From d359752407f8916c29ad53a5c30ac73e338f2797 Mon Sep 17 00:00:00 2001 From: Jason Wessel Date: Fri, 15 Feb 2008 14:55:53 -0600 Subject: [PATCH] kgdb: fix NMI hangs This patch fixes the hang regression with kgdb when the NMI interrupt comes in while the master core is returning from an exception. Adjust the NMI logic such that KGDB will not stop NMI exceptions from occurring by in general returning NOTIFY_DONE. It is not possible to distinguish the debug NMI sync vs the normal NMI apic interrupt so kgdb needs to catch the unknown NMI if it the debugger was previously active on one of the cpus. Signed-off-by: Jason Wessel Signed-off-by: Ingo Molnar --- arch/x86/kernel/kgdb.c | 18 +++++++++++++++--- arch/x86/kernel/traps_32.c | 2 ++ arch/x86/kernel/traps_64.c | 2 ++ include/asm-x86/kdebug.h | 1 + 4 files changed, 20 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c index 37194d6374..5d7a21119b 100644 --- a/arch/x86/kernel/kgdb.c +++ b/arch/x86/kernel/kgdb.c @@ -41,6 +41,7 @@ #include #include #include +#include #include #include @@ -290,6 +291,8 @@ single_step_cont(struct pt_regs *regs, struct die_args *args) return NOTIFY_STOP; } +static int was_in_debug_nmi[NR_CPUS]; + static int __kgdb_notify(struct die_args *args, unsigned long cmd) { struct pt_regs *regs = args->regs; @@ -299,15 +302,24 @@ static int __kgdb_notify(struct die_args *args, unsigned long cmd) if (atomic_read(&kgdb_active) != -1) { /* KGDB CPU roundup */ kgdb_nmicallback(raw_smp_processor_id(), regs); + was_in_debug_nmi[raw_smp_processor_id()] = 1; + touch_nmi_watchdog(); return NOTIFY_STOP; } return NOTIFY_DONE; case DIE_NMI_IPI: if (atomic_read(&kgdb_active) != -1) { - /* KGDB CPU roundup: */ - if (kgdb_nmicallback(raw_smp_processor_id(), regs)) - return NOTIFY_DONE; + /* KGDB CPU roundup */ + kgdb_nmicallback(raw_smp_processor_id(), regs); + was_in_debug_nmi[raw_smp_processor_id()] = 1; + touch_nmi_watchdog(); + } + return NOTIFY_DONE; + + case DIE_NMIUNKNOWN: + if (was_in_debug_nmi[raw_smp_processor_id()]) { + was_in_debug_nmi[raw_smp_processor_id()] = 0; return NOTIFY_STOP; } return NOTIFY_DONE; diff --git a/arch/x86/kernel/traps_32.c b/arch/x86/kernel/traps_32.c index b22c01e05a..c5421f30d6 100644 --- a/arch/x86/kernel/traps_32.c +++ b/arch/x86/kernel/traps_32.c @@ -708,6 +708,8 @@ io_check_error(unsigned char reason, struct pt_regs * regs) static __kprobes void unknown_nmi_error(unsigned char reason, struct pt_regs * regs) { + if (notify_die(DIE_NMIUNKNOWN, "nmi", regs, reason, 2, SIGINT) == NOTIFY_STOP) + return; #ifdef CONFIG_MCA /* Might actually be able to figure out what the guilty party * is. */ diff --git a/arch/x86/kernel/traps_64.c b/arch/x86/kernel/traps_64.c index 0454666819..055b1650c6 100644 --- a/arch/x86/kernel/traps_64.c +++ b/arch/x86/kernel/traps_64.c @@ -806,6 +806,8 @@ io_check_error(unsigned char reason, struct pt_regs * regs) static __kprobes void unknown_nmi_error(unsigned char reason, struct pt_regs * regs) { + if (notify_die(DIE_NMIUNKNOWN, "nmi", regs, reason, 2, SIGINT) == NOTIFY_STOP) + return; printk(KERN_EMERG "Uhhuh. NMI received for unknown reason %02x.\n", reason); printk(KERN_EMERG "Do you have a strange power saving mode enabled?\n"); diff --git a/include/asm-x86/kdebug.h b/include/asm-x86/kdebug.h index 99dcbafa15..35231240eb 100644 --- a/include/asm-x86/kdebug.h +++ b/include/asm-x86/kdebug.h @@ -20,6 +20,7 @@ enum die_val { DIE_CALL, DIE_NMI_IPI, DIE_PAGE_FAULT, + DIE_NMIUNKNOWN, }; extern void printk_address(unsigned long address, int reliable); -- 2.39.5