x32: Add x32 VDSO support
Add support for the x32 VDSO. The x32 VDSO takes advantage of the
similarity between the x86-64 and the x32 ABIs to contain the same
content, only the container is different, as the x32 VDSO obviously is
an x32 shared object.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/arch/x86/vdso/vma.c b/arch/x86/vdso/vma.c
index 153407c..1bbcc62 100644
--- a/arch/x86/vdso/vma.c
+++ b/arch/x86/vdso/vma.c
@@ -24,7 +24,44 @@
extern struct page *vdso_pages[];
static unsigned vdso_size;
-static void __init patch_vdso(void *vdso, size_t len)
+#ifdef CONFIG_X86_X32_ABI
+extern char vdsox32_start[], vdsox32_end[];
+extern struct page *vdsox32_pages[];
+static unsigned vdsox32_size;
+
+static void __init patch_vdsox32(void *vdso, size_t len)
+{
+ Elf32_Ehdr *hdr = vdso;
+ Elf32_Shdr *sechdrs, *alt_sec = 0;
+ char *secstrings;
+ void *alt_data;
+ int i;
+
+ BUG_ON(len < sizeof(Elf32_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++) {
+ Elf32_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_vdsox32: .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);
+}
+#endif
+
+static void __init patch_vdso64(void *vdso, size_t len)
{
Elf64_Ehdr *hdr = vdso;
Elf64_Shdr *sechdrs, *alt_sec = 0;
@@ -47,7 +84,7 @@
}
/* If we get here, it's probably a bug. */
- pr_warning("patch_vdso: .altinstructions not found\n");
+ pr_warning("patch_vdso64: .altinstructions not found\n");
return; /* nothing to patch */
found:
@@ -60,12 +97,20 @@
int npages = (vdso_end - vdso_start + PAGE_SIZE - 1) / PAGE_SIZE;
int i;
- patch_vdso(vdso_start, vdso_end - vdso_start);
+ patch_vdso64(vdso_start, vdso_end - vdso_start);
vdso_size = npages << PAGE_SHIFT;
for (i = 0; i < npages; i++)
vdso_pages[i] = virt_to_page(vdso_start + i*PAGE_SIZE);
+#ifdef CONFIG_X86_X32_ABI
+ patch_vdsox32(vdsox32_start, vdsox32_end - vdsox32_start);
+ npages = (vdsox32_end - vdsox32_start + PAGE_SIZE - 1) / PAGE_SIZE;
+ vdsox32_size = npages << PAGE_SHIFT;
+ for (i = 0; i < npages; i++)
+ vdsox32_pages[i] = virt_to_page(vdsox32_start + i*PAGE_SIZE);
+#endif
+
return 0;
}
subsys_initcall(init_vdso);
@@ -103,7 +148,10 @@
/* 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 uses_interp)
+static int setup_additional_pages(struct linux_binprm *bprm,
+ int uses_interp,
+ struct page **pages,
+ unsigned size)
{
struct mm_struct *mm = current->mm;
unsigned long addr;
@@ -113,8 +161,8 @@
return 0;
down_write(&mm->mmap_sem);
- addr = vdso_addr(mm->start_stack, vdso_size);
- addr = get_unmapped_area(NULL, addr, vdso_size, 0, 0);
+ addr = vdso_addr(mm->start_stack, size);
+ addr = get_unmapped_area(NULL, addr, size, 0, 0);
if (IS_ERR_VALUE(addr)) {
ret = addr;
goto up_fail;
@@ -122,11 +170,11 @@
current->mm->context.vdso = (void *)addr;
- ret = install_special_mapping(mm, addr, vdso_size,
+ ret = install_special_mapping(mm, addr, size,
VM_READ|VM_EXEC|
VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
VM_ALWAYSDUMP,
- vdso_pages);
+ pages);
if (ret) {
current->mm->context.vdso = NULL;
goto up_fail;
@@ -137,6 +185,20 @@
return ret;
}
+int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
+{
+ return setup_additional_pages (bprm, uses_interp, vdso_pages,
+ vdso_size);
+}
+
+#ifdef CONFIG_X86_X32_ABI
+int x32_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
+{
+ return setup_additional_pages (bprm, uses_interp, vdsox32_pages,
+ vdsox32_size);
+}
+#endif
+
static __init int vdso_setup(char *s)
{
vdso_enabled = simple_strtoul(s, NULL, 0);