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 <l...@amacapital.net>
---
arch/x86/include/asm/vdso.h | 3 ---
arch/x86/vdso/vdso2c.h | 7 -------
arch/x86/vdso/vma.c | 26 +++++++++++++++++++-------
3 files changed, 19 insertions(+), 17 deletions(-)
diff --git a/arch/x86/include/asm/vdso.h b/arch/x86/include/asm/vdso.h
index 3aa1f830c551..b730e7a74323 100644
--- a/arch/x86/include/asm/vdso.h
+++ b/arch/x86/include/asm/vdso.h
@@ -13,9 +13,6 @@ struct vdso_image {
void *data;
unsigned long size; /* Always a multiple of PAGE_SIZE */
- /* text_mapping.pages is big enough for data/size page pointers */
- struct vm_special_mapping text_mapping;
-
unsigned long alt, alt_len;
long sym_vvar_start; /* Negative offset to the vvar area */
diff --git a/arch/x86/vdso/vdso2c.h b/arch/x86/vdso/vdso2c.h
index fd57829b30d8..279f7af7cf5e 100644
--- a/arch/x86/vdso/vdso2c.h
+++ b/arch/x86/vdso/vdso2c.h
@@ -148,16 +148,9 @@ 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/vdso/vma.c b/arch/x86/vdso/vma.c
index 5cde3b82d1e9..0ae947eb7433 100644
--- a/arch/x86/vdso/vma.c
+++ b/arch/x86/vdso/vma.c
@@ -25,13 +25,7 @@ extern unsigned short vdso_sync_cpuid;
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 +
@@ -160,6 +154,24 @@ static int vvar_fault(struct vm_special_mapping *sm,
return VM_FAULT_SIGBUS;
}
+static int vdso_fault(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 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;
@@ -204,7 +216,7 @@ 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);
--
1.9.3
--
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