From 08078d00ab1749a6f84148a00d8d26572af4ec97 Mon Sep 17 00:00:00 2001

Message-Id: <08078d00ab1749a6f84148a00d8d26572af4ec97.1586900628.git.jpoimboe@redhat.com>

From: Josh Poimboeuf <jpoimboe@redhat.com>

Date: Tue, 14 Apr 2020 15:17:51 -0500

Subject: [PATCH] kpatch module integration test

This tests several things related to the patching of modules:

- 'kpatch_string' tests the referencing of a symbol which is outside the

  .o, but inside the patch module.

- alternatives patching (.altinstructions)

- paravirt patching (.parainstructions)

- jump labels (5.8+ kernels only) -- including dynamic printk

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>

---

 fs/nfsd/export.c         | 30 ++++++++++++++++++++++++++++++

 net/netlink/af_netlink.c |  5 +++++

 2 files changed, 35 insertions(+)

diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c

index a1143f7c2201..253c15ad82b2 100644

--- a/fs/nfsd/export.c

+++ b/fs/nfsd/export.c

@@ -1196,15 +1196,45 @@ static void exp_flags(struct seq_file *m, int flag, int fsid,

 	}

 }

+#include <linux/version.h>

+extern char *kpatch_string(void);

+

 static int e_show(struct seq_file *m, void *p)

 {

 	struct cache_head *cp = p;

 	struct svc_export *exp = container_of(cp, struct svc_export, h);

 	struct cache_detail *cd = m->private;

+#ifdef CONFIG_X86_64

+	unsigned long long sched_clock;

+

+	alternative("ud2", "call yield", X86_FEATURE_ALWAYS);

+	alternative("call yield", "ud2", X86_FEATURE_IA64);

+

+	sched_clock = paravirt_sched_clock();

+	if (!jiffies)

+		printk("kpatch: sched_clock: %llu\n", sched_clock);

+#endif

+

+	pr_debug("kpatch: pr_debug() test\n");

+

+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 8, 0)

+{

+	static DEFINE_STATIC_KEY_TRUE(kpatch_key);

+

+	if (static_branch_unlikely(&mcsafe_key))

+		printk("kpatch: mcsafe_key\n");

+

+	BUG_ON(!static_branch_likely(&kpatch_key));

+	static_branch_disable(&kpatch_key);

+	BUG_ON(static_branch_likely(&kpatch_key));

+	static_branch_enable(&kpatch_key);

+}

+#endif

 	if (p == SEQ_START_TOKEN) {

 		seq_puts(m, "# Version 1.1\n");

 		seq_puts(m, "# Path Client(Flags) # IPs\n");

+		seq_puts(m, kpatch_string());

 		return 0;

 	}

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c

index 44fa4ea5df76..dc36ec2901b8 100644

--- a/net/netlink/af_netlink.c

+++ b/net/netlink/af_netlink.c

@@ -2809,4 +2809,9 @@ static int __init netlink_proto_init(void)

 	panic("netlink_init: Cannot allocate nl_table\n");

 }

+char *kpatch_string(void)

+{

+	return "# kpatch\n";

+}

+

 core_initcall(netlink_proto_init);

-- 

2.21.1