Le 11/06/2022 à 01:35, ira.weiny@xxxxxxxxx a écrit :
> From: Ira Weiny <ira.weiny@xxxxxxxxx>
>
> x86 is missing a hardware check for pkey support in pkey_free(). While
> the net result is the same (-EINVAL returned), pkey_free() has well
> defined behavior which will be easier to maintain in one place.
>
> For powerpc the return code is -1 rather than -EINVAL. This changes
> that behavior slightly but this is very unlikely to break any user
> space.
>
> Lift the checks for pkey_free() to the core mm code and ensure
> consistency with returning -EINVAL.
>
> Cc: ahaas@xxxxxxxxxxxx
> Cc: clemensb@xxxxxxxxxxxx
> Cc: gdeepti@xxxxxxxxxxxx
> Cc: jkummerow@xxxxxxxxxxxx
> Cc: manoskouk@xxxxxxxxxxxx
> Cc: thibaudm@xxxxxxxxxxxx
> Cc: Florian Weimer <fweimer@xxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: linux-api@xxxxxxxxxxxxxxx
> Cc: Sohil Mehta <sohil.mehta@xxxxxxxxx>
> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
> Signed-off-by: Ira Weiny <ira.weiny@xxxxxxxxx>
>
> ---
> Thanks to Sohil for suggesting I mention the powerpc return value in the
> commit message.
>
> Also Sohil suggested changing mm_pkey_free() from int to void. This is
> added as a separate patch with his suggested by.
> ---
> arch/powerpc/include/asm/pkeys.h | 6 ------
> arch/x86/include/asm/pkeys.h | 3 ---
> mm/mprotect.c | 8 ++++++--
> 3 files changed, 6 insertions(+), 11 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h
> index 2c8351248793..e96aa91f817b 100644
> --- a/arch/powerpc/include/asm/pkeys.h
> +++ b/arch/powerpc/include/asm/pkeys.h
> @@ -107,12 +107,6 @@ static inline int mm_pkey_alloc(struct mm_struct *mm)
>
> static inline int mm_pkey_free(struct mm_struct *mm, int pkey)
> {
> - if (!mmu_has_feature(MMU_FTR_PKEY))
> - return -1;
> -
> - if (!mm_pkey_is_allocated(mm, pkey))
> - return -EINVAL;
> -
> __mm_pkey_free(mm, pkey);
>
> return 0;
If it returns always 0, the return value is pointless and the function
mm_pkey_free() should be changed to return void.
> diff --git a/arch/x86/include/asm/pkeys.h b/arch/x86/include/asm/pkeys.h
> index 2e6c04d8a45b..da02737cc4d1 100644
> --- a/arch/x86/include/asm/pkeys.h
> +++ b/arch/x86/include/asm/pkeys.h
> @@ -107,9 +107,6 @@ int mm_pkey_alloc(struct mm_struct *mm)
> static inline
> int mm_pkey_free(struct mm_struct *mm, int pkey)
> {
> - if (!mm_pkey_is_allocated(mm, pkey))
> - return -EINVAL;
> -
> mm_set_pkey_free(mm, pkey);
>
> return 0;
Same.
> diff --git a/mm/mprotect.c b/mm/mprotect.c
> index 56d35de33725..41458e729c27 100644
> --- a/mm/mprotect.c
> +++ b/mm/mprotect.c
> @@ -803,10 +803,14 @@ SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val)
>
> SYSCALL_DEFINE1(pkey_free, int, pkey)
> {
> - int ret;
> + int ret = -EINVAL;
Don't initialise 'ret'
> +
> + if (!arch_pkeys_enabled())
> + return ret;
Make it explicit, do 'return -EINVAL'
Once that is done, is there any point in having a fallback version of
mm_pkey_free() which returns -EINVAL ?
>
> mmap_write_lock(current->mm);
> - ret = mm_pkey_free(current->mm, pkey);
> + if (mm_pkey_is_allocated(current->mm, pkey))
> + ret = mm_pkey_free(current->mm, pkey);
Add:
else
ret = -EINVAL;
> mmap_write_unlock(current->mm);
>
> /*
