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authorAndy Lutomirski <luto@kernel.org>2015-12-30 05:12:22 +0100
committerIngo Molnar <mingo@kernel.org>2016-01-12 11:59:34 +0100
commit05ef76b20fc4297b0d3f8a956f1c809a8a1b3f1d (patch)
tree3c9e09fc792c155064cc041efc4716473dbf45d0 /arch/x86/entry
parentx86/vdso: Track each mm's loaded vDSO image as well as its base (diff)
downloadlinux-05ef76b20fc4297b0d3f8a956f1c809a8a1b3f1d.tar.xz
linux-05ef76b20fc4297b0d3f8a956f1c809a8a1b3f1d.zip
x86/vdso: Use .fault for the vDSO text mapping
The old scheme for mapping the vDSO text is rather complicated. vdso2c generates a struct vm_special_mapping and a blank .pages array of the correct size for each vdso image. Init code in vdso/vma.c populates the .pages array for each vDSO image, and the mapping code selects the appropriate struct vm_special_mapping. With .fault, we can use a less roundabout approach: vdso_fault() just returns the appropriate page for the selected vDSO image. Signed-off-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/f886954c186bafd74e1b967c8931d852ae199aa2.1451446564.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/entry')
-rw-r--r--arch/x86/entry/vdso/vdso2c.h7
-rw-r--r--arch/x86/entry/vdso/vma.c26
2 files changed, 19 insertions, 14 deletions
diff --git a/arch/x86/entry/vdso/vdso2c.h b/arch/x86/entry/vdso/vdso2c.h
index 0224987556ce..abe961c7c71c 100644
--- a/arch/x86/entry/vdso/vdso2c.h
+++ b/arch/x86/entry/vdso/vdso2c.h
@@ -150,16 +150,9 @@ static void BITSFUNC(go)(void *raw_addr, size_t raw_len,
}
fprintf(outfile, "\n};\n\n");
- fprintf(outfile, "static struct page *pages[%lu];\n\n",
- mapping_size / 4096);
-
fprintf(outfile, "const struct vdso_image %s = {\n", name);
fprintf(outfile, "\t.data = raw_data,\n");
fprintf(outfile, "\t.size = %lu,\n", mapping_size);
- fprintf(outfile, "\t.text_mapping = {\n");
- fprintf(outfile, "\t\t.name = \"[vdso]\",\n");
- fprintf(outfile, "\t\t.pages = pages,\n");
- fprintf(outfile, "\t},\n");
if (alt_sec) {
fprintf(outfile, "\t.alt = %lu,\n",
(unsigned long)GET_LE(&alt_sec->sh_offset));
diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 80b021067bd6..eb50d7c1f161 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -27,13 +27,7 @@ unsigned int __read_mostly vdso64_enabled = 1;
void __init init_vdso_image(const struct vdso_image *image)
{
- int i;
- int npages = (image->size) / PAGE_SIZE;
-
BUG_ON(image->size % PAGE_SIZE != 0);
- for (i = 0; i < npages; i++)
- image->text_mapping.pages[i] =
- virt_to_page(image->data + i*PAGE_SIZE);
apply_alternatives((struct alt_instr *)(image->data + image->alt),
(struct alt_instr *)(image->data + image->alt +
@@ -90,6 +84,24 @@ static unsigned long vdso_addr(unsigned long start, unsigned len)
#endif
}
+static int vdso_fault(const struct vm_special_mapping *sm,
+ struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+ const struct vdso_image *image = vma->vm_mm->context.vdso_image;
+
+ if (!image || (vmf->pgoff << PAGE_SHIFT) >= image->size)
+ return VM_FAULT_SIGBUS;
+
+ vmf->page = virt_to_page(image->data + (vmf->pgoff << PAGE_SHIFT));
+ get_page(vmf->page);
+ return 0;
+}
+
+static const struct vm_special_mapping text_mapping = {
+ .name = "[vdso]",
+ .fault = vdso_fault,
+};
+
static int map_vdso(const struct vdso_image *image, bool calculate_addr)
{
struct mm_struct *mm = current->mm;
@@ -131,7 +143,7 @@ static int map_vdso(const struct vdso_image *image, bool calculate_addr)
image->size,
VM_READ|VM_EXEC|
VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
- &image->text_mapping);
+ &text_mapping);
if (IS_ERR(vma)) {
ret = PTR_ERR(vma);