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.voront...@linaro.org>
---
include/linux/kgdb.h | 3 +++
kernel/debug/debug_core.c | 14 +++++++++++---
2 files changed, 14 insertions(+), 3 deletions(-)
diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h
index c4d2fc1..7800cce 100644
--- a/include/linux/kgdb.h
+++ b/include/linux/kgdb.h
@@ -240,6 +240,7 @@ extern void kgdb_arch_late(void);
* hardware breakpoints.
* @correct_hw_break: Allow an architecture to specify how to correct the
* hardware debug registers.
+ * @enable_nmi: Manage NMI-triggered entry to KGDB
*/
struct kgdb_arch {
unsigned char gdb_bpt_instr[BREAK_INSTR_SIZE];
@@ -252,6 +253,8 @@ struct kgdb_arch {
void (*disable_hw_break)(struct pt_regs *regs);
void (*remove_all_hw_break)(void);
void (*correct_hw_break)(void);
+
+ void (*enable_nmi)(bool on);
};
/**
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 0557f24..17e073c 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -672,6 +672,10 @@ 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 = 0;
+
+ if (arch_kgdb_ops.enable_nmi)
+ arch_kgdb_ops.enable_nmi(0);
ks->cpu = raw_smp_processor_id();
ks->ex_vector = evector;
@@ -681,11 +685,15 @@ kgdb_handle_exception(int evector, int signo, int ecode,
struct pt_regs *regs)
ks->linux_regs = regs;
if (kgdb_reenter_check(ks))
- return 0; /* Ouch, double exception ! */
+ goto out; /* Ouch, double exception ! */
if (kgdb_info[ks->cpu].enter_kgdb != 0)
- return 0;
+ goto out;
- return kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER);
+ ret = kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER);
+out:
+ if (arch_kgdb_ops.enable_nmi)
+ arch_kgdb_ops.enable_nmi(1);
+ return ret;
}
int kgdb_nmicallback(int cpu, void *regs)
--
1.7.11.5
--
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