The new arch callback should manage NMIs that usually cause KGDB to enter. That is, not all NMIs should be enabled/disabled, but only those that issue kgdb_handle_exception().
We must mask it as serial-line interrupt can be used as an NMI, so if the original KGDB-entry cause was say a breakpoint, then every input to KDB console will cause KGDB to reenter, which we don't want.
Signed-off-by: Anton Vorontsov anton.vorontsov@linaro.org --- include/linux/kgdb.h | 13 +++++++++++++ kernel/debug/debug_core.c | 13 ++++++++++++- 2 files changed, 25 insertions(+), 1 deletion(-)
diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h index c4d2fc1..e0c0a2e 100644 --- a/include/linux/kgdb.h +++ b/include/linux/kgdb.h @@ -221,6 +221,19 @@ extern int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt); */ extern void kgdb_arch_late(void);
+/** + * kgdb_arch_enable_nmi - Enable or disable KGDB-entry NMI + * @on: Flag to either enable or disable an NMI + * + * This function manages NMIs that usually cause KGDB to enter. That is, + * not all NMIs should be enabled or disabled, but only those that issue + * kgdb_handle_exception(). + * + * The call counts disable/enable requests, it returns 1 if NMI has been + * actually enabled after the call, and a value <= 0 if it is still + * disabled. + */ +extern int kgdb_arch_enable_nmi(bool on);
/** * struct kgdb_arch - Describe architecture specific values. diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c index 0557f24..38b0ab2 100644 --- a/kernel/debug/debug_core.c +++ b/kernel/debug/debug_core.c @@ -214,6 +214,11 @@ int __weak kgdb_skipexception(int exception, struct pt_regs *regs) return 0; }
+int __weak kgdb_arch_enable_nmi(bool on) +{ + return 0; +} + /* * Some architectures need cache flushes when we set/clear a * breakpoint: @@ -672,6 +677,9 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs) { struct kgdb_state kgdb_var; struct kgdb_state *ks = &kgdb_var; + int ret; + + kgdb_arch_enable_nmi(0);
ks->cpu = raw_smp_processor_id(); ks->ex_vector = evector; @@ -685,7 +693,10 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs) if (kgdb_info[ks->cpu].enter_kgdb != 0) return 0;
- return kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER); + ret = kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER); + + kgdb_arch_enable_nmi(1); + return ret; }
int kgdb_nmicallback(int cpu, void *regs)