Functions in the .opd section on ppc64 are currently ignored as they don't contain mcount calls -- they are excluded by the ftrace filter. Therefore, pahole cannot produce a .BTF section from vmlinux and kernel build fails on ppc64. Remove the ftrace filter completely as was discussed: https://lore.kernel.org/bpf/20210501001653.x3b4rk4vk4iqv3n7@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ https://lore.kernel.org/bpf/YI%2FLgjLxo9VCN%2Fd+@krava/ [v2] remove sh and sym_sec_idx from collect_function as suggested by Jirka Signed-off-by: Jiri Slaby <jslaby@xxxxxxx> Cc: Martin KaFai Lau <kafai@xxxxxx> Cc: Jiri Olsa <jolsa@xxxxxxxxxx> --- btf_encoder.c | 285 ++------------------------------------------------ 1 file changed, 7 insertions(+), 278 deletions(-) diff --git a/btf_encoder.c b/btf_encoder.c index 80e896961d4e..7e1117c58449 100644 --- a/btf_encoder.c +++ b/btf_encoder.c @@ -27,17 +27,8 @@ */ #define KSYM_NAME_LEN 128 -struct funcs_layout { - unsigned long mcount_start; - unsigned long mcount_stop; - unsigned long mcount_sec_idx; -}; - struct elf_function { const char *name; - unsigned long addr; - unsigned long size; - unsigned long sh_addr; bool generated; }; @@ -64,12 +55,9 @@ static void delete_functions(void) #define max(x, y) ((x) < (y) ? (y) : (x)) #endif -static int collect_function(struct btf_elf *btfe, GElf_Sym *sym, - size_t sym_sec_idx) +static int collect_function(struct btf_elf *btfe, GElf_Sym *sym) { struct elf_function *new; - static GElf_Shdr sh; - static size_t last_idx; const char *name; if (elf_sym__type(sym) != STT_FUNC) @@ -91,257 +79,12 @@ static int collect_function(struct btf_elf *btfe, GElf_Sym *sym, functions = new; } - if (sym_sec_idx != last_idx) { - if (!elf_section_by_idx(btfe->elf, &sh, sym_sec_idx)) - return 0; - last_idx = sym_sec_idx; - } - functions[functions_cnt].name = name; - functions[functions_cnt].addr = elf_sym__value(sym); - functions[functions_cnt].size = elf_sym__size(sym); - functions[functions_cnt].sh_addr = sh.sh_addr; functions[functions_cnt].generated = false; functions_cnt++; return 0; } -static int addrs_cmp(const void *_a, const void *_b) -{ - const __u64 *a = _a; - const __u64 *b = _b; - - if (*a == *b) - return 0; - return *a < *b ? -1 : 1; -} - -static int get_vmlinux_addrs(struct btf_elf *btfe, struct funcs_layout *fl, - __u64 **paddrs, __u64 *pcount) -{ - __u64 *addrs, count, offset; - unsigned int addr_size, i; - Elf_Data *data; - GElf_Shdr shdr; - Elf_Scn *sec; - - /* Initialize for the sake of all error paths below. */ - *paddrs = NULL; - *pcount = 0; - - if (!fl->mcount_start || !fl->mcount_stop) - return 0; - - /* - * Find mcount addressed marked by __start_mcount_loc - * and __stop_mcount_loc symbols and load them into - * sorted array. - */ - sec = elf_getscn(btfe->elf, fl->mcount_sec_idx); - if (!sec || !gelf_getshdr(sec, &shdr)) { - fprintf(stderr, "Failed to get section(%lu) header.\n", - fl->mcount_sec_idx); - return -1; - } - - /* Get address size from processed file's ELF class. */ - addr_size = gelf_getclass(btfe->elf) == ELFCLASS32 ? 4 : 8; - - offset = fl->mcount_start - shdr.sh_addr; - count = (fl->mcount_stop - fl->mcount_start) / addr_size; - - data = elf_getdata(sec, 0); - if (!data) { - fprintf(stderr, "Failed to get section(%lu) data.\n", - fl->mcount_sec_idx); - return -1; - } - - addrs = malloc(count * sizeof(addrs[0])); - if (!addrs) { - fprintf(stderr, "Failed to allocate memory for ftrace addresses.\n"); - return -1; - } - - if (addr_size == sizeof(__u64)) { - memcpy(addrs, data->d_buf + offset, count * addr_size); - } else { - for (i = 0; i < count; i++) - addrs[i] = (__u64) *((__u32 *) (data->d_buf + offset + i * addr_size)); - } - - *paddrs = addrs; - *pcount = count; - return 0; -} - -static int -get_kmod_addrs(struct btf_elf *btfe, __u64 **paddrs, __u64 *pcount) -{ - __u64 *addrs, count; - unsigned int addr_size, i; - GElf_Shdr shdr_mcount; - Elf_Data *data; - Elf_Scn *sec; - - /* Initialize for the sake of all error paths below. */ - *paddrs = NULL; - *pcount = 0; - - /* get __mcount_loc */ - sec = elf_section_by_name(btfe->elf, &btfe->ehdr, &shdr_mcount, - "__mcount_loc", NULL); - if (!sec) { - if (btf_elf__verbose) { - printf("%s: '%s' doesn't have __mcount_loc section\n", __func__, - btfe->filename); - } - return 0; - } - - data = elf_getdata(sec, NULL); - if (!data) { - fprintf(stderr, "Failed to data for __mcount_loc section.\n"); - return -1; - } - - /* Get address size from processed file's ELF class. */ - addr_size = gelf_getclass(btfe->elf) == ELFCLASS32 ? 4 : 8; - - count = data->d_size / addr_size; - - addrs = malloc(count * sizeof(addrs[0])); - if (!addrs) { - fprintf(stderr, "Failed to allocate memory for ftrace addresses.\n"); - return -1; - } - - if (addr_size == sizeof(__u64)) { - memcpy(addrs, data->d_buf, count * addr_size); - } else { - for (i = 0; i < count; i++) - addrs[i] = (__u64) *((__u32 *) (data->d_buf + i * addr_size)); - } - - /* - * We get Elf object from dwfl_module_getelf function, - * which performs all possible relocations, including - * __mcount_loc section. - * - * So addrs array now contains relocated values, which - * we need take into account when we compare them to - * functions values, see comment in setup_functions - * function. - */ - *paddrs = addrs; - *pcount = count; - return 0; -} - -static int is_ftrace_func(struct elf_function *func, __u64 *addrs, __u64 count) -{ - __u64 start = func->addr; - __u64 addr, end = func->addr + func->size; - - /* - * The invariant here is addr[r] that is the smallest address - * that is >= than function start addr. Except the corner case - * where there is no such r, but for that we have a final check - * in the return. - */ - size_t l = 0, r = count - 1, m; - - /* make sure we don't use invalid r */ - if (count == 0) - return false; - - while (l < r) { - m = l + (r - l) / 2; - addr = addrs[m]; - - if (addr >= start) { - /* we satisfy invariant, so tighten r */ - r = m; - } else { - /* m is not good enough as l, maybe m + 1 will be */ - l = m + 1; - } - } - - return start <= addrs[r] && addrs[r] < end; -} - -static int setup_functions(struct btf_elf *btfe, struct funcs_layout *fl) -{ - __u64 *addrs, count, i; - int functions_valid = 0; - bool kmod = false; - - /* - * Check if we are processing vmlinux image and - * get mcount data if it's detected. - */ - if (get_vmlinux_addrs(btfe, fl, &addrs, &count)) - return -1; - - /* - * Check if we are processing kernel module and - * get mcount data if it's detected. - */ - if (!addrs) { - if (get_kmod_addrs(btfe, &addrs, &count)) - return -1; - kmod = true; - } - - if (!addrs) { - if (btf_elf__verbose) - printf("ftrace symbols not detected, falling back to DWARF data\n"); - delete_functions(); - return 0; - } - - qsort(addrs, count, sizeof(addrs[0]), addrs_cmp); - qsort(functions, functions_cnt, sizeof(functions[0]), functions_cmp); - - /* - * Let's got through all collected functions and filter - * out those that are not in ftrace. - */ - for (i = 0; i < functions_cnt; i++) { - struct elf_function *func = &functions[i]; - /* - * For vmlinux image both addrs[x] and functions[x]::addr - * values are final address and are comparable. - * - * For kernel module addrs[x] is final address, but - * functions[x]::addr is relative address within section - * and needs to be relocated by adding sh_addr. - */ - if (kmod) - func->addr += func->sh_addr; - - /* Make sure function is within ftrace addresses. */ - if (is_ftrace_func(func, addrs, count)) { - /* - * We iterate over sorted array, so we can easily skip - * not valid item and move following valid field into - * its place, and still keep the 'new' array sorted. - */ - if (i != functions_valid) - functions[functions_valid] = functions[i]; - functions_valid++; - } - } - - functions_cnt = functions_valid; - free(addrs); - - if (btf_elf__verbose) - printf("Found %d functions!\n", functions_cnt); - return 0; -} - static struct elf_function *find_function(const struct btf_elf *btfe, const char *name) { @@ -620,23 +363,8 @@ static int collect_percpu_var(struct btf_elf *btfe, GElf_Sym *sym, return 0; } -static void collect_symbol(GElf_Sym *sym, struct funcs_layout *fl, - size_t sym_sec_idx) -{ - if (!fl->mcount_start && - !strcmp("__start_mcount_loc", elf_sym__name(sym, btfe->symtab))) { - fl->mcount_start = sym->st_value; - fl->mcount_sec_idx = sym_sec_idx; - } - - if (!fl->mcount_stop && - !strcmp("__stop_mcount_loc", elf_sym__name(sym, btfe->symtab))) - fl->mcount_stop = sym->st_value; -} - static int collect_symbols(struct btf_elf *btfe, bool collect_percpu_vars) { - struct funcs_layout fl = { }; Elf32_Word sym_sec_idx; uint32_t core_id; GElf_Sym sym; @@ -648,9 +376,8 @@ static int collect_symbols(struct btf_elf *btfe, bool collect_percpu_vars) elf_symtab__for_each_symbol_index(btfe->symtab, core_id, sym, sym_sec_idx) { if (collect_percpu_vars && collect_percpu_var(btfe, &sym, sym_sec_idx)) return -1; - if (collect_function(btfe, &sym, sym_sec_idx)) + if (collect_function(btfe, &sym)) return -1; - collect_symbol(&sym, &fl, sym_sec_idx); } if (collect_percpu_vars) { @@ -661,9 +388,11 @@ static int collect_symbols(struct btf_elf *btfe, bool collect_percpu_vars) printf("Found %d per-CPU variables!\n", percpu_var_cnt); } - if (functions_cnt && setup_functions(btfe, &fl)) { - fprintf(stderr, "Failed to filter DWARF functions\n"); - return -1; + if (functions_cnt) { + qsort(functions, functions_cnt, sizeof(functions[0]), functions_cmp); + + if (btf_elf__verbose) + printf("Found %d functions!\n", functions_cnt); } return 0; -- 2.31.1
