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author | Thomas Gleixner <tglx@linutronix.de> | 2007-10-11 11:17:10 +0200 |
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committer | Thomas Gleixner <tglx@linutronix.de> | 2007-10-11 11:17:10 +0200 |
commit | 7648b1330c335601b7c09c25f77a03cda128fcab (patch) | |
tree | 8b92b501dc746b135bf9019472b425e8ef052714 /arch/x86/vdso/vma.c | |
parent | 185f3d38900f750a4566f87cde6a178f3595a115 (diff) | |
download | kernel-crypto-7648b1330c335601b7c09c25f77a03cda128fcab.tar.gz kernel-crypto-7648b1330c335601b7c09c25f77a03cda128fcab.tar.xz kernel-crypto-7648b1330c335601b7c09c25f77a03cda128fcab.zip |
x86_64: move vdso
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/vdso/vma.c')
-rw-r--r-- | arch/x86/vdso/vma.c | 140 |
1 files changed, 140 insertions, 0 deletions
diff --git a/arch/x86/vdso/vma.c b/arch/x86/vdso/vma.c new file mode 100644 index 00000000000..ff9333e5fb0 --- /dev/null +++ b/arch/x86/vdso/vma.c @@ -0,0 +1,140 @@ +/* + * Set up the VMAs to tell the VM about the vDSO. + * Copyright 2007 Andi Kleen, SUSE Labs. + * Subject to the GPL, v.2 + */ +#include <linux/mm.h> +#include <linux/err.h> +#include <linux/sched.h> +#include <linux/init.h> +#include <linux/random.h> +#include <asm/vsyscall.h> +#include <asm/vgtod.h> +#include <asm/proto.h> +#include "voffset.h" + +int vdso_enabled = 1; + +#define VEXTERN(x) extern typeof(__ ## x) *vdso_ ## x; +#include "vextern.h" +#undef VEXTERN + +extern char vdso_kernel_start[], vdso_start[], vdso_end[]; +extern unsigned short vdso_sync_cpuid; + +struct page **vdso_pages; + +static inline void *var_ref(void *vbase, char *var, char *name) +{ + unsigned offset = var - &vdso_kernel_start[0] + VDSO_TEXT_OFFSET; + void *p = vbase + offset; + if (*(void **)p != (void *)VMAGIC) { + printk("VDSO: variable %s broken\n", name); + vdso_enabled = 0; + } + return p; +} + +static int __init init_vdso_vars(void) +{ + int npages = (vdso_end - vdso_start + PAGE_SIZE - 1) / PAGE_SIZE; + int i; + char *vbase; + + vdso_pages = kmalloc(sizeof(struct page *) * npages, GFP_KERNEL); + if (!vdso_pages) + goto oom; + for (i = 0; i < npages; i++) { + struct page *p; + p = alloc_page(GFP_KERNEL); + if (!p) + goto oom; + vdso_pages[i] = p; + copy_page(page_address(p), vdso_start + i*PAGE_SIZE); + } + + vbase = vmap(vdso_pages, npages, 0, PAGE_KERNEL); + if (!vbase) + goto oom; + + if (memcmp(vbase, "\177ELF", 4)) { + printk("VDSO: I'm broken; not ELF\n"); + vdso_enabled = 0; + } + +#define V(x) *(typeof(x) *) var_ref(vbase, (char *)RELOC_HIDE(&x, 0), #x) +#define VEXTERN(x) \ + V(vdso_ ## x) = &__ ## x; +#include "vextern.h" +#undef VEXTERN + return 0; + + oom: + printk("Cannot allocate vdso\n"); + vdso_enabled = 0; + return -ENOMEM; +} +__initcall(init_vdso_vars); + +struct linux_binprm; + +/* Put the vdso above the (randomized) stack with another randomized offset. + This way there is no hole in the middle of address space. + To save memory make sure it is still in the same PTE as the stack top. + This doesn't give that many random bits */ +static unsigned long vdso_addr(unsigned long start, unsigned len) +{ + unsigned long addr, end; + unsigned offset; + end = (start + PMD_SIZE - 1) & PMD_MASK; + if (end >= TASK_SIZE64) + end = TASK_SIZE64; + end -= len; + /* This loses some more bits than a modulo, but is cheaper */ + offset = get_random_int() & (PTRS_PER_PTE - 1); + addr = start + (offset << PAGE_SHIFT); + if (addr >= end) + addr = end; + return addr; +} + +/* Setup a VMA at program startup for the vsyscall page. + Not called for compat tasks */ +int arch_setup_additional_pages(struct linux_binprm *bprm, int exstack) +{ + struct mm_struct *mm = current->mm; + unsigned long addr; + int ret; + unsigned len = round_up(vdso_end - vdso_start, PAGE_SIZE); + + if (!vdso_enabled) + return 0; + + down_write(&mm->mmap_sem); + addr = vdso_addr(mm->start_stack, len); + addr = get_unmapped_area(NULL, addr, len, 0, 0); + if (IS_ERR_VALUE(addr)) { + ret = addr; + goto up_fail; + } + + ret = install_special_mapping(mm, addr, len, + VM_READ|VM_EXEC| + VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC| + VM_ALWAYSDUMP, + vdso_pages); + if (ret) + goto up_fail; + + current->mm->context.vdso = (void *)addr; +up_fail: + up_write(&mm->mmap_sem); + return ret; +} + +static __init int vdso_setup(char *s) +{ + vdso_enabled = simple_strtoul(s, NULL, 0); + return 0; +} +__setup("vdso=", vdso_setup); |