linux-kernel - Re: [PATCH] RISC-V: Add address map dumper

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Message-Id: <20191111215647.GB10647@linux.ibm.com>
Date:   Mon, 11 Nov 2019 22:56:48 +0100
From:   Mike Rapoport <rppt@...ux.ibm.com>
To:     Yash Shah <yash.shah@...ive.com>
Cc:     "Paul Walmsley ( Sifive)" <paul.walmsley@...ive.com>,
        "linux-riscv@...ts.infradead.org" <linux-riscv@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "palmer@...belt.com" <palmer@...belt.com>,
        "aou@...s.berkeley.edu" <aou@...s.berkeley.edu>,
        "Anup.Patel@....com" <Anup.Patel@....com>,
        "logang@...tatee.com" <logang@...tatee.com>,
        "ren_guo@...ky.com" <ren_guo@...ky.com>,
        "bmeng.cn@...il.com" <bmeng.cn@...il.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        Sachin Ghadi <sachin.ghadi@...ive.com>
Subject: Re: [PATCH] RISC-V: Add address map dumper

Hi,

On Mon, Nov 11, 2019 at 05:27:25AM +0000, Yash Shah wrote:
> Add support for dumping the kernel address space layout to the console.
> User can enable CONFIG_DEBUG_VM_LAYOUT to dump the virtual memory region
> into dmesg buffer during boot-up.
> 
> Signed-off-by: Yash Shah <yash.shah@...ive.com>
> ---
> This patch is based on Linux 5.4-rc6 and tested on SiFive HiFive Unleashed
> board.
> ---
>  arch/riscv/Kconfig.debug |  9 +++++++++
>  arch/riscv/mm/init.c     | 30 ++++++++++++++++++++++++++++++
>  2 files changed, 39 insertions(+)
> 
> diff --git a/arch/riscv/Kconfig.debug b/arch/riscv/Kconfig.debug
> index e69de29..cdedfd3 100644
> --- a/arch/riscv/Kconfig.debug
> +++ b/arch/riscv/Kconfig.debug
> @@ -0,0 +1,9 @@
> +config DEBUG_VM_LAYOUT

I believe this could be enabled when CONFIG_DEBUG_VM=y without adding yet
another architecture specific Kconfig option.

> +	bool "Print virtual memory layout on boot up"
> +	depends on DEBUG_KERNEL
> +	help
> +	  Say Y here if you want to dump the kernel virtual memory layout to
> +	  dmesg log on boot up. This information is only useful for kernel
> +	  developers who are working in architecture specific areas of the
> +	  kernel. It is probably not a good idea to enable this feature in a
> +	  production kernel.
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index 79cfb35..fcb8144 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -55,6 +55,36 @@ void __init mem_init(void)
>  	memblock_free_all();
>  
>  	mem_init_print_info(NULL);
> +#ifdef CONFIG_DEBUG_VM_LAYOUT
> +#define MLK(b, t) b, t, (((t) - (b)) >> 10)
> +#define MLM(b, t) b, t, (((t) - (b)) >> 20)
> +#define MLK_ROUNDUP(b, t) b, t, DIV_ROUND_UP(((t) - (b)), SZ_1K)
> +
> +
> +	pr_notice("Virtual kernel memory layout:\n"
> +			"    fixmap  : 0x%08lx - 0x%08lx   (%4ld kB)\n"
> +			"    vmemmap : 0x%08lx - 0x%08lx   (%4ld MB)\n"
> +			"    vmalloc : 0x%08lx - 0x%08lx   (%4ld MB)\n"
> +			"    lowmem  : 0x%08lx - 0x%08lx   (%4ld MB)\n"
> +			"      .init : 0x%px - 0x%px   (%4td kB)\n"
> +			"      .text : 0x%px - 0x%px   (%4td kB)\n"
> +			"      .data : 0x%px - 0x%px   (%4td kB)\n"
> +			"       .bss : 0x%px - 0x%px   (%4td kB)\n",
> +
> +			MLK(FIXADDR_START, FIXADDR_TOP),
> +			MLM(VMEMMAP_START, VMEMMAP_END),
> +			MLM(VMALLOC_START, VMALLOC_END),
> +			MLM(PAGE_OFFSET, (unsigned long)high_memory),
> +
> +			MLK_ROUNDUP(__init_begin, __init_end),
> +			MLK_ROUNDUP(_text, _etext),
> +			MLK_ROUNDUP(_sdata, _edata),
> +			MLK_ROUNDUP(__bss_start, __bss_stop));
> +
> +#undef MLK
> +#undef MLM
> +#undef MLK_ROUNDUP
> +#endif
>  }
>  
>  #ifdef CONFIG_BLK_DEV_INITRD
> -- 
> 2.7.4
> 

-- 
Sincerely yours,
Mike.