powerpc: Add __must_check to set_memory_...()

[PATCH] powerpc: Add __must_check to set_memory_...()

Posted by Christophe Leroy 2 months, 3 weeks ago

After the following powerpc commits, all calls to set_memory_...()
functions check returned value.
- Commit 8f17bd2f4196 ("powerpc: Handle error in mark_rodata_ro() and
mark_initmem_nx()")
- Commit f7f18e30b468 ("powerpc/kprobes: Handle error returned by
set_memory_rox()")
- Commit 009cf11d4aab ("powerpc: Don't ignore errors from
set_memory_{n}p() in __kernel_map_pages()")
- Commit 9cbacb834b4a ("powerpc: Don't ignore errors from
set_memory_{n}p() in __kernel_map_pages()")
- Commit 78cb0945f714 ("powerpc: Handle error in mark_rodata_ro() and
mark_initmem_nx()")

All calls in core parts of the kernel also always check returned value,
can be looked at with following query:

  $ git grep -w -e set_memory_ro -e set_memory_rw -e set_memory_x -e set_memory_nx -e set_memory_rox `find . -maxdepth 1 -type d | grep -v arch | grep /`

It is now possible to flag those functions with __must_check to make
sure no new unchecked call it added.

Link: https://github.com/KSPP/linux/issues/7
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/include/asm/set_memory.h | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/include/asm/set_memory.h b/arch/powerpc/include/asm/set_memory.h
index 9a025b776a4b..9c8d5747755d 100644
--- a/arch/powerpc/include/asm/set_memory.h
+++ b/arch/powerpc/include/asm/set_memory.h
@@ -12,37 +12,37 @@
 
 int change_memory_attr(unsigned long addr, int numpages, long action);
 
-static inline int set_memory_ro(unsigned long addr, int numpages)
+static inline int __must_check set_memory_ro(unsigned long addr, int numpages)
 {
 	return change_memory_attr(addr, numpages, SET_MEMORY_RO);
 }
 
-static inline int set_memory_rw(unsigned long addr, int numpages)
+static inline int __must_check set_memory_rw(unsigned long addr, int numpages)
 {
 	return change_memory_attr(addr, numpages, SET_MEMORY_RW);
 }
 
-static inline int set_memory_nx(unsigned long addr, int numpages)
+static inline int __must_check set_memory_nx(unsigned long addr, int numpages)
 {
 	return change_memory_attr(addr, numpages, SET_MEMORY_NX);
 }
 
-static inline int set_memory_x(unsigned long addr, int numpages)
+static inline int __must_check set_memory_x(unsigned long addr, int numpages)
 {
 	return change_memory_attr(addr, numpages, SET_MEMORY_X);
 }
 
-static inline int set_memory_np(unsigned long addr, int numpages)
+static inline int __must_check set_memory_np(unsigned long addr, int numpages)
 {
 	return change_memory_attr(addr, numpages, SET_MEMORY_NP);
 }
 
-static inline int set_memory_p(unsigned long addr, int numpages)
+static inline int __must_check set_memory_p(unsigned long addr, int numpages)
 {
 	return change_memory_attr(addr, numpages, SET_MEMORY_P);
 }
 
-static inline int set_memory_rox(unsigned long addr, int numpages)
+static inline int __must_check set_memory_rox(unsigned long addr, int numpages)
 {
 	return change_memory_attr(addr, numpages, SET_MEMORY_ROX);
 }
-- 
2.44.0

Re: [PATCH] powerpc: Add __must_check to set_memory_...()

Posted by Michael Ellerman 1 week, 6 days ago

On Sat, 07 Sep 2024 17:40:41 +0200, Christophe Leroy wrote:
> After the following powerpc commits, all calls to set_memory_...()
> functions check returned value.
> - Commit 8f17bd2f4196 ("powerpc: Handle error in mark_rodata_ro() and
> mark_initmem_nx()")
> - Commit f7f18e30b468 ("powerpc/kprobes: Handle error returned by
> set_memory_rox()")
> - Commit 009cf11d4aab ("powerpc: Don't ignore errors from
> set_memory_{n}p() in __kernel_map_pages()")
> - Commit 9cbacb834b4a ("powerpc: Don't ignore errors from
> set_memory_{n}p() in __kernel_map_pages()")
> - Commit 78cb0945f714 ("powerpc: Handle error in mark_rodata_ro() and
> mark_initmem_nx()")
> 
> [...]

Applied to powerpc/next.

[1/1] powerpc: Add __must_check to set_memory_...()
      https://git.kernel.org/powerpc/c/2abbd6d5fbe0eae3752b44c963248e19292e5104

cheers

Re: [PATCH] powerpc: Add __must_check to set_memory_...()

Posted by Christophe Leroy 3 weeks, 3 days ago

Hi Michael,

Le 07/09/2024 à 17:40, Christophe Leroy a écrit :
> After the following powerpc commits, all calls to set_memory_...()
> functions check returned value.
> - Commit 8f17bd2f4196 ("powerpc: Handle error in mark_rodata_ro() and
> mark_initmem_nx()")
> - Commit f7f18e30b468 ("powerpc/kprobes: Handle error returned by
> set_memory_rox()")
> - Commit 009cf11d4aab ("powerpc: Don't ignore errors from
> set_memory_{n}p() in __kernel_map_pages()")
> - Commit 9cbacb834b4a ("powerpc: Don't ignore errors from
> set_memory_{n}p() in __kernel_map_pages()")
> - Commit 78cb0945f714 ("powerpc: Handle error in mark_rodata_ro() and
> mark_initmem_nx()")
> 
> All calls in core parts of the kernel also always check returned value,
> can be looked at with following query:
> 
>    $ git grep -w -e set_memory_ro -e set_memory_rw -e set_memory_x -e set_memory_nx -e set_memory_rox `find . -maxdepth 1 -type d | grep -v arch | grep /`
> 
> It is now possible to flag those functions with __must_check to make
> sure no new unchecked call it added.
> 
> Link: https://github.com/KSPP/linux/issues/7
> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>

Do you plan to take this patch anytime soon ?

The generic part of the same was already applied in previous cycle, see 
https://github.com/torvalds/linux/commit/82ce8e2f31a1eb05b1527c3d807bea40031df913

Discussion at 
https://lore.kernel.org/all/b0fe75b4-c1bb-47f7-a7c3-2534b31c1780@csgroup.eu/T/ 
suggests that it would be beneficial to enforce return checking.

Christophe


> ---
>   arch/powerpc/include/asm/set_memory.h | 14 +++++++-------
>   1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/set_memory.h b/arch/powerpc/include/asm/set_memory.h
> index 9a025b776a4b..9c8d5747755d 100644
> --- a/arch/powerpc/include/asm/set_memory.h
> +++ b/arch/powerpc/include/asm/set_memory.h
> @@ -12,37 +12,37 @@
>   
>   int change_memory_attr(unsigned long addr, int numpages, long action);
>   
> -static inline int set_memory_ro(unsigned long addr, int numpages)
> +static inline int __must_check set_memory_ro(unsigned long addr, int numpages)
>   {
>   	return change_memory_attr(addr, numpages, SET_MEMORY_RO);
>   }
>   
> -static inline int set_memory_rw(unsigned long addr, int numpages)
> +static inline int __must_check set_memory_rw(unsigned long addr, int numpages)
>   {
>   	return change_memory_attr(addr, numpages, SET_MEMORY_RW);
>   }
>   
> -static inline int set_memory_nx(unsigned long addr, int numpages)
> +static inline int __must_check set_memory_nx(unsigned long addr, int numpages)
>   {
>   	return change_memory_attr(addr, numpages, SET_MEMORY_NX);
>   }
>   
> -static inline int set_memory_x(unsigned long addr, int numpages)
> +static inline int __must_check set_memory_x(unsigned long addr, int numpages)
>   {
>   	return change_memory_attr(addr, numpages, SET_MEMORY_X);
>   }
>   
> -static inline int set_memory_np(unsigned long addr, int numpages)
> +static inline int __must_check set_memory_np(unsigned long addr, int numpages)
>   {
>   	return change_memory_attr(addr, numpages, SET_MEMORY_NP);
>   }
>   
> -static inline int set_memory_p(unsigned long addr, int numpages)
> +static inline int __must_check set_memory_p(unsigned long addr, int numpages)
>   {
>   	return change_memory_attr(addr, numpages, SET_MEMORY_P);
>   }
>   
> -static inline int set_memory_rox(unsigned long addr, int numpages)
> +static inline int __must_check set_memory_rox(unsigned long addr, int numpages)
>   {
>   	return change_memory_attr(addr, numpages, SET_MEMORY_ROX);
>   }

Re: [PATCH] powerpc: Add __must_check to set_memory_...()

Posted by Michael Ellerman 3 weeks, 3 days ago

Christophe Leroy <christophe.leroy@csgroup.eu> writes:
> Hi Michael,
>
> Le 07/09/2024 à 17:40, Christophe Leroy a écrit :
>> After the following powerpc commits, all calls to set_memory_...()
>> functions check returned value.
>> - Commit 8f17bd2f4196 ("powerpc: Handle error in mark_rodata_ro() and
>> mark_initmem_nx()")
>> - Commit f7f18e30b468 ("powerpc/kprobes: Handle error returned by
>> set_memory_rox()")
>> - Commit 009cf11d4aab ("powerpc: Don't ignore errors from
>> set_memory_{n}p() in __kernel_map_pages()")
>> - Commit 9cbacb834b4a ("powerpc: Don't ignore errors from
>> set_memory_{n}p() in __kernel_map_pages()")
>> - Commit 78cb0945f714 ("powerpc: Handle error in mark_rodata_ro() and
>> mark_initmem_nx()")
>> 
>> All calls in core parts of the kernel also always check returned value,
>> can be looked at with following query:
>> 
>>    $ git grep -w -e set_memory_ro -e set_memory_rw -e set_memory_x -e set_memory_nx -e set_memory_rox `find . -maxdepth 1 -type d | grep -v arch | grep /`
>> 
>> It is now possible to flag those functions with __must_check to make
>> sure no new unchecked call it added.
>> 
>> Link: https://github.com/KSPP/linux/issues/7
>> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
>
> Do you plan to take this patch anytime soon ?
>
> The generic part of the same was already applied in previous cycle, see 
> https://github.com/torvalds/linux/commit/82ce8e2f31a1eb05b1527c3d807bea40031df913

I was waiting for the generic part to land, sorry I missed it.

Will put this in next now.

cheers

[PATCH] set_memory: Add __must_check to generic stubs

Posted by Christophe Leroy 2 months, 3 weeks ago

Following query shows that architectures that don't provide
asm/set_memory.h don't use set_memory_...() functions.

  $ git grep set_memory_ alpha arc csky hexagon loongarch m68k microblaze mips nios2 openrisc parisc sh sparc um xtensa

Following query shows that all core users of set_memory_...()
functions always take returned value into account:

  $ git grep -w -e set_memory_ro -e set_memory_rw -e set_memory_x -e set_memory_nx -e set_memory_rox `find . -maxdepth 1 -type d | grep -v arch | grep /`

set_memory_...() functions can fail, leaving the memory attributes
unchanged. Make sure all callers check the returned code.

Link: https://github.com/KSPP/linux/issues/7
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 include/linux/set_memory.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/linux/set_memory.h b/include/linux/set_memory.h
index 95ac8398ee72..e7aec20fb44f 100644
--- a/include/linux/set_memory.h
+++ b/include/linux/set_memory.h
@@ -8,10 +8,10 @@
 #ifdef CONFIG_ARCH_HAS_SET_MEMORY
 #include <asm/set_memory.h>
 #else
-static inline int set_memory_ro(unsigned long addr, int numpages) { return 0; }
-static inline int set_memory_rw(unsigned long addr, int numpages) { return 0; }
-static inline int set_memory_x(unsigned long addr,  int numpages) { return 0; }
-static inline int set_memory_nx(unsigned long addr, int numpages) { return 0; }
+static inline int __must_check set_memory_ro(unsigned long addr, int numpages) { return 0; }
+static inline int __must_check set_memory_rw(unsigned long addr, int numpages) { return 0; }
+static inline int __must_check set_memory_x(unsigned long addr,  int numpages) { return 0; }
+static inline int __must_check set_memory_nx(unsigned long addr, int numpages) { return 0; }
 #endif
 
 #ifndef set_memory_rox
-- 
2.44.0