File crash-xen-pvops.patch of Package crash.24895

From 4badc6229c69f5cd9da7eb7bdf400a53ec6db01a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Petr=20Tesa=C5=99=C3=ADk?= <ptesarik@suse.cz>
Date: Fri, 25 Jun 2021 17:21:18 +0200
Subject: [PATCH] Fix pvops Xen detection for kernels >= v4.20

Upstream: accepted - expected crash 7.3.1
Git-commit: 4badc6229c69f5cd9da7eb7bdf400a53ec6db01a

Kernel commit 5c83511bdb9832c86be20fb86b783356e2f58062 removed
pv_init_ops, and later commit 054ac8ad5ebe4a69e1f0e842483821ddbe560121
removed the Xen-specific paravirt patch function. As a result, pvops Xen
dumps are no longer recognized as Xen dumps, and virtual-to-physical
translation fails.

Use the value of xen_start_info to determine whether the kernel is
running in Xen PV mode. This pointer is set during the initialization of
a PV domain. Kudos to Juergen Gross, who suggested this check.

Signed-off-by: Petr Tesarik <ptesarik@suse.com>
---
 kernel.c | 34 ++++++++++++++++++++++++++++------
 1 file changed, 28 insertions(+), 6 deletions(-)

diff --git a/kernel.c b/kernel.c
index e123f76..36fdea2 100644
--- a/kernel.c
+++ b/kernel.c
@@ -95,6 +95,7 @@ static ulong __dump_audit(char *);
 static void dump_audit(void);
 static char *vmcoreinfo_read_string(const char *);
 static void check_vmcoreinfo(void);
+static int is_pvops_xen(void);
 
 
 /*
@@ -109,7 +110,6 @@ kernel_init()
 	char *rqstruct;
 	char *rq_timestamp_name = NULL;
 	char *irq_desc_type_name;	
-	ulong pv_init_ops;
 	struct gnu_request req;
 
 	if (pc->flags & KERNEL_DEBUG_QUERY)
@@ -169,11 +169,7 @@ kernel_init()
                        	error(FATAL, "cannot malloc m2p page.");
 	}
 
-	if (PVOPS() && symbol_exists("pv_init_ops") &&
-	    readmem(symbol_value("pv_init_ops"), KVADDR, &pv_init_ops,
-	    sizeof(void *), "pv_init_ops", RETURN_ON_ERROR) &&
-	    ((p1 = value_symbol(pv_init_ops)) &&
-	    (STREQ(p1, "xen_patch") || STREQ(p1, "paravirt_patch_default")))) {
+	if (is_pvops_xen()) {
 		kt->flags |= ARCH_XEN | ARCH_PVOPS_XEN;
 		kt->xen_flags |= WRITABLE_PAGE_TABLES;
 		if (machine_type("X86"))
@@ -10709,6 +10705,32 @@ paravirt_init(void)
 	}
 }
 
+static int
+is_pvops_xen(void)
+{
+	ulong addr;
+	char *sym;
+
+	if (!PVOPS())
+		return FALSE;
+
+	if (symbol_exists("pv_init_ops") &&
+	    readmem(symbol_value("pv_init_ops"), KVADDR, &addr,
+	    sizeof(void *), "pv_init_ops", RETURN_ON_ERROR) &&
+	    (sym = value_symbol(addr)) &&
+	    (STREQ(sym, "xen_patch") ||
+	     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;
+
+	return FALSE;
+}
+
 /*
  *  Get the kernel's xtime timespec from its relevant location.
  */
-- 
2.33.1