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Commit 1b3f2a72 authored by Andy Lutomirski's avatar Andy Lutomirski Committed by H. Peter Anvin
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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: default avatarAndy Lutomirski <luto@mit.edu>
Link: http://lkml.kernel.org/r/e73112e4381fff29e31b882c2d0856822edaea53.1310563276.git.luto@mit.edu


Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent 59e97e4d

arch/x86/vdso/vma.c

+33 −0
Original line number Diff line number Diff line
@@ -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)