From b0b49f2673f011cad7deeabf7a683b388c351278 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Thu, 13 Mar 2014 16:01:26 -0700 Subject: x86, vdso: Remove compat vdso support The compat vDSO is a complicated hack that's needed to maintain compatibility with a small range of glibc versions. This removes it and replaces it with a much simpler hack: a config option to disable the 32-bit vDSO by default. This also changes the default value of CONFIG_COMPAT_VDSO to n -- users configuring kernels from scratch almost certainly want that choice. Signed-off-by: Andy Lutomirski Link: http://lkml.kernel.org/r/4bb4690899106eb11430b1186d5cc66ca9d1660c.1394751608.git.luto@amacapital.net Signed-off-by: H. Peter Anvin --- arch/x86/vdso/vdso-layout.lds.S | 2 +- arch/x86/vdso/vdso32-setup.c | 232 ++++---------------------------------- arch/x86/vdso/vdso32/vdso32.lds.S | 2 - 3 files changed, 22 insertions(+), 214 deletions(-) (limited to 'arch/x86/vdso') diff --git a/arch/x86/vdso/vdso-layout.lds.S b/arch/x86/vdso/vdso-layout.lds.S index 634a2cf62046..8c550c1976f3 100644 --- a/arch/x86/vdso/vdso-layout.lds.S +++ b/arch/x86/vdso/vdso-layout.lds.S @@ -6,7 +6,7 @@ SECTIONS { - . = VDSO_PRELINK + SIZEOF_HEADERS; + . = SIZEOF_HEADERS; .hash : { *(.hash) } :text .gnu.hash : { *(.gnu.hash) } diff --git a/arch/x86/vdso/vdso32-setup.c b/arch/x86/vdso/vdso32-setup.c index d6bfb876cfb0..ab20c04b688a 100644 --- a/arch/x86/vdso/vdso32-setup.c +++ b/arch/x86/vdso/vdso32-setup.c @@ -26,16 +26,10 @@ #include #include -enum { - VDSO_DISABLED = 0, - VDSO_ENABLED = 1, - VDSO_COMPAT = 2, -}; - #ifdef CONFIG_COMPAT_VDSO -#define VDSO_DEFAULT VDSO_COMPAT +#define VDSO_DEFAULT 0 #else -#define VDSO_DEFAULT VDSO_ENABLED +#define VDSO_DEFAULT 1 #endif #ifdef CONFIG_X86_64 @@ -43,13 +37,6 @@ enum { #define arch_setup_additional_pages syscall32_setup_pages #endif -/* - * This is the difference between the prelinked addresses in the vDSO images - * and the VDSO_HIGH_BASE address where CONFIG_COMPAT_VDSO places the vDSO - * in the user address space. - */ -#define VDSO_ADDR_ADJUST (VDSO_HIGH_BASE - (unsigned long)VDSO32_PRELINK) - /* * Should the kernel map a VDSO page into processes and pass its * address down to glibc upon exec()? @@ -60,6 +47,9 @@ static int __init vdso_setup(char *s) { vdso_enabled = simple_strtoul(s, NULL, 0); + if (vdso_enabled > 1) + pr_warn("vdso32 values other than 0 and 1 are no longer allowed; vdso disabled\n"); + return 1; } @@ -76,123 +66,6 @@ __setup_param("vdso=", vdso32_setup, vdso_setup, 0); EXPORT_SYMBOL_GPL(vdso_enabled); #endif -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_ADDR_ADJUST; - } - } -} - -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_ADDR_ADJUST; - 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_ADDR_ADJUST; - 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, SELFMAG) != 0 || - !elf_check_arch_ia32(ehdr) || - ehdr->e_type != ET_DYN); - - ehdr->e_entry += VDSO_ADDR_ADJUST; - - /* rebase phdrs */ - phdr = (void *)ehdr + ehdr->e_phoff; - for (i = 0; i < ehdr->e_phnum; i++) { - phdr[i].p_vaddr += VDSO_ADDR_ADJUST; - - /* 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_ADDR_ADJUST; - - if (shdr[i].sh_type == SHT_SYMTAB || - shdr[i].sh_type == SHT_DYNSYM) - reloc_symtab(ehdr, shdr[i].sh_offset, - shdr[i].sh_size); - } -} - static struct page *vdso32_pages[1]; #ifdef CONFIG_X86_64 @@ -212,12 +85,6 @@ void syscall32_cpu_init(void) wrmsrl(MSR_CSTAR, ia32_cstar_target); } -#define compat_uses_vma 1 - -static inline void map_compat_vdso(int map) -{ -} - #else /* CONFIG_X86_32 */ #define vdso32_sysenter() (boot_cpu_has(X86_FEATURE_SEP)) @@ -241,37 +108,6 @@ void enable_sep_cpu(void) 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; - - return 0; -} - -#define compat_uses_vma 0 - -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(vdso32_pages[0]) << PAGE_SHIFT, - map ? PAGE_READONLY_EXEC : PAGE_NONE); - - /* flush stray tlbs */ - flush_tlb_all(); -} - #endif /* CONFIG_X86_64 */ int __init sysenter_setup(void) @@ -282,10 +118,6 @@ int __init sysenter_setup(void) vdso32_pages[0] = virt_to_page(syscall_page); -#ifdef CONFIG_X86_32 - gate_vma_init(); -#endif - if (vdso32_syscall()) { vsyscall = &vdso32_syscall_start; vsyscall_len = &vdso32_syscall_end - &vdso32_syscall_start; @@ -298,7 +130,6 @@ int __init sysenter_setup(void) } memcpy(syscall_page, vsyscall, vsyscall_len); - relocate_vdso(syscall_page); return 0; } @@ -309,48 +140,35 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) struct mm_struct *mm = current->mm; unsigned long addr; int ret = 0; - bool compat; #ifdef CONFIG_X86_X32_ABI if (test_thread_flag(TIF_X32)) return x32_setup_additional_pages(bprm, uses_interp); #endif - if (vdso_enabled == VDSO_DISABLED) + if (vdso_enabled != 1) /* Other values all mean "disabled" */ return 0; 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; - } + addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0); + if (IS_ERR_VALUE(addr)) { + ret = addr; + goto up_fail; } current->mm->context.vdso = (void *)addr; - if (compat_uses_vma || !compat) { - /* - * MAYWRITE to allow gdb to COW and set breakpoints - */ - ret = install_special_mapping(mm, addr, PAGE_SIZE, - VM_READ|VM_EXEC| - VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, - vdso32_pages); - - if (ret) - goto up_fail; - } + /* + * MAYWRITE to allow gdb to COW and set breakpoints + */ + ret = install_special_mapping(mm, addr, PAGE_SIZE, + VM_READ|VM_EXEC| + VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, + vdso32_pages); + + if (ret) + goto up_fail; current_thread_info()->sysenter_return = VDSO32_SYMBOL(addr, SYSENTER_RETURN); @@ -411,20 +229,12 @@ const char *arch_vma_name(struct vm_area_struct *vma) struct vm_area_struct *get_gate_vma(struct mm_struct *mm) { - /* - * Check to see if the corresponding 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 mm_struct *mm, unsigned long addr) { - const struct vm_area_struct *vma = get_gate_vma(mm); - - return vma && addr >= vma->vm_start && addr < vma->vm_end; + return 0; } int in_gate_area_no_mm(unsigned long addr) diff --git a/arch/x86/vdso/vdso32/vdso32.lds.S b/arch/x86/vdso/vdso32/vdso32.lds.S index 976124bb5f92..90e7aa90dbe4 100644 --- a/arch/x86/vdso/vdso32/vdso32.lds.S +++ b/arch/x86/vdso/vdso32/vdso32.lds.S @@ -8,7 +8,6 @@ * values visible using the asm-x86/vdso.h macros from the kernel proper. */ -#define VDSO_PRELINK 0 #include "../vdso-layout.lds.S" /* The ELF entry point can be used to set the AT_SYSINFO value. */ @@ -31,7 +30,6 @@ VERSION /* * Symbols we define here called VDSO* get their values into vdso32-syms.h. */ -VDSO32_PRELINK = VDSO_PRELINK; VDSO32_vsyscall = __kernel_vsyscall; VDSO32_sigreturn = __kernel_sigreturn; VDSO32_rt_sigreturn = __kernel_rt_sigreturn; -- cgit v1.2.3