Hi Qi, Xen folks,

-----Original Message-----
> Since the xen_start_info on the arm/arm64 platform is static defined:
> 
> ./arm/xen/enlighten.c:40:static struct start_info _xen_start_info;
> ./arm/xen/enlighten.c:41:struct start_info *xen_start_info = &_xen_start_info;
> ./arm/xen/enlighten.c:42:EXPORT_SYMBOL(xen_start_info);
> 
> The is_pvops_xen() in commit 4badc6229c69f5cd9da7eb7bdf400a53ec6db01a
> ("Fix pvops Xen detection for kernels >= v4.20") always return TRUE.
> Then the following error will be reported because p2m_mid_missing
> and xen_p2m_addr are not defined:
> 
>       crash: cannot resolve "p2m_top"
> 
> Fix it by using xen_vcpu_id instead of xen_start_info to detect Xen dumps.
> 
> Signed-off-by: Qi Zheng <[email protected]>
> ---
>  kernel.c | 21 ++++++++++++++++-----
>  1 file changed, 16 insertions(+), 5 deletions(-)
> 
> diff --git a/kernel.c b/kernel.c
> index f4598ea..b216fbe 100644
> --- a/kernel.c
> +++ b/kernel.c
> @@ -10745,6 +10745,9 @@ is_pvops_xen(void)
>  {
>       ulong addr;
>       char *sym;
> +     struct syment * sp;
> +     ulong ptr;
> +     int i;
> 
>       if (!PVOPS())
>               return FALSE;
> @@ -10757,11 +10760,19 @@ is_pvops_xen(void)
>            STREQ(sym, "paravirt_patch_default")))
>               return TRUE;
> 
> -     if (symbol_exists("xen_start_info") &&
> -         readmem(symbol_value("xen_start_info"), KVADDR, &addr,
> -         sizeof(void *), "xen_start_info", RETURN_ON_ERROR) &&
> -         addr != 0)
> -             return TRUE;
> +     sp = per_cpu_symbol_search("xen_vcpu_id");
> +     if (sp) {
> +             for (i = 0; i < NR_CPUS; i++) {
> +                     if (!kt->__per_cpu_offset[i])
> +                             continue;

Thanks for the patch.

But seems that kt->__per_cpu_offset is initialized after the is_pvops_xen()
call.  So this block always return FALSE?

Is there any other variable that we can use?  or another solution..

Thanks,
Kazu

> +
> +                     ptr = sp->value + kt->__per_cpu_offset[i];
> +                     if (ptr && readmem(ptr, KVADDR, &ptr, sizeof(uint32_t),
> +                         "xen_vcpu_id", FAULT_ON_ERROR))
> +                             return TRUE;
> +                     return FALSE;
> +             }
> +     }
> 
>       return FALSE;
>  }
> --
> 2.11.0


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