9 files changed, 59 insertions, 83 deletions

diff --git a/arch/arc/kernel/kgdb.c b/arch/arc/kernel/kgdb.c
index 0932851028e0..68d9fe4b5aa7 100644
--- a/arch/arc/kernel/kgdb.c
+++ b/arch/arc/kernel/kgdb.c
@@ -192,18 +192,12 @@ void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip)
         instruction_pointer(regs) = ip;
 }
 
-static void kgdb_call_nmi_hook(void *ignored)
+void kgdb_call_nmi_hook(void *ignored)
 {
+        /* Default implementation passes get_irq_regs() but we don't */
         kgdb_nmicallback(raw_smp_processor_id(), NULL);
 }
 
-void kgdb_roundup_cpus(void)
-{
-        local_irq_enable();
-        smp_call_function(kgdb_call_nmi_hook, NULL, 0);
-        local_irq_disable();
-}
-
 struct kgdb_arch arch_kgdb_ops = {
         /* breakpoint instruction: TRAP_S 0x3 */
 #ifdef CONFIG_CPU_BIG_ENDIAN
diff --git a/arch/arm/kernel/kgdb.c b/arch/arm/kernel/kgdb.c
index f21077b077be..d9a69e941463 100644
--- a/arch/arm/kernel/kgdb.c
+++ b/arch/arm/kernel/kgdb.c
@@ -170,18 +170,6 @@ static struct undef_hook kgdb_compiled_brkpt_hook = {
         .fn                     = kgdb_compiled_brk_fn
 };
 
-static void kgdb_call_nmi_hook(void *ignored)
-{
-       kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
-}
-
-void kgdb_roundup_cpus(void)
-{
-       local_irq_enable();
-       smp_call_function(kgdb_call_nmi_hook, NULL, 0);
-       local_irq_disable();
-}
-
 static int __kgdb_notify(struct die_args *args, unsigned long cmd)
 {
         struct pt_regs *regs = args->regs;
diff --git a/arch/arm64/kernel/kgdb.c b/arch/arm64/kernel/kgdb.c
index 12c339ff6e75..da880247c734 100644
--- a/arch/arm64/kernel/kgdb.c
+++ b/arch/arm64/kernel/kgdb.c
@@ -284,18 +284,6 @@ static struct step_hook kgdb_step_hook = {
         .fn             = kgdb_step_brk_fn
 };
 
-static void kgdb_call_nmi_hook(void *ignored)
-{
-        kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
-}
-
-void kgdb_roundup_cpus(void)
-{
-        local_irq_enable();
-        smp_call_function(kgdb_call_nmi_hook, NULL, 0);
-        local_irq_disable();
-}
-
 static int __kgdb_notify(struct die_args *args, unsigned long cmd)
 {
         struct pt_regs *regs = args->regs;
diff --git a/arch/hexagon/kernel/kgdb.c b/arch/hexagon/kernel/kgdb.c
index 012e0e230ac2..b95d12038a4e 100644
--- a/arch/hexagon/kernel/kgdb.c
+++ b/arch/hexagon/kernel/kgdb.c
@@ -115,33 +115,6 @@ void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
         instruction_pointer(regs) = pc;
 }
 
-#ifdef CONFIG_SMP
-
-/**
- * kgdb_roundup_cpus - Get other CPUs into a holding pattern
- *
- * On SMP systems, we need to get the attention of the other CPUs
- * and get them be in a known state.  This should do what is needed
- * to get the other CPUs to call kgdb_wait(). Note that on some arches,
- * the NMI approach is not used for rounding up all the CPUs. For example,
- * in case of MIPS, smp_call_function() is used to roundup CPUs.
- *
- * On non-SMP systems, this is not called.
- */
-
-static void hexagon_kgdb_nmi_hook(void *ignored)
-{
-        kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
-}
-
-void kgdb_roundup_cpus(void)
-{
-        local_irq_enable();
-        smp_call_function(hexagon_kgdb_nmi_hook, NULL, 0);
-        local_irq_disable();
-}
-#endif
-
 
 /*  Not yet working  */
 void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs,
diff --git a/arch/mips/kernel/kgdb.c b/arch/mips/kernel/kgdb.c
index 2b05effc17b4..42f057a6c215 100644
--- a/arch/mips/kernel/kgdb.c
+++ b/arch/mips/kernel/kgdb.c
@@ -207,7 +207,7 @@ void arch_kgdb_breakpoint(void)
                 ".set\treorder");
 }
 
-static void kgdb_call_nmi_hook(void *ignored)
+void kgdb_call_nmi_hook(void *ignored)
 {
         mm_segment_t old_fs;
 
@@ -219,13 +219,6 @@ static void kgdb_call_nmi_hook(void *ignored)
         set_fs(old_fs);
 }
 
-void kgdb_roundup_cpus(void)
-{
-        local_irq_enable();
-        smp_call_function(kgdb_call_nmi_hook, NULL, 0);
-        local_irq_disable();
-}
-
 static int compute_signal(int tt)
 {
         struct hard_trap_info *ht;
diff --git a/arch/powerpc/kernel/kgdb.c b/arch/powerpc/kernel/kgdb.c
index b0e804844be0..b4ce54d73337 100644
--- a/arch/powerpc/kernel/kgdb.c
+++ b/arch/powerpc/kernel/kgdb.c
@@ -117,7 +117,7 @@ int kgdb_skipexception(int exception, struct pt_regs *regs)
         return kgdb_isremovedbreak(regs->nip);
 }
 
-static int kgdb_call_nmi_hook(struct pt_regs *regs)
+static int kgdb_debugger_ipi(struct pt_regs *regs)
 {
         kgdb_nmicallback(raw_smp_processor_id(), regs);
         return 0;
@@ -502,7 +502,7 @@ int kgdb_arch_init(void)
         old__debugger_break_match = __debugger_break_match;
         old__debugger_fault_handler = __debugger_fault_handler;
 
-        __debugger_ipi = kgdb_call_nmi_hook;
+        __debugger_ipi = kgdb_debugger_ipi;
         __debugger = kgdb_debugger;
         __debugger_bpt = kgdb_handle_breakpoint;
         __debugger_sstep = kgdb_singlestep;
diff --git a/arch/sh/kernel/kgdb.c b/arch/sh/kernel/kgdb.c
index cc57630f6bf2..14e012ad7c57 100644
--- a/arch/sh/kernel/kgdb.c
+++ b/arch/sh/kernel/kgdb.c
@@ -314,18 +314,6 @@ BUILD_TRAP_HANDLER(singlestep)
         local_irq_restore(flags);
 }
 
-static void kgdb_call_nmi_hook(void *ignored)
-{
-        kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
-}
-
-void kgdb_roundup_cpus(void)
-{
-        local_irq_enable();
-        smp_call_function(kgdb_call_nmi_hook, NULL, 0);
-        local_irq_disable();
-}
-
 static int __kgdb_notify(struct die_args *args, unsigned long cmd)
 {
         int ret;
diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h
index 05e5b2eb0d32..24422865cd18 100644
--- a/include/linux/kgdb.h
+++ b/include/linux/kgdb.h
@@ -177,13 +177,24 @@ kgdb_arch_handle_exception(int vector, int signo, int err_code,
                            struct pt_regs *regs);
 
 /**
+ *      kgdb_call_nmi_hook - Call kgdb_nmicallback() on the current CPU
+ *      @ignored: This parameter is only here to match the prototype.
+ *
+ *      If you're using the default implementation of kgdb_roundup_cpus()
+ *      this function will be called per CPU.  If you don't implement
+ *      kgdb_call_nmi_hook() a default will be used.
+ */
+
+extern void kgdb_call_nmi_hook(void *ignored);
+
+/**
  *      kgdb_roundup_cpus - Get other CPUs into a holding pattern
  *
  *      On SMP systems, we need to get the attention of the other CPUs
  *      and get them into a known state.  This should do what is needed
  *      to get the other CPUs to call kgdb_wait(). Note that on some arches,
- *      the NMI approach is not used for rounding up all the CPUs. For example,
- *      in case of MIPS, smp_call_function() is used to roundup CPUs.
+ *      the NMI approach is not used for rounding up all the CPUs.  Normally
+ *      those architectures can just not implement this and get the default.
  *
  *      On non-SMP systems, this is not called.
  */
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index f3cadda45f07..10db2833a423 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -55,6 +55,7 @@
 #include <linux/mm.h>
 #include <linux/vmacache.h>
 #include <linux/rcupdate.h>
+#include <linux/irq.h>
 
 #include <asm/cacheflush.h>
 #include <asm/byteorder.h>
@@ -220,6 +221,46 @@ int __weak kgdb_skipexception(int exception, struct pt_regs *regs)
         return 0;
 }
 
+#ifdef CONFIG_SMP
+
+/*
+ * Default (weak) implementation for kgdb_roundup_cpus
+ */
+
+static DEFINE_PER_CPU(call_single_data_t, kgdb_roundup_csd);
+
+void __weak kgdb_call_nmi_hook(void *ignored)
+{
+        /*
+         * NOTE: get_irq_regs() is supposed to get the registers from
+         * before the IPI interrupt happened and so is supposed to
+         * show where the processor was.  In some situations it's
+         * possible we might be called without an IPI, so it might be
+         * safer to figure out how to make kgdb_breakpoint() work
+         * properly here.
+         */
+        kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
+}
+
+void __weak kgdb_roundup_cpus(void)
+{
+        call_single_data_t *csd;
+        int this_cpu = raw_smp_processor_id();
+        int cpu;
+
+        for_each_online_cpu(cpu) {
+                /* No need to roundup ourselves */
+                if (cpu == this_cpu)
+                        continue;
+
+                csd = &per_cpu(kgdb_roundup_csd, cpu);
+                csd->func = kgdb_call_nmi_hook;
+                smp_call_function_single_async(cpu, csd);
+        }
+}
+
+#endif
+
 /*
  * Some architectures need cache flushes when we set/clear a
  * breakpoint: