* [PATCH] arm64: mm: fix location of _etext
@ 2016-06-23 10:46 Ard Biesheuvel
2016-06-23 11:40 ` Mark Rutland
0 siblings, 1 reply; 4+ messages in thread
From: Ard Biesheuvel @ 2016-06-23 10:46 UTC (permalink / raw)
To: linux-arm-kernel
As Kees Cook notes in the ARM counterpart of this patch [0]:
The _etext position is defined to be the end of the kernel text code,
and should not include any part of the data segments. This interferes
with things that might check memory ranges and expect executable code
up to _etext.
In particular, Kees is referring to the HARDENED_USERCOPY patch set [1],
which rejects attempts to call copy_to_user() on kernel ranges containing
executable code, but does allow access to the .rodata segment. Regardless
of whether one may or may not agree with the distinction, it makes sense
for _etext to have the same meaning across architectures.
So let's put _etext where it belongs, between .text and .rodata, and fix
up existing references to use __init_begin instead, which, unlike
__end_rodata, includes the exception and notes sections as well.
The _etext references in kaslr.c are left untouched, since its references
to [_stext, _etext) are meant to capture potential jump instruction targets,
and so disregarding .rodata is actually an improvement here.
[0] http://article.gmane.org/gmane.linux.kernel/2245084
[1] http://thread.gmane.org/gmane.linux.kernel.hardened.devel/2502
Reported-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
arch/arm64/kernel/setup.c | 4 ++--
arch/arm64/kernel/vmlinux.lds.S | 7 ++++---
arch/arm64/mm/init.c | 4 ++--
arch/arm64/mm/mmu.c | 16 ++++++++--------
4 files changed, 16 insertions(+), 15 deletions(-)
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 3279defabaa2..f8b4837d1805 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -202,7 +202,7 @@ static void __init request_standard_resources(void)
struct resource *res;
kernel_code.start = virt_to_phys(_text);
- kernel_code.end = virt_to_phys(_etext - 1);
+ kernel_code.end = virt_to_phys(__init_begin - 1);
kernel_data.start = virt_to_phys(_sdata);
kernel_data.end = virt_to_phys(_end - 1);
@@ -232,7 +232,7 @@ void __init setup_arch(char **cmdline_p)
sprintf(init_utsname()->machine, ELF_PLATFORM);
init_mm.start_code = (unsigned long) _text;
- init_mm.end_code = (unsigned long) _etext;
+ init_mm.end_code = (unsigned long) __init_begin;
init_mm.end_data = (unsigned long) _edata;
init_mm.brk = (unsigned long) _end;
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index 435e820e898d..0de7be4f1a9d 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -131,12 +131,13 @@ SECTIONS
}
. = ALIGN(SEGMENT_ALIGN);
- RO_DATA(PAGE_SIZE) /* everything from this point to */
- EXCEPTION_TABLE(8) /* _etext will be marked RO NX */
+ _etext = .; /* End of text section */
+
+ RO_DATA(PAGE_SIZE) /* everything from this point to */
+ EXCEPTION_TABLE(8) /* __init_begin will be marked RO NX */
NOTES
. = ALIGN(SEGMENT_ALIGN);
- _etext = .; /* End of text and rodata section */
__init_begin = .;
INIT_TEXT_SECTION(8)
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index d45f8627012c..7bc5bed0220a 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -430,9 +430,9 @@ void __init mem_init(void)
pr_cont(" vmalloc : 0x%16lx - 0x%16lx (%6ld GB)\n",
MLG(VMALLOC_START, VMALLOC_END));
pr_cont(" .text : 0x%p" " - 0x%p" " (%6ld KB)\n",
- MLK_ROUNDUP(_text, __start_rodata));
+ MLK_ROUNDUP(_text, _etext));
pr_cont(" .rodata : 0x%p" " - 0x%p" " (%6ld KB)\n",
- MLK_ROUNDUP(__start_rodata, _etext));
+ MLK_ROUNDUP(__start_rodata, __init_begin));
pr_cont(" .init : 0x%p" " - 0x%p" " (%6ld KB)\n",
MLK_ROUNDUP(__init_begin, __init_end));
pr_cont(" .data : 0x%p" " - 0x%p" " (%6ld KB)\n",
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 0f85a46c3e18..a263a5d19bd9 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -386,7 +386,7 @@ static void create_mapping_late(phys_addr_t phys, unsigned long virt,
static void __init __map_memblock(pgd_t *pgd, phys_addr_t start, phys_addr_t end)
{
unsigned long kernel_start = __pa(_text);
- unsigned long kernel_end = __pa(_etext);
+ unsigned long kernel_end = __pa(__init_begin);
/*
* Take care not to create a writable alias for the
@@ -417,7 +417,7 @@ static void __init __map_memblock(pgd_t *pgd, phys_addr_t start, phys_addr_t end
early_pgtable_alloc);
/*
- * Map the linear alias of the [_text, _etext) interval as
+ * Map the linear alias of the [_text, __init_begin) interval as
* read-only/non-executable. This makes the contents of the
* region accessible to subsystems such as hibernate, but
* protects it from inadvertent modification or execution.
@@ -449,14 +449,14 @@ void mark_rodata_ro(void)
{
unsigned long section_size;
- section_size = (unsigned long)__start_rodata - (unsigned long)_text;
+ section_size = (unsigned long)_etext - (unsigned long)_text;
create_mapping_late(__pa(_text), (unsigned long)_text,
section_size, PAGE_KERNEL_ROX);
/*
- * mark .rodata as read only. Use _etext rather than __end_rodata to
- * cover NOTES and EXCEPTION_TABLE.
+ * mark .rodata as read only. Use __init_begin rather than __end_rodata
+ * to cover NOTES and EXCEPTION_TABLE.
*/
- section_size = (unsigned long)_etext - (unsigned long)__start_rodata;
+ section_size = (unsigned long)__init_begin - (unsigned long)__start_rodata;
create_mapping_late(__pa(__start_rodata), (unsigned long)__start_rodata,
section_size, PAGE_KERNEL_RO);
}
@@ -499,8 +499,8 @@ static void __init map_kernel(pgd_t *pgd)
{
static struct vm_struct vmlinux_text, vmlinux_rodata, vmlinux_init, vmlinux_data;
- map_kernel_segment(pgd, _text, __start_rodata, PAGE_KERNEL_EXEC, &vmlinux_text);
- map_kernel_segment(pgd, __start_rodata, _etext, PAGE_KERNEL, &vmlinux_rodata);
+ map_kernel_segment(pgd, _text, _etext, PAGE_KERNEL_EXEC, &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, _data, _end, PAGE_KERNEL, &vmlinux_data);
--
2.7.4
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH] arm64: mm: fix location of _etext
2016-06-23 10:46 [PATCH] arm64: mm: fix location of _etext Ard Biesheuvel
@ 2016-06-23 11:40 ` Mark Rutland
2016-06-23 11:49 ` Ard Biesheuvel
0 siblings, 1 reply; 4+ messages in thread
From: Mark Rutland @ 2016-06-23 11:40 UTC (permalink / raw)
To: linux-arm-kernel
On Thu, Jun 23, 2016 at 12:46:32PM +0200, Ard Biesheuvel wrote:
> As Kees Cook notes in the ARM counterpart of this patch [0]:
>
> The _etext position is defined to be the end of the kernel text code,
> and should not include any part of the data segments. This interferes
> with things that might check memory ranges and expect executable code
> up to _etext.
>
> In particular, Kees is referring to the HARDENED_USERCOPY patch set [1],
> which rejects attempts to call copy_to_user() on kernel ranges containing
> executable code, but does allow access to the .rodata segment. Regardless
> of whether one may or may not agree with the distinction, it makes sense
> for _etext to have the same meaning across architectures.
I certainly agree with this.
> So let's put _etext where it belongs, between .text and .rodata, and fix
> up existing references to use __init_begin instead, which, unlike
> __end_rodata, includes the exception and notes sections as well.
>
> The _etext references in kaslr.c are left untouched, since its references
> to [_stext, _etext) are meant to capture potential jump instruction targets,
> and so disregarding .rodata is actually an improvement here.
>
> [0] http://article.gmane.org/gmane.linux.kernel/2245084
> [1] http://thread.gmane.org/gmane.linux.kernel.hardened.devel/2502
>
> Reported-by: Kees Cook <keescook@chromium.org>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
> arch/arm64/kernel/setup.c | 4 ++--
> arch/arm64/kernel/vmlinux.lds.S | 7 ++++---
> arch/arm64/mm/init.c | 4 ++--
> arch/arm64/mm/mmu.c | 16 ++++++++--------
> 4 files changed, 16 insertions(+), 15 deletions(-)
>
> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> index 3279defabaa2..f8b4837d1805 100644
> --- a/arch/arm64/kernel/setup.c
> +++ b/arch/arm64/kernel/setup.c
> @@ -202,7 +202,7 @@ static void __init request_standard_resources(void)
> struct resource *res;
>
> kernel_code.start = virt_to_phys(_text);
> - kernel_code.end = virt_to_phys(_etext - 1);
> + kernel_code.end = virt_to_phys(__init_begin - 1);
> kernel_data.start = virt_to_phys(_sdata);
> kernel_data.end = virt_to_phys(_end - 1);
Given that these resources are coarse to begin with, I guess it doesn't
matter that we're capturing rodata friends here, and this retains the
existing behaviour.
> @@ -232,7 +232,7 @@ void __init setup_arch(char **cmdline_p)
>
> sprintf(init_utsname()->machine, ELF_PLATFORM);
> init_mm.start_code = (unsigned long) _text;
> - init_mm.end_code = (unsigned long) _etext;
> + init_mm.end_code = (unsigned long) __init_begin;
Why does this need to be __init_begin?
We don't have code in .rodata, the exception tables, or notes, so
shouldn't this be left pointing at _etext if we're tightening things up?
> init_mm.end_data = (unsigned long) _edata;
> init_mm.brk = (unsigned long) _end;
>
> diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
> index 435e820e898d..0de7be4f1a9d 100644
> --- a/arch/arm64/kernel/vmlinux.lds.S
> +++ b/arch/arm64/kernel/vmlinux.lds.S
> @@ -131,12 +131,13 @@ SECTIONS
> }
>
> . = ALIGN(SEGMENT_ALIGN);
> - RO_DATA(PAGE_SIZE) /* everything from this point to */
> - EXCEPTION_TABLE(8) /* _etext will be marked RO NX */
> + _etext = .; /* End of text section */
> +
> + RO_DATA(PAGE_SIZE) /* everything from this point to */
> + EXCEPTION_TABLE(8) /* __init_begin will be marked RO NX */
> NOTES
>
> . = ALIGN(SEGMENT_ALIGN);
> - _etext = .; /* End of text and rodata section */
> __init_begin = .;
>
> INIT_TEXT_SECTION(8)
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index d45f8627012c..7bc5bed0220a 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -430,9 +430,9 @@ void __init mem_init(void)
> pr_cont(" vmalloc : 0x%16lx - 0x%16lx (%6ld GB)\n",
> MLG(VMALLOC_START, VMALLOC_END));
> pr_cont(" .text : 0x%p" " - 0x%p" " (%6ld KB)\n",
> - MLK_ROUNDUP(_text, __start_rodata));
> + MLK_ROUNDUP(_text, _etext));
> pr_cont(" .rodata : 0x%p" " - 0x%p" " (%6ld KB)\n",
> - MLK_ROUNDUP(__start_rodata, _etext));
> + MLK_ROUNDUP(__start_rodata, __init_begin));
> pr_cont(" .init : 0x%p" " - 0x%p" " (%6ld KB)\n",
> MLK_ROUNDUP(__init_begin, __init_end));
> pr_cont(" .data : 0x%p" " - 0x%p" " (%6ld KB)\n",
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 0f85a46c3e18..a263a5d19bd9 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -386,7 +386,7 @@ static void create_mapping_late(phys_addr_t phys, unsigned long virt,
> static void __init __map_memblock(pgd_t *pgd, phys_addr_t start, phys_addr_t end)
> {
> unsigned long kernel_start = __pa(_text);
> - unsigned long kernel_end = __pa(_etext);
> + unsigned long kernel_end = __pa(__init_begin);
>
> /*
> * Take care not to create a writable alias for the
> @@ -417,7 +417,7 @@ static void __init __map_memblock(pgd_t *pgd, phys_addr_t start, phys_addr_t end
> early_pgtable_alloc);
>
> /*
> - * Map the linear alias of the [_text, _etext) interval as
> + * Map the linear alias of the [_text, __init_begin) interval as
> * read-only/non-executable. This makes the contents of the
> * region accessible to subsystems such as hibernate, but
> * protects it from inadvertent modification or execution.
There are a couple of comments regarding overlap that are probably worth
updating to say "text + rodata" rather than "text". Strictly speaking
they're already slightly wrong, but this is a good opportunity to fix
them up.
> @@ -449,14 +449,14 @@ void mark_rodata_ro(void)
> {
> unsigned long section_size;
>
> - section_size = (unsigned long)__start_rodata - (unsigned long)_text;
> + section_size = (unsigned long)_etext - (unsigned long)_text;
> create_mapping_late(__pa(_text), (unsigned long)_text,
> section_size, PAGE_KERNEL_ROX);
> /*
> - * mark .rodata as read only. Use _etext rather than __end_rodata to
> - * cover NOTES and EXCEPTION_TABLE.
> + * mark .rodata as read only. Use __init_begin rather than __end_rodata
> + * to cover NOTES and EXCEPTION_TABLE.
> */
> - section_size = (unsigned long)_etext - (unsigned long)__start_rodata;
> + section_size = (unsigned long)__init_begin - (unsigned long)__start_rodata;
> create_mapping_late(__pa(__start_rodata), (unsigned long)__start_rodata,
> section_size, PAGE_KERNEL_RO);
> }
> @@ -499,8 +499,8 @@ static void __init map_kernel(pgd_t *pgd)
> {
> static struct vm_struct vmlinux_text, vmlinux_rodata, vmlinux_init, vmlinux_data;
>
> - map_kernel_segment(pgd, _text, __start_rodata, PAGE_KERNEL_EXEC, &vmlinux_text);
> - map_kernel_segment(pgd, __start_rodata, _etext, PAGE_KERNEL, &vmlinux_rodata);
> + map_kernel_segment(pgd, _text, _etext, PAGE_KERNEL_EXEC, &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, _data, _end, PAGE_KERNEL, &vmlinux_data);
> --
> 2.7.4
>
Other than the above, this looks good to me!
Thanks,
Mark.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH] arm64: mm: fix location of _etext
2016-06-23 11:40 ` Mark Rutland
@ 2016-06-23 11:49 ` Ard Biesheuvel
2016-06-23 12:31 ` Mark Rutland
0 siblings, 1 reply; 4+ messages in thread
From: Ard Biesheuvel @ 2016-06-23 11:49 UTC (permalink / raw)
To: linux-arm-kernel
On 23 June 2016 at 13:40, Mark Rutland <mark.rutland@arm.com> wrote:
> On Thu, Jun 23, 2016 at 12:46:32PM +0200, Ard Biesheuvel wrote:
>> As Kees Cook notes in the ARM counterpart of this patch [0]:
>>
>> The _etext position is defined to be the end of the kernel text code,
>> and should not include any part of the data segments. This interferes
>> with things that might check memory ranges and expect executable code
>> up to _etext.
>>
>> In particular, Kees is referring to the HARDENED_USERCOPY patch set [1],
>> which rejects attempts to call copy_to_user() on kernel ranges containing
>> executable code, but does allow access to the .rodata segment. Regardless
>> of whether one may or may not agree with the distinction, it makes sense
>> for _etext to have the same meaning across architectures.
>
> I certainly agree with this.
>
>> So let's put _etext where it belongs, between .text and .rodata, and fix
>> up existing references to use __init_begin instead, which, unlike
>> __end_rodata, includes the exception and notes sections as well.
>>
>> The _etext references in kaslr.c are left untouched, since its references
>> to [_stext, _etext) are meant to capture potential jump instruction targets,
>> and so disregarding .rodata is actually an improvement here.
>>
>> [0] http://article.gmane.org/gmane.linux.kernel/2245084
>> [1] http://thread.gmane.org/gmane.linux.kernel.hardened.devel/2502
>>
>> Reported-by: Kees Cook <keescook@chromium.org>
>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>> ---
>> arch/arm64/kernel/setup.c | 4 ++--
>> arch/arm64/kernel/vmlinux.lds.S | 7 ++++---
>> arch/arm64/mm/init.c | 4 ++--
>> arch/arm64/mm/mmu.c | 16 ++++++++--------
>> 4 files changed, 16 insertions(+), 15 deletions(-)
>>
>> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
>> index 3279defabaa2..f8b4837d1805 100644
>> --- a/arch/arm64/kernel/setup.c
>> +++ b/arch/arm64/kernel/setup.c
>> @@ -202,7 +202,7 @@ static void __init request_standard_resources(void)
>> struct resource *res;
>>
>> kernel_code.start = virt_to_phys(_text);
>> - kernel_code.end = virt_to_phys(_etext - 1);
>> + kernel_code.end = virt_to_phys(__init_begin - 1);
>> kernel_data.start = virt_to_phys(_sdata);
>> kernel_data.end = virt_to_phys(_end - 1);
>
> Given that these resources are coarse to begin with, I guess it doesn't
> matter that we're capturing rodata friends here, and this retains the
> existing behaviour.
>
Indeed.
>> @@ -232,7 +232,7 @@ void __init setup_arch(char **cmdline_p)
>>
>> sprintf(init_utsname()->machine, ELF_PLATFORM);
>> init_mm.start_code = (unsigned long) _text;
>> - init_mm.end_code = (unsigned long) _etext;
>> + init_mm.end_code = (unsigned long) __init_begin;
>
> Why does this need to be __init_begin?
>
> We don't have code in .rodata, the exception tables, or notes, so
> shouldn't this be left pointing at _etext if we're tightening things up?
>
You are right, and I am happy to change that in the same patch.
Strictly speaking, it is a separate change, but that applies equally
to not updating the _etext references in kaslr.c
>> init_mm.end_data = (unsigned long) _edata;
>> init_mm.brk = (unsigned long) _end;
>>
>> diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
>> index 435e820e898d..0de7be4f1a9d 100644
>> --- a/arch/arm64/kernel/vmlinux.lds.S
>> +++ b/arch/arm64/kernel/vmlinux.lds.S
>> @@ -131,12 +131,13 @@ SECTIONS
>> }
>>
>> . = ALIGN(SEGMENT_ALIGN);
>> - RO_DATA(PAGE_SIZE) /* everything from this point to */
>> - EXCEPTION_TABLE(8) /* _etext will be marked RO NX */
>> + _etext = .; /* End of text section */
>> +
>> + RO_DATA(PAGE_SIZE) /* everything from this point to */
>> + EXCEPTION_TABLE(8) /* __init_begin will be marked RO NX */
>> NOTES
>>
>> . = ALIGN(SEGMENT_ALIGN);
>> - _etext = .; /* End of text and rodata section */
>> __init_begin = .;
>>
>> INIT_TEXT_SECTION(8)
>> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
>> index d45f8627012c..7bc5bed0220a 100644
>> --- a/arch/arm64/mm/init.c
>> +++ b/arch/arm64/mm/init.c
>> @@ -430,9 +430,9 @@ void __init mem_init(void)
>> pr_cont(" vmalloc : 0x%16lx - 0x%16lx (%6ld GB)\n",
>> MLG(VMALLOC_START, VMALLOC_END));
>> pr_cont(" .text : 0x%p" " - 0x%p" " (%6ld KB)\n",
>> - MLK_ROUNDUP(_text, __start_rodata));
>> + MLK_ROUNDUP(_text, _etext));
>> pr_cont(" .rodata : 0x%p" " - 0x%p" " (%6ld KB)\n",
>> - MLK_ROUNDUP(__start_rodata, _etext));
>> + MLK_ROUNDUP(__start_rodata, __init_begin));
>> pr_cont(" .init : 0x%p" " - 0x%p" " (%6ld KB)\n",
>> MLK_ROUNDUP(__init_begin, __init_end));
>> pr_cont(" .data : 0x%p" " - 0x%p" " (%6ld KB)\n",
>> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
>> index 0f85a46c3e18..a263a5d19bd9 100644
>> --- a/arch/arm64/mm/mmu.c
>> +++ b/arch/arm64/mm/mmu.c
>> @@ -386,7 +386,7 @@ static void create_mapping_late(phys_addr_t phys, unsigned long virt,
>> static void __init __map_memblock(pgd_t *pgd, phys_addr_t start, phys_addr_t end)
>> {
>> unsigned long kernel_start = __pa(_text);
>> - unsigned long kernel_end = __pa(_etext);
>> + unsigned long kernel_end = __pa(__init_begin);
>>
>> /*
>> * Take care not to create a writable alias for the
>> @@ -417,7 +417,7 @@ static void __init __map_memblock(pgd_t *pgd, phys_addr_t start, phys_addr_t end
>> early_pgtable_alloc);
>>
>> /*
>> - * Map the linear alias of the [_text, _etext) interval as
>> + * Map the linear alias of the [_text, __init_begin) interval as
>> * read-only/non-executable. This makes the contents of the
>> * region accessible to subsystems such as hibernate, but
>> * protects it from inadvertent modification or execution.
>
> There are a couple of comments regarding overlap that are probably worth
> updating to say "text + rodata" rather than "text". Strictly speaking
> they're already slightly wrong, but this is a good opportunity to fix
> them up.
>
OK
>> @@ -449,14 +449,14 @@ void mark_rodata_ro(void)
>> {
>> unsigned long section_size;
>>
>> - section_size = (unsigned long)__start_rodata - (unsigned long)_text;
>> + section_size = (unsigned long)_etext - (unsigned long)_text;
>> create_mapping_late(__pa(_text), (unsigned long)_text,
>> section_size, PAGE_KERNEL_ROX);
>> /*
>> - * mark .rodata as read only. Use _etext rather than __end_rodata to
>> - * cover NOTES and EXCEPTION_TABLE.
>> + * mark .rodata as read only. Use __init_begin rather than __end_rodata
>> + * to cover NOTES and EXCEPTION_TABLE.
>> */
>> - section_size = (unsigned long)_etext - (unsigned long)__start_rodata;
>> + section_size = (unsigned long)__init_begin - (unsigned long)__start_rodata;
>> create_mapping_late(__pa(__start_rodata), (unsigned long)__start_rodata,
>> section_size, PAGE_KERNEL_RO);
>> }
>> @@ -499,8 +499,8 @@ static void __init map_kernel(pgd_t *pgd)
>> {
>> static struct vm_struct vmlinux_text, vmlinux_rodata, vmlinux_init, vmlinux_data;
>>
>> - map_kernel_segment(pgd, _text, __start_rodata, PAGE_KERNEL_EXEC, &vmlinux_text);
>> - map_kernel_segment(pgd, __start_rodata, _etext, PAGE_KERNEL, &vmlinux_rodata);
>> + map_kernel_segment(pgd, _text, _etext, PAGE_KERNEL_EXEC, &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, _data, _end, PAGE_KERNEL, &vmlinux_data);
>> --
>> 2.7.4
>>
>
> Other than the above, this looks good to me!
>
Thanks,
Ard.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH] arm64: mm: fix location of _etext
2016-06-23 11:49 ` Ard Biesheuvel
@ 2016-06-23 12:31 ` Mark Rutland
0 siblings, 0 replies; 4+ messages in thread
From: Mark Rutland @ 2016-06-23 12:31 UTC (permalink / raw)
To: linux-arm-kernel
On Thu, Jun 23, 2016 at 01:49:05PM +0200, Ard Biesheuvel wrote:
> On 23 June 2016 at 13:40, Mark Rutland <mark.rutland@arm.com> wrote:
> > On Thu, Jun 23, 2016 at 12:46:32PM +0200, Ard Biesheuvel wrote:
> >> @@ -232,7 +232,7 @@ void __init setup_arch(char **cmdline_p)
> >>
> >> sprintf(init_utsname()->machine, ELF_PLATFORM);
> >> init_mm.start_code = (unsigned long) _text;
> >> - init_mm.end_code = (unsigned long) _etext;
> >> + init_mm.end_code = (unsigned long) __init_begin;
> >
> > Why does this need to be __init_begin?
> >
> > We don't have code in .rodata, the exception tables, or notes, so
> > shouldn't this be left pointing at _etext if we're tightening things up?
> >
>
> You are right, and I am happy to change that in the same patch.
> Strictly speaking, it is a separate change, but that applies equally
> to not updating the _etext references in kaslr.c
Ok. FWIW, with that and the comment fixup:
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Thanks,
Mark.
^ permalink raw reply [flat|nested] 4+ messages in thread
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2016-06-23 10:46 [PATCH] arm64: mm: fix location of _etext Ard Biesheuvel
2016-06-23 11:40 ` Mark Rutland
2016-06-23 11:49 ` Ard Biesheuvel
2016-06-23 12:31 ` Mark Rutland
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