diff options
Diffstat (limited to 'arch/i386/kernel/sysenter.c')
| -rw-r--r-- | arch/i386/kernel/sysenter.c | 145 |
1 files changed, 94 insertions, 51 deletions
diff --git a/arch/i386/kernel/sysenter.c b/arch/i386/kernel/sysenter.c index e5a958379ac9..0b9768ee1e8d 100644 --- a/arch/i386/kernel/sysenter.c +++ b/arch/i386/kernel/sysenter.c @@ -23,16 +23,25 @@ #include <asm/pgtable.h> #include <asm/unistd.h> #include <asm/elf.h> +#include <asm/tlbflush.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()? */ -#ifdef CONFIG_PARAVIRT -unsigned int __read_mostly vdso_enabled = 0; -#else -unsigned int __read_mostly vdso_enabled = 1; -#endif +unsigned int __read_mostly vdso_enabled = VDSO_DEFAULT; EXPORT_SYMBOL_GPL(vdso_enabled); @@ -47,7 +56,6 @@ __setup("vdso=", vdso_setup); extern asmlinkage void sysenter_entry(void); -#ifdef CONFIG_COMPAT_VDSO static __init void reloc_symtab(Elf32_Ehdr *ehdr, unsigned offset, unsigned size) { @@ -164,11 +172,6 @@ static __init void relocate_vdso(Elf32_Ehdr *ehdr) shdr[i].sh_size); } } -#else -static inline void relocate_vdso(Elf32_Ehdr *ehdr) -{ -} -#endif /* COMPAT_VDSO */ void enable_sep_cpu(void) { @@ -188,6 +191,25 @@ 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; + /* + * 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. @@ -196,6 +218,22 @@ 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); @@ -204,10 +242,9 @@ int __init sysenter_setup(void) syscall_pages[0] = virt_to_page(syscall_page); -#ifdef CONFIG_COMPAT_VDSO - __set_fixmap(FIX_VDSO, __pa(syscall_page), PAGE_READONLY_EXEC); + gate_vma_init(); + printk("Compat vDSO mapped to %08lx.\n", __fix_to_virt(FIX_VDSO)); -#endif if (!boot_cpu_has(X86_FEATURE_SEP)) { vsyscall = &vsyscall_int80_start; @@ -226,42 +263,57 @@ int __init sysenter_setup(void) /* Defined in vsyscall-sysenter.S */ extern void SYSENTER_RETURN; -#ifdef __HAVE_ARCH_GATE_AREA /* 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; + bool compat; down_write(&mm->mmap_sem); - 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; + /* 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 = - (void *)VDSO_SYM(&SYSENTER_RETURN); -up_fail: + (void *)VDSO_SYM(&SYSENTER_RETURN); + + up_fail: up_write(&mm->mmap_sem); + return ret; } @@ -274,6 +326,11 @@ const char *arch_vma_name(struct vm_area_struct *vma) 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; } @@ -286,17 +343,3 @@ int in_gate_area_no_task(unsigned long addr) { return 0; } -#else /* !__HAVE_ARCH_GATE_AREA */ -int arch_setup_additional_pages(struct linux_binprm *bprm, int exstack) -{ - /* - * If not creating userspace VMA, simply set vdso to point to - * fixmap page. - */ - current->mm->context.vdso = (void *)VDSO_HIGH_BASE; - current_thread_info()->sysenter_return = - (void *)VDSO_SYM(&SYSENTER_RETURN); - - return 0; -} -#endif /* __HAVE_ARCH_GATE_AREA */ |