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author | Andy Lutomirski <luto@kernel.org> | 2015-12-29 20:12:22 -0800 |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2016-01-12 11:59:34 +0100 |
commit | 05ef76b20fc4297b0d3f8a956f1c809a8a1b3f1d (patch) | |
tree | 3c9e09fc792c155064cc041efc4716473dbf45d0 /arch/x86/entry | |
parent | 352b78c62f27b356b182008acd3117f3ee03ffd2 (diff) | |
download | linux-05ef76b20fc4297b0d3f8a956f1c809a8a1b3f1d.tar.bz2 |
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.h | 7 | ||||
-rw-r--r-- | arch/x86/entry/vdso/vma.c | 26 |
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); |