cregit-Linux how code gets into the kernel

Release 4.7 kernel/gcov/gcc_4_7.c

Directory: kernel/gcov
/*
 *  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 <linux/vmalloc.h>
#include "gcov.h"

#if (__GNUC__ > 5) || (__GNUC__ == 5 && __GNUC_MINOR__ >= 1)

#define GCOV_COUNTERS			10
#elif __GNUC__ == 4 && __GNUC_MINOR__ >= 9

#define GCOV_COUNTERS			9
#else

#define GCOV_COUNTERS			8
#endif


#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;
	
struct gcov_fn_info **functions;
};

/**
 * gcov_info_filename - return info filename
 * @info: profiling data set
 */

const char *gcov_info_filename(struct gcov_info *info) { return info->filename; }

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/** * gcov_info_version - return info version * @info: profiling data set */
unsigned int gcov_info_version(struct gcov_info *info) { return info->version; }

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/** * 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; }

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/** * 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; }

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/** * 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; }

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/* 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; }

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/* 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; }

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/** * gcov_info_reset - reset profiling data to zero * @info: profiling data set */
void gcov_info_reset(struct gcov_info *info) { struct gcov_ctr_info *ci_ptr; unsigned int fi_idx; unsigned int ct_idx; for (fi_idx = 0; fi_idx < info->n_functions; fi_idx++) { ci_ptr = info->functions[fi_idx]->ctrs; for (ct_idx = 0; ct_idx < GCOV_COUNTERS; ct_idx++) { if (!counter_active(info, ct_idx)) continue; memset(ci_ptr->values, 0, sizeof(gcov_type) * ci_ptr->num); ci_ptr++; } } }

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/** * 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); }

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/** * 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) { struct gcov_ctr_info *dci_ptr; struct gcov_ctr_info *sci_ptr; unsigned int fi_idx; unsigned int ct_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 (ct_idx = 0; ct_idx < GCOV_COUNTERS; ct_idx++) { if (!counter_active(src, ct_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++; } } }

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/** * 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; /* dst counter info */ struct gcov_ctr_info *sci_ptr; /* src counter info */ unsigned int active; unsigned int fi_idx; /* function info idx */ unsigned int ct_idx; /* counter type idx */ size_t fi_size; /* function info size */ size_t cv_size; /* counter values size */ dup = kmemdup(info, sizeof(*dup), GFP_KERNEL); if (!dup) return NULL; dup->next = NULL; dup->filename = NULL; dup->functions = NULL; dup->filename = kstrdup(info->filename, GFP_KERNEL); if (!dup->filename) goto err_free; dup->functions = kcalloc(info->n_functions, sizeof(struct gcov_fn_info *), GFP_KERNEL); if (!dup->functions) goto err_free; active = num_counter_active(info); fi_size = sizeof(struct gcov_fn_info); fi_size += sizeof(struct gcov_ctr_info) * active; for (fi_idx = 0; fi_idx < info->n_functions; fi_idx++) { dup->functions[fi_idx] = kzalloc(fi_size, GFP_KERNEL); if (!dup->functions[fi_idx]) goto err_free; *(dup->functions[fi_idx]) = *(info->functions[fi_idx]); sci_ptr = info->functions[fi_idx]->ctrs; dci_ptr = dup->functions[fi_idx]->ctrs; for (ct_idx = 0; ct_idx < active; ct_idx++) { cv_size = sizeof(gcov_type) * sci_ptr->num; dci_ptr->values = vmalloc(cv_size); if (!dci_ptr->values) goto err_free; dci_ptr->num = sci_ptr->num; memcpy(dci_ptr->values, sci_ptr->values, cv_size); sci_ptr++; dci_ptr++; } } return dup; err_free: gcov_info_free(dup); return NULL; }

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/** * 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 ct_idx; 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 (ct_idx = 0; ct_idx < active; ct_idx++, ci_ptr++) vfree(ci_ptr->values); kfree(info->functions[fi_idx]); } free_info: kfree(info->functions); kfree(info->filename); kfree(info); }

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#define ITER_STRIDE PAGE_SIZE /** * struct gcov_iterator - specifies current file position in logical records * @info: associated profiling data * @buffer: buffer containing file data * @size: size of buffer * @pos: current position in file */ struct gcov_iterator { struct gcov_info *info; void *buffer; size_t size; loff_t pos; }; /** * store_gcov_u32 - store 32 bit number in gcov format to buffer * @buffer: target buffer or NULL * @off: offset into the buffer * @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. Returns the number of bytes stored. If @buffer is %NULL, doesn't * store anything. */
static size_t store_gcov_u32(void *buffer, size_t off, u32 v) { u32 *data; if (buffer) { data = buffer + off; *data = v; } return sizeof(*data); }

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/** * store_gcov_u64 - store 64 bit number in gcov format to buffer * @buffer: target buffer or NULL * @off: offset into the buffer * @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. Returns the number of bytes stored. If @buffer is %NULL, doesn't store * anything. */
static size_t store_gcov_u64(void *buffer, size_t off, u64 v) { u32 *data; if (buffer) { data = buffer + off; data[0] = (v & 0xffffffffUL); data[1] = (v >> 32); } return sizeof(*data) * 2; }

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/** * convert_to_gcda - convert profiling data set to gcda file format * @buffer: the buffer to store file data or %NULL if no data should be stored * @info: profiling data set to be converted * * Returns the number of bytes that were/would have been stored into the buffer. */
static size_t convert_to_gcda(char *buffer, struct gcov_info *info) { struct gcov_fn_info *fi_ptr; struct gcov_ctr_info *ci_ptr; unsigned int fi_idx; unsigned int ct_idx; unsigned int cv_idx; size_t pos = 0; /* File header. */ pos += store_gcov_u32(buffer, pos, GCOV_DATA_MAGIC); pos += store_gcov_u32(buffer, pos, info->version); pos += store_gcov_u32(buffer, pos, info->stamp); for (fi_idx = 0; fi_idx < info->n_functions; fi_idx++) { fi_ptr = info->functions[fi_idx]; /* Function record. */ pos += store_gcov_u32(buffer, pos, GCOV_TAG_FUNCTION); pos += store_gcov_u32(buffer, pos, GCOV_TAG_FUNCTION_LENGTH); pos += store_gcov_u32(buffer, pos, fi_ptr->ident); pos += store_gcov_u32(buffer, pos, fi_ptr->lineno_checksum); pos += store_gcov_u32(buffer, pos, fi_ptr->cfg_checksum); ci_ptr = fi_ptr->ctrs; for (ct_idx = 0; ct_idx < GCOV_COUNTERS; ct_idx++) { if (!counter_active(info, ct_idx)) continue; /* Counter record. */ pos += store_gcov_u32(buffer, pos, GCOV_TAG_FOR_COUNTER(ct_idx)); pos += store_gcov_u32(buffer, pos, ci_ptr->num * 2); for (cv_idx = 0; cv_idx < ci_ptr->num; cv_idx++) { pos += store_gcov_u64(buffer, pos, ci_ptr->values[cv_idx]); } ci_ptr++; } } return pos; }

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/** * 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), GFP_KERNEL); if (!iter) goto err_free; iter->info = info; /* Dry-run to get the actual buffer size. */ iter->size = convert_to_gcda(NULL, info); iter->buffer = vmalloc(iter->size); if (!iter->buffer) goto err_free; convert_to_gcda(iter->buffer, info); return iter; err_free: kfree(iter); return NULL; }

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/** * gcov_iter_get_info - return profiling data set for given file iterator * @iter: file iterator */
void gcov_iter_free(struct gcov_iterator *iter) { vfree(iter->buffer); kfree(iter); }

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/** * 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; }

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/** * gcov_iter_start - reset file iterator to starting position * @iter: file iterator */
void gcov_iter_start(struct gcov_iterator *iter) { iter->pos = 0; }

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/** * 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) { if (iter->pos < iter->size) iter->pos += ITER_STRIDE; if (iter->pos >= iter->size) return -EINVAL; return 0; }

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/** * 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) { size_t len; if (iter->pos >= iter->size) return -EINVAL; len = ITER_STRIDE; if (iter->pos + len > iter->size) len = iter->size - iter->pos; seq_write(seq, iter->buffer + iter->pos, len); return 0; }

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Directory: kernel/gcov
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