Re: [PATCH v2 40/43] powerpc/64s: Make kuap_check_amr() and kuap_get_and_check_amr() generic

[Nicholas Piggin]

Excerpts from Christophe Leroy's message of March 9, 2021 10:10 pm:
> In preparation of porting powerpc32 to C syscall entry/exit,
> rename kuap_check_amr() and kuap_get_and_check_amr() as kuap_check()
> and kuap_get_and_check(), and move in the generic asm/kup.h the stub
> for when CONFIG_PPC_KUAP is not selected.

Looks pretty straightforward to me.

While you're renaming things, could kuap_check_amr() be changed to
kuap_assert_locked() or similar? Otherwise,

Reviewed-by: Nicholas Piggin <npiggin@xxxxxxxxx>

> 
> Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
> ---
>  arch/powerpc/include/asm/book3s/64/kup.h | 24 ++----------------------
>  arch/powerpc/include/asm/kup.h           | 10 +++++++++-
>  arch/powerpc/kernel/interrupt.c          | 12 ++++++------
>  arch/powerpc/kernel/irq.c                |  2 +-
>  4 files changed, 18 insertions(+), 30 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/book3s/64/kup.h b/arch/powerpc/include/asm/book3s/64/kup.h
> index 8bd905050896..d9b07e9998be 100644
> --- a/arch/powerpc/include/asm/book3s/64/kup.h
> +++ b/arch/powerpc/include/asm/book3s/64/kup.h
> @@ -287,7 +287,7 @@ static inline void kuap_kernel_restore(struct pt_regs *regs,
>  	 */
>  }
>  
> -static inline unsigned long kuap_get_and_check_amr(void)
> +static inline unsigned long kuap_get_and_check(void)
>  {
>  	if (mmu_has_feature(MMU_FTR_BOOK3S_KUAP)) {
>  		unsigned long amr = mfspr(SPRN_AMR);
> @@ -298,27 +298,7 @@ static inline unsigned long kuap_get_and_check_amr(void)
>  	return 0;
>  }
>  
> -#else /* CONFIG_PPC_PKEY */
> -
> -static inline void kuap_user_restore(struct pt_regs *regs)
> -{
> -}
> -
> -static inline void kuap_kernel_restore(struct pt_regs *regs, unsigned long amr)
> -{
> -}
> -
> -static inline unsigned long kuap_get_and_check_amr(void)
> -{
> -	return 0;
> -}
> -
> -#endif /* CONFIG_PPC_PKEY */
> -
> -
> -#ifdef CONFIG_PPC_KUAP
> -
> -static inline void kuap_check_amr(void)
> +static inline void kuap_check(void)
>  {
>  	if (IS_ENABLED(CONFIG_PPC_KUAP_DEBUG) && mmu_has_feature(MMU_FTR_BOOK3S_KUAP))
>  		WARN_ON_ONCE(mfspr(SPRN_AMR) != AMR_KUAP_BLOCKED);
> diff --git a/arch/powerpc/include/asm/kup.h b/arch/powerpc/include/asm/kup.h
> index 25671f711ec2..b7efa46b3109 100644
> --- a/arch/powerpc/include/asm/kup.h
> +++ b/arch/powerpc/include/asm/kup.h
> @@ -74,7 +74,15 @@ bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
>  	return false;
>  }
>  
> -static inline void kuap_check_amr(void) { }
> +static inline void kuap_check(void) { }
> +static inline void kuap_save_and_lock(struct pt_regs *regs) { }
> +static inline void kuap_user_restore(struct pt_regs *regs) { }
> +static inline void kuap_kernel_restore(struct pt_regs *regs, unsigned long amr) { }
> +
> +static inline unsigned long kuap_get_and_check(void)
> +{
> +	return 0;
> +}
>  
>  /*
>   * book3s/64/kup-radix.h defines these functions for the !KUAP case to flush
> diff --git a/arch/powerpc/kernel/interrupt.c b/arch/powerpc/kernel/interrupt.c
> index 727b7848c9cc..40ed55064e54 100644
> --- a/arch/powerpc/kernel/interrupt.c
> +++ b/arch/powerpc/kernel/interrupt.c
> @@ -76,7 +76,7 @@ notrace long system_call_exception(long r3, long r4, long r5,
>  	} else
>  #endif
>  #ifdef CONFIG_PPC64
> -		kuap_check_amr();
> +		kuap_check();
>  #endif
>  
>  	booke_restore_dbcr0();
> @@ -254,7 +254,7 @@ notrace unsigned long syscall_exit_prepare(unsigned long r3,
>  	CT_WARN_ON(ct_state() == CONTEXT_USER);
>  
>  #ifdef CONFIG_PPC64
> -	kuap_check_amr();
> +	kuap_check();
>  #endif
>  
>  	regs->result = r3;
> @@ -380,7 +380,7 @@ notrace unsigned long interrupt_exit_user_prepare(struct pt_regs *regs, unsigned
>  	 * AMR can only have been unlocked if we interrupted the kernel.
>  	 */
>  #ifdef CONFIG_PPC64
> -	kuap_check_amr();
> +	kuap_check();
>  #endif
>  
>  	local_irq_save(flags);
> @@ -451,7 +451,7 @@ notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs, unsign
>  	unsigned long flags;
>  	unsigned long ret = 0;
>  #ifdef CONFIG_PPC64
> -	unsigned long amr;
> +	unsigned long kuap;
>  #endif
>  
>  	if (!IS_ENABLED(CONFIG_BOOKE) && !IS_ENABLED(CONFIG_40x) &&
> @@ -467,7 +467,7 @@ notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs, unsign
>  		CT_WARN_ON(ct_state() == CONTEXT_USER);
>  
>  #ifdef CONFIG_PPC64
> -	amr = kuap_get_and_check_amr();
> +	kuap = kuap_get_and_check();
>  #endif
>  
>  	if (unlikely(current_thread_info()->flags & _TIF_EMULATE_STACK_STORE)) {
> @@ -511,7 +511,7 @@ notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs, unsign
>  	 * value from the check above.
>  	 */
>  #ifdef CONFIG_PPC64
> -	kuap_kernel_restore(regs, amr);
> +	kuap_kernel_restore(regs, kuap);
>  #endif
>  
>  	return ret;
> diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
> index d71fd10a1dd4..3b18d2b2c702 100644
> --- a/arch/powerpc/kernel/irq.c
> +++ b/arch/powerpc/kernel/irq.c
> @@ -282,7 +282,7 @@ static inline void replay_soft_interrupts_irqrestore(void)
>  	 * and re-locking AMR but we shouldn't get here in the first place,
>  	 * hence the warning.
>  	 */
> -	kuap_check_amr();
> +	kuap_check();
>  
>  	if (kuap_state != AMR_KUAP_BLOCKED)
>  		set_kuap(AMR_KUAP_BLOCKED);
> -- 
> 2.25.0
> 
>