {
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{
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.procname = "vsyscall32",
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.data = &sysctl_vsyscall32,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = proc_dointvec
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},
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{}
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};
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static ctl_table abi_root_table2[] = {
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{
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.ctl_name = CTL_ABI,
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.procname = "abi",
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.mode = 0555,
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.child = abi_table2
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},
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{}
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};
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static __init int ia32_binfmt_init(void)
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{
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register_sysctl_table(abi_root_table2);
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return 0;
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}
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__initcall(ia32_binfmt_init);
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#endif
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#else /* CONFIG_X86_32 */
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const char *arch_vma_name(struct vm_area_struct *vma)
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{
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if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso)
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return "[vdso]";
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return NULL;
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}
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struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
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{
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struct mm_struct *mm = tsk->mm;
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/* Check to see if this task was created in compat vdso mode */
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if (mm && mm->context.vdso == (void *)VDSO_HIGH_BASE)
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return &gate_vma;
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return NULL;
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}
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int in_gate_area(struct task_struct *task, unsigned long addr)
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{
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const struct vm_area_struct *vma = get_gate_vma(task);
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return vma && addr >= vma->vm_start && addr < vma->vm_end;
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}
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int in_gate_area_no_task(unsigned long addr)
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{
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return 0;
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}
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#endif /* CONFIG_X86_64 */
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