[Crash-utility] [PATCHv5 3/3] crash-utility/arm64: assign page_offset with kernel configure value

[HAGIO KAZUHITO(萩尾 一仁)]

-----Original Message-----
> On RHEL9, crash hits a bug when executing "crash /proc/kcore" :
>    seek error: kernel virtual address: ffff6a0f3fff0000 type: "pmd page"
> 
> The kernel virtual address does not vary with va_actual bits, instead,
> is determined by configuration value. But crash does not observe this
> fact.
> 
> Since this disagreement only happens if 52-bits kernel on 48 bits platform,
> it can be handled only if "phys_offset_nominal < 0".
> 
> Signed-off-by: Pingfan Liu <piliu at redhat.com>
> Cc: HAGIO KAZUHITO <k-hagio-ab at nec.com>
> Cc: Lianbo Jiang <lijiang at redhat.com>
> Cc: Bhupesh Sharma <bhupesh.sharma at linaro.org>
> To: crash-utility at redhat.com
> ---
>  arm64.c | 10 +++++++++-
>  defs.h  |  1 +
>  2 files changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/arm64.c b/arm64.c
> index f1bac84..7cc19e8 100644
> --- a/arm64.c
> +++ b/arm64.c
> @@ -221,7 +221,15 @@ arm64_init(int when)
>  		arm64_calc_VA_BITS();
>  		arm64_calc_KERNELPACMASK();
>  		ms = machdep->machspec;
> -		if (ms->VA_BITS_ACTUAL) {
> +		/* For 52-bits kernel running on 48 bits platform */
> +		if (ms->phys_offset_nominal < 0) {

Maybe I miss something, is the ms->phys_offset_nominal set at this point?

                if (ms->phys_offset_nominal < 0) {
...
                /* use machdep parameters */
                arm64_calc_phys_offset();  <<-- set here?
                arm64_calc_physvirt_offset();

Thanks,
Kazu

> +			ms->page_offset = ARM64_FLIP_PAGE_OFFSET;
> +			/* useless on arm64 */
> +			machdep->identity_map_base = ARM64_FLIP_PAGE_OFFSET;
> +			machdep->kvbase = ARM64_FLIP_PAGE_OFFSET;
> +			ms->userspace_top = ARM64_USERSPACE_TOP_ACTUAL;
> +		/* For 52-bits on 52-bits platform, or 48-bits on 48 */
> +		} else if (ms->VA_BITS_ACTUAL) {
>  			ms->page_offset = ARM64_FLIP_PAGE_OFFSET_ACTUAL;
>  			machdep->identity_map_base = ARM64_FLIP_PAGE_OFFSET_ACTUAL;
>  			machdep->kvbase = ARM64_FLIP_PAGE_OFFSET_ACTUAL;
> diff --git a/defs.h b/defs.h
> index 1007c69..f804212 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -3224,6 +3224,7 @@ typedef signed int s32;
>  #define ARM64_PAGE_OFFSET    ((0xffffffffffffffffUL) \
>  					<< (machdep->machspec->VA_BITS - 1))
>  /* kernels > v5.4 the kernel VA space is flipped */
> +#define ARM64_FLIP_PAGE_OFFSET (-(1UL) << machdep->machspec->CONFIG_ARM64_VA_BITS)
>  #define ARM64_FLIP_PAGE_OFFSET_ACTUAL ((0xffffffffffffffffUL) \
>  					- ((1UL) << machdep->machspec->VA_BITS_ACTUAL) + 1)
> 
> --
> 2.29.2