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 <luto@amacapital.net> Link: http://lkml.kernel.org/r/4bb4690899106eb11430b1186d5cc66ca9d1660c.1394751608.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
Andy Lutomirski
H. Peter Anvin
Родитель
fa389e2202
Коммит
b0b49f2673
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@ -3409,14 +3409,24 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
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of CONFIG_HIGHPTE.
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vdso= [X86,SH]
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vdso=2: enable compat VDSO (default with COMPAT_VDSO)
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vdso=1: enable VDSO (default)
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On X86_32, this is an alias for vdso32=. Otherwise:
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vdso=1: enable VDSO (the default)
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vdso=0: disable VDSO mapping
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vdso32= [X86]
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vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
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vdso32=1: enable 32-bit VDSO (default)
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vdso32=0: disable 32-bit VDSO mapping
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vdso32= [X86] Control the 32-bit vDSO
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vdso32=1: enable 32-bit VDSO
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vdso32=0 or vdso32=2: disable 32-bit VDSO
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See the help text for CONFIG_COMPAT_VDSO for more
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details. If CONFIG_COMPAT_VDSO is set, the default is
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vdso32=0; otherwise, the default is vdso32=1.
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For compatibility with older kernels, vdso32=2 is an
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alias for vdso32=0.
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Try vdso32=0 if you encounter an error that says:
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dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
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vector= [IA-64,SMP]
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vector=percpu: enable percpu vector domain
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@ -1836,17 +1836,29 @@ config DEBUG_HOTPLUG_CPU0
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If unsure, say N.
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config COMPAT_VDSO
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def_bool y
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prompt "Compat VDSO support"
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def_bool n
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prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
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depends on X86_32 || IA32_EMULATION
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---help---
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Map the 32-bit VDSO to the predictable old-style address too.
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Certain buggy versions of glibc will crash if they are
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presented with a 32-bit vDSO that is not mapped at the address
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indicated in its segment table.
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Say N here if you are running a sufficiently recent glibc
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version (2.3.3 or later), to remove the high-mapped
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VDSO mapping and to exclusively use the randomized VDSO.
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The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
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and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
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49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
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the only released version with the bug, but OpenSUSE 9
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contains a buggy "glibc 2.3.2".
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If unsure, say Y.
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The symptom of the bug is that everything crashes on startup, saying:
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dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
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Saying Y here changes the default value of the vdso32 boot
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option from 1 to 0, which turns off the 32-bit vDSO entirely.
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This works around the glibc bug but hurts performance.
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If unsure, say N: if you are compiling your own kernel, you
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are unlikely to be using a buggy version of glibc.
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config CMDLINE_BOOL
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bool "Built-in kernel command line"
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@ -281,16 +281,12 @@ do { \
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#define STACK_RND_MASK (0x7ff)
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#define VDSO_HIGH_BASE (__fix_to_virt(FIX_VDSO))
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#define ARCH_DLINFO ARCH_DLINFO_IA32(vdso_enabled)
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/* update AT_VECTOR_SIZE_ARCH if the number of NEW_AUX_ENT entries changes */
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#else /* CONFIG_X86_32 */
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#define VDSO_HIGH_BASE 0xffffe000U /* CONFIG_COMPAT_VDSO address */
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/* 1GB for 64bit, 8MB for 32bit */
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#define STACK_RND_MASK (test_thread_flag(TIF_ADDR32) ? 0x7ff : 0x3fffff)
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@ -40,15 +40,8 @@
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*/
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extern unsigned long __FIXADDR_TOP;
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#define FIXADDR_TOP ((unsigned long)__FIXADDR_TOP)
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#define FIXADDR_USER_START __fix_to_virt(FIX_VDSO)
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#define FIXADDR_USER_END __fix_to_virt(FIX_VDSO - 1)
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#else
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#define FIXADDR_TOP (VSYSCALL_END-PAGE_SIZE)
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/* Only covers 32bit vsyscalls currently. Need another set for 64bit. */
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#define FIXADDR_USER_START ((unsigned long)VSYSCALL32_VSYSCALL)
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#define FIXADDR_USER_END (FIXADDR_USER_START + PAGE_SIZE)
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#endif
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@ -74,7 +67,6 @@ extern unsigned long __FIXADDR_TOP;
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enum fixed_addresses {
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#ifdef CONFIG_X86_32
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FIX_HOLE,
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FIX_VDSO,
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#else
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VSYSCALL_LAST_PAGE,
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VSYSCALL_FIRST_PAGE = VSYSCALL_LAST_PAGE
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@ -2,8 +2,6 @@
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#define _ASM_X86_VDSO_H
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#if defined CONFIG_X86_32 || defined CONFIG_COMPAT
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extern const char VDSO32_PRELINK[];
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/*
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* Given a pointer to the vDSO image, find the pointer to VDSO32_name
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* as that symbol is defined in the vDSO sources or linker script.
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@ -11,8 +9,7 @@ extern const char VDSO32_PRELINK[];
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#define VDSO32_SYMBOL(base, name) \
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({ \
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extern const char VDSO32_##name[]; \
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(void __user *)(VDSO32_##name - VDSO32_PRELINK + \
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(unsigned long)(base)); \
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(void __user *)(VDSO32_##name + (unsigned long)(base)); \
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})
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#endif
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@ -6,7 +6,7 @@
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SECTIONS
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{
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. = VDSO_PRELINK + SIZEOF_HEADERS;
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. = SIZEOF_HEADERS;
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.hash : { *(.hash) } :text
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.gnu.hash : { *(.gnu.hash) }
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@ -26,16 +26,10 @@
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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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#define VDSO_DEFAULT 0
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#else
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#define VDSO_DEFAULT VDSO_ENABLED
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#define VDSO_DEFAULT 1
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#endif
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#ifdef CONFIG_X86_64
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@ -43,13 +37,6 @@ enum {
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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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@ -60,6 +47,9 @@ 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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if (vdso_enabled > 1)
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pr_warn("vdso32 values other than 0 and 1 are no longer allowed; vdso disabled\n");
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return 1;
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}
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@ -76,123 +66,6 @@ __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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@ -212,12 +85,6 @@ void syscall32_cpu_init(void)
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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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@ -241,37 +108,6 @@ void enable_sep_cpu(void)
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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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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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@ -282,10 +118,6 @@ int __init sysenter_setup(void)
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vdso32_pages[0] = virt_to_page(syscall_page);
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|
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#ifdef CONFIG_X86_32
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gate_vma_init();
|
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#endif
|
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|
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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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|
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@ -298,7 +130,6 @@ int __init sysenter_setup(void)
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}
|
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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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|
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return 0;
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}
|
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|
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@ -309,48 +140,35 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
|
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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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|
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#ifdef CONFIG_X86_X32_ABI
|
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if (test_thread_flag(TIF_X32))
|
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return x32_setup_additional_pages(bprm, uses_interp);
|
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#endif
|
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|
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if (vdso_enabled == VDSO_DISABLED)
|
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if (vdso_enabled != 1) /* Other values all mean "disabled" */
|
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return 0;
|
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|
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down_write(&mm->mmap_sem);
|
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|
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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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|
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map_compat_vdso(compat);
|
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|
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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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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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current->mm->context.vdso = (void *)addr;
|
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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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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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vdso32_pages);
|
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/*
|
||||
* MAYWRITE to allow gdb to COW and set breakpoints
|
||||
*/
|
||||
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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vdso32_pages);
|
||||
|
||||
if (ret)
|
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goto up_fail;
|
||||
}
|
||||
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)
|
||||
|
|
|
|||
|
|
@ -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;
|
||||
|
|
|
|||
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