summaryrefslogtreecommitdiffstats
path: root/kernel
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2019-01-01 15:38:14 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2019-01-01 15:38:14 -0800
commitfcf010449ebe1db0cb68b2c6410972a782f2bd14 (patch)
tree56707e5d99776025aa5ffaf27cd97ca924622d36 /kernel
parentfbea8c7c793397cdf4ba53a32f99b656467b7c7f (diff)
parentcc0282975b3f887005c380adcf0af95915f0c1bb (diff)
downloadlinux-fcf010449ebe1db0cb68b2c6410972a782f2bd14.tar.bz2
Merge tag 'kgdb-4.21-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/danielt/linux
Pull kgdb updates from Daniel Thompson: "Mostly clean ups although while Doug's was chasing down a odd lockdep warning he also did some work to improved debugger resilience when some CPUs fail to respond to the round up request. The main changes are: - Fixing a lockdep warning on architectures that cannot use an NMI for the round up plus related changes to make CPU round up and all CPU backtrace more resilient. - Constify the arch ops tables - A couple of other small clean ups Two of the three patchsets here include changes that spill over into arch/. Changes in the arch space are relatively narrow in scope (and directly related to kgdb). Didn't get comprehensive acks but all impacted maintainers were Cc:ed in good time" * tag 'kgdb-4.21-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/danielt/linux: kgdb/treewide: constify struct kgdb_arch arch_kgdb_ops mips/kgdb: prepare arch_kgdb_ops for constness kdb: use bool for binary state indicators kdb: Don't back trace on a cpu that didn't round up kgdb: Don't round up a CPU that failed rounding up before kgdb: Fix kgdb_roundup_cpus() for arches who used smp_call_function() kgdb: Remove irq flags from roundup
Diffstat (limited to 'kernel')
-rw-r--r--kernel/debug/debug_core.c65
-rw-r--r--kernel/debug/debug_core.h1
-rw-r--r--kernel/debug/kdb/kdb_bt.c11
-rw-r--r--kernel/debug/kdb/kdb_debugger.c7
-rw-r--r--kernel/debug/kdb/kdb_main.c14
5 files changed, 82 insertions, 16 deletions
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 65c0f1363788..5cc608de6883 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 +221,62 @@ 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;
+ int ret;
+
+ for_each_online_cpu(cpu) {
+ /* No need to roundup ourselves */
+ if (cpu == this_cpu)
+ continue;
+
+ csd = &per_cpu(kgdb_roundup_csd, cpu);
+
+ /*
+ * If it didn't round up last time, don't try again
+ * since smp_call_function_single_async() will block.
+ *
+ * If rounding_up is false then we know that the
+ * previous call must have at least started and that
+ * means smp_call_function_single_async() won't block.
+ */
+ if (kgdb_info[cpu].rounding_up)
+ continue;
+ kgdb_info[cpu].rounding_up = true;
+
+ csd->func = kgdb_call_nmi_hook;
+ ret = smp_call_function_single_async(cpu, csd);
+ if (ret)
+ kgdb_info[cpu].rounding_up = false;
+ }
+}
+
+#endif
+
/*
* Some architectures need cache flushes when we set/clear a
* breakpoint:
@@ -535,6 +592,8 @@ return_normal:
arch_kgdb_ops.correct_hw_break();
if (trace_on)
tracing_on();
+ kgdb_info[cpu].debuggerinfo = NULL;
+ kgdb_info[cpu].task = NULL;
kgdb_info[cpu].exception_state &=
~(DCPU_WANT_MASTER | DCPU_IS_SLAVE);
kgdb_info[cpu].enter_kgdb--;
@@ -593,7 +652,7 @@ return_normal:
/* Signal the other CPUs to enter kgdb_wait() */
else if ((!kgdb_single_step) && kgdb_do_roundup)
- kgdb_roundup_cpus(flags);
+ kgdb_roundup_cpus();
#endif
/*
@@ -667,6 +726,8 @@ kgdb_restore:
if (trace_on)
tracing_on();
+ kgdb_info[cpu].debuggerinfo = NULL;
+ kgdb_info[cpu].task = NULL;
kgdb_info[cpu].exception_state &=
~(DCPU_WANT_MASTER | DCPU_IS_SLAVE);
kgdb_info[cpu].enter_kgdb--;
@@ -747,6 +808,8 @@ int kgdb_nmicallback(int cpu, void *regs)
struct kgdb_state kgdb_var;
struct kgdb_state *ks = &kgdb_var;
+ kgdb_info[cpu].rounding_up = false;
+
memset(ks, 0, sizeof(struct kgdb_state));
ks->cpu = cpu;
ks->linux_regs = regs;
diff --git a/kernel/debug/debug_core.h b/kernel/debug/debug_core.h
index 127d9bc49fb4..b4a7c326d546 100644
--- a/kernel/debug/debug_core.h
+++ b/kernel/debug/debug_core.h
@@ -42,6 +42,7 @@ struct debuggerinfo_struct {
int ret_state;
int irq_depth;
int enter_kgdb;
+ bool rounding_up;
};
extern struct debuggerinfo_struct kgdb_info[];
diff --git a/kernel/debug/kdb/kdb_bt.c b/kernel/debug/kdb/kdb_bt.c
index 7921ae4fca8d..7e2379aa0a1e 100644
--- a/kernel/debug/kdb/kdb_bt.c
+++ b/kernel/debug/kdb/kdb_bt.c
@@ -186,7 +186,16 @@ kdb_bt(int argc, const char **argv)
kdb_printf("btc: cpu status: ");
kdb_parse("cpu\n");
for_each_online_cpu(cpu) {
- sprintf(buf, "btt 0x%px\n", KDB_TSK(cpu));
+ void *kdb_tsk = KDB_TSK(cpu);
+
+ /* If a CPU failed to round up we could be here */
+ if (!kdb_tsk) {
+ kdb_printf("WARNING: no task for cpu %ld\n",
+ cpu);
+ continue;
+ }
+
+ sprintf(buf, "btt 0x%px\n", kdb_tsk);
kdb_parse(buf);
touch_nmi_watchdog();
}
diff --git a/kernel/debug/kdb/kdb_debugger.c b/kernel/debug/kdb/kdb_debugger.c
index 15e1a7af5dd0..53a0df6e4d92 100644
--- a/kernel/debug/kdb/kdb_debugger.c
+++ b/kernel/debug/kdb/kdb_debugger.c
@@ -118,13 +118,6 @@ int kdb_stub(struct kgdb_state *ks)
kdb_bp_remove();
KDB_STATE_CLEAR(DOING_SS);
KDB_STATE_SET(PAGER);
- /* zero out any offline cpu data */
- for_each_present_cpu(i) {
- if (!cpu_online(i)) {
- kgdb_info[i].debuggerinfo = NULL;
- kgdb_info[i].task = NULL;
- }
- }
if (ks->err_code == DIE_OOPS || reason == KDB_REASON_OOPS) {
ks->pass_exception = 1;
KDB_FLAG_SET(CATASTROPHIC);
diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index d72b32c66f7d..82a3b32a7cfc 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -658,7 +658,7 @@ static void kdb_cmderror(int diag)
*/
struct defcmd_set {
int count;
- int usable;
+ bool usable;
char *name;
char *usage;
char *help;
@@ -666,7 +666,7 @@ struct defcmd_set {
};
static struct defcmd_set *defcmd_set;
static int defcmd_set_count;
-static int defcmd_in_progress;
+static bool defcmd_in_progress;
/* Forward references */
static int kdb_exec_defcmd(int argc, const char **argv);
@@ -676,9 +676,9 @@ static int kdb_defcmd2(const char *cmdstr, const char *argv0)
struct defcmd_set *s = defcmd_set + defcmd_set_count - 1;
char **save_command = s->command;
if (strcmp(argv0, "endefcmd") == 0) {
- defcmd_in_progress = 0;
+ defcmd_in_progress = false;
if (!s->count)
- s->usable = 0;
+ s->usable = false;
if (s->usable)
/* macros are always safe because when executed each
* internal command re-enters kdb_parse() and is
@@ -695,7 +695,7 @@ static int kdb_defcmd2(const char *cmdstr, const char *argv0)
if (!s->command) {
kdb_printf("Could not allocate new kdb_defcmd table for %s\n",
cmdstr);
- s->usable = 0;
+ s->usable = false;
return KDB_NOTIMP;
}
memcpy(s->command, save_command, s->count * sizeof(*(s->command)));
@@ -737,7 +737,7 @@ static int kdb_defcmd(int argc, const char **argv)
defcmd_set_count * sizeof(*defcmd_set));
s = defcmd_set + defcmd_set_count;
memset(s, 0, sizeof(*s));
- s->usable = 1;
+ s->usable = true;
s->name = kdb_strdup(argv[1], GFP_KDB);
if (!s->name)
goto fail_name;
@@ -756,7 +756,7 @@ static int kdb_defcmd(int argc, const char **argv)
s->help[strlen(s->help)-1] = '\0';
}
++defcmd_set_count;
- defcmd_in_progress = 1;
+ defcmd_in_progress = true;
kfree(save_defcmd_set);
return 0;
fail_help: