linux-kernel - Re: [PATCH] riscv: fixup max_low_pfn with PFN

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 15 Jan 2019 07:36:13 -0800
From:   Christoph Hellwig <hch@...radead.org>
To:     guoren@...nel.org
Cc:     palmer@...ive.com, aou@...s.berkeley.edu,
        linux-arch@...r.kernel.org, linux-riscv@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Guo Ren <ren_guo@...ky.com>,
        Mao Han <mao_han@...ky.com>
Subject: Re: [PATCH] riscv: fixup max_low_pfn with PFN_DOWN.

On Sat, Jan 12, 2019 at 04:16:27PM +0800, guoren@...nel.org wrote:
> From: Guo Ren <ren_guo@...ky.com>
> 
> max_low_pfn should be pfn_size not byte_size.
> 
> Signed-off-by: Guo Ren <ren_guo@...ky.com>
> Signed-off-by: Mao Han <mao_han@...ky.com>
> Cc: Palmer Dabbelt <palmer@...ive.com>
> Cc: Albert Ou <aou@...s.berkeley.edu>
> ---
>  arch/riscv/kernel/setup.c | 2 +-
>  arch/riscv/mm/init.c      | 3 ++-
>  2 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
> index fc8006a..5463e67 100644
> --- a/arch/riscv/kernel/setup.c
> +++ b/arch/riscv/kernel/setup.c
> @@ -174,7 +174,7 @@ static void __init setup_bootmem(void)
>  	BUG_ON(mem_size == 0);
>  
>  	set_max_mapnr(PFN_DOWN(mem_size));
> -	max_low_pfn = memblock_end_of_DRAM();
> +	max_low_pfn = PFN_DOWN(memblock_end_of_DRAM());

I know it is used just above, but can we please just switch this
code to use >> PAGE_SHIFT instead of PFN_DOWN, which just horribly
obsfucates what is going on?

>  
>  #ifdef CONFIG_BLK_DEV_INITRD
>  	setup_initrd();
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index 1d9bfaf..658ebf6 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -28,7 +28,8 @@ static void __init zone_sizes_init(void)
>  	unsigned long max_zone_pfns[MAX_NR_ZONES] = { 0, };
>  
>  #ifdef CONFIG_ZONE_DMA32
> -	max_zone_pfns[ZONE_DMA32] = PFN_DOWN(min(4UL * SZ_1G, max_low_pfn));
> +	max_zone_pfns[ZONE_DMA32] = PFN_DOWN(min(4UL * SZ_1G,
> +			(unsigned long) PFN_PHYS(max_low_pfn)));
>  #endif

Same comment as above here, plus I think we should just use
memblock_end_of_DRAM directly, e.g. something like:

static const phys_addr_t max_dma32_addr = 4UL * SZ_1G;

	max_zone_pfns[ZONE_DMA32] =
		min(memblock_end_of_DRAM(), max_dma32_addr) >> PAGE_SHIFT;