From 5a14fead07bcf4e0acc877a8d9e1d1f40a441153 Mon Sep 17 00:00:00 2001 From: Anton Vorontsov Date: Mon, 24 Sep 2012 14:27:50 -0700 Subject: kernel/debug: Mask KGDB NMI upon entry 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 Acked-by: Jason Wessel Signed-off-by: Greg Kroah-Hartman --- kernel/debug/debug_core.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) (limited to 'kernel/debug/debug_core.c') diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c index 0557f24c6bca..17e073c309e6 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) -- cgit v1.2.3 From f30fed10c440a25937e509860fa207399b26efe5 Mon Sep 17 00:00:00 2001 From: Jason Wessel Date: Fri, 12 Oct 2012 06:37:33 -0500 Subject: kgdb: Add module event hooks Allow gdb to auto load kernel modules when it is attached, which makes it trivially easy to debug module init functions or pre-set breakpoints in a kernel module that has not loaded yet. Signed-off-by: Jason Wessel --- kernel/debug/debug_core.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'kernel/debug/debug_core.c') diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c index 0557f24c6bca..8bfa373cd5fd 100644 --- a/kernel/debug/debug_core.c +++ b/kernel/debug/debug_core.c @@ -688,6 +688,22 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs) return kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER); } +/* + * GDB places a breakpoint at this function to know dynamically + * loaded objects. It's not defined static so that only one instance with this + * name exists in the kernel. + */ + +static int module_event(struct notifier_block *self, unsigned long val, + void *data) +{ + return 0; +} + +static struct notifier_block dbg_module_load_nb = { + .notifier_call = module_event, +}; + int kgdb_nmicallback(int cpu, void *regs) { #ifdef CONFIG_SMP @@ -816,6 +832,7 @@ static void kgdb_register_callbacks(void) kgdb_arch_init(); if (!dbg_is_early) kgdb_arch_late(); + register_module_notifier(&dbg_module_load_nb); register_reboot_notifier(&dbg_reboot_notifier); atomic_notifier_chain_register(&panic_notifier_list, &kgdb_panic_event_nb); @@ -839,6 +856,7 @@ static void kgdb_unregister_callbacks(void) if (kgdb_io_module_registered) { kgdb_io_module_registered = 0; unregister_reboot_notifier(&dbg_reboot_notifier); + unregister_module_notifier(&dbg_module_load_nb); atomic_notifier_chain_unregister(&panic_notifier_list, &kgdb_panic_event_nb); kgdb_arch_exit(); -- cgit v1.2.3