kgdb: fix several kgdb regressions

kgdb core fixes:
- Check to see that mm->mmap_cache is not null before calling
  flush_cache_range(), else on arch=ARM it will cause a fatal
  fault.

- Breakpoints should only be restored if they are in the BP_ACTIVE
  state.

- Fix a typo in comments to "kgdb_register_io_module"

x86 kgdb fixes:
- Fix the x86 arch handler such that on a kill or detach that the
  appropriate cleanup on the single stepping flags gets run.

- Add in the DIE_NMIWATCHDOG call for x86_64

- Touch the nmi watchdog before returning the system to normal
  operation after performing any kind of kgdb operation, else
  the possibility exists to trigger the watchdog.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 8 insertions, 6 deletions

diff --git a/kernel/kgdb.c b/kernel/kgdb.c
index 31425e0fbf20..85b7e5b934a7 100644
--- a/kernel/kgdb.c
+++ b/kernel/kgdb.c
@@ -600,7 +600,7 @@ static void kgdb_flush_swbreak_addr(unsigned long addr)
         if (!CACHE_FLUSH_IS_SAFE)
                 return;
 
-        if (current->mm) {
+        if (current->mm && current->mm->mmap_cache) {
                 flush_cache_range(current->mm->mmap_cache,
                                   addr, addr + BREAK_INSTR_SIZE);
         } else {
@@ -729,14 +729,16 @@ int remove_all_break(void)
 
         /* Clear memory breakpoints. */
         for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
-                if (kgdb_break[i].state != BP_SET)
-                        continue;
+                if (kgdb_break[i].state != BP_ACTIVE)
+                        goto setundefined;
                 addr = kgdb_break[i].bpt_addr;
                 error = kgdb_arch_remove_breakpoint(addr,
                                 kgdb_break[i].saved_instr);
                 if (error)
-                        return error;
-                kgdb_break[i].state = BP_REMOVED;
+                        printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n",
+                           addr);
+setundefined:
+                kgdb_break[i].state = BP_UNDEFINED;
         }
 
         /* Clear hardware breakpoints. */
@@ -1605,7 +1607,7 @@ static void kgdb_initial_breakpoint(void)
 }
 
 /**
- *      kkgdb_register_io_module - register KGDB IO module
+ *      kgdb_register_io_module - register KGDB IO module
  *      @new_kgdb_io_ops: the io ops vector
  *
  *      Register it with the KGDB core.