On 2022/12/08 13:25, Pavankumar Kondeti wrote:
> After the commit 0d9b1ffefabe ("arm64: mm: make vabits_actual
> a build time constant if possible") introduced in v5.19
> Linux kernel, the crash will not find vabits_actual symbol
> if if VA_BITS <= 48. Add a fallback option to initialize VA_BITS
> based on the user supplied machdep option.
>
> Tested ramdumps loading in both 6.0 and 5.15 kernels.
>
> Signed-off-by: Pavankumar Kondeti <quic_pkondeti@xxxxxxxxxxx>
This looks good to me.
Acked-by: Kazuhito Hagio <k-hagio-ab@xxxxxxx>
This is a memo about vabits_actual for future reference...
if VA_BITS <= 48:
ramdump (no vmcoreinfo)
ver < 5.4 ... use old calculation
5.4 <= ver < 5.19 ... require "-m vabits_actual=N"
5.19 <= ver ... require "-m vabits_actual=N" <-- this patch adds
vmcore (with vmcoreinfo)
ver < 5.4 ... use old calculation
5.4 <= ver < 5.9 ... guess from NUMBER(VA_BITS) or "-m vabits_actual"
5.9 <= ver ... use NUMBER(TCR_EL1_T1SZ)
/proc/kcore
ver < 5.4 ... use old calculation
5.4 <= ver < 5.19 ... read vabits_actual
5.19 <= ver ... use NUMBER(TCR_EL1_T1SZ)
# maybe bugs here :)
Thanks,
Kazu
> ---
> arm64.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/arm64.c b/arm64.c
> index c3e26a3..7125458 100644
> --- a/arm64.c
> +++ b/arm64.c
> @@ -4671,6 +4671,10 @@ arm64_calc_VA_BITS(void)
> return;
> } else if (arm64_set_va_bits_by_tcr()) {
> return;
> + } else if (machdep->machspec->VA_BITS_ACTUAL) {
> + machdep->machspec->VA_BITS = machdep->machspec->VA_BITS_ACTUAL;
> + machdep->machspec->VA_START = _VA_START(machdep->machspec->VA_BITS_ACTUAL);
> + return;
> }
>
> if (!(sp = symbol_search("swapper_pg_dir")) &&
--
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