* [PATCH] arm64: fix rodata=full again
@ 2022-11-03 17:00 Ard Biesheuvel
2022-11-07 15:42 ` Will Deacon
2022-11-08 19:53 ` Catalin Marinas
0 siblings, 2 replies; 3+ messages in thread
From: Ard Biesheuvel @ 2022-11-03 17:00 UTC (permalink / raw)
To: linux-arm-kernel; +Cc: catalin.marinas, will, mark.rutland, Ard Biesheuvel
Commit 2e8cff0a0eee87b2 ("arm64: fix rodata=full") addressed a couple of
issues with the rodata= kernel command line option, which is not a
simple boolean on arm64, and inadvertently got broken due to changes in
the generic bool handling.
Unfortunately, the resulting code never clears the rodata_full boolean
variable if it defaults to true and rodata=on or rodata=off is passed,
as the generic code is not aware of the existence of this variable.
Given the way this code is plumbed together, clearing rodata_full when
returning false from arch_parse_debug_rodata() may result in
inconsistencies if the generic code decides that it cannot parse the
right hand side, so the best way to deal with this is to only take
rodata_full in account if rodata_enabled is also true.
Fixes: 2e8cff0a0eee87b2 ("arm64: fix rodata=full")
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
arch/arm64/mm/pageattr.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
index d107c3d434e22455..5922178d7a064c1c 100644
--- a/arch/arm64/mm/pageattr.c
+++ b/arch/arm64/mm/pageattr.c
@@ -26,7 +26,7 @@ bool can_set_direct_map(void)
* mapped at page granularity, so that it is possible to
* protect/unprotect single pages.
*/
- return rodata_full || debug_pagealloc_enabled() ||
+ return (rodata_enabled && rodata_full) || debug_pagealloc_enabled() ||
IS_ENABLED(CONFIG_KFENCE);
}
@@ -102,7 +102,8 @@ static int change_memory_common(unsigned long addr, int numpages,
* If we are manipulating read-only permissions, apply the same
* change to the linear mapping of the pages that back this VM area.
*/
- if (rodata_full && (pgprot_val(set_mask) == PTE_RDONLY ||
+ if (rodata_enabled &&
+ rodata_full && (pgprot_val(set_mask) == PTE_RDONLY ||
pgprot_val(clear_mask) == PTE_RDONLY)) {
for (i = 0; i < area->nr_pages; i++) {
__change_memory_common((u64)page_address(area->pages[i]),
--
2.35.1
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^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] arm64: fix rodata=full again
2022-11-03 17:00 [PATCH] arm64: fix rodata=full again Ard Biesheuvel
@ 2022-11-07 15:42 ` Will Deacon
2022-11-08 19:53 ` Catalin Marinas
1 sibling, 0 replies; 3+ messages in thread
From: Will Deacon @ 2022-11-07 15:42 UTC (permalink / raw)
To: Ard Biesheuvel; +Cc: linux-arm-kernel, catalin.marinas, mark.rutland
On Thu, Nov 03, 2022 at 06:00:15PM +0100, Ard Biesheuvel wrote:
> Commit 2e8cff0a0eee87b2 ("arm64: fix rodata=full") addressed a couple of
> issues with the rodata= kernel command line option, which is not a
> simple boolean on arm64, and inadvertently got broken due to changes in
> the generic bool handling.
>
> Unfortunately, the resulting code never clears the rodata_full boolean
> variable if it defaults to true and rodata=on or rodata=off is passed,
> as the generic code is not aware of the existence of this variable.
>
> Given the way this code is plumbed together, clearing rodata_full when
> returning false from arch_parse_debug_rodata() may result in
> inconsistencies if the generic code decides that it cannot parse the
> right hand side, so the best way to deal with this is to only take
> rodata_full in account if rodata_enabled is also true.
>
> Fixes: 2e8cff0a0eee87b2 ("arm64: fix rodata=full")
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> ---
> arch/arm64/mm/pageattr.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
> index d107c3d434e22455..5922178d7a064c1c 100644
> --- a/arch/arm64/mm/pageattr.c
> +++ b/arch/arm64/mm/pageattr.c
> @@ -26,7 +26,7 @@ bool can_set_direct_map(void)
> * mapped at page granularity, so that it is possible to
> * protect/unprotect single pages.
> */
> - return rodata_full || debug_pagealloc_enabled() ||
> + return (rodata_enabled && rodata_full) || debug_pagealloc_enabled() ||
> IS_ENABLED(CONFIG_KFENCE);
> }
>
> @@ -102,7 +102,8 @@ static int change_memory_common(unsigned long addr, int numpages,
> * If we are manipulating read-only permissions, apply the same
> * change to the linear mapping of the pages that back this VM area.
> */
> - if (rodata_full && (pgprot_val(set_mask) == PTE_RDONLY ||
> + if (rodata_enabled &&
> + rodata_full && (pgprot_val(set_mask) == PTE_RDONLY ||
> pgprot_val(clear_mask) == PTE_RDONLY)) {
> for (i = 0; i < area->nr_pages; i++) {
> __change_memory_common((u64)page_address(area->pages[i]),
> --
> 2.35.1
Hmm, I dislike how error-prone this is, but thanks for the fix:
Acked-by: Will Deacon <will@kernel.org>
Will
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] arm64: fix rodata=full again
2022-11-03 17:00 [PATCH] arm64: fix rodata=full again Ard Biesheuvel
2022-11-07 15:42 ` Will Deacon
@ 2022-11-08 19:53 ` Catalin Marinas
1 sibling, 0 replies; 3+ messages in thread
From: Catalin Marinas @ 2022-11-08 19:53 UTC (permalink / raw)
To: Ard Biesheuvel, linux-arm-kernel; +Cc: Will Deacon, mark.rutland
On Thu, 3 Nov 2022 18:00:15 +0100, Ard Biesheuvel wrote:
> Commit 2e8cff0a0eee87b2 ("arm64: fix rodata=full") addressed a couple of
> issues with the rodata= kernel command line option, which is not a
> simple boolean on arm64, and inadvertently got broken due to changes in
> the generic bool handling.
>
> Unfortunately, the resulting code never clears the rodata_full boolean
> variable if it defaults to true and rodata=on or rodata=off is passed,
> as the generic code is not aware of the existence of this variable.
>
> [...]
Applied to arm64 (for-next/fixes), thanks!
[1/1] arm64: fix rodata=full again
https://git.kernel.org/arm64/c/2081b3bd0c11
--
Catalin
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^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-11-03 17:00 [PATCH] arm64: fix rodata=full again Ard Biesheuvel
2022-11-07 15:42 ` Will Deacon
2022-11-08 19:53 ` Catalin Marinas
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