[Crash-utility] [PATCH v2] arm64: fix kernel memory map handling for kaslr-enabled kernel

[Pratyush Anand]

On 26/05/2016:05:13:30 PM, AKASHI Takahiro wrote:
> On Wed, May 25, 2016 at 10:28:10AM -0400, Dave Anderson wrote:

[...]

> > > (This is the reason that I don't think we need a VMCOREINFO for
> > > CONFIG_RANDOMIZE_BASE.)
> > 
> > Well, as long as there's a way to avoid that unnecessary/confusing
> > warning message for non-KASLR new-vmemmap kernels.
> > 
> > I also wonder whether makedumpfile could use it?
> 
> -> Pratyush?

Since  second kernel's initrd cannot include a large file like VMLINUX, so
makedumpfile should also work without passing '-x vmlinux'.  Therefore,
makedumpfile will need some minimal symbol's values to be passed in vmcore.

IIUC, then you need to pass CONFIG_RANDOMIZE_BASE in order to calculate
PHYS_OFFSET. If yes, then why not to pass PHYS_OFFSET itself into vmcore.

Following numbers in vmcore [1] is helping me out in implementing __pa() and
__va() for all page table sizes and levels.

VMCOREINFO_NUMBER(pgtable_levels);
VMCOREINFO_NUMBER(va_bits);
VMCOREINFO_NUMBER(page_shift);
VMCOREINFO_NUMBER(phys_offset);
VMCOREINFO_NUMBER(config_kasan);
VMCOREINFO_NUMBER(kimage_voffset);

~Pratyush

[1]
https://github.com/pratyushanand/linux/blob/7011e478aae3e568cc8dca15b6c128fe728416f7/arch/arm64/kernel/machine_kexec.c#L275