Hi Matt,
On Mon, Dec 19, 2016 at 12:04:54PM +0000, Matt Redfearn wrote:
> On 19/12/16 02:07, Serge Semin wrote:
> > It's useful to have some printed map of the kernel virtual memory,
> > at least for debugging purpose.
> >
> > Signed-off-by: Serge Semin <fancer.lancer@xxxxxxxxx>
> > ---
> > @@ -106,6 +107,49 @@ static void __init zone_sizes_init(void)
> > }
> >
> > /*
> > + * Print out kernel memory 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)
> > +static void __init mem_print_kmap_info(void)
> > +{
> > + pr_notice("Virtual kernel memory layout:\n"
> > + " lowmem : 0x%08lx - 0x%08lx (%4ld MB)\n"
> > + " vmalloc : 0x%08lx - 0x%08lx (%4ld MB)\n"
> > +#ifdef CONFIG_HIGHMEM
> > + " pkmap : 0x%08lx - 0x%08lx (%4ld MB)\n"
> > +#endif
> > + " fixmap : 0x%08lx - 0x%08lx (%4ld kB)\n"
> > + " .text : 0x%p" " - 0x%p" " (%4td kB)\n"
> > + " .data : 0x%p" " - 0x%p" " (%4td kB)\n"
> > + " .init : 0x%p" " - 0x%p" " (%4td kB)\n",
> > + MLM(PAGE_OFFSET, (unsigned long)high_memory),
> > + MLM(VMALLOC_START, VMALLOC_END),
> > +#ifdef CONFIG_HIGHMEM
> > + MLM(PKMAP_BASE, (PKMAP_BASE) + (LAST_PKMAP)*(PAGE_SIZE)),
> > +#endif
> > + MLK(FIXADDR_START, FIXADDR_TOP),
> > + MLK_ROUNDUP(_text, _etext),
> > + MLK_ROUNDUP(_sdata, _edata),
> > + MLK_ROUNDUP(__init_begin, __init_end));
>
> Please drop printing the kernel addresses, or at least only do it if
> KASLR is not turned on, otherwise you're removing the advantage of
> KASLR, that critical kernel addresses cannot be determined easily from
> userspace.
According to Documentation/printk-formats.txt, this is what %pK is for.
Better to use that instead?
Cheers
James
>
> It may be better to merge the functionality of show_kernel_relocation
> http://lxr.free-electrons.com/source/arch/mips/kernel/relocate.c#L354
> into this function, but only print it under the same conditions as
> currently, i.e.
> #if defined(CONFIG_DEBUG_KERNEL) && defined(CONFIG_DEBUG_INFO)
> http://lxr.free-electrons.com/source/arch/mips/kernel/setup.c#L530
>
> Thanks,
> Matt
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