[RFC PATCH 2/4] gcov: add support for gcc 4.7 gcov format

[Frantisek Hrbata]

The gcov in-memory format changed in gcc 4.7. The biggest change, which
requires this special implementation, is that gcov_info no longer contains
array of counters for each counter type for all functions and gcov_fn_info is
not used for mapping of function's counters to these arrays(offset). Now each
gcov_fn_info contans it's counters, which makes things a little bit easier.

This is heavily based on the previous gcc_3_4.c implementation.

Signed-off-by: Frantisek Hrbata <fhrbata@xxxxxxxxxx>
---
 kernel/gcov/base.c    |   6 +
 kernel/gcov/gcc_4_7.c | 612 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 618 insertions(+)
 create mode 100644 kernel/gcov/gcc_4_7.c

diff --git a/kernel/gcov/base.c b/kernel/gcov/base.c
index 912576a..f45b75b 100644
--- a/kernel/gcov/base.c
+++ b/kernel/gcov/base.c
@@ -79,6 +79,12 @@ void __gcov_merge_delta(gcov_type *counters, unsigned int n_counters)
 }
 EXPORT_SYMBOL(__gcov_merge_delta);
 
+void __gcov_merge_ior(gcov_type *counters, unsigned int n_counters)
+{
+	/* Unused. */
+}
+EXPORT_SYMBOL(__gcov_merge_ior);
+
 /**
  * gcov_enable_events - enable event reporting through gcov_event()
  *
diff --git a/kernel/gcov/gcc_4_7.c b/kernel/gcov/gcc_4_7.c
new file mode 100644
index 0000000..31bee00
--- /dev/null
+++ b/kernel/gcov/gcc_4_7.c
@@ -0,0 +1,612 @@
+/*
+ *  This code provides functions to handle gcc's profiling data format
+ *  introduced with gcc 4.7.
+ *
+ *  This file is based heavily on gcc_3_4.c file.
+ *
+ *  For a better understanding, refer to gcc source:
+ *  gcc/gcov-io.h
+ *  libgcc/libgcov.c
+ *
+ *  Uses gcc-internal data definitions.
+ */
+
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/seq_file.h>
+#include "gcov.h"
+
+#define GCOV_COUNTERS			8
+#define GCOV_TAG_FUNCTION_LENGTH	3
+
+static struct gcov_info *gcov_info_head;
+
+/**
+ * struct gcov_ctr_info - information about counters for a single function
+ * @num: number of counter values for this type
+ * @values: array of counter values for this type
+ *
+ * This data is generated by gcc during compilation and doesn't change
+ * at run-time with the exception of the values array.
+ */
+struct gcov_ctr_info {
+	unsigned int num;
+	gcov_type *values;
+};
+
+/**
+ * struct gcov_fn_info - profiling meta data per function
+ * @key: comdat key
+ * @ident: unique ident of function
+ * @lineno_checksum: function lineo_checksum
+ * @cfg_checksum: function cfg checksum
+ * @ctrs: instrumented counters
+ *
+ * This data is generated by gcc during compilation and doesn't change
+ * at run-time.
+ *
+ * Information about a single function.  This uses the trailing array
+ * idiom. The number of counters is determined from the merge pointer
+ * array in gcov_info.  The key is used to detect which of a set of
+ * comdat functions was selected -- it points to the gcov_info object
+ * of the object file containing the selected comdat function.
+ */
+struct gcov_fn_info {
+	const struct gcov_info *key;
+	unsigned int ident;
+	unsigned int lineno_checksum;
+	unsigned int cfg_checksum;
+	struct gcov_ctr_info ctrs[0];
+};
+
+/**
+ * struct gcov_info - profiling data per object file
+ * @version: gcov version magic indicating the gcc version used for compilation
+ * @next: list head for a singly-linked list
+ * @stamp: uniquifying time stamp
+ * @filename: name of the associated gcov data file
+ * @merge: merge functions (null for unused counter type)
+ * @n_functions: number of instrumented functions
+ * @functions: pointer to pointers to function information
+ *
+ * This data is generated by gcc during compilation and doesn't change
+ * at run-time with the exception of the next pointer.
+ */
+struct gcov_info {
+	unsigned int version;
+	struct gcov_info *next;
+	unsigned int stamp;
+	const char *filename;
+	void (*merge[GCOV_COUNTERS])(gcov_type *, unsigned int);
+	unsigned int n_functions;
+	const struct gcov_fn_info *const *functions;
+};
+
+/**
+ * gcov_info_filename - return info filename
+ * @info: profiling data set
+ */
+const char *gcov_info_filename(struct gcov_info *info)
+{
+	return info->filename;
+}
+
+/**
+ * gcov_info_version - return info version
+ * @info: profiling data set
+ */
+unsigned int gcov_info_version(struct gcov_info *info)
+{
+	return info->version;
+}
+
+/**
+ * gcov_info_next - return next profiling data set
+ * @info: profiling data set
+ *
+ * Returns next gcov_info following @info or first gcov_info in the chain if
+ * @info is %NULL.
+ */
+struct gcov_info *gcov_info_next(struct gcov_info *info)
+{
+	if (!info)
+		return gcov_info_head;
+
+	return info->next;
+}
+
+/**
+ * gcov_info_link - link/add profiling data set to the list
+ * @info: profiling data set
+ */
+void gcov_info_link(struct gcov_info *info)
+{
+	info->next = gcov_info_head;
+	gcov_info_head = info;
+}
+
+/**
+ * gcov_info_unlink - unlink/remove profiling data set from the list
+ * @prev: previous profiling data set
+ * @info: profiling data set
+ */
+void gcov_info_unlink(struct gcov_info *prev, struct gcov_info *info)
+{
+	if (prev)
+		prev->next = info->next;
+	else
+		gcov_info_head = info->next;
+}
+
+/* Symbolic links to be created for each profiling data file. */
+const struct gcov_link gcov_link[] = {
+	{ OBJ_TREE, "gcno" },	/* Link to .gcno file in $(objtree). */
+	{ 0, NULL},
+};
+
+/*
+ * Determine whether a counter is active. Doesn't change at run-time.
+ */
+static int counter_active(struct gcov_info *info, unsigned int type)
+{
+	return info->merge[type] ? 1 : 0;
+}
+
+/* Determine number of active counters. Based on gcc magic. */
+static unsigned int num_counter_active(struct gcov_info *info)
+{
+	unsigned int i;
+	unsigned int result = 0;
+
+	for (i = 0; i < GCOV_COUNTERS; i++) {
+		if (counter_active(info, i))
+			result++;
+	}
+	return result;
+}
+
+/**
+ * gcov_info_reset - reset profiling data to zero
+ * @info: profiling data set
+ */
+void gcov_info_reset(struct gcov_info *info)
+{
+	const struct gcov_ctr_info *ci_ptr;
+	unsigned int fi_idx;
+	unsigned int t_idx;
+
+	for (fi_idx = 0; fi_idx < info->n_functions; fi_idx++)
+	{
+		ci_ptr = info->functions[fi_idx]->ctrs;
+
+		for (t_idx = 0; t_idx < GCOV_COUNTERS; t_idx++) {
+			if (!counter_active(info, t_idx))
+				continue;
+
+			memset(ci_ptr->values, 0,
+					sizeof(gcov_type) * ci_ptr->num);
+			ci_ptr++;
+		}
+	}
+}
+
+/**
+ * gcov_info_is_compatible - check if profiling data can be added
+ * @info1: first profiling data set
+ * @info2: second profiling data set
+ *
+ * Returns non-zero if profiling data can be added, zero otherwise.
+ */
+int gcov_info_is_compatible(struct gcov_info *info1, struct gcov_info *info2)
+{
+	return (info1->stamp == info2->stamp);
+}
+
+/**
+ * gcov_info_add - add up profiling data
+ * @dest: profiling data set to which data is added
+ * @source: profiling data set which is added
+ *
+ * Adds profiling counts of @source to @dest.
+ */
+void gcov_info_add(struct gcov_info *dst, struct gcov_info *src)
+{
+	const struct gcov_ctr_info *dci_ptr;
+	const struct gcov_ctr_info *sci_ptr;
+	unsigned int fi_idx;
+	unsigned int t_idx;
+	unsigned int val_idx;
+
+	for (fi_idx = 0; fi_idx < src->n_functions; fi_idx++)
+	{
+		dci_ptr = dst->functions[fi_idx]->ctrs;
+		sci_ptr = src->functions[fi_idx]->ctrs;
+
+		for (t_idx = 0; t_idx < GCOV_COUNTERS; t_idx++) {
+			if (!counter_active(src, t_idx))
+				continue;
+
+			for (val_idx = 0; val_idx < sci_ptr->num; val_idx++)
+				dci_ptr->values[val_idx] +=
+					sci_ptr->values[val_idx];
+
+			dci_ptr++;
+			sci_ptr++;
+		}
+	}
+}
+
+/**
+ * gcov_info_dup - duplicate profiling data set
+ * @info: profiling data set to duplicate
+ *
+ * Return newly allocated duplicate on success, %NULL on error.
+ */
+struct gcov_info *gcov_info_dup(struct gcov_info *info)
+{
+	struct gcov_info *dup;
+	struct gcov_ctr_info *dci_ptr;
+	struct gcov_ctr_info *sci_ptr;
+	size_t size;
+	unsigned int active;
+	unsigned int fi_idx;
+	unsigned int t_idx;
+
+	dup = kmalloc(sizeof(struct gcov_info), GFP_KERNEL);
+	if (!dup)
+		return NULL;
+
+	*dup = *info;
+	dup->next = NULL;
+	dup->filename = NULL;
+	dup->functions = NULL;
+
+	dup->filename = kstrdup(info->filename, GFP_KERNEL);
+	if (!dup->filename)
+		goto err_free;
+
+	size = sizeof(void *) * info->n_functions;
+	dup->functions = kzalloc(size, GFP_KERNEL);
+	if (!dup->functions)
+		goto err_free;
+
+	active = num_counter_active(info);
+	size = sizeof(struct gcov_fn_info);
+	size += sizeof(struct gcov_ctr_info) * active;
+
+	for (fi_idx = 0; fi_idx < info->n_functions; fi_idx++) {
+		*(struct gcov_fn_info **)&dup->functions[fi_idx] =
+			kzalloc(size, GFP_KERNEL);
+		if (!dup->functions[fi_idx])
+			goto err_free;
+
+		*(struct gcov_fn_info *)&(*(dup->functions[fi_idx])) =
+			*(info->functions[fi_idx]);
+
+		sci_ptr = (struct gcov_ctr_info *)info->functions[fi_idx]->ctrs;
+		dci_ptr = (struct gcov_ctr_info *)dup->functions[fi_idx]->ctrs;
+
+		for (t_idx = 0; t_idx < GCOV_COUNTERS; t_idx++) {
+			if (!counter_active(info, t_idx))
+				continue;
+
+			dci_ptr->values = kmemdup(sci_ptr->values,
+				sizeof(gcov_type) * sci_ptr->num, GFP_KERNEL);
+
+			if (!dci_ptr->values)
+				goto err_free;
+
+			dci_ptr->num = sci_ptr->num;
+
+			sci_ptr++;
+			dci_ptr++;
+		}
+	}
+
+	return dup;
+err_free:
+	gcov_info_free(dup);
+	return NULL;
+}
+
+/**
+ * gcov_info_free - release memory for profiling data set duplicate
+ * @info: profiling data set duplicate to free
+ */
+void gcov_info_free(struct gcov_info *info)
+{
+	unsigned int active;
+	unsigned int fi_idx;
+	unsigned int t_idx;
+	const struct gcov_ctr_info *ci_ptr;
+
+	if (!info->functions)
+		goto free_info;
+
+	active = num_counter_active(info);
+
+	for (fi_idx = 0; fi_idx < info->n_functions; fi_idx++) {
+		if (!info->functions[fi_idx])
+			continue;
+
+		ci_ptr = info->functions[fi_idx]->ctrs;
+
+		for (t_idx = 0; t_idx < GCOV_COUNTERS; t_idx++) {
+			if (!counter_active(info, t_idx))
+				continue;
+
+			if (!ci_ptr->values)
+				continue;
+
+			kfree(ci_ptr->values);
+
+			ci_ptr++;
+		}
+
+		kfree(info->functions[fi_idx]);
+	}
+
+free_info:
+	kfree(info->functions);
+	kfree(info->filename);
+	kfree(info);
+}
+
+/**
+ * struct gcov_iterator - specifies current file position in logical records
+ * @info: associated profiling data
+ * @record: record type
+ * @function: function number
+ * @type: counter type
+ * @count: index into values array
+ * @num_types: number of counter types
+ * @type_info: helper array to get current counter type
+ */
+struct gcov_iterator {
+	struct gcov_info *info;
+	int record;
+	unsigned int function;
+	unsigned int type;
+	unsigned int count;
+	int num_types;
+	int type_info[0];
+};
+
+static const struct gcov_fn_info *get_func(struct gcov_iterator *iter)
+{
+	return iter->info->functions[iter->function];
+}
+
+static const struct gcov_ctr_info *get_ctr(struct gcov_iterator *iter)
+{
+	return &get_func(iter)->ctrs[iter->type];
+}
+
+static gcov_type get_cnt_type(struct gcov_iterator *iter)
+{
+	return iter->type_info[iter->type];
+}
+
+static gcov_type get_cnt_val(struct gcov_iterator *iter)
+{
+	return get_ctr(iter)->values[iter->count];
+}
+
+/**
+ * gcov_iter_new - allocate and initialize profiling data iterator
+ * @info: profiling data set to be iterated
+ *
+ * Return file iterator on success, %NULL otherwise.
+ */
+struct gcov_iterator *gcov_iter_new(struct gcov_info *info)
+{
+	struct gcov_iterator *iter;
+
+	iter = kzalloc(sizeof(struct gcov_iterator) +
+			num_counter_active(info) * sizeof(int), GFP_KERNEL);
+	if (iter)
+		iter->info = info;
+
+	return iter;
+}
+
+/**
+ * gcov_iter_get_info - return profiling data set for given file iterator
+ * @iter: file iterator
+ */
+void gcov_iter_free(struct gcov_iterator *iter)
+{
+	kfree(iter);
+}
+
+/**
+ * gcov_iter_get_info - return profiling data set for given file iterator
+ * @iter: file iterator
+ */
+struct gcov_info *gcov_iter_get_info(struct gcov_iterator *iter)
+{
+	return iter->info;
+}
+
+/**
+ * gcov_iter_start - reset file iterator to starting position
+ * @iter: file iterator
+ */
+void gcov_iter_start(struct gcov_iterator *iter)
+{
+	int i;
+
+	iter->record = 0;
+	iter->function = 0;
+	iter->type = 0;
+	iter->count = 0;
+	iter->num_types = 0;
+
+	for (i = 0; i < GCOV_COUNTERS; i++) {
+		if (counter_active(iter->info, i))
+			iter->type_info[iter->num_types++] = i;
+	}
+}
+
+/* Mapping of logical record number to actual file content. */
+#define RECORD_FILE_MAGIC		0
+#define RECORD_GCOV_VERSION		1
+#define RECORD_TIME_STAMP		2
+#define RECORD_FUNCTION_TAG		3
+#define RECORD_FUNCTION_TAG_LEN		4
+#define RECORD_FUNCTION_IDENT		5
+#define RECORD_FUNCTION_LINENO_CHECK	6
+#define RECORD_FUNCTION_CFG_CHECK	7
+#define RECORD_COUNT_TAG		8
+#define RECORD_COUNT_LEN		9
+#define RECORD_COUNT			10
+
+/**
+ * gcov_iter_next - advance file iterator to next logical record
+ * @iter: file iterator
+ *
+ * Return zero if new position is valid, non-zero if iterator has reached end.
+ */
+int gcov_iter_next(struct gcov_iterator *iter)
+{
+	switch (iter->record) {
+	case RECORD_FILE_MAGIC:
+	case RECORD_GCOV_VERSION:
+	case RECORD_FUNCTION_TAG:
+	case RECORD_FUNCTION_TAG_LEN:
+	case RECORD_FUNCTION_IDENT:
+	case RECORD_FUNCTION_LINENO_CHECK:
+	case RECORD_COUNT_TAG:
+		/* Advance to next record */
+		iter->record++;
+		break;
+
+	case RECORD_COUNT:
+		iter->count++;
+		/* fall through */
+	case RECORD_COUNT_LEN:
+		if (iter->count < get_ctr(iter)->num) {
+			iter->record = RECORD_COUNT;
+			break;
+		}
+		iter->count = 0;
+		iter->type++;
+		/* fall through */
+	case RECORD_FUNCTION_CFG_CHECK:
+		if (iter->type < iter->num_types) {
+			iter->record = RECORD_COUNT_TAG;
+			break;
+		}
+		iter->type = 0;
+		iter->function++;
+		/* fall through */
+	case RECORD_TIME_STAMP:
+		if (iter->function < iter->info->n_functions)
+			iter->record = RECORD_FUNCTION_TAG;
+		else
+			iter->record = -1;
+		break;
+	}
+
+	/* Check for EOF. */
+	if (iter->record == -1)
+		return -EINVAL;
+	else
+		return 0;
+}
+
+/**
+ * seq_write_gcov_u32 - write 32 bit number in gcov format to seq_file
+ * @seq: seq_file handle
+ * @v: value to be stored
+ *
+ * Number format defined by gcc: numbers are recorded in the 32 bit
+ * unsigned binary form of the endianness of the machine generating the
+ * file.
+ */
+static int seq_write_gcov_u32(struct seq_file *seq, u32 v)
+{
+	return seq_write(seq, &v, sizeof(v));
+}
+
+/**
+ * seq_write_gcov_u64 - write 64 bit number in gcov format to seq_file
+ * @seq: seq_file handle
+ * @v: value to be stored
+ *
+ * Number format defined by gcc: numbers are recorded in the 32 bit
+ * unsigned binary form of the endianness of the machine generating the
+ * file. 64 bit numbers are stored as two 32 bit numbers, the low part
+ * first.
+ */
+static int seq_write_gcov_u64(struct seq_file *seq, u64 v)
+{
+	u32 data[2];
+
+	data[0] = (v & 0xffffffffUL);
+	data[1] = (v >> 32);
+	return seq_write(seq, data, sizeof(data));
+}
+
+/**
+ * gcov_iter_write - write data for current pos to seq_file
+ * @iter: file iterator
+ * @seq: seq_file handle
+ *
+ * Return zero on success, non-zero otherwise.
+ */
+int gcov_iter_write(struct gcov_iterator *iter, struct seq_file *seq)
+{
+	switch (iter->record) {
+	case RECORD_FILE_MAGIC:
+		seq_write_gcov_u32(seq, GCOV_DATA_MAGIC);
+		break;
+
+	case RECORD_GCOV_VERSION:
+		seq_write_gcov_u32(seq, iter->info->version);
+		break;
+
+	case RECORD_TIME_STAMP:
+		seq_write_gcov_u32(seq, iter->info->stamp);
+		break;
+
+	case RECORD_FUNCTION_TAG:
+		seq_write_gcov_u32(seq, GCOV_TAG_FUNCTION);
+		break;
+
+	case RECORD_FUNCTION_TAG_LEN:
+		seq_write_gcov_u32(seq, GCOV_TAG_FUNCTION_LENGTH);
+		break;
+
+	case RECORD_FUNCTION_IDENT:
+		seq_write_gcov_u32(seq, get_func(iter)->ident);
+		break;
+
+	case RECORD_FUNCTION_LINENO_CHECK:
+		seq_write_gcov_u32(seq, get_func(iter)->lineno_checksum);
+		break;
+
+	case RECORD_FUNCTION_CFG_CHECK:
+		seq_write_gcov_u32(seq, get_func(iter)->cfg_checksum);
+		break;
+
+	case RECORD_COUNT_TAG:
+		seq_write_gcov_u32(seq,
+				GCOV_TAG_FOR_COUNTER(get_cnt_type(iter)));
+		break;
+
+	case RECORD_COUNT_LEN:
+		seq_write_gcov_u32(seq, get_ctr(iter)->num * 2);
+		break;
+
+	case RECORD_COUNT:
+		seq_write_gcov_u64(seq, get_cnt_val(iter));
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
-- 
1.8.3.1

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