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arm64: mmu: Place guard page after mapping of kernel image 

The vast majority of virtual allocations in the vmalloc region are followed
by a guard page, which can help to avoid overruning on vma into another,
which may map a read-sensitive device.

This patch adds a guard page to the end of the kernel image mapping (i.e.
following the data/bss segments).

Cc: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
hifive-unleashed-5.1
Will Deacon 2017-07-24 11:46:09 +01:00
parent a3287c41ff
commit 92bbd16e50
1 changed files with 11 additions and 7 deletions
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18
arch/arm64/mm/mmu.c
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@ -496,7 +496,7 @@ void mark_rodata_ro(void)
static void __init map_kernel_segment(pgd_t *pgd, void *va_start, void *va_end,
pgprot_t prot, struct vm_struct *vma,
int flags)
int flags, unsigned long vm_flags)
{
phys_addr_t pa_start = __pa_symbol(va_start);
unsigned long size = va_end - va_start;
@ -507,10 +507,13 @@ static void __init map_kernel_segment(pgd_t *pgd, void *va_start, void *va_end,
__create_pgd_mapping(pgd, pa_start, (unsigned long)va_start, size, prot,
early_pgtable_alloc, flags);
if (!(vm_flags & VM_NO_GUARD))
size += PAGE_SIZE;
vma->addr = va_start;
vma->phys_addr = pa_start;
vma->size = size;
vma->flags = VM_MAP;
vma->flags = VM_MAP | vm_flags;
vma->caller = __builtin_return_address(0);
vm_area_add_early(vma);
@ -541,14 +544,15 @@ static void __init map_kernel(pgd_t *pgd)
* Only rodata will be remapped with different permissions later on,
* all other segments are allowed to use contiguous mappings.
*/
map_kernel_segment(pgd, _text, _etext, text_prot, &vmlinux_text, 0);
map_kernel_segment(pgd, _text, _etext, text_prot, &vmlinux_text, 0,
VM_NO_GUARD);
map_kernel_segment(pgd, __start_rodata, __inittext_begin, PAGE_KERNEL,
&vmlinux_rodata, NO_CONT_MAPPINGS);
&vmlinux_rodata, NO_CONT_MAPPINGS, VM_NO_GUARD);
map_kernel_segment(pgd, __inittext_begin, __inittext_end, text_prot,
&vmlinux_inittext, 0);
&vmlinux_inittext, 0, VM_NO_GUARD);
map_kernel_segment(pgd, __initdata_begin, __initdata_end, PAGE_KERNEL,
&vmlinux_initdata, 0);
map_kernel_segment(pgd, _data, _end, PAGE_KERNEL, &vmlinux_data, 0);
&vmlinux_initdata, 0, VM_NO_GUARD);
map_kernel_segment(pgd, _data, _end, PAGE_KERNEL, &vmlinux_data, 0, 0);
if (!pgd_val(*pgd_offset_raw(pgd, FIXADDR_START))) {
/*