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| author | Andy Lutomirski <luto@mit.edu> | 2011-07-13 17:24:11 +0400 |
|---|---|---|
| committer | H. Peter Anvin <hpa@linux.intel.com> | 2011-07-13 22:23:07 +0400 |
| commit | 1b3f2a72bbcfdf92e368a44448c45eb639b05b5e (patch) | |
| tree | 99932e5554b80458fd6769f433c96fea8cbab1de | |
| parent | 59e97e4d6fbcd5b74a94cb48bcbfc6f8478a5e93 (diff) | |
| download | linux-1b3f2a72bbcfdf92e368a44448c45eb639b05b5e.tar.xz | |
x86-64: Allow alternative patching in the vDSO
This code is short enough and different enough from the module
loader that it's not worth trying to share anything.
Signed-off-by: Andy Lutomirski <luto@mit.edu>
Link: http://lkml.kernel.org/r/e73112e4381fff29e31b882c2d0856822edaea53.1310563276.git.luto@mit.edu
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
| -rw-r--r-- | arch/x86/vdso/vma.c | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/arch/x86/vdso/vma.c b/arch/x86/vdso/vma.c index 7abd2be0f9b9..c39938d1332f 100644 --- a/arch/x86/vdso/vma.c +++ b/arch/x86/vdso/vma.c @@ -23,11 +23,44 @@ extern unsigned short vdso_sync_cpuid; static struct page **vdso_pages; static unsigned vdso_size; +static void __init patch_vdso(void *vdso, size_t len) +{ + Elf64_Ehdr *hdr = vdso; + Elf64_Shdr *sechdrs, *alt_sec = 0; + char *secstrings; + void *alt_data; + int i; + + BUG_ON(len < sizeof(Elf64_Ehdr)); + BUG_ON(memcmp(hdr->e_ident, ELFMAG, SELFMAG) != 0); + + sechdrs = (void *)hdr + hdr->e_shoff; + secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; + + for (i = 1; i < hdr->e_shnum; i++) { + Elf64_Shdr *shdr = &sechdrs[i]; + if (!strcmp(secstrings + shdr->sh_name, ".altinstructions")) { + alt_sec = shdr; + goto found; + } + } + + /* If we get here, it's probably a bug. */ + pr_warning("patch_vdso: .altinstructions not found\n"); + return; /* nothing to patch */ + +found: + alt_data = (void *)hdr + alt_sec->sh_offset; + apply_alternatives(alt_data, alt_data + alt_sec->sh_size); +} + static int __init init_vdso_vars(void) { int npages = (vdso_end - vdso_start + PAGE_SIZE - 1) / PAGE_SIZE; int i; + patch_vdso(vdso_start, vdso_end - vdso_start); + vdso_size = npages << PAGE_SHIFT; vdso_pages = kmalloc(sizeof(struct page *) * npages, GFP_KERNEL); if (!vdso_pages) |