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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#include <sys/types.h>#include <sys/stat.h>#include <getopt.h>#include <fcntl.h>#include <stdio.h>#include <stdlib.h>#include <stdbool.h>#include <string.h>#include <unistd.h>#include <errno.h>#include <pthread.h>
#include "elf-parse.h"
static Elf_Shdr *check_data_sec;static Elf_Shdr *tracepoint_data_sec;
static inline void *get_index(void *start, int entsize, int index){ return start + (entsize * index);}
static int compare_strings(const void *a, const void *b){ const char *av = *(const char **)a; const char *bv = *(const char **)b;
return strcmp(av, bv);}
struct elf_tracepoint { Elf_Ehdr *ehdr; const char **array; int count;};
#define REALLOC_SIZE (1 << 10)#define REALLOC_MASK (REALLOC_SIZE - 1)
static int add_string(const char *str, const char ***vals, int *count){ const char **array = *vals;
if (!(*count & REALLOC_MASK)) { int size = (*count) + REALLOC_SIZE;
array = realloc(array, sizeof(char *) * size); if (!array) { fprintf(stderr, "Failed memory allocation\n"); free(*vals); *vals = NULL; return -1; } *vals = array; }
array[(*count)++] = str; return 0;}
/** * for_each_shdr_str - iterator that reads strings that are in an ELF section. * @len: "int" to hold the length of the current string * @ehdr: A pointer to the ehdr of the ELF file * @sec: The section that has the strings to iterate on * * This is a for loop that iterates over all the nul terminated strings * that are in a given ELF section. The variable "str" will hold * the current string for each iteration and the passed in @len will * contain the strlen() of that string. */#define for_each_shdr_str(len, ehdr, sec) \ for (const char *str = (void *)(ehdr) + shdr_offset(sec), \ *end = str + shdr_size(sec); \ len = strlen(str), str < end; \ str += (len) + 1)
static void make_trace_array(struct elf_tracepoint *etrace){ Elf_Ehdr *ehdr = etrace->ehdr; const char **vals = NULL; int count = 0; int len;
etrace->array = NULL;
/* * The __tracepoint_check section is filled with strings of the * names of tracepoints (in tracepoint_strings). Create an array * that points to each string and then sort the array. */ for_each_shdr_str(len, ehdr, check_data_sec) { if (!len) continue; if (add_string(str, &vals, &count) < 0) return; }
/* If CONFIG_TRACEPOINT_VERIFY_USED is not set, there's nothing to do */ if (!count) return;
qsort(vals, count, sizeof(char *), compare_strings);
etrace->array = vals; etrace->count = count;}
static int find_event(const char *str, void *array, size_t size){ return bsearch(&str, array, size, sizeof(char *), compare_strings) != NULL;}
static void check_tracepoints(struct elf_tracepoint *etrace, const char *fname){ Elf_Ehdr *ehdr = etrace->ehdr; int len;
if (!etrace->array) return;
/* * The __tracepoints_strings section holds all the names of the * defined tracepoints. If any of them are not in the * __tracepoint_check_section it means they are not used. */ for_each_shdr_str(len, ehdr, tracepoint_data_sec) { if (!len) continue; if (!find_event(str, etrace->array, etrace->count)) { fprintf(stderr, "warning: tracepoint '%s' is unused", str); if (fname) fprintf(stderr, " in module %s\n", fname); else fprintf(stderr, "\n"); } }
free(etrace->array);}
static void *tracepoint_check(struct elf_tracepoint *etrace, const char *fname){ make_trace_array(etrace); check_tracepoints(etrace, fname);
return NULL;}
static int process_tracepoints(bool mod, void *addr, const char *fname){ struct elf_tracepoint etrace = {0}; Elf_Ehdr *ehdr = addr; Elf_Shdr *shdr_start; Elf_Shdr *string_sec; const char *secstrings; unsigned int shnum; unsigned int shstrndx; int shentsize; int idx; int done = 2;
shdr_start = (Elf_Shdr *)((char *)ehdr + ehdr_shoff(ehdr)); shentsize = ehdr_shentsize(ehdr);
shstrndx = ehdr_shstrndx(ehdr); if (shstrndx == SHN_XINDEX) shstrndx = shdr_link(shdr_start); string_sec = get_index(shdr_start, shentsize, shstrndx); secstrings = (const char *)ehdr + shdr_offset(string_sec);
shnum = ehdr_shnum(ehdr); if (shnum == SHN_UNDEF) shnum = shdr_size(shdr_start);
for (int i = 0; done && i < shnum; i++) { Elf_Shdr *shdr = get_index(shdr_start, shentsize, i);
idx = shdr_name(shdr);
/* locate the __tracepoint_check in vmlinux */ if (!strcmp(secstrings + idx, "__tracepoint_check")) { check_data_sec = shdr; done--; }
/* locate the __tracepoints_ptrs section in vmlinux */ if (!strcmp(secstrings + idx, "__tracepoints_strings")) { tracepoint_data_sec = shdr; done--; } }
/* * Modules may not have either section. But if it has one section, * it should have both of them. */ if (mod && !check_data_sec && !tracepoint_data_sec) return 0;
if (!check_data_sec) { if (mod) { fprintf(stderr, "warning: Module %s has only unused tracepoints\n", fname); /* Do not fail build */ return 0; } fprintf(stderr, "no __tracepoint_check in file: %s\n", fname); return -1; }
if (!tracepoint_data_sec) { /* A module may reference only exported tracepoints */ if (mod) return 0; fprintf(stderr, "no __tracepoint_strings in file: %s\n", fname); return -1; }
if (!mod) fname = NULL;
etrace.ehdr = ehdr; tracepoint_check(&etrace, fname); return 0;}
int main(int argc, char *argv[]){ int n_error = 0; size_t size = 0; void *addr = NULL; bool mod = false;
if (argc > 1 && strcmp(argv[1], "--module") == 0) { mod = true; argc--; argv++; }
if (argc < 2) { if (mod) fprintf(stderr, "usage: tracepoint-update --module module...\n"); else fprintf(stderr, "usage: tracepoint-update vmlinux...\n"); return 0; }
/* Process each file in turn, allowing deep failure. */ for (int i = 1; i < argc; i++) { addr = elf_map(argv[i], &size, 1 << ET_REL); if (!addr) { ++n_error; continue; }
if (process_tracepoints(mod, addr, argv[i])) ++n_error;
elf_unmap(addr, size); }
return !!n_error;}