kgdb: fix to kill breakpoints on initmem after boot

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>

diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h
index 0444b44..392a367 100644 (file)
--- a/include/linux/kgdb.h
+++ b/include/linux/kgdb.h
@@ -359,9 +359,11 @@ 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 3648c9f..53b2788 100644 (file)
--- a/init/main.c
+++ b/init/main.c
@@ -1426,6 +1426,7 @@ 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 b636d51..4708aec 100644 (file)
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -455,6 +455,17 @@ 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)
 {