Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Fri, 18 Jun 2021 23:58:43 -0700 (PDT)
Subject:     Re: [PATCH] riscv: kasan: Fix MODULES_VADDR evaluation due to local variables' name
In-Reply-To: <20210618220136.21f32b98@xhacker>
CC:     ryabinin.a.a@gmail.com, glider@google.com, andreyknvl@gmail.com,
        dvyukov@google.com, Paul Walmsley <paul.walmsley@sifive.com>,
        aou@eecs.berkeley.edu, alex@ghiti.fr, kasan-dev@googlegroups.com,
        linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
From:   Palmer Dabbelt <palmer@dabbelt.com>
To:     jszhang3@mail.ustc.edu.cn
Message-ID: <mhng-b491e8d5-d7dc-4f5e-8b96-84d47360d85d@palmerdabbelt-glaptop>
Mime-Version: 1.0 (MHng)
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 8bit
Precedence: bulk

On Fri, 18 Jun 2021 07:01:36 PDT (-0700), jszhang3@mail.ustc.edu.cn wrote:
> From: Jisheng Zhang <jszhang@kernel.org>
>
> commit 2bfc6cd81bd1 ("riscv: Move kernel mapping outside of linear
> mapping") makes use of MODULES_VADDR to populate kernel, BPF, modules
> mapping. Currently, MODULES_VADDR is defined as below for RV64:
>
> | #define MODULES_VADDR   (PFN_ALIGN((unsigned long)&_end) - SZ_2G)
>
> But kasan_init() has two local variables which are also named as _start,
> _end, so MODULES_VADDR is evaluated with the local variable _end
> rather than the global "_end" as we expected. Fix this issue by
> renaming the two local variables.
>
> Fixes: 2bfc6cd81bd1 ("riscv: Move kernel mapping outside of linear mapping")
> Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
> ---
>  arch/riscv/mm/kasan_init.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/riscv/mm/kasan_init.c b/arch/riscv/mm/kasan_init.c
> index 55c113345460..d7189c8714a9 100644
> --- a/arch/riscv/mm/kasan_init.c
> +++ b/arch/riscv/mm/kasan_init.c
> @@ -169,7 +169,7 @@ static void __init kasan_shallow_populate(void *start, void *end)
>
>  void __init kasan_init(void)
>  {
> -	phys_addr_t _start, _end;
> +	phys_addr_t p_start, p_end;
>  	u64 i;
>
>  	/*
> @@ -189,9 +189,9 @@ void __init kasan_init(void)
>  			(void *)kasan_mem_to_shadow((void *)VMALLOC_END));
>
>  	/* Populate the linear mapping */
> -	for_each_mem_range(i, &_start, &_end) {
> -		void *start = (void *)__va(_start);
> -		void *end = (void *)__va(_end);
> +	for_each_mem_range(i, &p_start, &p_end) {
> +		void *start = (void *)__va(p_start);
> +		void *end = (void *)__va(p_end);
>
>  		if (start >= end)
>  			break;

Thanks for this.  I'd prefer a cleaner fix for tihs (maybe more '_'s in 
_end?), but I don't think we can do that without touching a bunch of 
code.  Given that this is necessary to make the fix work for me, I'm 
just going to take it as-is.

This is on fixes.