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arm64: mmu: apply strict permissions to .init.text and .init.data

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To avoid having mappings that are writable and executable at the same
time, split the init region into a .init.text region that is mapped
read-only, and a .init.data region that is mapped non-executable.

This is possible now that the alternative patching occurs via the linear
mapping, and the linear alias of the init region is always mapped writable
(but never executable).

Since the alternatives descriptions themselves are read-only data, move
those into the .init.text region.

Reviewed-by: Laura Abbott <labbott@redhat.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Ard Biesheuvel
2017-03-09 21:52:03 +01:00
committed by Catalin Marinas
parent 28b066da69
commit 2ebe088b73
3 changed files with 26 additions and 13 deletions
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12
arch/arm64/mm/mmu.c
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@@ -459,7 +459,8 @@ early_param("rodata", parse_rodata);
*/
static void __init map_kernel(pgd_t *pgd)
{
static struct vm_struct vmlinux_text, vmlinux_rodata, vmlinux_init, vmlinux_data;
static struct vm_struct vmlinux_text, vmlinux_rodata, vmlinux_inittext,
vmlinux_initdata, vmlinux_data;
/*
* External debuggers may need to write directly to the text
@@ -469,9 +470,12 @@ static void __init map_kernel(pgd_t *pgd)
pgprot_t text_prot = rodata_enabled ? PAGE_KERNEL_ROX : PAGE_KERNEL_EXEC;
map_kernel_segment(pgd, _text, _etext, text_prot, &vmlinux_text);
map_kernel_segment(pgd, __start_rodata, __init_begin, PAGE_KERNEL, &vmlinux_rodata);
map_kernel_segment(pgd, __init_begin, __init_end, PAGE_KERNEL_EXEC,
&vmlinux_init);
map_kernel_segment(pgd, __start_rodata, __inittext_begin, PAGE_KERNEL,
&vmlinux_rodata);
map_kernel_segment(pgd, __inittext_begin, __inittext_end, text_prot,
&vmlinux_inittext);
map_kernel_segment(pgd, __initdata_begin, __initdata_end, PAGE_KERNEL,
&vmlinux_initdata);
map_kernel_segment(pgd, _data, _end, PAGE_KERNEL, &vmlinux_data);
if (!pgd_val(*pgd_offset_raw(pgd, FIXADDR_START))) {