path: root/kernel/gcov/gcc_3_4.c

// SPDX-License-Identifier: GPL-2.0
/*
 *  This code provides functions to handle gcc's profiling data format
 *  introduced with gcc 3.4. Future versions of gcc may change the gcov
 *  format (as happened before), so all format-specific information needs
 *  to be kept modular and easily exchangeable.
 *
 *  This file is based on gcc-internal definitions. Functions and data
 *  structures are defined to be compatible with gcc counterparts.
 *  For a better understanding, refer to gcc source: gcc/gcov-io.h.
 *
 *    Copyright IBM Corp. 2009
 *    Author(s): Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
 *
 *    Uses gcc-internal data definitions.
 */

#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/seq_file.h>
#include <linux/vmalloc.h>
#include "gcov.h"

#define GCOV_COUNTERS		5

static struct gcov_info *gcov_info_head;

/**
 * struct gcov_fn_info - profiling meta data per function
 * @ident: object file-unique function identifier
 * @checksum: function checksum
 * @n_ctrs: number of values per counter type belonging to this function
 *
 * This data is generated by gcc during compilation and doesn't change
 * at run-time.
 */
struct gcov_fn_info {
	unsigned int ident;
	unsigned int checksum;
	unsigned int n_ctrs[0];
};

/**
 * struct gcov_ctr_info - profiling data per counter type
 * @num: number of counter values for this type
 * @values: array of counter values for this type
 * @merge: merge function for counter values of this type (unused)
 *
 * 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;
	void		(*merge)(gcov_type *, unsigned int);
};

/**
 * 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: time stamp
 * @filename: name of the associated gcov data file
 * @n_functions: number of instrumented functions
 * @functions: function data
 * @ctr_mask: mask specifying which counter types are active
 * @counts: counter data per counter type
 *
 * 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;
	unsigned int			n_functions;
	const struct gcov_fn_info	*functions;
	unsigned int			ctr_mask;
	struct gcov_ctr_info		counts[0];
};

/**
 * 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. Based on gcc magic. Doesn't change
 * at run-time.
 */
static int counter_active(struct gcov_info *info, unsigned int type)
{
	return (1 << type) & info->ctr_mask;
}

/* 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)
{
	unsigned int active = num_counter_active(info);
	unsigned int i;

	for (i = 0; i < active; i++) {
		memset(info->counts[i].values, 0,
		       info->counts[i].num * sizeof(gcov_type));
	}
}

/**
 * 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 *dest, struct gcov_info *source)
{
	unsigned int i;
	unsigned int j;

	for (i = 0; i < num_counter_active(dest); i++) {
		for (j = 0; j < dest->counts[i].num; j++) {
			dest->counts[i].values[j] +=
				source->counts[i].values[j];
		}
	}
}

/* Get size of function info entry. Based on gcc magic. */
static size_t get_fn_size(struct gcov_info *info)
{
	size_t size;

	size = sizeof(struct gcov_fn_info) + num_counter_active(info) *
	       sizeof(unsigned int);
	if (__alignof__(struct gcov_fn_info) > sizeof(unsigned int))
		size = ALIGN(size, __alignof__(struct gcov_fn_info));
	return size;
}

/* Get address of function info entry. Based on gcc magic. */
static struct gcov_fn_info *get_fn_info(struct gcov_info *info, unsigned int fn)
{
	return (struct gcov_fn_info *)
		((char *) info->functions + fn * get_fn_size(info));
}

/**
 * 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;
	unsigned int i;
	unsigned int active;

	/* Duplicate gcov_info. */
	active = num_counter_active(info);
	dup = kzalloc(sizeof(struct gcov_info) +
		      sizeof(struct gcov_ctr_info) * active, GFP_KERNEL);
	if (!dup)
		return NULL;
	dup->version		= info->version;
	dup->stamp		= info->stamp;
	dup->n_functions	= info->n_functions;
	dup->ctr_mask		= info->ctr_mask;
	/* Duplicate filename. */
	dup->filename		= kstrdup(info->filename, GFP_KERNEL);
	if (!dup->filename)
		goto err_free;
	/* Duplicate table of functions. */
	dup->functions = kmemdup(info->functions, info->n_functions *
				 get_fn_size(info), GFP_KERNEL);
	if (!dup->functions)
		goto err_free;
	/* Duplicate counter arrays. */
	for (i = 0; i < active ; i++) {
		struct gcov_ctr_info *ctr = &info->counts[i];
		size_t size = ctr->num * sizeof(gcov_type);

		dup->counts[i].num = ctr->num;
		dup->counts[i].merge = ctr->merge;
		dup->counts[i].values = vmalloc(size);
		if (!dup->counts[i].values)
			goto err_free;
		memcpy(dup->counts[i].values, ctr->values, size);