From 13e83186c91a1e0990cbd2d4ef6b7d572bcc9277 Mon Sep 17 00:00:00 2001
From: Sumit Garg <sumit.garg@linaro.org>
Date: Thu, 25 Feb 2021 17:22:38 -0800
Subject: [PATCH] kgdb: fix to kill breakpoints on initmem after boot

commit d54ce6158e354f5358a547b96299ecd7f3725393 upstream.

Currently breakpoints in kernel .init.text section are not handled
correctly while allowing to remove them even after corresponding pages
have been freed.

Fix it via killing .init.text section breakpoints just prior to initmem
pages being freed.

Doug: "HW breakpoints aren't handled by this patch but it's probably
not such a big deal".

Link: https://lkml.kernel.org/r/20210224081652.587785-1-sumit.garg@linaro.org
Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Suggested-by: Doug Anderson <dianders@chromium.org>
Acked-by: Doug Anderson <dianders@chromium.org>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Tested-by: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 include/linux/kgdb.h      |  2 ++
 init/main.c               |  1 +
 kernel/debug/debug_core.c | 11 +++++++++++
 3 files changed, 14 insertions(+)

diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h
index 0d6cf64c8bb1..3c755f6eaefd 100644
--- a/include/linux/kgdb.h
+++ b/include/linux/kgdb.h
@@ -360,9 +360,11 @@ extern atomic_t			kgdb_active;
 extern bool dbg_is_early;
 extern void __init dbg_late_init(void);
 extern void kgdb_panic(const char *msg);
+extern void kgdb_free_init_mem(void);
 #else /* ! CONFIG_KGDB */
 #define in_dbg_master() (0)
 #define dbg_late_init()
 static inline void kgdb_panic(const char *msg) {}
+static inline void kgdb_free_init_mem(void) { }
 #endif /* ! CONFIG_KGDB */
 #endif /* _KGDB_H_ */
diff --git a/init/main.c b/init/main.c
index 9d964511fe0c..d9d914111251 100644
--- a/init/main.c
+++ b/init/main.c
@@ -1417,6 +1417,7 @@ static int __ref kernel_init(void *unused)
 	async_synchronize_full();
 	kprobe_free_init_mem();
 	ftrace_free_init_mem();
+	kgdb_free_init_mem();
 	free_initmem();
 	mark_readonly();
 
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 1e75a8923a8d..8661eb2b1771 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -456,6 +456,17 @@ setundefined:
 	return 0;
 }
 
+void kgdb_free_init_mem(void)
+{
+	int i;
+
+	/* Clear init memory breakpoints. */
+	for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
+		if (init_section_contains((void *)kgdb_break[i].bpt_addr, 0))
+			kgdb_break[i].state = BP_UNDEFINED;
+	}
+}
+
 #ifdef CONFIG_KGDB_KDB
 void kdb_dump_stack_on_cpu(int cpu)
 {