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>

diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index 7d651ad..8c7e555 100644 (file)
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -370,6 +370,8 @@ int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
                ptr = &remcomInBuffer[1];
                if (kgdb_hex2long(&ptr, &addr))
                        linux_regs->ip = addr;
+       case 'D':
+       case 'k':
                newPC = linux_regs->ip;
 
                /* clear the trace bit */
@@ -480,6 +482,8 @@ static int __kgdb_notify(struct die_args *args, unsigned long cmd)
        if (kgdb_handle_exception(args->trapnr, args->signr, args->err, regs))
                return NOTIFY_DONE;
 
+       /* Must touch watchdog before return to normal operation */
+       touch_nmi_watchdog();
        return NOTIFY_STOP;
 }
 

diff --git a/arch/x86/kernel/traps_64.c b/arch/x86/kernel/traps_64.c
index 055b165..4e07332 100644 (file)
--- a/arch/x86/kernel/traps_64.c
+++ b/arch/x86/kernel/traps_64.c
@@ -600,8 +600,13 @@ void die(const char * str, struct pt_regs * regs, long err)
 
 void __kprobes die_nmi(char *str, struct pt_regs *regs, int do_panic)
 {
-       unsigned long flags = oops_begin();
+       unsigned long flags;
+
+       if (notify_die(DIE_NMIWATCHDOG, str, regs, 0, 2, SIGINT) ==
+           NOTIFY_STOP)
+               return;
 
+       flags = oops_begin();
        /*
         * We are in trouble anyway, lets at least try
         * to get a message out.

diff --git a/kernel/kgdb.c b/kernel/kgdb.c
index 31425e0..85b7e5b 100644 (file)
--- 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.