Add trace library

Add a library which supports tracing of execution using built-in gcc
features and a microsecond timer. This can be used to record a list of
function which are executed, along with a timestamp for each. Later
this information can be sent to the host for processing.

Signed-off-by: Simon Glass <sjg@chromium.org>

lib/trace.c

@@ -0,0 +1,379 @@
+/*
+ * Copyright (c) 2012 The Chromium OS Authors.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <common.h>
+#include <trace.h>
+#include <asm/io.h>
+#include <asm/sections.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+static char trace_enabled __attribute__((section(".data")));
+static char trace_inited __attribute__((section(".data")));
+
+/* The header block at the start of the trace memory area */
+struct trace_hdr {
+	int func_count;		/* Total number of function call sites */
+	u64 call_count;		/* Total number of tracked function calls */
+	u64 untracked_count;	/* Total number of untracked function calls */
+	int funcs_used;		/* Total number of functions used */
+
+	/*
+	 * Call count for each function. This is indexed by the word offset
+	 * of the function from gd->relocaddr
+	 */
+	uintptr_t *call_accum;
+
+	/* Function trace list */
+	struct trace_call *ftrace;	/* The function call records */
+	ulong ftrace_size;	/* Num. of ftrace records we have space for */
+	ulong ftrace_count;	/* Num. of ftrace records written */
+	ulong ftrace_too_deep_count;	/* Functions that were too deep */
+
+	int depth;
+	int depth_limit;
+	int max_depth;
+};
+
+static struct trace_hdr *hdr;	/* Pointer to start of trace buffer */
+
+static inline uintptr_t __attribute__((no_instrument_function))
+		func_ptr_to_num(void *func_ptr)
+{
+	uintptr_t offset = (uintptr_t)func_ptr;
+
+#ifdef CONFIG_SANDBOX
+	offset -= (uintptr_t)&_init;
+#else
+	if (gd->flags & GD_FLG_RELOC)
+		offset -= gd->relocaddr;
+	else
+		offset -= CONFIG_SYS_TEXT_BASE;
+#endif
+	return offset / FUNC_SITE_SIZE;
+}
+
+static void __attribute__((no_instrument_function)) add_ftrace(void *func_ptr,
+				void *caller, ulong flags)
+{
+	if (hdr->depth > hdr->depth_limit) {
+		hdr->ftrace_too_deep_count++;
+		return;
+	}
+	if (hdr->ftrace_count < hdr->ftrace_size) {
+		struct trace_call *rec = &hdr->ftrace[hdr->ftrace_count];
+
+		rec->func = func_ptr_to_num(func_ptr);
+		rec->caller = func_ptr_to_num(caller);
+		rec->flags = flags | (timer_get_us() & FUNCF_TIMESTAMP_MASK);
+	}
+	hdr->ftrace_count++;
+}
+
+static void __attribute__((no_instrument_function)) add_textbase(void)
+{
+	if (hdr->ftrace_count < hdr->ftrace_size) {
+		struct trace_call *rec = &hdr->ftrace[hdr->ftrace_count];
+
+		rec->func = CONFIG_SYS_TEXT_BASE;
+		rec->caller = 0;
+		rec->flags = FUNCF_TEXTBASE;
+	}
+	hdr->ftrace_count++;
+}
+
+/**
+ * This is called on every function entry
+ *
+ * We add to our tally for this function and add to the list of called
+ * functions.
+ *
+ * @param func_ptr	Pointer to function being entered
+ * @param caller	Pointer to function which called this function
+ */
+void __attribute__((no_instrument_function)) __cyg_profile_func_enter(
+		void *func_ptr, void *caller)
+{
+	if (trace_enabled) {
+		int func;
+
+		add_ftrace(func_ptr, caller, FUNCF_ENTRY);
+		func = func_ptr_to_num(func_ptr);
+		if (func < hdr->func_count) {
+			hdr->call_accum[func]++;
+			hdr->call_count++;
+		} else {
+			hdr->untracked_count++;
+		}
+		hdr->depth++;
+		if (hdr->depth > hdr->depth_limit)
+			hdr->max_depth = hdr->depth;
+	}
+}
+
+/**
+ * This is called on every function exit
+ *
+ * We do nothing here.
+ *
+ * @param func_ptr	Pointer to function being entered
+ * @param caller	Pointer to function which called this function
+ */
+void __attribute__((no_instrument_function)) __cyg_profile_func_exit(
+		void *func_ptr, void *caller)
+{
+	if (trace_enabled) {
+		add_ftrace(func_ptr, caller, FUNCF_EXIT);
+		hdr->depth--;
+	}
+}
+
+/**
+ * Produce a list of called functions
+ *
+ * The information is written into the supplied buffer - a header followed
+ * by a list of function records.
+ *
+ * @param buff		Buffer to place list into
+ * @param buff_size	Size of buffer
+ * @param needed	Returns size of buffer needed, which may be
+ *			greater than buff_size if we ran out of space.
+ * @return 0 if ok, -1 if space was exhausted
+ */
+int trace_list_functions(void *buff, int buff_size, unsigned int *needed)
+{
+	struct trace_output_hdr *output_hdr = NULL;
+	void *end, *ptr = buff;
+	int func;
+	int upto;
+
+	end = buff ? buff + buff_size : NULL;
+
+	/* Place some header information */
+	if (ptr + sizeof(struct trace_output_hdr) < end)
+		output_hdr = ptr;
+	ptr += sizeof(struct trace_output_hdr);
+
+	/* Add information about each function */
+	for (func = upto = 0; func < hdr->func_count; func++) {
+		int calls = hdr->call_accum[func];
+
+		if (!calls)
+			continue;
+
+		if (ptr + sizeof(struct trace_output_func) < end) {
+			struct trace_output_func *stats = ptr;
+
+			stats->offset = func * FUNC_SITE_SIZE;
+			stats->call_count = calls;
+			upto++;
+		}
+		ptr += sizeof(struct trace_output_func);
+	}
+
+	/* Update the header */
+	if (output_hdr) {
+		output_hdr->rec_count = upto;
+		output_hdr->type = TRACE_CHUNK_FUNCS;
+	}
+
+	/* Work out how must of the buffer we used */
+	*needed = ptr - buff;
+	if (ptr > end)
+		return -1;
+	return 0;
+}
+
+int trace_list_calls(void *buff, int buff_size, unsigned *needed)
+{
+	struct trace_output_hdr *output_hdr = NULL;
+	void *end, *ptr = buff;
+	int rec, upto;
+	int count;
+
+	end = buff ? buff + buff_size : NULL;
+
+	/* Place some header information */
+	if (ptr + sizeof(struct trace_output_hdr) < end)
+		output_hdr = ptr;
+	ptr += sizeof(struct trace_output_hdr);
+
+	/* Add information about each call */
+	count = hdr->ftrace_count;
+	if (count > hdr->ftrace_size)
+		count = hdr->ftrace_size;
+	for (rec = upto = 0; rec < count; rec++) {
+		if (ptr + sizeof(struct trace_call) < end) {
+			struct trace_call *call = &hdr->ftrace[rec];
+			struct trace_call *out = ptr;
+
+			out->func = call->func * FUNC_SITE_SIZE;
+			out->caller = call->caller * FUNC_SITE_SIZE;
+			out->flags = call->flags;
+			upto++;
+		}
+		ptr += sizeof(struct trace_call);
+	}
+
+	/* Update the header */
+	if (output_hdr) {
+		output_hdr->rec_count = upto;
+		output_hdr->type = TRACE_CHUNK_CALLS;
+	}
+
+	/* Work out how must of the buffer we used */
+	*needed = ptr - buff;
+	if (ptr > end)
+		return -1;
+	return 0;
+}
+
+/* Print basic information about tracing */
+void trace_print_stats(void)
+{
+	ulong count;
+
+#ifndef FTRACE
+	puts("Warning: make U-Boot with FTRACE to enable function instrumenting.\n");
+	puts("You will likely get zeroed data here\n");
+#endif
+	if (!trace_inited) {
+		printf("Trace is disabled\n");
+		return;
+	}
+	print_grouped_ull(hdr->func_count, 10);
+	puts(" function sites\n");
+	print_grouped_ull(hdr->call_count, 10);
+	puts(" function calls\n");
+	print_grouped_ull(hdr->untracked_count, 10);
+	puts(" untracked function calls\n");
+	count = min(hdr->ftrace_count, hdr->ftrace_size);
+	print_grouped_ull(count, 10);
+	puts(" traced function calls");
+	if (hdr->ftrace_count > hdr->ftrace_size) {
+		printf(" (%lu dropped due to overflow)",
+		       hdr->ftrace_count - hdr->ftrace_size);
+	}
+	puts("\n");
+	printf("%15d maximum observed call depth\n", hdr->max_depth);
+	printf("%15d call depth limit\n", hdr->depth_limit);
+	print_grouped_ull(hdr->ftrace_too_deep_count, 10);
+	puts(" calls not traced due to depth\n");
+}
+
+void __attribute__((no_instrument_function)) trace_set_enabled(int enabled)
+{
+	trace_enabled = enabled != 0;
+}
+
+/**
+ * Init the tracing system ready for used, and enable it
+ *
+ * @param buff		Pointer to trace buffer
+ * @param buff_size	Size of trace buffer
+ */
+int __attribute__((no_instrument_function)) trace_init(void *buff,
+		size_t buff_size)
+{
+	ulong func_count = gd->mon_len / FUNC_SITE_SIZE;
+	size_t needed;
+	int was_disabled = !trace_enabled;
+
+	if (!was_disabled) {
+#ifdef CONFIG_TRACE_EARLY
+		char *end;
+		ulong used;
+
+		/*
+		 * Copy over the early trace data if we have it. Disable
+		 * tracing while we are doing this.
+		 */
+		trace_enabled = 0;
+		hdr = map_sysmem(CONFIG_TRACE_EARLY_ADDR,
+				 CONFIG_TRACE_EARLY_SIZE);
+		end = (char *)&hdr->ftrace[hdr->ftrace_count];
+		used = end - (char *)hdr;
+		printf("trace: copying %08lx bytes of early data from %x to %08lx\n",
+		       used, CONFIG_TRACE_EARLY_ADDR,
+		       (ulong)map_to_sysmem(buff));
+		memcpy(buff, hdr, used);
+#else
+		puts("trace: already enabled\n");
+		return -1;
+#endif
+	}
+	hdr = (struct trace_hdr *)buff;
+	needed = sizeof(*hdr) + func_count * sizeof(uintptr_t);
+	if (needed > buff_size) {
+		printf("trace: buffer size %zd bytes: at least %zd needed\n",
+		       buff_size, needed);
+		return -1;
+	}
+
+	if (was_disabled)
+		memset(hdr, '\0', needed);
+	hdr->func_count = func_count;
+	hdr->call_accum = (uintptr_t *)(hdr + 1);
+
+	/* Use any remaining space for the timed function trace */
+	hdr->ftrace = (struct trace_call *)(buff + needed);
+	hdr->ftrace_size = (buff_size - needed) / sizeof(*hdr->ftrace);
+	add_textbase();
+
+	puts("trace: enabled\n");
+	hdr->depth_limit = 15;
+	trace_enabled = 1;
+	trace_inited = 1;
+	return 0;
+}
+
+#ifdef CONFIG_TRACE_EARLY
+int __attribute__((no_instrument_function)) trace_early_init(void)
+{
+	ulong func_count = gd->mon_len / FUNC_SITE_SIZE;
+	size_t buff_size = CONFIG_TRACE_EARLY_SIZE;
+	size_t needed;
+
+	/* We can ignore additional calls to this function */
+	if (trace_enabled)
+		return 0;
+
+	hdr = map_sysmem(CONFIG_TRACE_EARLY_ADDR, CONFIG_TRACE_EARLY_SIZE);
+	needed = sizeof(*hdr) + func_count * sizeof(uintptr_t);
+	if (needed > buff_size) {
+		printf("trace: buffer size is %zd bytes, at least %zd needed\n",
+		       buff_size, needed);
+		return -1;
+	}
+
+	memset(hdr, '\0', needed);
+	hdr->call_accum = (uintptr_t *)(hdr + 1);
+	hdr->func_count = func_count;
+
+	/* Use any remaining space for the timed function trace */
+	hdr->ftrace = (struct trace_call *)((char *)hdr + needed);
+	hdr->ftrace_size = (buff_size - needed) / sizeof(*hdr->ftrace);
+	add_textbase();
+	hdr->depth_limit = 200;
+	printf("trace: early enable at %08x\n", CONFIG_TRACE_EARLY_ADDR);
+
+	trace_enabled = 1;
+	return 0;
+}
+#endif