Re: [Crash-utility] [PATCH] Fix pvops Xen detection for arm machine

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 <zhengqi.arch(a)bytedance.com&gt; > --- > 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