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authorDave Martin <Dave.Martin@arm.com>2015-01-28 12:48:53 +0000
committerSteven Rostedt <rostedt@goodmis.org>2015-01-28 10:34:47 -0500
commit6ea22486ba46bcb665de36514094d74575cd1330 (patch)
treeb0db72c5d2b7dc79a7937f05443a05f1ac5a64c4
parent69a1c994cc540cc84469acf9952f72b899b38e8b (diff)
downloadop-kernel-dev-6ea22486ba46bcb665de36514094d74575cd1330.zip
op-kernel-dev-6ea22486ba46bcb665de36514094d74575cd1330.tar.gz
tracing: Add array printing helper
If a trace event contains an array, there is currently no standard way to format this for text output. Drivers are currently hacking around this by a) local hacks that use the trace_seq functionailty directly, or b) just not printing that information. For fixed size arrays, formatting of the elements can be open-coded, but this gets cumbersome for arrays of non-trivial size. These approaches result in non-standard content of the event format description delivered to userspace, so userland tools needs to be taught to understand and parse each array printing method individually. This patch implements a __print_array() helper that tracepoint implementations can use instead of reinventing it. A simple C-style syntax is used to delimit the array and its elements {like,this}. So that the helpers can be used with large static arrays as well as dynamic arrays, they take a pointer and element count: they can be used with __get_dynamic_array() for use with dynamic arrays. Link: http://lkml.kernel.org/r/1422449335-8289-2-git-send-email-javi.merino@arm.com Cc: Ingo Molnar <mingo@redhat.com> Signed-off-by: Dave Martin <Dave.Martin@arm.com> Signed-off-by: Javi Merino <javi.merino@arm.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
-rw-r--r--include/linux/ftrace_event.h4
-rw-r--r--include/trace/ftrace.h9
-rw-r--r--kernel/trace/trace_output.c44
3 files changed, 57 insertions, 0 deletions
diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index 0bebb5c..5aa4a92 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -44,6 +44,10 @@ const char *ftrace_print_bitmask_seq(struct trace_seq *p, void *bitmask_ptr,
const char *ftrace_print_hex_seq(struct trace_seq *p,
const unsigned char *buf, int len);
+const char *ftrace_print_array_seq(struct trace_seq *p,
+ const void *buf, int buf_len,
+ size_t el_size);
+
struct trace_iterator;
struct trace_event;
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index 139b506..304901f 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -263,6 +263,14 @@
#undef __print_hex
#define __print_hex(buf, buf_len) ftrace_print_hex_seq(p, buf, buf_len)
+#undef __print_array
+#define __print_array(array, count, el_size) \
+ ({ \
+ BUILD_BUG_ON(el_size != 1 && el_size != 2 && \
+ el_size != 4 && el_size != 8); \
+ ftrace_print_array_seq(p, array, count, el_size); \
+ })
+
#undef DECLARE_EVENT_CLASS
#define DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print) \
static notrace enum print_line_t \
@@ -674,6 +682,7 @@ static inline void ftrace_test_probe_##call(void) \
#undef __get_dynamic_array_len
#undef __get_str
#undef __get_bitmask
+#undef __print_array
#undef TP_printk
#define TP_printk(fmt, args...) "\"" fmt "\", " __stringify(args)
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index b77b9a6..692bf71 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -177,6 +177,50 @@ ftrace_print_hex_seq(struct trace_seq *p, const unsigned char *buf, int buf_len)
}
EXPORT_SYMBOL(ftrace_print_hex_seq);
+const char *
+ftrace_print_array_seq(struct trace_seq *p, const void *buf, int buf_len,
+ size_t el_size)
+{
+ const char *ret = trace_seq_buffer_ptr(p);
+ const char *prefix = "";
+ void *ptr = (void *)buf;
+
+ trace_seq_putc(p, '{');
+
+ while (ptr < buf + buf_len) {
+ switch (el_size) {
+ case 1:
+ trace_seq_printf(p, "%s0x%x", prefix,
+ *(u8 *)ptr);
+ break;
+ case 2:
+ trace_seq_printf(p, "%s0x%x", prefix,
+ *(u16 *)ptr);
+ break;
+ case 4:
+ trace_seq_printf(p, "%s0x%x", prefix,
+ *(u32 *)ptr);
+ break;
+ case 8:
+ trace_seq_printf(p, "%s0x%llx", prefix,
+ *(u64 *)ptr);
+ break;
+ default:
+ trace_seq_printf(p, "BAD SIZE:%zu 0x%x", el_size,
+ *(u8 *)ptr);
+ el_size = 1;
+ }
+ prefix = ",";
+ ptr += el_size;
+ }
+
+ trace_seq_putc(p, '}');
+ trace_seq_putc(p, 0);
+
+ return ret;
+}
+EXPORT_SYMBOL(ftrace_print_array_seq);
+
int ftrace_raw_output_prep(struct trace_iterator *iter,
struct trace_event *trace_event)
{
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