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

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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/arm64/include/asm/sections.h
View File

@ -24,6 +24,8 @@ extern char __hibernate_exit_text_start[], __hibernate_exit_text_end[];
extern char __hyp_idmap_text_start[], __hyp_idmap_text_end[];
extern char __hyp_text_start[], __hyp_text_end[];
extern char __idmap_text_start[], __idmap_text_end[];
extern char __initdata_begin[], __initdata_end[];
extern char __inittext_begin[], __inittext_end[];
extern char __irqentry_text_start[], __irqentry_text_end[];
extern char __mmuoff_data_start[], __mmuoff_data_end[];

25
arch/arm64/kernel/vmlinux.lds.S
View File

@ -143,12 +143,27 @@ SECTIONS
. = ALIGN(SEGMENT_ALIGN);
__init_begin = .;
__inittext_begin = .;
INIT_TEXT_SECTION(8)
.exit.text : {
ARM_EXIT_KEEP(EXIT_TEXT)
}
. = ALIGN(4);
.altinstructions : {
__alt_instructions = .;
*(.altinstructions)
__alt_instructions_end = .;
}
.altinstr_replacement : {
*(.altinstr_replacement)
}
. = ALIGN(PAGE_SIZE);
__inittext_end = .;
__initdata_begin = .;
.init.data : {
INIT_DATA
INIT_SETUP(16)
@ -164,15 +179,6 @@ SECTIONS
PERCPU_SECTION(L1_CACHE_BYTES)
. = ALIGN(4);
.altinstructions : {
__alt_instructions = .;
*(.altinstructions)
__alt_instructions_end = .;
}
.altinstr_replacement : {
*(.altinstr_replacement)
}
.rela : ALIGN(8) {
*(.rela .rela*)
}
@ -181,6 +187,7 @@ SECTIONS
__rela_size = SIZEOF(.rela);
. = ALIGN(SEGMENT_ALIGN);
__initdata_end = .;
__init_end = .;
_data = .;

12
arch/arm64/mm/mmu.c
View File

@ -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))) {