Re: [PATCH] powerpc/pkeys: Remove unused code

[Ram Pai <linuxram@us.ibm.com>]

On Tue, Feb 02, 2021 at 08:30:50PM +0530, Sandipan Das wrote:
> This removes arch_supports_pkeys(), arch_usable_pkeys() and
> thread_pkey_regs_*() which are remnants from the following:
> 
> commit 06bb53b33804 ("powerpc: store and restore the pkey state across context switches")
> commit 2cd4bd192ee9 ("powerpc/pkeys: Fix handling of pkey state across fork()")
> commit cf43d3b26452 ("powerpc: Enable pkey subsystem")
> 
> arch_supports_pkeys() and arch_usable_pkeys() were unused
> since their introduction while thread_pkey_regs_*() became
> unused after the introduction of the following:
> 
> commit d5fa30e6993f ("powerpc/book3s64/pkeys: Reset userspace AMR correctly on exec")
> commit 48a8ab4eeb82 ("powerpc/book3s64/pkeys: Don't update SPRN_AMR when in kernel mode")
> 
> Signed-off-by: Sandipan Das <sandipan@linux.ibm.com>
> ---
>  arch/powerpc/include/asm/mmu_context.h | 3 ---
>  arch/powerpc/include/asm/pkeys.h       | 6 ------
>  2 files changed, 9 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h
> index d5821834dba9..652ce85f9410 100644
> --- a/arch/powerpc/include/asm/mmu_context.h
> +++ b/arch/powerpc/include/asm/mmu_context.h
> @@ -282,9 +282,6 @@ static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
>  }
> 
>  #define pkey_mm_init(mm)
> -#define thread_pkey_regs_save(thread)
> -#define thread_pkey_regs_restore(new_thread, old_thread)
> -#define thread_pkey_regs_init(thread)
>  #define arch_dup_pkeys(oldmm, mm)
> 
>  static inline u64 pte_to_hpte_pkey_bits(u64 pteflags, unsigned long flags)
> diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h
> index a7951049e129..59a2c7dbc78f 100644
> --- a/arch/powerpc/include/asm/pkeys.h
> +++ b/arch/powerpc/include/asm/pkeys.h
> @@ -169,10 +169,4 @@ static inline bool arch_pkeys_enabled(void)
>  }
> 
>  extern void pkey_mm_init(struct mm_struct *mm);
> -extern bool arch_supports_pkeys(int cap);
> -extern unsigned int arch_usable_pkeys(void);
> -extern void thread_pkey_regs_save(struct thread_struct *thread);
> -extern void thread_pkey_regs_restore(struct thread_struct *new_thread,
> -				     struct thread_struct *old_thread);
> -extern void thread_pkey_regs_init(struct thread_struct *thread);
>  #endif /*_ASM_POWERPC_KEYS_H */

Looking at this code after a long time. Though I do not entirely understand,
the reason to change the logic for save and restore of the
AMR/IAMR register, I do understand that with those changes these three
function-prototypes became unnecessary.

Reviewed-by: Ram Pai <linuxram@us.ibm.com>


RP