Re: [PATCH 10/12] mips: Print the kernel virtual mem layout on debugging

Mike Rapoport
2019-04-24T13:47:27Z

On Wed, Apr 24, 2019 at 01:47:46AM +0300, Serge Semin wrote:
> It is useful at least for debugging to have the kernel virtual
> memory layout printed at boot time so to have the full information
> about the booted kernel. Make the printing optional and available
> only when DEBUG_KERNEL config is enabled so not to leak a sensitive
> kernel information.
>
> Signed-off-by: Serge Semin <fancer.lancer@gmail.com>
> ---
> arch/mips/mm/init.c | 49 +++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 49 insertions(+)
>
> diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c
> index bbb196ad5f26..c338bbd03b2a 100644
> --- a/arch/mips/mm/init.c
> +++ b/arch/mips/mm/init.c
> @@ -31,6 +31,7 @@
> #include <linux/gfp.h>
> #include <linux/kcore.h>
> #include <linux/initrd.h>
> +#include <linux/sizes.h>
>
> #include <asm/bootinfo.h>
> #include <asm/cachectl.h>
> @@ -56,6 +57,53 @@ unsigned long empty_zero_page, zero_page_mask;
> EXPORT_SYMBOL_GPL(empty_zero_page);
> EXPORT_SYMBOL(zero_page_mask);
>
> +/*
> + * Print out the kernel virtual memory layout
> + */
> +#define MLK(b, t) (void *)b, (void *)t, ((t) - (b)) >> 10
> +#define MLM(b, t) (void *)b, (void *)t, ((t) - (b)) >> 20
> +#define MLK_ROUNDUP(b, t) (void *)b, (void *)t, DIV_ROUND_UP(((t) - (b)), SZ_1K)
> +static void __init mem_print_kmap_info(void)
> +{
> +#ifdef CONFIG_DEBUG_KERNEL

Maybe CONFIG_DEBUG_VM?

> + pr_notice("Kernel virtual memory layout:\n"
> + " lowmem : 0x%px - 0x%px (%4ld MB)\n"
> + " .text : 0x%px - 0x%px (%4td kB)\n"
> + " .data : 0x%px - 0x%px (%4td kB)\n"
> + " .init : 0x%px - 0x%px (%4td kB)\n"
> + " .bss : 0x%px - 0x%px (%4td kB)\n"
> + " vmalloc : 0x%px - 0x%px (%4ld MB)\n"
> +#ifdef CONFIG_HIGHMEM
> + " pkmap : 0x%px - 0x%px (%4ld MB)\n"
> +#endif
> + " fixmap : 0x%px - 0x%px (%4ld kB)\n",
> + MLM(PAGE_OFFSET, (unsigned long)high_memory),
> + MLK_ROUNDUP(_text, _etext),
> + MLK_ROUNDUP(_sdata, _edata),
> + MLK_ROUNDUP(__init_begin, __init_end),
> + MLK_ROUNDUP(__bss_start, __bss_stop),
> + MLM(VMALLOC_START, VMALLOC_END),
> +#ifdef CONFIG_HIGHMEM
> + MLM(PKMAP_BASE, (PKMAP_BASE) + (LAST_PKMAP)*(PAGE_SIZE)),
> +#endif
> + MLK(FIXADDR_START, FIXADDR_TOP));
> +
> + /* Check some fundamental inconsistencies. May add something else? */
> +#ifdef CONFIG_HIGHMEM
> + BUILD_BUG_ON(VMALLOC_END < PAGE_OFFSET);
> + BUG_ON(VMALLOC_END < (unsigned long)high_memory);
> + BUILD_BUG_ON((PKMAP_BASE) + (LAST_PKMAP)*(PAGE_SIZE) < PAGE_OFFSET);
> + BUG_ON((PKMAP_BASE) + (LAST_PKMAP)*(PAGE_SIZE) <
> + (unsigned long)high_memory);
> +#endif
> + BUILD_BUG_ON(FIXADDR_TOP < PAGE_OFFSET);
> + BUG_ON(FIXADDR_TOP < (unsigned long)high_memory);
> +#endif /* CONFIG_DEBUG_KERNEL */
> +}
> +#undef MLK
> +#undef MLM
> +#undef MLK_ROUNDUP
> +
> /*
> * Not static inline because used by IP27 special magic initialization code
> */
> @@ -479,6 +527,7 @@ void __init mem_init(void)
> setup_zero_pages(); /* Setup zeroed pages. */
> mem_init_free_highmem();
> mem_init_print_info(NULL);
> + mem_print_kmap_info();
>
> #ifdef CONFIG_64BIT
> if ((unsigned long) &_text > (unsigned long) CKSEG0)
> --
> 2.21.0
>

--
Sincerely yours,
Mike.