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-rw-r--r--include/linux/ftrace_event.h6
-rw-r--r--include/trace/ftrace.h83
-rw-r--r--kernel/trace/trace_event_profile.c61
-rw-r--r--kernel/trace/trace_syscalls.c97
4 files changed, 199 insertions, 48 deletions
diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index bc103d7b1ca8..4ec5e67e18cf 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -4,6 +4,7 @@
#include <linux/ring_buffer.h>
#include <linux/trace_seq.h>
#include <linux/percpu.h>
+#include <linux/hardirq.h>
struct trace_array;
struct tracer;
@@ -134,6 +135,11 @@ struct ftrace_event_call {
void (*profile_disable)(void);
};
+#define FTRACE_MAX_PROFILE_SIZE 2048
+
+extern char *trace_profile_buf;
+extern char *trace_profile_buf_nmi;
+
#define MAX_FILTER_PRED 32
#define MAX_FILTER_STR_VAL 256 /* Should handle KSYM_SYMBOL_LEN */
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index a822087857e9..a0361cb69769 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -648,11 +648,12 @@ __attribute__((section("_ftrace_events"))) event_##call = { \
* struct ftrace_raw_##call *entry;
* u64 __addr = 0, __count = 1;
* unsigned long irq_flags;
+ * struct trace_entry *ent;
* int __entry_size;
* int __data_size;
+ * int __cpu
* int pc;
*
- * local_save_flags(irq_flags);
* pc = preempt_count();
*
* __data_size = ftrace_get_offsets_<call>(&__data_offsets, args);
@@ -663,25 +664,34 @@ __attribute__((section("_ftrace_events"))) event_##call = { \
* sizeof(u64));
* __entry_size -= sizeof(u32);
*
- * do {
- * char raw_data[__entry_size]; <- allocate our sample in the stack
- * struct trace_entry *ent;
+ * // Protect the non nmi buffer
+ * // This also protects the rcu read side
+ * local_irq_save(irq_flags);
+ * __cpu = smp_processor_id();
+ *
+ * if (in_nmi())
+ * raw_data = rcu_dereference(trace_profile_buf_nmi);
+ * else
+ * raw_data = rcu_dereference(trace_profile_buf);
+ *
+ * if (!raw_data)
+ * goto end;
*
- * zero dead bytes from alignment to avoid stack leak to userspace:
+ * raw_data = per_cpu_ptr(raw_data, __cpu);
*
- * *(u64 *)(&raw_data[__entry_size - sizeof(u64)]) = 0ULL;
- * entry = (struct ftrace_raw_<call> *)raw_data;
- * ent = &entry->ent;
- * tracing_generic_entry_update(ent, irq_flags, pc);
- * ent->type = event_call->id;
+ * //zero dead bytes from alignment to avoid stack leak to userspace:
+ * *(u64 *)(&raw_data[__entry_size - sizeof(u64)]) = 0ULL;
+ * entry = (struct ftrace_raw_<call> *)raw_data;
+ * ent = &entry->ent;
+ * tracing_generic_entry_update(ent, irq_flags, pc);
+ * ent->type = event_call->id;
*
- * <tstruct> <- do some jobs with dynamic arrays
+ * <tstruct> <- do some jobs with dynamic arrays
*
- * <assign> <- affect our values
+ * <assign> <- affect our values
*
- * perf_tpcounter_event(event_call->id, __addr, __count, entry,
- * __entry_size); <- submit them to perf counter
- * } while (0);
+ * perf_tpcounter_event(event_call->id, __addr, __count, entry,
+ * __entry_size); <- submit them to perf counter
*
* }
*/
@@ -704,11 +714,13 @@ static void ftrace_profile_##call(proto) \
struct ftrace_raw_##call *entry; \
u64 __addr = 0, __count = 1; \
unsigned long irq_flags; \
+ struct trace_entry *ent; \
int __entry_size; \
int __data_size; \
+ char *raw_data; \
+ int __cpu; \
int pc; \
\
- local_save_flags(irq_flags); \
pc = preempt_count(); \
\
__data_size = ftrace_get_offsets_##call(&__data_offsets, args); \
@@ -716,23 +728,38 @@ static void ftrace_profile_##call(proto) \
sizeof(u64)); \
__entry_size -= sizeof(u32); \
\
- do { \
- char raw_data[__entry_size]; \
- struct trace_entry *ent; \
+ if (WARN_ONCE(__entry_size > FTRACE_MAX_PROFILE_SIZE, \
+ "profile buffer not large enough")) \
+ return; \
+ \
+ local_irq_save(irq_flags); \
+ __cpu = smp_processor_id(); \
\
- *(u64 *)(&raw_data[__entry_size - sizeof(u64)]) = 0ULL; \
- entry = (struct ftrace_raw_##call *)raw_data; \
- ent = &entry->ent; \
- tracing_generic_entry_update(ent, irq_flags, pc); \
- ent->type = event_call->id; \
+ if (in_nmi()) \
+ raw_data = rcu_dereference(trace_profile_buf_nmi); \
+ else \
+ raw_data = rcu_dereference(trace_profile_buf); \
\
- tstruct \
+ if (!raw_data) \
+ goto end; \
\
- { assign; } \
+ raw_data = per_cpu_ptr(raw_data, __cpu); \
\
- perf_tpcounter_event(event_call->id, __addr, __count, entry,\
+ *(u64 *)(&raw_data[__entry_size - sizeof(u64)]) = 0ULL; \
+ entry = (struct ftrace_raw_##call *)raw_data; \
+ ent = &entry->ent; \
+ tracing_generic_entry_update(ent, irq_flags, pc); \
+ ent->type = event_call->id; \
+ \
+ tstruct \
+ \
+ { assign; } \
+ \
+ perf_tpcounter_event(event_call->id, __addr, __count, entry, \
__entry_size); \
- } while (0); \
+ \
+end: \
+ local_irq_restore(irq_flags); \
\
}
diff --git a/kernel/trace/trace_event_profile.c b/kernel/trace/trace_event_profile.c
index df4a74efd50c..3aaa77c3309b 100644
--- a/kernel/trace/trace_event_profile.c
+++ b/kernel/trace/trace_event_profile.c
@@ -8,12 +8,52 @@
#include <linux/module.h>
#include "trace.h"
+/*
+ * We can't use a size but a type in alloc_percpu()
+ * So let's create a dummy type that matches the desired size
+ */
+typedef struct {char buf[FTRACE_MAX_PROFILE_SIZE];} profile_buf_t;
+
+char *trace_profile_buf;
+char *trace_profile_buf_nmi;
+
+/* Count the events in use (per event id, not per instance) */
+static int total_profile_count;
+
static int ftrace_profile_enable_event(struct ftrace_event_call *event)
{
+ char *buf;
+ int ret = -ENOMEM;
+
if (atomic_inc_return(&event->profile_count))
return 0;
- return event->profile_enable();
+ if (!total_profile_count++) {
+ buf = (char *)alloc_percpu(profile_buf_t);
+ if (!buf)
+ goto fail_buf;
+
+ rcu_assign_pointer(trace_profile_buf, buf);
+
+ buf = (char *)alloc_percpu(profile_buf_t);
+ if (!buf)
+ goto fail_buf_nmi;
+
+ rcu_assign_pointer(trace_profile_buf_nmi, buf);
+ }
+
+ ret = event->profile_enable();
+ if (!ret)
+ return 0;
+
+ kfree(trace_profile_buf_nmi);
+fail_buf_nmi:
+ kfree(trace_profile_buf);
+fail_buf:
+ total_profile_count--;
+ atomic_dec(&event->profile_count);
+
+ return ret;
}
int ftrace_profile_enable(int event_id)
@@ -36,10 +76,29 @@ int ftrace_profile_enable(int event_id)
static void ftrace_profile_disable_event(struct ftrace_event_call *event)
{
+ char *buf, *nmi_buf;
+
if (!atomic_add_negative(-1, &event->profile_count))
return;
event->profile_disable();
+
+ if (!--total_profile_count) {
+ buf = trace_profile_buf;
+ rcu_assign_pointer(trace_profile_buf, NULL);
+
+ nmi_buf = trace_profile_buf_nmi;
+ rcu_assign_pointer(trace_profile_buf_nmi, NULL);
+
+ /*
+ * Ensure every events in profiling have finished before
+ * releasing the buffers
+ */
+ synchronize_sched();
+
+ free_percpu(buf);
+ free_percpu(nmi_buf);
+ }
}
void ftrace_profile_disable(int event_id)
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 8712ce3c6a0e..7a3550cf2597 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -384,10 +384,13 @@ static int sys_prof_refcount_exit;
static void prof_syscall_enter(struct pt_regs *regs, long id)
{
- struct syscall_trace_enter *rec;
struct syscall_metadata *sys_data;
+ struct syscall_trace_enter *rec;
+ unsigned long flags;
+ char *raw_data;
int syscall_nr;
int size;
+ int cpu;
syscall_nr = syscall_get_nr(current, regs);
if (!test_bit(syscall_nr, enabled_prof_enter_syscalls))
@@ -402,20 +405,38 @@ static void prof_syscall_enter(struct pt_regs *regs, long id)
size = ALIGN(size + sizeof(u32), sizeof(u64));
size -= sizeof(u32);
- do {
- char raw_data[size];
+ if (WARN_ONCE(size > FTRACE_MAX_PROFILE_SIZE,
+ "profile buffer not large enough"))
+ return;
+
+ /* Protect the per cpu buffer, begin the rcu read side */
+ local_irq_save(flags);
- /* zero the dead bytes from align to not leak stack to user */
- *(u64 *)(&raw_data[size - sizeof(u64)]) = 0ULL;
+ cpu = smp_processor_id();
+
+ if (in_nmi())
+ raw_data = rcu_dereference(trace_profile_buf_nmi);
+ else
+ raw_data = rcu_dereference(trace_profile_buf);
+
+ if (!raw_data)
+ goto end;
- rec = (struct syscall_trace_enter *) raw_data;
- tracing_generic_entry_update(&rec->ent, 0, 0);
- rec->ent.type = sys_data->enter_id;
- rec->nr = syscall_nr;
- syscall_get_arguments(current, regs, 0, sys_data->nb_args,
- (unsigned long *)&rec->args);
- perf_tpcounter_event(sys_data->enter_id, 0, 1, rec, size);
- } while(0);
+ raw_data = per_cpu_ptr(raw_data, cpu);
+
+ /* zero the dead bytes from align to not leak stack to user */
+ *(u64 *)(&raw_data[size - sizeof(u64)]) = 0ULL;
+
+ rec = (struct syscall_trace_enter *) raw_data;
+ tracing_generic_entry_update(&rec->ent, 0, 0);
+ rec->ent.type = sys_data->enter_id;
+ rec->nr = syscall_nr;
+ syscall_get_arguments(current, regs, 0, sys_data->nb_args,
+ (unsigned long *)&rec->args);
+ perf_tpcounter_event(sys_data->enter_id, 0, 1, rec, size);
+
+end:
+ local_irq_restore(flags);
}
int reg_prof_syscall_enter(char *name)
@@ -460,8 +481,12 @@ void unreg_prof_syscall_enter(char *name)
static void prof_syscall_exit(struct pt_regs *regs, long ret)
{
struct syscall_metadata *sys_data;
- struct syscall_trace_exit rec;
+ struct syscall_trace_exit *rec;
+ unsigned long flags;
int syscall_nr;
+ char *raw_data;
+ int size;
+ int cpu;
syscall_nr = syscall_get_nr(current, regs);
if (!test_bit(syscall_nr, enabled_prof_exit_syscalls))
@@ -471,12 +496,46 @@ static void prof_syscall_exit(struct pt_regs *regs, long ret)
if (!sys_data)
return;
- tracing_generic_entry_update(&rec.ent, 0, 0);
- rec.ent.type = sys_data->exit_id;
- rec.nr = syscall_nr;
- rec.ret = syscall_get_return_value(current, regs);
+ /* We can probably do that at build time */
+ size = ALIGN(sizeof(*rec) + sizeof(u32), sizeof(u64));
+ size -= sizeof(u32);
- perf_tpcounter_event(sys_data->exit_id, 0, 1, &rec, sizeof(rec));
+ /*
+ * Impossible, but be paranoid with the future
+ * How to put this check outside runtime?
+ */
+ if (WARN_ONCE(size > FTRACE_MAX_PROFILE_SIZE,
+ "exit event has grown above profile buffer size"))
+ return;
+
+ /* Protect the per cpu buffer, begin the rcu read side */
+ local_irq_save(flags);
+ cpu = smp_processor_id();
+
+ if (in_nmi())
+ raw_data = rcu_dereference(trace_profile_buf_nmi);
+ else
+ raw_data = rcu_dereference(trace_profile_buf);
+
+ if (!raw_data)
+ goto end;
+
+ raw_data = per_cpu_ptr(raw_data, cpu);
+
+ /* zero the dead bytes from align to not leak stack to user */
+ *(u64 *)(&raw_data[size - sizeof(u64)]) = 0ULL;
+
+ rec = (struct syscall_trace_exit *)raw_data;
+
+ tracing_generic_entry_update(&rec->ent, 0, 0);
+ rec->ent.type = sys_data->exit_id;
+ rec->nr = syscall_nr;
+ rec->ret = syscall_get_return_value(current, regs);
+
+ perf_tpcounter_event(sys_data->exit_id, 0, 1, rec, size);
+
+end:
+ local_irq_restore(flags);
}
int reg_prof_syscall_exit(char *name)
generated by cgit v1.2.3 (git 2.0.4) at 2024-05-20 23:34:09 +0000