linux-kernel - Re: [PATCH v2 08/19] arm/vdso: Remove vdso pointer from mm->context

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Date:   Tue, 24 Nov 2020 07:22:11 +0100
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Dmitry Safonov <dima@...sta.com>, linux-kernel@...r.kernel.org
Cc:     Dmitry Safonov <0x7f454c46@...il.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andy Lutomirski <luto@...nel.org>,
        Arnd Bergmann <arnd@...db.de>, Borislav Petkov <bp@...en8.de>,
        Catalin Marinas <catalin.marinas@....com>,
        Guo Ren <guoren@...nel.org>, "H. Peter Anvin" <hpa@...or.com>,
        Ingo Molnar <mingo@...hat.com>,
        Oleg Nesterov <oleg@...hat.com>,
        Russell King <linux@...linux.org.uk>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Will Deacon <will@...nel.org>, x86@...nel.org
Subject: Re: [PATCH v2 08/19] arm/vdso: Remove vdso pointer from mm->context



Le 24/11/2020 à 01:29, Dmitry Safonov a écrit :
> Not used any more.

But what about mremap() ? Maybe you should explain why you can remove it ?

> 
> Signed-off-by: Dmitry Safonov <dima@...sta.com>
> ---
>   arch/arm/include/asm/mmu.h |  3 ---
>   arch/arm/kernel/vdso.c     | 12 ------------
>   2 files changed, 15 deletions(-)
> 
> diff --git a/arch/arm/include/asm/mmu.h b/arch/arm/include/asm/mmu.h
> index 1592a4264488..2397b0a19f59 100644
> --- a/arch/arm/include/asm/mmu.h
> +++ b/arch/arm/include/asm/mmu.h
> @@ -12,9 +12,6 @@ typedef struct {
>   #endif
>   	unsigned int	vmalloc_seq;
>   	unsigned long	sigpage;
> -#ifdef CONFIG_VDSO
> -	unsigned long	vdso;
> -#endif
>   #ifdef CONFIG_BINFMT_ELF_FDPIC
>   	unsigned long	exec_fdpic_loadmap;
>   	unsigned long	interp_fdpic_loadmap;
> diff --git a/arch/arm/kernel/vdso.c b/arch/arm/kernel/vdso.c
> index 710e5ca99a53..4b39c7d8f525 100644
> --- a/arch/arm/kernel/vdso.c
> +++ b/arch/arm/kernel/vdso.c
> @@ -47,17 +47,8 @@ static const struct vm_special_mapping vdso_data_mapping = {
>   	.pages = &vdso_data_page,
>   };
>   
> -static int vdso_mremap(const struct vm_special_mapping *sm,
> -		struct vm_area_struct *new_vma)
> -{
> -	current->mm->context.vdso = new_vma->vm_start;
> -
> -	return 0;
> -}
> -
>   static struct vm_special_mapping vdso_text_mapping __ro_after_init = {
>   	.name = "[vdso]",
> -	.mremap = vdso_mremap,
>   };
>   
>   struct elfinfo {
> @@ -239,8 +230,6 @@ void arm_install_vdso(struct mm_struct *mm, unsigned long addr,
>   	struct vm_area_struct *vma;
>   	unsigned long len;
>   
> -	mm->context.vdso = 0;
> -
>   	if (vdso_text_pagelist == NULL)
>   		return;
>   
> @@ -258,7 +247,6 @@ void arm_install_vdso(struct mm_struct *mm, unsigned long addr,
>   	if (IS_ERR(vma))
>   		return;
>   
> -	mm->context.vdso = addr;
>   	*sysinfo_ehdr = addr;
>   }
>   
>