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From 7eba220e1a7d443cad6716dd83d4953ffd62d566 Mon Sep 17 00:00:00 2001
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From: Qi Zheng <zhengqi.arch@bytedance.com>
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Date: Tue, 21 Dec 2021 15:40:31 +0800
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Subject: [PATCH 1/2] Fix pvops Xen detection for arm machine
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Since the xen_start_info on the arm/arm64 platform points to a static
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variable '_xen_start_info'(see its definition as below), which makes
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that the address of xen_start_info will never be null.
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arch/arm/xen/enlighten.c:40:static struct start_info _xen_start_info;
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arch/arm/xen/enlighten.c:41:struct start_info *xen_start_info = &_xen_start_info;
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arch/arm/xen/enlighten.c:42:EXPORT_SYMBOL(xen_start_info);
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As a result, the is_pvops_xen() in commit 4badc6229c69 ("Fix pvops
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Xen detection for kernels >= v4.20") always returns TRUE because it
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can always read out the non-null address of xen_start_info, finally
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the following error will be reported on arm/arm64 platform(non-Xen
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environment) because p2m_mid_missing and xen_p2m_addr are not defined:
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crash: cannot resolve "p2m_top"
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For the arm/arm64 platform, fix it by using xen_vcpu_info instead of
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xen_start_info to detect Xen dumps.
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In addition, also explicitly narrow the scope of the xen_start_info
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check to x86 with the machine_type(), there is no need to check it on
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other architectures.
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Fixes: 4badc6229c69 ("Fix pvops Xen detection for kernels >= v4.20")
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Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
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Acked-by: Kazuhito Hagio <k-hagio-ab@nec.com>
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---
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kernel.c | 20 +++++++++++++++-----
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1 file changed, 15 insertions(+), 5 deletions(-)
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diff --git a/kernel.c b/kernel.c
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index f4598ea217a3..37b7af74ed2e 100644
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--- a/kernel.c
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+++ b/kernel.c
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@@ -10757,11 +10757,21 @@ is_pvops_xen(void)
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STREQ(sym, "paravirt_patch_default")))
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return TRUE;
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- if (symbol_exists("xen_start_info") &&
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- readmem(symbol_value("xen_start_info"), KVADDR, &addr,
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- sizeof(void *), "xen_start_info", RETURN_ON_ERROR) &&
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- addr != 0)
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- return TRUE;
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+ if (machine_type("X86") || machine_type("X86_64")) {
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+ if (symbol_exists("xen_start_info") &&
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+ readmem(symbol_value("xen_start_info"), KVADDR, &addr,
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+ sizeof(void *), "xen_start_info", RETURN_ON_ERROR) &&
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+ addr != 0)
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+ return TRUE;
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+ }
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+
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+ if (machine_type("ARM") || machine_type("ARM64")) {
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+ if (symbol_exists("xen_vcpu_info") &&
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+ readmem(symbol_value("xen_vcpu_info"), KVADDR, &addr,
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+ sizeof(void *), "xen_vcpu_info", RETURN_ON_ERROR) &&
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+ addr != 0)
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+ return TRUE;
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+ }
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return FALSE;
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}
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--
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2.20.1
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