Commit b0b49f26 authored by Andy Lutomirski's avatar Andy Lutomirski Committed by H. Peter Anvin

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: default avatarAndy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/r/4bb4690899106eb11430b1186d5cc66ca9d1660c.1394751608.git.luto@amacapital.netSigned-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent fa389e22
...@@ -3409,14 +3409,24 @@ bytes respectively. Such letter suffixes can also be entirely omitted. ...@@ -3409,14 +3409,24 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
of CONFIG_HIGHPTE. of CONFIG_HIGHPTE.
vdso= [X86,SH] vdso= [X86,SH]
vdso=2: enable compat VDSO (default with COMPAT_VDSO) On X86_32, this is an alias for vdso32=. Otherwise:
vdso=1: enable VDSO (default)
vdso=1: enable VDSO (the default)
vdso=0: disable VDSO mapping vdso=0: disable VDSO mapping
vdso32= [X86] vdso32= [X86] Control the 32-bit vDSO
vdso32=2: enable compat VDSO (default with COMPAT_VDSO) vdso32=1: enable 32-bit VDSO
vdso32=1: enable 32-bit VDSO (default) vdso32=0 or vdso32=2: disable 32-bit VDSO
vdso32=0: disable 32-bit VDSO mapping
See the help text for CONFIG_COMPAT_VDSO for more
details. If CONFIG_COMPAT_VDSO is set, the default is
vdso32=0; otherwise, the default is vdso32=1.
For compatibility with older kernels, vdso32=2 is an
alias for vdso32=0.
Try vdso32=0 if you encounter an error that says:
dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
vector= [IA-64,SMP] vector= [IA-64,SMP]
vector=percpu: enable percpu vector domain vector=percpu: enable percpu vector domain
......
...@@ -1836,17 +1836,29 @@ config DEBUG_HOTPLUG_CPU0 ...@@ -1836,17 +1836,29 @@ config DEBUG_HOTPLUG_CPU0
If unsure, say N. If unsure, say N.
config COMPAT_VDSO config COMPAT_VDSO
def_bool y def_bool n
prompt "Compat VDSO support" prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
depends on X86_32 || IA32_EMULATION depends on X86_32 || IA32_EMULATION
---help--- ---help---
Map the 32-bit VDSO to the predictable old-style address too. Certain buggy versions of glibc will crash if they are
presented with a 32-bit vDSO that is not mapped at the address
indicated in its segment table.
Say N here if you are running a sufficiently recent glibc The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
version (2.3.3 or later), to remove the high-mapped and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
VDSO mapping and to exclusively use the randomized VDSO. 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
the only released version with the bug, but OpenSUSE 9
contains a buggy "glibc 2.3.2".
If unsure, say Y. The symptom of the bug is that everything crashes on startup, saying:
dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
Saying Y here changes the default value of the vdso32 boot
option from 1 to 0, which turns off the 32-bit vDSO entirely.
This works around the glibc bug but hurts performance.
If unsure, say N: if you are compiling your own kernel, you
are unlikely to be using a buggy version of glibc.
config CMDLINE_BOOL config CMDLINE_BOOL
bool "Built-in kernel command line" bool "Built-in kernel command line"
......
...@@ -281,16 +281,12 @@ do { \ ...@@ -281,16 +281,12 @@ do { \
#define STACK_RND_MASK (0x7ff) #define STACK_RND_MASK (0x7ff)
#define VDSO_HIGH_BASE (__fix_to_virt(FIX_VDSO))
#define ARCH_DLINFO ARCH_DLINFO_IA32(vdso_enabled) #define ARCH_DLINFO ARCH_DLINFO_IA32(vdso_enabled)
/* update AT_VECTOR_SIZE_ARCH if the number of NEW_AUX_ENT entries changes */ /* update AT_VECTOR_SIZE_ARCH if the number of NEW_AUX_ENT entries changes */
#else /* CONFIG_X86_32 */ #else /* CONFIG_X86_32 */
#define VDSO_HIGH_BASE 0xffffe000U /* CONFIG_COMPAT_VDSO address */
/* 1GB for 64bit, 8MB for 32bit */ /* 1GB for 64bit, 8MB for 32bit */
#define STACK_RND_MASK (test_thread_flag(TIF_ADDR32) ? 0x7ff : 0x3fffff) #define STACK_RND_MASK (test_thread_flag(TIF_ADDR32) ? 0x7ff : 0x3fffff)
......
...@@ -40,15 +40,8 @@ ...@@ -40,15 +40,8 @@
*/ */
extern unsigned long __FIXADDR_TOP; extern unsigned long __FIXADDR_TOP;
#define FIXADDR_TOP ((unsigned long)__FIXADDR_TOP) #define FIXADDR_TOP ((unsigned long)__FIXADDR_TOP)
#define FIXADDR_USER_START __fix_to_virt(FIX_VDSO)
#define FIXADDR_USER_END __fix_to_virt(FIX_VDSO - 1)
#else #else
#define FIXADDR_TOP (VSYSCALL_END-PAGE_SIZE) #define FIXADDR_TOP (VSYSCALL_END-PAGE_SIZE)
/* Only covers 32bit vsyscalls currently. Need another set for 64bit. */
#define FIXADDR_USER_START ((unsigned long)VSYSCALL32_VSYSCALL)
#define FIXADDR_USER_END (FIXADDR_USER_START + PAGE_SIZE)
#endif #endif
...@@ -74,7 +67,6 @@ extern unsigned long __FIXADDR_TOP; ...@@ -74,7 +67,6 @@ extern unsigned long __FIXADDR_TOP;
enum fixed_addresses { enum fixed_addresses {
#ifdef CONFIG_X86_32 #ifdef CONFIG_X86_32
FIX_HOLE, FIX_HOLE,
FIX_VDSO,
#else #else
VSYSCALL_LAST_PAGE, VSYSCALL_LAST_PAGE,
VSYSCALL_FIRST_PAGE = VSYSCALL_LAST_PAGE VSYSCALL_FIRST_PAGE = VSYSCALL_LAST_PAGE
......
...@@ -2,8 +2,6 @@ ...@@ -2,8 +2,6 @@
#define _ASM_X86_VDSO_H #define _ASM_X86_VDSO_H
#if defined CONFIG_X86_32 || defined CONFIG_COMPAT #if defined CONFIG_X86_32 || defined CONFIG_COMPAT
extern const char VDSO32_PRELINK[];
/* /*
* Given a pointer to the vDSO image, find the pointer to VDSO32_name * Given a pointer to the vDSO image, find the pointer to VDSO32_name
* as that symbol is defined in the vDSO sources or linker script. * as that symbol is defined in the vDSO sources or linker script.
...@@ -11,8 +9,7 @@ extern const char VDSO32_PRELINK[]; ...@@ -11,8 +9,7 @@ extern const char VDSO32_PRELINK[];
#define VDSO32_SYMBOL(base, name) \ #define VDSO32_SYMBOL(base, name) \
({ \ ({ \
extern const char VDSO32_##name[]; \ extern const char VDSO32_##name[]; \
(void __user *)(VDSO32_##name - VDSO32_PRELINK + \ (void __user *)(VDSO32_##name + (unsigned long)(base)); \
(unsigned long)(base)); \
}) })
#endif #endif
......
...@@ -6,7 +6,7 @@ ...@@ -6,7 +6,7 @@
SECTIONS SECTIONS
{ {
. = VDSO_PRELINK + SIZEOF_HEADERS; . = SIZEOF_HEADERS;
.hash : { *(.hash) } :text .hash : { *(.hash) } :text
.gnu.hash : { *(.gnu.hash) } .gnu.hash : { *(.gnu.hash) }
......
...@@ -26,16 +26,10 @@ ...@@ -26,16 +26,10 @@
#include <asm/vdso.h> #include <asm/vdso.h>
#include <asm/proto.h> #include <asm/proto.h>
enum {
VDSO_DISABLED = 0,
VDSO_ENABLED = 1,
VDSO_COMPAT = 2,
};
#ifdef CONFIG_COMPAT_VDSO #ifdef CONFIG_COMPAT_VDSO
#define VDSO_DEFAULT VDSO_COMPAT #define VDSO_DEFAULT 0
#else #else
#define VDSO_DEFAULT VDSO_ENABLED #define VDSO_DEFAULT 1
#endif #endif
#ifdef CONFIG_X86_64 #ifdef CONFIG_X86_64
...@@ -43,13 +37,6 @@ enum { ...@@ -43,13 +37,6 @@ enum {
#define arch_setup_additional_pages syscall32_setup_pages #define arch_setup_additional_pages syscall32_setup_pages
#endif #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 * Should the kernel map a VDSO page into processes and pass its
* address down to glibc upon exec()? * address down to glibc upon exec()?
...@@ -60,6 +47,9 @@ static int __init vdso_setup(char *s) ...@@ -60,6 +47,9 @@ static int __init vdso_setup(char *s)
{ {
vdso_enabled = simple_strtoul(s, NULL, 0); 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; return 1;
} }
...@@ -76,123 +66,6 @@ __setup_param("vdso=", vdso32_setup, vdso_setup, 0); ...@@ -76,123 +66,6 @@ __setup_param("vdso=", vdso32_setup, vdso_setup, 0);
EXPORT_SYMBOL_GPL(vdso_enabled); EXPORT_SYMBOL_GPL(vdso_enabled);
#endif #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]; static struct page *vdso32_pages[1];
#ifdef CONFIG_X86_64 #ifdef CONFIG_X86_64
...@@ -212,12 +85,6 @@ void syscall32_cpu_init(void) ...@@ -212,12 +85,6 @@ void syscall32_cpu_init(void)
wrmsrl(MSR_CSTAR, ia32_cstar_target); wrmsrl(MSR_CSTAR, ia32_cstar_target);
} }
#define compat_uses_vma 1
static inline void map_compat_vdso(int map)
{
}
#else /* CONFIG_X86_32 */ #else /* CONFIG_X86_32 */
#define vdso32_sysenter() (boot_cpu_has(X86_FEATURE_SEP)) #define vdso32_sysenter() (boot_cpu_has(X86_FEATURE_SEP))
...@@ -241,37 +108,6 @@ void enable_sep_cpu(void) ...@@ -241,37 +108,6 @@ void enable_sep_cpu(void)
put_cpu(); 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 */ #endif /* CONFIG_X86_64 */
int __init sysenter_setup(void) int __init sysenter_setup(void)
...@@ -282,10 +118,6 @@ int __init sysenter_setup(void) ...@@ -282,10 +118,6 @@ int __init sysenter_setup(void)
vdso32_pages[0] = virt_to_page(syscall_page); vdso32_pages[0] = virt_to_page(syscall_page);
#ifdef CONFIG_X86_32
gate_vma_init();
#endif
if (vdso32_syscall()) { if (vdso32_syscall()) {
vsyscall = &vdso32_syscall_start; vsyscall = &vdso32_syscall_start;
vsyscall_len = &vdso32_syscall_end - &vdso32_syscall_start; vsyscall_len = &vdso32_syscall_end - &vdso32_syscall_start;
...@@ -298,7 +130,6 @@ int __init sysenter_setup(void) ...@@ -298,7 +130,6 @@ int __init sysenter_setup(void)
} }
memcpy(syscall_page, vsyscall, vsyscall_len); memcpy(syscall_page, vsyscall, vsyscall_len);
relocate_vdso(syscall_page);
return 0; return 0;
} }
...@@ -309,48 +140,35 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) ...@@ -309,48 +140,35 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
struct mm_struct *mm = current->mm; struct mm_struct *mm = current->mm;
unsigned long addr; unsigned long addr;
int ret = 0; int ret = 0;
bool compat;
#ifdef CONFIG_X86_X32_ABI #ifdef CONFIG_X86_X32_ABI
if (test_thread_flag(TIF_X32)) if (test_thread_flag(TIF_X32))
return x32_setup_additional_pages(bprm, uses_interp); return x32_setup_additional_pages(bprm, uses_interp);
#endif #endif
if (vdso_enabled == VDSO_DISABLED) if (vdso_enabled != 1) /* Other values all mean "disabled" */
return 0; return 0;
down_write(&mm->mmap_sem); down_write(&mm->mmap_sem);
/* Test compat mode once here, in case someone addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
changes it via sysctl */ if (IS_ERR_VALUE(addr)) {
compat = (vdso_enabled == VDSO_COMPAT); ret = addr;
goto up_fail;
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;
}
} }
current->mm->context.vdso = (void *)addr; current->mm->context.vdso = (void *)addr;
if (compat_uses_vma || !compat) { /*
/* * MAYWRITE to allow gdb to COW and set breakpoints
* MAYWRITE to allow gdb to COW and set breakpoints */
*/ ret = install_special_mapping(mm, addr, PAGE_SIZE,
ret = install_special_mapping(mm, addr, PAGE_SIZE, VM_READ|VM_EXEC|
VM_READ|VM_EXEC| VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, vdso32_pages);
vdso32_pages);
if (ret)
if (ret) goto up_fail;
goto up_fail;
}
current_thread_info()->sysenter_return = current_thread_info()->sysenter_return =
VDSO32_SYMBOL(addr, SYSENTER_RETURN); VDSO32_SYMBOL(addr, SYSENTER_RETURN);
...@@ -411,20 +229,12 @@ const char *arch_vma_name(struct vm_area_struct *vma) ...@@ -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) 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; return NULL;
} }
int in_gate_area(struct mm_struct *mm, unsigned long addr) int in_gate_area(struct mm_struct *mm, unsigned long addr)
{ {
const struct vm_area_struct *vma = get_gate_vma(mm); return 0;
return vma && addr >= vma->vm_start && addr < vma->vm_end;
} }
int in_gate_area_no_mm(unsigned long addr) int in_gate_area_no_mm(unsigned long addr)
......
...@@ -8,7 +8,6 @@ ...@@ -8,7 +8,6 @@
* values visible using the asm-x86/vdso.h macros from the kernel proper. * values visible using the asm-x86/vdso.h macros from the kernel proper.
*/ */
#define VDSO_PRELINK 0
#include "../vdso-layout.lds.S" #include "../vdso-layout.lds.S"
/* The ELF entry point can be used to set the AT_SYSINFO value. */ /* The ELF entry point can be used to set the AT_SYSINFO value. */
...@@ -31,7 +30,6 @@ VERSION ...@@ -31,7 +30,6 @@ VERSION
/* /*
* Symbols we define here called VDSO* get their values into vdso32-syms.h. * Symbols we define here called VDSO* get their values into vdso32-syms.h.
*/ */
VDSO32_PRELINK = VDSO_PRELINK;
VDSO32_vsyscall = __kernel_vsyscall; VDSO32_vsyscall = __kernel_vsyscall;
VDSO32_sigreturn = __kernel_sigreturn; VDSO32_sigreturn = __kernel_sigreturn;
VDSO32_rt_sigreturn = __kernel_rt_sigreturn; VDSO32_rt_sigreturn = __kernel_rt_sigreturn;
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