![Greg Hackmann](/assets/img/avatar_default.png)
LLVM uses profiling data that's deliberately similar to GCC, but has a very different way of exporting that data. LLVM calls llvm_gcov_init() once per module, and provides a couple of callbacks that we can use to ask for more data. We care about the "writeout" callback, which in turn calls back into compiler-rt/this module to dump all the gathered coverage data to disk: llvm_gcda_start_file() llvm_gcda_emit_function() llvm_gcda_emit_arcs() llvm_gcda_emit_function() llvm_gcda_emit_arcs() [... repeats for each function ...] llvm_gcda_summary_info() llvm_gcda_end_file() This design is much more stateless and unstructured than gcc's, and is intended to run at process exit. This forces us to keep some local state about which module we're dealing with at the moment. On the other hand, it also means we don't depend as much on how LLVM represents profiling data internally. See LLVM's lib/Transforms/Instrumentation/GCOVProfiling.cpp for more details on how this works, particularly GCOVProfiler::emitProfileArcs(), GCOVProfiler::insertCounterWriteout(), and GCOVProfiler::insertFlush(). [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/20190417225328.208129-1-trong@android.com Signed-off-by: Greg Hackmann <ghackmann@android.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Tri Vo <trong@android.com> Co-developed-by: Nick Desaulniers <ndesaulniers@google.com> Co-developed-by: Tri Vo <trong@android.com> Tested-by: Trilok Soni <tsoni@quicinc.com> Tested-by: Prasad Sodagudi <psodagud@quicinc.com> Tested-by: Tri Vo <trong@android.com> Tested-by: Daniel Mentz <danielmentz@google.com> Tested-by: Petri Gynther <pgynther@google.com> Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
574 lines
14 KiB
C
574 lines
14 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* This code provides functions to handle gcc's profiling data format
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* introduced with gcc 3.4. Future versions of gcc may change the gcov
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* format (as happened before), so all format-specific information needs
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* to be kept modular and easily exchangeable.
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*
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* This file is based on gcc-internal definitions. Functions and data
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* structures are defined to be compatible with gcc counterparts.
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* For a better understanding, refer to gcc source: gcc/gcov-io.h.
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*
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* Copyright IBM Corp. 2009
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* Author(s): Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
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*
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* Uses gcc-internal data definitions.
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*/
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#include <linux/errno.h>
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#include <linux/slab.h>
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#include <linux/string.h>
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#include <linux/seq_file.h>
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#include <linux/vmalloc.h>
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#include "gcov.h"
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#define GCOV_COUNTERS 5
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static struct gcov_info *gcov_info_head;
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/**
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* struct gcov_fn_info - profiling meta data per function
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* @ident: object file-unique function identifier
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* @checksum: function checksum
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* @n_ctrs: number of values per counter type belonging to this function
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*
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* This data is generated by gcc during compilation and doesn't change
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* at run-time.
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*/
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struct gcov_fn_info {
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unsigned int ident;
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unsigned int checksum;
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unsigned int n_ctrs[0];
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};
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/**
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* struct gcov_ctr_info - profiling data per counter type
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* @num: number of counter values for this type
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* @values: array of counter values for this type
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* @merge: merge function for counter values of this type (unused)
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*
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* This data is generated by gcc during compilation and doesn't change
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* at run-time with the exception of the values array.
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*/
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struct gcov_ctr_info {
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unsigned int num;
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gcov_type *values;
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void (*merge)(gcov_type *, unsigned int);
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};
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/**
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* struct gcov_info - profiling data per object file
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* @version: gcov version magic indicating the gcc version used for compilation
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* @next: list head for a singly-linked list
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* @stamp: time stamp
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* @filename: name of the associated gcov data file
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* @n_functions: number of instrumented functions
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* @functions: function data
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* @ctr_mask: mask specifying which counter types are active
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* @counts: counter data per counter type
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*
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* This data is generated by gcc during compilation and doesn't change
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* at run-time with the exception of the next pointer.
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*/
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struct gcov_info {
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unsigned int version;
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struct gcov_info *next;
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unsigned int stamp;
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const char *filename;
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unsigned int n_functions;
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const struct gcov_fn_info *functions;
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unsigned int ctr_mask;
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struct gcov_ctr_info counts[0];
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};
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/**
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* gcov_info_filename - return info filename
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* @info: profiling data set
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*/
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const char *gcov_info_filename(struct gcov_info *info)
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{
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return info->filename;
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}
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/**
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* gcov_info_version - return info version
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* @info: profiling data set
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*/
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unsigned int gcov_info_version(struct gcov_info *info)
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{
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return info->version;
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}
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/**
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* gcov_info_next - return next profiling data set
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* @info: profiling data set
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*
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* Returns next gcov_info following @info or first gcov_info in the chain if
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* @info is %NULL.
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*/
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struct gcov_info *gcov_info_next(struct gcov_info *info)
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{
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if (!info)
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return gcov_info_head;
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return info->next;
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}
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/**
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* gcov_info_link - link/add profiling data set to the list
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* @info: profiling data set
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*/
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void gcov_info_link(struct gcov_info *info)
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{
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info->next = gcov_info_head;
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gcov_info_head = info;
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}
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/**
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* gcov_info_unlink - unlink/remove profiling data set from the list
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* @prev: previous profiling data set
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* @info: profiling data set
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*/
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void gcov_info_unlink(struct gcov_info *prev, struct gcov_info *info)
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{
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if (prev)
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prev->next = info->next;
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else
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gcov_info_head = info->next;
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}
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/**
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* gcov_info_within_module - check if a profiling data set belongs to a module
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* @info: profiling data set
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* @mod: module
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*
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* Returns true if profiling data belongs module, false otherwise.
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*/
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bool gcov_info_within_module(struct gcov_info *info, struct module *mod)
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{
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return within_module((unsigned long)info, mod);
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}
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/* Symbolic links to be created for each profiling data file. */
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const struct gcov_link gcov_link[] = {
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{ OBJ_TREE, "gcno" }, /* Link to .gcno file in $(objtree). */
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{ 0, NULL},
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};
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/*
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* Determine whether a counter is active. Based on gcc magic. Doesn't change
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* at run-time.
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*/
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static int counter_active(struct gcov_info *info, unsigned int type)
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{
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return (1 << type) & info->ctr_mask;
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}
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/* Determine number of active counters. Based on gcc magic. */
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static unsigned int num_counter_active(struct gcov_info *info)
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{
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unsigned int i;
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unsigned int result = 0;
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for (i = 0; i < GCOV_COUNTERS; i++) {
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if (counter_active(info, i))
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result++;
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}
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return result;
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}
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/**
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* gcov_info_reset - reset profiling data to zero
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* @info: profiling data set
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*/
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void gcov_info_reset(struct gcov_info *info)
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{
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unsigned int active = num_counter_active(info);
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unsigned int i;
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for (i = 0; i < active; i++) {
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memset(info->counts[i].values, 0,
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info->counts[i].num * sizeof(gcov_type));
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}
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}
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/**
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* gcov_info_is_compatible - check if profiling data can be added
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* @info1: first profiling data set
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* @info2: second profiling data set
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*
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* Returns non-zero if profiling data can be added, zero otherwise.
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*/
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int gcov_info_is_compatible(struct gcov_info *info1, struct gcov_info *info2)
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{
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return (info1->stamp == info2->stamp);
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}
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/**
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* gcov_info_add - add up profiling data
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* @dest: profiling data set to which data is added
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* @source: profiling data set which is added
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*
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* Adds profiling counts of @source to @dest.
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*/
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void gcov_info_add(struct gcov_info *dest, struct gcov_info *source)
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{
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unsigned int i;
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unsigned int j;
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for (i = 0; i < num_counter_active(dest); i++) {
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for (j = 0; j < dest->counts[i].num; j++) {
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dest->counts[i].values[j] +=
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source->counts[i].values[j];
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}
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}
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}
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/* Get size of function info entry. Based on gcc magic. */
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static size_t get_fn_size(struct gcov_info *info)
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{
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size_t size;
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size = sizeof(struct gcov_fn_info) + num_counter_active(info) *
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sizeof(unsigned int);
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if (__alignof__(struct gcov_fn_info) > sizeof(unsigned int))
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size = ALIGN(size, __alignof__(struct gcov_fn_info));
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return size;
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}
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/* Get address of function info entry. Based on gcc magic. */
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static struct gcov_fn_info *get_fn_info(struct gcov_info *info, unsigned int fn)
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{
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return (struct gcov_fn_info *)
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((char *) info->functions + fn * get_fn_size(info));
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}
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/**
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* gcov_info_dup - duplicate profiling data set
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* @info: profiling data set to duplicate
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*
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* Return newly allocated duplicate on success, %NULL on error.
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*/
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struct gcov_info *gcov_info_dup(struct gcov_info *info)
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{
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struct gcov_info *dup;
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unsigned int i;
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unsigned int active;
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/* Duplicate gcov_info. */
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active = num_counter_active(info);
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dup = kzalloc(struct_size(dup, counts, active), GFP_KERNEL);
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if (!dup)
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return NULL;
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dup->version = info->version;
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dup->stamp = info->stamp;
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dup->n_functions = info->n_functions;
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dup->ctr_mask = info->ctr_mask;
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/* Duplicate filename. */
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dup->filename = kstrdup(info->filename, GFP_KERNEL);
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if (!dup->filename)
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goto err_free;
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/* Duplicate table of functions. */
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dup->functions = kmemdup(info->functions, info->n_functions *
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get_fn_size(info), GFP_KERNEL);
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if (!dup->functions)
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goto err_free;
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/* Duplicate counter arrays. */
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for (i = 0; i < active ; i++) {
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struct gcov_ctr_info *ctr = &info->counts[i];
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size_t size = ctr->num * sizeof(gcov_type);
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dup->counts[i].num = ctr->num;
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dup->counts[i].merge = ctr->merge;
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dup->counts[i].values = vmalloc(size);
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if (!dup->counts[i].values)
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goto err_free;
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memcpy(dup->counts[i].values, ctr->values, size);
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}
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return dup;
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err_free:
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gcov_info_free(dup);
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return NULL;
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}
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/**
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* gcov_info_free - release memory for profiling data set duplicate
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* @info: profiling data set duplicate to free
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*/
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void gcov_info_free(struct gcov_info *info)
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{
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unsigned int active = num_counter_active(info);
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unsigned int i;
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for (i = 0; i < active ; i++)
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vfree(info->counts[i].values);
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kfree(info->functions);
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kfree(info->filename);
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kfree(info);
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}
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/**
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* struct type_info - iterator helper array
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* @ctr_type: counter type
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* @offset: index of the first value of the current function for this type
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*
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* This array is needed to convert the in-memory data format into the in-file
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* data format:
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*
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* In-memory:
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* for each counter type
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* for each function
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* values
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*
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* In-file:
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* for each function
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* for each counter type
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* values
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*
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* See gcc source gcc/gcov-io.h for more information on data organization.
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*/
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struct type_info {
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int ctr_type;
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unsigned int offset;
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};
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/**
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* struct gcov_iterator - specifies current file position in logical records
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* @info: associated profiling data
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* @record: record type
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* @function: function number
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* @type: counter type
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* @count: index into values array
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* @num_types: number of counter types
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* @type_info: helper array to get values-array offset for current function
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*/
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struct gcov_iterator {
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struct gcov_info *info;
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int record;
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unsigned int function;
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unsigned int type;
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unsigned int count;
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int num_types;
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struct type_info type_info[0];
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};
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static struct gcov_fn_info *get_func(struct gcov_iterator *iter)
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{
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return get_fn_info(iter->info, iter->function);
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}
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static struct type_info *get_type(struct gcov_iterator *iter)
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{
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return &iter->type_info[iter->type];
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}
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/**
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* gcov_iter_new - allocate and initialize profiling data iterator
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* @info: profiling data set to be iterated
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*
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* Return file iterator on success, %NULL otherwise.
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*/
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struct gcov_iterator *gcov_iter_new(struct gcov_info *info)
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{
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struct gcov_iterator *iter;
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iter = kzalloc(struct_size(iter, type_info, num_counter_active(info)),
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GFP_KERNEL);
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if (iter)
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iter->info = info;
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return iter;
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}
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/**
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* gcov_iter_free - release memory for iterator
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* @iter: file iterator to free
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*/
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void gcov_iter_free(struct gcov_iterator *iter)
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{
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kfree(iter);
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}
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/**
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* gcov_iter_get_info - return profiling data set for given file iterator
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* @iter: file iterator
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*/
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struct gcov_info *gcov_iter_get_info(struct gcov_iterator *iter)
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{
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return iter->info;
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}
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/**
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* gcov_iter_start - reset file iterator to starting position
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* @iter: file iterator
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*/
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void gcov_iter_start(struct gcov_iterator *iter)
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{
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int i;
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iter->record = 0;
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iter->function = 0;
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iter->type = 0;
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iter->count = 0;
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iter->num_types = 0;
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for (i = 0; i < GCOV_COUNTERS; i++) {
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if (counter_active(iter->info, i)) {
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iter->type_info[iter->num_types].ctr_type = i;
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iter->type_info[iter->num_types++].offset = 0;
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}
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}
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}
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/* Mapping of logical record number to actual file content. */
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#define RECORD_FILE_MAGIC 0
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#define RECORD_GCOV_VERSION 1
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#define RECORD_TIME_STAMP 2
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#define RECORD_FUNCTION_TAG 3
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#define RECORD_FUNCTON_TAG_LEN 4
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#define RECORD_FUNCTION_IDENT 5
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#define RECORD_FUNCTION_CHECK 6
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#define RECORD_COUNT_TAG 7
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#define RECORD_COUNT_LEN 8
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#define RECORD_COUNT 9
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/**
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* gcov_iter_next - advance file iterator to next logical record
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* @iter: file iterator
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*
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* Return zero if new position is valid, non-zero if iterator has reached end.
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*/
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int gcov_iter_next(struct gcov_iterator *iter)
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{
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switch (iter->record) {
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case RECORD_FILE_MAGIC:
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case RECORD_GCOV_VERSION:
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case RECORD_FUNCTION_TAG:
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case RECORD_FUNCTON_TAG_LEN:
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case RECORD_FUNCTION_IDENT:
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case RECORD_COUNT_TAG:
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/* Advance to next record */
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iter->record++;
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break;
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case RECORD_COUNT:
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/* Advance to next count */
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iter->count++;
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/* fall through */
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case RECORD_COUNT_LEN:
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if (iter->count < get_func(iter)->n_ctrs[iter->type]) {
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iter->record = 9;
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break;
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}
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/* Advance to next counter type */
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get_type(iter)->offset += iter->count;
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iter->count = 0;
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iter->type++;
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/* fall through */
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case RECORD_FUNCTION_CHECK:
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if (iter->type < iter->num_types) {
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iter->record = 7;
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break;
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}
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/* Advance to next function */
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iter->type = 0;
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iter->function++;
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/* fall through */
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case RECORD_TIME_STAMP:
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if (iter->function < iter->info->n_functions)
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iter->record = 3;
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else
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iter->record = -1;
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break;
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}
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/* Check for EOF. */
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if (iter->record == -1)
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return -EINVAL;
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else
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return 0;
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}
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/**
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* seq_write_gcov_u32 - write 32 bit number in gcov format to seq_file
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* @seq: seq_file handle
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* @v: value to be stored
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*
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* Number format defined by gcc: numbers are recorded in the 32 bit
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* unsigned binary form of the endianness of the machine generating the
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* file.
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*/
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static int seq_write_gcov_u32(struct seq_file *seq, u32 v)
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{
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return seq_write(seq, &v, sizeof(v));
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}
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/**
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* seq_write_gcov_u64 - write 64 bit number in gcov format to seq_file
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* @seq: seq_file handle
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* @v: value to be stored
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*
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* 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)
|
|
{
|
|
int rc = -EINVAL;
|
|
|
|
switch (iter->record) {
|
|
case RECORD_FILE_MAGIC:
|
|
rc = seq_write_gcov_u32(seq, GCOV_DATA_MAGIC);
|
|
break;
|
|
case RECORD_GCOV_VERSION:
|
|
rc = seq_write_gcov_u32(seq, iter->info->version);
|
|
break;
|
|
case RECORD_TIME_STAMP:
|
|
rc = seq_write_gcov_u32(seq, iter->info->stamp);
|
|
break;
|
|
case RECORD_FUNCTION_TAG:
|
|
rc = seq_write_gcov_u32(seq, GCOV_TAG_FUNCTION);
|
|
break;
|
|
case RECORD_FUNCTON_TAG_LEN:
|
|
rc = seq_write_gcov_u32(seq, 2);
|
|
break;
|
|
case RECORD_FUNCTION_IDENT:
|
|
rc = seq_write_gcov_u32(seq, get_func(iter)->ident);
|
|
break;
|
|
case RECORD_FUNCTION_CHECK:
|
|
rc = seq_write_gcov_u32(seq, get_func(iter)->checksum);
|
|
break;
|
|
case RECORD_COUNT_TAG:
|
|
rc = seq_write_gcov_u32(seq,
|
|
GCOV_TAG_FOR_COUNTER(get_type(iter)->ctr_type));
|
|
break;
|
|
case RECORD_COUNT_LEN:
|
|
rc = seq_write_gcov_u32(seq,
|
|
get_func(iter)->n_ctrs[iter->type] * 2);
|
|
break;
|
|
case RECORD_COUNT:
|
|
rc = seq_write_gcov_u64(seq,
|
|
iter->info->counts[iter->type].
|
|
values[iter->count + get_type(iter)->offset]);
|
|
break;
|
|
}
|
|
return rc;
|
|
}
|