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![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>
582 lines
14 KiB
C
582 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 4.7.
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*
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* This file is based heavily on gcc_3_4.c file.
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*
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* For a better understanding, refer to gcc source:
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* gcc/gcov-io.h
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* libgcc/libgcov.c
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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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#if (__GNUC__ >= 7)
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#define GCOV_COUNTERS 9
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#elif (__GNUC__ > 5) || (__GNUC__ == 5 && __GNUC_MINOR__ >= 1)
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#define GCOV_COUNTERS 10
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#elif __GNUC__ == 4 && __GNUC_MINOR__ >= 9
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#define GCOV_COUNTERS 9
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#else
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#define GCOV_COUNTERS 8
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#endif
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#define GCOV_TAG_FUNCTION_LENGTH 3
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static struct gcov_info *gcov_info_head;
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/**
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* struct gcov_ctr_info - information about counters for a single function
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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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*
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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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};
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/**
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* struct gcov_fn_info - profiling meta data per function
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* @key: comdat key
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* @ident: unique ident of function
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* @lineno_checksum: function lineo_checksum
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* @cfg_checksum: function cfg checksum
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* @ctrs: instrumented counters
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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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* Information about a single function. This uses the trailing array
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* idiom. The number of counters is determined from the merge pointer
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* array in gcov_info. The key is used to detect which of a set of
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* comdat functions was selected -- it points to the gcov_info object
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* of the object file containing the selected comdat function.
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*/
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struct gcov_fn_info {
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const struct gcov_info *key;
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unsigned int ident;
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unsigned int lineno_checksum;
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unsigned int cfg_checksum;
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struct gcov_ctr_info ctrs[0];
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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: uniquifying time stamp
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* @filename: name of the associated gcov data file
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* @merge: merge functions (null for unused counter type)
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* @n_functions: number of instrumented functions
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* @functions: pointer to pointers to function information
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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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void (*merge[GCOV_COUNTERS])(gcov_type *, unsigned int);
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unsigned int n_functions;
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struct gcov_fn_info **functions;
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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. Doesn't change 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 info->merge[type] ? 1 : 0;
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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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struct gcov_ctr_info *ci_ptr;
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unsigned int fi_idx;
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unsigned int ct_idx;
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for (fi_idx = 0; fi_idx < info->n_functions; fi_idx++) {
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ci_ptr = info->functions[fi_idx]->ctrs;
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for (ct_idx = 0; ct_idx < GCOV_COUNTERS; ct_idx++) {
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if (!counter_active(info, ct_idx))
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continue;
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memset(ci_ptr->values, 0,
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sizeof(gcov_type) * ci_ptr->num);
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ci_ptr++;
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}
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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 *dst, struct gcov_info *src)
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{
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struct gcov_ctr_info *dci_ptr;
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struct gcov_ctr_info *sci_ptr;
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unsigned int fi_idx;
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unsigned int ct_idx;
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unsigned int val_idx;
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for (fi_idx = 0; fi_idx < src->n_functions; fi_idx++) {
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dci_ptr = dst->functions[fi_idx]->ctrs;
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sci_ptr = src->functions[fi_idx]->ctrs;
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for (ct_idx = 0; ct_idx < GCOV_COUNTERS; ct_idx++) {
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if (!counter_active(src, ct_idx))
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continue;
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for (val_idx = 0; val_idx < sci_ptr->num; val_idx++)
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dci_ptr->values[val_idx] +=
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sci_ptr->values[val_idx];
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dci_ptr++;
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sci_ptr++;
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}
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}
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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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struct gcov_ctr_info *dci_ptr; /* dst counter info */
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struct gcov_ctr_info *sci_ptr; /* src counter info */
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unsigned int active;
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unsigned int fi_idx; /* function info idx */
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unsigned int ct_idx; /* counter type idx */
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size_t fi_size; /* function info size */
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size_t cv_size; /* counter values size */
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dup = kmemdup(info, sizeof(*dup), GFP_KERNEL);
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if (!dup)
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return NULL;
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dup->next = NULL;
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dup->filename = NULL;
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dup->functions = NULL;
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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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dup->functions = kcalloc(info->n_functions,
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sizeof(struct gcov_fn_info *), GFP_KERNEL);
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if (!dup->functions)
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goto err_free;
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active = num_counter_active(info);
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fi_size = sizeof(struct gcov_fn_info);
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fi_size += sizeof(struct gcov_ctr_info) * active;
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for (fi_idx = 0; fi_idx < info->n_functions; fi_idx++) {
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dup->functions[fi_idx] = kzalloc(fi_size, GFP_KERNEL);
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if (!dup->functions[fi_idx])
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goto err_free;
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*(dup->functions[fi_idx]) = *(info->functions[fi_idx]);
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sci_ptr = info->functions[fi_idx]->ctrs;
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dci_ptr = dup->functions[fi_idx]->ctrs;
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for (ct_idx = 0; ct_idx < active; ct_idx++) {
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cv_size = sizeof(gcov_type) * sci_ptr->num;
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dci_ptr->values = vmalloc(cv_size);
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if (!dci_ptr->values)
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goto err_free;
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dci_ptr->num = sci_ptr->num;
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memcpy(dci_ptr->values, sci_ptr->values, cv_size);
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sci_ptr++;
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dci_ptr++;
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}
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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;
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unsigned int fi_idx;
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unsigned int ct_idx;
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struct gcov_ctr_info *ci_ptr;
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if (!info->functions)
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goto free_info;
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active = num_counter_active(info);
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for (fi_idx = 0; fi_idx < info->n_functions; fi_idx++) {
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if (!info->functions[fi_idx])
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continue;
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ci_ptr = info->functions[fi_idx]->ctrs;
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for (ct_idx = 0; ct_idx < active; ct_idx++, ci_ptr++)
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vfree(ci_ptr->values);
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kfree(info->functions[fi_idx]);
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}
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free_info:
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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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#define ITER_STRIDE PAGE_SIZE
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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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* @buffer: buffer containing file data
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* @size: size of buffer
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* @pos: current position in file
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*/
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struct gcov_iterator {
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struct gcov_info *info;
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void *buffer;
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size_t size;
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loff_t pos;
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};
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/**
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* store_gcov_u32 - store 32 bit number in gcov format to buffer
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* @buffer: target buffer or NULL
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* @off: offset into the buffer
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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. Returns the number of bytes stored. If @buffer is %NULL, doesn't
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* store anything.
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*/
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static size_t store_gcov_u32(void *buffer, size_t off, u32 v)
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{
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u32 *data;
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if (buffer) {
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data = buffer + off;
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*data = v;
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}
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return sizeof(*data);
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}
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/**
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* store_gcov_u64 - store 64 bit number in gcov format to buffer
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* @buffer: target buffer or NULL
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* @off: offset into the buffer
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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. 64 bit numbers are stored as two 32 bit numbers, the low part
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* first. Returns the number of bytes stored. If @buffer is %NULL, doesn't store
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* anything.
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*/
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static size_t store_gcov_u64(void *buffer, size_t off, u64 v)
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{
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u32 *data;
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if (buffer) {
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data = buffer + off;
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data[0] = (v & 0xffffffffUL);
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data[1] = (v >> 32);
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}
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return sizeof(*data) * 2;
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}
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/**
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* convert_to_gcda - convert profiling data set to gcda file format
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* @buffer: the buffer to store file data or %NULL if no data should be stored
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* @info: profiling data set to be converted
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*
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* Returns the number of bytes that were/would have been stored into the buffer.
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*/
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static size_t convert_to_gcda(char *buffer, struct gcov_info *info)
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{
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struct gcov_fn_info *fi_ptr;
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struct gcov_ctr_info *ci_ptr;
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unsigned int fi_idx;
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unsigned int ct_idx;
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unsigned int cv_idx;
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size_t pos = 0;
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/* File header. */
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pos += store_gcov_u32(buffer, pos, GCOV_DATA_MAGIC);
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pos += store_gcov_u32(buffer, pos, info->version);
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pos += store_gcov_u32(buffer, pos, info->stamp);
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for (fi_idx = 0; fi_idx < info->n_functions; fi_idx++) {
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fi_ptr = info->functions[fi_idx];
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/* Function record. */
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pos += store_gcov_u32(buffer, pos, GCOV_TAG_FUNCTION);
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pos += store_gcov_u32(buffer, pos, GCOV_TAG_FUNCTION_LENGTH);
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pos += store_gcov_u32(buffer, pos, fi_ptr->ident);
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pos += store_gcov_u32(buffer, pos, fi_ptr->lineno_checksum);
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pos += store_gcov_u32(buffer, pos, fi_ptr->cfg_checksum);
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ci_ptr = fi_ptr->ctrs;
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for (ct_idx = 0; ct_idx < GCOV_COUNTERS; ct_idx++) {
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if (!counter_active(info, ct_idx))
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continue;
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/* Counter record. */
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pos += store_gcov_u32(buffer, pos,
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GCOV_TAG_FOR_COUNTER(ct_idx));
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pos += store_gcov_u32(buffer, pos, ci_ptr->num * 2);
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for (cv_idx = 0; cv_idx < ci_ptr->num; cv_idx++) {
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pos += store_gcov_u64(buffer, pos,
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ci_ptr->values[cv_idx]);
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}
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ci_ptr++;
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}
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}
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return pos;
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}
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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(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;
|
|
}
|
|
|
|
|
|
/**
|
|
* 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);
|
|
}
|
|
|
|
/**
|
|
* 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)
|
|
{
|
|
iter->pos = 0;
|
|
}
|
|
|
|
/**
|
|
* 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;
|
|
}
|
|
|
|
/**
|
|
* 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;
|
|
}
|