Messages in this thread Patch in this message | | | From | Anton Vorontsov <> | Subject | [PATCH 02/11] kernel/debug: Mask KGDB NMI upon entry | Date | Mon, 30 Jul 2012 04:58:11 -0700 |
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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) -- 1.7.10.4
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