linux-kernel - Re: [PATCH 04/24] arm: use asm-generic/mmu

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Message-ID: <86611bf1-13b2-65e5-50d5-b0701020cd3e@synopsys.com>
Date:   Tue, 28 Jul 2020 04:14:18 +0000
From:   Vineet Gupta <Vineet.Gupta1@...opsys.com>
To:     Nicholas Piggin <npiggin@...il.com>,
        "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        Arnd Bergmann <arnd@...db.de>,
        Russell King <linux@...linux.org.uk>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        arcml <linux-snps-arc@...ts.infradead.org>
Subject: Re: [PATCH 04/24] arm: use asm-generic/mmu_context.h for no-op
 implementations

On 7/27/20 8:33 PM, Nicholas Piggin wrote:
> Cc: Russell King <linux@...linux.org.uk>
> Cc: linux-arm-kernel@...ts.infradead.org
> Signed-off-by: Nicholas Piggin <npiggin@...il.com>
> ---
>  arch/arm/include/asm/mmu_context.h | 26 +++-----------------------
>  1 file changed, 3 insertions(+), 23 deletions(-)
> 
> diff --git a/arch/arm/include/asm/mmu_context.h b/arch/arm/include/asm/mmu_context.h
> index f99ed524fe41..84e58956fcab 100644
> --- a/arch/arm/include/asm/mmu_context.h
> +++ b/arch/arm/include/asm/mmu_context.h
> @@ -26,6 +26,8 @@ void __check_vmalloc_seq(struct mm_struct *mm);
>  #ifdef CONFIG_CPU_HAS_ASID
>  
>  void check_and_switch_context(struct mm_struct *mm, struct task_struct *tsk);
> +
> +#define init_new_context init_new_context
>  static inline int
>  init_new_context(struct task_struct *tsk, struct mm_struct *mm)
>  {
> @@ -92,32 +94,10 @@ static inline void finish_arch_post_lock_switch(void)
>  
>  #endif	/* CONFIG_MMU */
>  
> -static inline int
> -init_new_context(struct task_struct *tsk, struct mm_struct *mm)
> -{
> -	return 0;
> -}
> -
> -
>  #endif	/* CONFIG_CPU_HAS_ASID */
>  
> -#define destroy_context(mm)		do { } while(0)
>  #define activate_mm(prev,next)		switch_mm(prev, next, NULL)

Actually this can also go away too.

ARM switch_mm(prev, next, tsk) -> check_and_switch_context(next, tsk) but latter
doesn't use @tsk at all. With patch below, you can remove above as well...

-------->
From 672e0f78a94892794057a5a7542d85b71c1369c4 Mon Sep 17 00:00:00 2001
From: Vineet Gupta <vgupta@...opsys.com>
Date: Mon, 27 Jul 2020 21:12:42 -0700
Subject: [PATCH] ARM: mm: check_and_switch_context() doesn't use @tsk arg

Signed-off-by: Vineet Gupta <vgupta@...opsys.com>
---
 arch/arm/include/asm/efi.h         | 2 +-
 arch/arm/include/asm/mmu_context.h | 5 ++---
 arch/arm/mm/context.c              | 2 +-
 3 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/arch/arm/include/asm/efi.h b/arch/arm/include/asm/efi.h
index 5dcf3c6011b7..0995b308149d 100644
--- a/arch/arm/include/asm/efi.h
+++ b/arch/arm/include/asm/efi.h
@@ -37,7 +37,7 @@ int efi_set_mapping_permissions(struct mm_struct *mm,
efi_memory_desc_t *md);

 static inline void efi_set_pgd(struct mm_struct *mm)
 {
-	check_and_switch_context(mm, NULL);
+	check_and_switch_context(mm);
 }

 void efi_virtmap_load(void);
diff --git a/arch/arm/include/asm/mmu_context.h b/arch/arm/include/asm/mmu_context.h
index f99ed524fe41..c96360fa3466 100644
--- a/arch/arm/include/asm/mmu_context.h
+++ b/arch/arm/include/asm/mmu_context.h
@@ -25,7 +25,7 @@ void __check_vmalloc_seq(struct mm_struct *mm);

 #ifdef CONFIG_CPU_HAS_ASID

-void check_and_switch_context(struct mm_struct *mm, struct task_struct *tsk);
+void check_and_switch_context(struct mm_struct *mm);
 static inline int
 init_new_context(struct task_struct *tsk, struct mm_struct *mm)
 {
@@ -47,8 +47,7 @@ static inline void a15_erratum_get_cpumask(int this_cpu, struct
mm_struct *mm,

 #ifdef CONFIG_MMU

-static inline void check_and_switch_context(struct mm_struct *mm,
-					    struct task_struct *tsk)
+static inline void check_and_switch_context(struct mm_struct *mm)
 {
 	if (unlikely(mm->context.vmalloc_seq != init_mm.context.vmalloc_seq))
 		__check_vmalloc_seq(mm);
diff --git a/arch/arm/mm/context.c b/arch/arm/mm/context.c
index b7525b433f3e..86c411e1d7cb 100644
--- a/arch/arm/mm/context.c
+++ b/arch/arm/mm/context.c
@@ -234,7 +234,7 @@ static u64 new_context(struct mm_struct *mm, unsigned int cpu)
 	return asid | generation;
 }

-void check_and_switch_context(struct mm_struct *mm, struct task_struct *tsk)
+void check_and_switch_context(struct mm_struct *mm)
 {
 	unsigned long flags;
 	unsigned int cpu = smp_processor_id();
-- 
2.20.1