This patch adds a kgdb_nmicallin() interface that can be used by external NMI handlers to call the KGDB/KDB handler. The primary need for this is for those types of NMI interrupts where all the CPUs have already received the NMI signal. Therefore no send_IPI(NMI) is required, and in fact it will cause a 2nd unhandled NMI to occur. This generates the "Dazed and Confuzed" messages. Since all the CPUs are getting the NMI at roughly the same time, it's not guaranteed that the first CPU that hits the NMI handler will manage to enter KGDB and set the dbg_master_lock before the slaves start entering. The new argument "send_ready" was added for KGDB to signal the NMI handler to release the slave CPUs for entry into KGDB. Signed-off-by: Mike Travis Reviewed-by: Dimitri Sivanich Reviewed-by: Hedi Berriche Acked-by: Jason Wessel --- v3: make entry into SYSTEM_NMI section more specific --- include/linux/kdb.h | 1 + include/linux/kgdb.h | 1 + kernel/debug/debug_core.c | 30 +++++++++++++++++++++++++++++- kernel/debug/debug_core.h | 1 + kernel/debug/kdb/kdb_debugger.c | 5 ++++- kernel/debug/kdb/kdb_main.c | 3 +++ 6 files changed, 39 insertions(+), 2 deletions(-) --- linux.orig/include/linux/kdb.h +++ linux/include/linux/kdb.h @@ -109,6 +109,7 @@ typedef enum { KDB_REASON_RECURSE, /* Recursive entry to kdb; * regs probably valid */ KDB_REASON_SSTEP, /* Single Step trap. - regs valid */ + KDB_REASON_SYSTEM_NMI, /* In NMI due to SYSTEM cmd; regs valid */ } kdb_reason_t; extern int kdb_trap_printk; --- linux.orig/include/linux/kgdb.h +++ linux/include/linux/kgdb.h @@ -310,6 +310,7 @@ extern int kgdb_handle_exception(int ex_vector, int signo, int err_code, struct pt_regs *regs); extern int kgdb_nmicallback(int cpu, void *regs); +extern int kgdb_nmicallin(int cpu, int trapnr, void *regs, atomic_t *snd_rdy); extern void gdbstub_exit(int status); extern int kgdb_single_step; --- linux.orig/kernel/debug/debug_core.c +++ linux/kernel/debug/debug_core.c @@ -575,8 +575,12 @@ return_normal: raw_spin_lock(&dbg_slave_lock); #ifdef CONFIG_SMP + /* If SYSTEM_NMI, slaves are already waiting */ + if (ks->err_code == KDB_REASON_SYSTEM_NMI) + atomic_set(ks->send_ready, 1); + /* Signal the other CPUs to enter kgdb_wait() */ - if ((!kgdb_single_step) && kgdb_do_roundup) + else if ((!kgdb_single_step) && kgdb_do_roundup) kgdb_roundup_cpus(flags); #endif @@ -729,6 +733,30 @@ int kgdb_nmicallback(int cpu, void *regs return 0; } #endif + return 1; +} + +int kgdb_nmicallin(int cpu, int trapnr, void *regs, atomic_t *send_ready) +{ +#ifdef CONFIG_SMP + if (!kgdb_io_ready(0) || !send_ready) + return 1; + + if (kgdb_info[cpu].enter_kgdb == 0) { + struct kgdb_state kgdb_var; + struct kgdb_state *ks = &kgdb_var; + + memset(ks, 0, sizeof(struct kgdb_state)); + ks->cpu = cpu; + ks->ex_vector = trapnr; + ks->signo = SIGTRAP; + ks->err_code = KDB_REASON_SYSTEM_NMI; + ks->linux_regs = regs; + ks->send_ready = send_ready; + kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER); + return 0; + } +#endif return 1; } --- linux.orig/kernel/debug/debug_core.h +++ linux/kernel/debug/debug_core.h @@ -26,6 +26,7 @@ struct kgdb_state { unsigned long threadid; long kgdb_usethreadid; struct pt_regs *linux_regs; + atomic_t *send_ready; }; /* Exception state values */ --- linux.orig/kernel/debug/kdb/kdb_debugger.c +++ linux/kernel/debug/kdb/kdb_debugger.c @@ -69,7 +69,10 @@ int kdb_stub(struct kgdb_state *ks) if (atomic_read(&kgdb_setting_breakpoint)) reason = KDB_REASON_KEYBOARD; - if (in_nmi()) + if (ks->err_code == KDB_REASON_SYSTEM_NMI && ks->signo == SIGTRAP) + reason = KDB_REASON_SYSTEM_NMI; + + else if (in_nmi()) reason = KDB_REASON_NMI; for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++) { --- linux.orig/kernel/debug/kdb/kdb_main.c +++ linux/kernel/debug/kdb/kdb_main.c @@ -1200,6 +1200,9 @@ static int kdb_local(kdb_reason_t reason instruction_pointer(regs)); kdb_dumpregs(regs); break; + case KDB_REASON_SYSTEM_NMI: + kdb_printf("due to System NonMaskable Interrupt\n"); + break; case KDB_REASON_NMI: kdb_printf("due to NonMaskable Interrupt @ " kdb_machreg_fmt "\n", -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/