From: Sumit Garg <sumit.garg@xxxxxxxxxx> Subject: 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@xxxxxxxxxx Signed-off-by: Sumit Garg <sumit.garg@xxxxxxxxxx> Suggested-by: Doug Anderson <dianders@xxxxxxxxxxxx> Acked-by: Doug Anderson <dianders@xxxxxxxxxxxx> Acked-by: Daniel Thompson <daniel.thompson@xxxxxxxxxx> Tested-by: Daniel Thompson <daniel.thompson@xxxxxxxxxx> Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx> Cc: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx> Cc: Jason Wessel <jason.wessel@xxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/kgdb.h | 2 ++ init/main.c | 1 + kernel/debug/debug_core.c | 11 +++++++++++ 3 files changed, 14 insertions(+) --- a/include/linux/kgdb.h~kgdb-fix-to-kill-breakpoints-on-initmem-after-boot +++ a/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_ */ --- a/init/main.c~kgdb-fix-to-kill-breakpoints-on-initmem-after-boot +++ a/init/main.c @@ -1426,6 +1426,7 @@ static int __ref kernel_init(void *unuse async_synchronize_full(); kprobe_free_init_mem(); ftrace_free_init_mem(); + kgdb_free_init_mem(); free_initmem(); mark_readonly(); --- a/kernel/debug/debug_core.c~kgdb-fix-to-kill-breakpoints-on-initmem-after-boot +++ a/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) { _
