/* * probe-finder.c : C expression to kprobe event converter * * Written by Masami Hiramatsu * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. * */ #include #include #include #include #include #include #include #include #include #include #include #include #include "string.h" #include "event.h" #include "debug.h" #include "util.h" #include "probe-finder.h" /* * Generic dwarf analysis helpers */ #define X86_32_MAX_REGS 8 const char *x86_32_regs_table[X86_32_MAX_REGS] = { "%ax", "%cx", "%dx", "%bx", "$stack", /* Stack address instead of %sp */ "%bp", "%si", "%di", }; #define X86_64_MAX_REGS 16 const char *x86_64_regs_table[X86_64_MAX_REGS] = { "%ax", "%dx", "%cx", "%bx", "%si", "%di", "%bp", "%sp", "%r8", "%r9", "%r10", "%r11", "%r12", "%r13", "%r14", "%r15", }; /* TODO: switching by dwarf address size */ #ifdef __x86_64__ #define ARCH_MAX_REGS X86_64_MAX_REGS #define arch_regs_table x86_64_regs_table #else #define ARCH_MAX_REGS X86_32_MAX_REGS #define arch_regs_table x86_32_regs_table #endif /* Return architecture dependent register string (for kprobe-tracer) */ static const char *get_arch_regstr(unsigned int n) { return (n <= ARCH_MAX_REGS) ? arch_regs_table[n] : NULL; } /* * Compare the tail of two strings. * Return 0 if whole of either string is same as another's tail part. */ static int strtailcmp(const char *s1, const char *s2) { int i1 = strlen(s1); int i2 = strlen(s2); while (--i1 >= 0 && --i2 >= 0) { if (s1[i1] != s2[i2]) return s1[i1] - s2[i2]; } return 0; } /* Line number list operations */ /* Add a line to line number list */ static void line_list__add_line(struct list_head *head, unsigned int line) { struct line_node *ln; struct list_head *p; /* Reverse search, because new line will be the last one */ list_for_each_entry_reverse(ln, head, list) { if (ln->line < line) { p = &ln->list; goto found; } else if (ln->line == line) /* Already exist */ return ; } /* List is empty, or the smallest entry */ p = head; found: pr_debug("line list: add a line %u\n", line); ln = zalloc(sizeof(struct line_node)); DIE_IF(ln == NULL); ln->line = line; INIT_LIST_HEAD(&ln->list); list_add(&ln->list, p); } /* Check if the line in line number list */ static int line_list__has_line(struct list_head *head, unsigned int line) { struct line_node *ln; /* Reverse search, because new line will be the last one */ list_for_each_entry(ln, head, list) if (ln->line == line) return 1; return 0; } /* Init line number list */ static void line_list__init(struct list_head *head) { INIT_LIST_HEAD(head); } /* Free line number list */ static void line_list__free(struct list_head *head) { struct line_node *ln; while (!list_empty(head)) { ln = list_first_entry(head, struct line_node, list); list_del(&ln->list); free(ln); } } /* Dwarf wrappers */ /* Find the realpath of the target file. */ static const char *cu_find_realpath(Dwarf_Die *cu_die, const char *fname) { Dwarf_Files *files; size_t nfiles, i; const char *src = NULL; int ret; if (!fname) return NULL; ret = dwarf_getsrcfiles(cu_die, &files, &nfiles); if (ret != 0) return NULL; for (i = 0; i < nfiles; i++) { src = dwarf_filesrc(files, i, NULL, NULL); if (strtailcmp(src, fname) == 0) break; } return src; } struct __addr_die_search_param { Dwarf_Addr addr; Dwarf_Die *die_mem; }; static int __die_search_func_cb(Dwarf_Die *fn_die, void *data) { struct __addr_die_search_param *ad = data; if (dwarf_tag(fn_die) == DW_TAG_subprogram && dwarf_haspc(fn_die, ad->addr)) { memcpy(ad->die_mem, fn_die, sizeof(Dwarf_Die)); return DWARF_CB_ABORT; } return DWARF_CB_OK; } /* Search a real subprogram including this line, */ static Dwarf_Die *die_get_real_subprogram(Dwarf_Die *cu_die, Dwarf_Addr addr, Dwarf_Die *die_mem) { struct __addr_die_search_param ad; ad.addr = addr; ad.die_mem = die_mem; /* dwarf_getscopes can't find subprogram. */ if (!dwarf_getfuncs(cu_die, __die_search_func_cb, &ad, 0)) return NULL; else return die_mem; } /* Similar to dwarf_getfuncs, but returns inlined_subroutine if exists. */ static Dwarf_Die *die_get_inlinefunc(Dwarf_Die *sp_die, Dwarf_Addr addr, Dwarf_Die *die_mem) { Dwarf_Die child_die; int ret; ret = dwarf_child(sp_die, die_mem); if (ret != 0) return NULL; do { if (dwarf_tag(die_mem) == DW_TAG_inlined_subroutine && dwarf_haspc(die_mem, addr)) return die_mem; if (die_get_inlinefunc(die_mem, addr, &child_die)) { memcpy(die_mem, &child_die, sizeof(Dwarf_Die)); return die_mem; } } while (dwarf_siblingof(die_mem, die_mem) == 0); return NULL; } /* Compare diename and tname */ static bool die_compare_name(Dwarf_Die *dw_die, const char *tname) { const char *name; name = dwarf_diename(dw_die); DIE_IF(name == NULL); return strcmp(tname, name); } /* Get entry pc(or low pc, 1st entry of ranges) of the die */ static Dwarf_Addr die_get_entrypc(Dwarf_Die *dw_die) { Dwarf_Addr epc; int ret; ret = dwarf_entrypc(dw_die, &epc); DIE_IF(ret == -1); return epc; } /* Get a variable die */ static Dwarf_Die *die_find_variable(Dwarf_Die *sp_die, const char *name, Dwarf_Die *die_mem) { Dwarf_Die child_die; int tag; int ret; ret = dwarf_child(sp_die, die_mem); if (ret != 0) return NULL; do { tag = dwarf_tag(die_mem); if ((tag == DW_TAG_formal_parameter || tag == DW_TAG_variable) && (die_compare_name(die_mem, name) == 0)) return die_mem; if (die_find_variable(die_mem, name, &child_die)) { memcpy(die_mem, &child_die, sizeof(Dwarf_Die)); return die_mem; } } while (dwarf_siblingof(die_mem, die_mem) == 0); return NULL; } /* * Probe finder related functions */ /* Show a location */ static void show_location(Dwarf_Op *op, struct probe_finder *pf) { unsigned int regn; Dwarf_Word offs = 0; int deref = 0, ret; const char *regs; /* TODO: support CFA */ /* If this is based on frame buffer, set the offset */ if (op->atom == DW_OP_fbreg) { if (pf->fb_ops == NULL) die("The attribute of frame base is not supported.\n"); deref = 1; offs = op->number; op = &pf->fb_ops[0]; } if (op->atom >= DW_OP_breg0 && op->atom <= DW_OP_breg31) { regn = op->atom - DW_OP_breg0; offs += op->number; deref = 1; } else if (op->atom >= DW_OP_reg0 && op->atom <= DW_OP_reg31) { regn = op->atom - DW_OP_reg0; } else if (op->atom == DW_OP_bregx) { regn = op->number; offs += op->number2; deref = 1; } else if (op->atom == DW_OP_regx) { regn = op->number; } else die("DW_OP %d is not supported.", op->atom); regs = get_arch_regstr(regn); if (!regs) die("%u exceeds max register number.", regn); if (deref) ret = snprintf(pf->buf, pf->len, " %s=%+jd(%s)", pf->var, (intmax_t)offs, regs); else ret = snprintf(pf->buf, pf->len, " %s=%s", pf->var, regs); DIE_IF(ret < 0); DIE_IF(ret >= pf->len); } /* Show a variables in kprobe event format */ static void show_variable(Dwarf_Die *vr_die, struct probe_finder *pf) { Dwarf_Attribute attr; Dwarf_Op *expr; size_t nexpr; int ret; if (dwarf_attr(vr_die, DW_AT_location, &attr) == NULL) goto error; /* TODO: handle more than 1 exprs */ ret = dwarf_getlocation_addr(&attr, pf->addr, &expr, &nexpr, 1); if (ret <= 0 || nexpr == 0) goto error; show_location(expr, pf); /* *expr will be cached in libdw. Don't free it. */ return ; error: /* TODO: Support const_value */ die("Failed to find the location of %s at this address.\n" " Perhaps, it has been optimized out.", pf->var); } /* Find a variable in a subprogram die */ static void find_variable(Dwarf_Die *sp_die, struct probe_finder *pf) { int ret; Dwarf_Die vr_die; /* TODO: Support struct members and arrays */ if (!is_c_varname(pf->var)) { /* Output raw parameters */ ret = snprintf(pf->buf, pf->len, " %s", pf->var); DIE_IF(ret < 0); DIE_IF(ret >= pf->len); return ; } pr_debug("Searching '%s' variable in context.\n", pf->var); /* Search child die for local variables and parameters. */ if (!die_find_variable(sp_die, pf->var, &vr_die)) die("Failed to find '%s' in this function.", pf->var); show_variable(&vr_die, pf); } /* Show a probe point to output buffer */ static void show_probe_point(Dwarf_Die *sp_die, struct probe_finder *pf) { struct probe_point *pp = pf->pp; Dwarf_Addr eaddr; Dwarf_Die die_mem; const char *name; char tmp[MAX_PROBE_BUFFER]; int ret, i, len; Dwarf_Attribute fb_attr; size_t nops; /* If no real subprogram, find a real one */ if (!sp_die || dwarf_tag(sp_die) != DW_TAG_subprogram) { sp_die = die_get_real_subprogram(&pf->cu_die, pf->addr, &die_mem); if (!sp_die) die("Probe point is not found in subprograms."); } /* Output name of probe point */ name = dwarf_diename(sp_die); if (name) { dwarf_entrypc(sp_die, &eaddr); ret = snprintf(tmp, MAX_PROBE_BUFFER, "%s+%lu", name, (unsigned long)(pf->addr - eaddr)); /* Copy the function name if possible */ if (!pp->function) { pp->function = strdup(name); pp->offset = (size_t)(pf->addr - eaddr); } } else { /* This function has no name. */ ret = snprintf(tmp, MAX_PROBE_BUFFER, "0x%jx", (uintmax_t)pf->addr); if (!pp->function) { /* TODO: Use _stext */ pp->function = strdup(""); pp->offset = (size_t)pf->addr; } } DIE_IF(ret < 0); DIE_IF(ret >= MAX_PROBE_BUFFER); len = ret; pr_debug("Probe point found: %s\n", tmp); /* Get the frame base attribute/ops */ dwarf_attr(sp_die, DW_AT_frame_base, &fb_attr); ret = dwarf_getlocation_addr(&fb_attr, pf->addr, &pf->fb_ops, &nops, 1); if (ret <= 0 || nops == 0) pf->fb_ops = NULL; /* Find each argument */ /* TODO: use dwarf_cfi_addrframe */ for (i = 0; i < pp->nr_args; i++) { pf->var = pp->args[i]; pf->buf = &tmp[len]; pf->len = MAX_PROBE_BUFFER - len; find_variable(sp_die, pf); len += strlen(pf->buf); } /* *pf->fb_ops will be cached in libdw. Don't free it. */ pf->fb_ops = NULL; if (pp->found == MAX_PROBES) die("Too many( > %d) probe point found.\n", MAX_PROBES); pp->probes[pp->found] = strdup(tmp); pp->found++; } /* Find probe point from its line number */ static void find_probe_point_by_line(struct probe_finder *pf) { Dwarf_Lines *lines; Dwarf_Line *line; size_t nlines, i; Dwarf_Addr addr; int lineno; int ret; ret = dwarf_getsrclines(&pf->cu_die, &lines, &nlines); DIE_IF(ret != 0); for (i = 0; i < nlines; i++) { line = dwarf_onesrcline(lines, i); dwarf_lineno(line, &lineno); if (lineno != pf->lno) continue; /* TODO: Get fileno from line, but how? */ if (strtailcmp(dwarf_linesrc(line, NULL, NULL), pf->fname) != 0) continue; ret = dwarf_lineaddr(line, &addr); DIE_IF(ret != 0); pr_debug("Probe line found: line[%d]:%d addr:0x%jx\n", (int)i, lineno, (uintmax_t)addr); pf->addr = addr; show_probe_point(NULL, pf); /* Continuing, because target line might be inlined. */ } } /* Find lines which match lazy pattern */ static int find_lazy_match_lines(struct list_head *head, const char *fname, const char *pat) { char *fbuf, *p1, *p2; int fd, line, nlines = 0; struct stat st; fd = open(fname, O_RDONLY); if (fd < 0) die("failed to open %s", fname); DIE_IF(fstat(fd, &st) < 0); fbuf = malloc(st.st_size + 2); DIE_IF(fbuf == NULL); DIE_IF(read(fd, fbuf, st.st_size) < 0); close(fd); fbuf[st.st_size] = '\n'; /* Dummy line */ fbuf[st.st_size + 1] = '\0'; p1 = fbuf; line = 1; while ((p2 = strchr(p1, '\n')) != NULL) { *p2 = '\0'; if (strlazymatch(p1, pat)) { line_list__add_line(head, line); nlines++; } line++; p1 = p2 + 1; } free(fbuf); return nlines; } /* Find probe points from lazy pattern */ static void find_probe_point_lazy(Dwarf_Die *sp_die, struct probe_finder *pf) { Dwarf_Lines *lines; Dwarf_Line *line; size_t nlines, i; Dwarf_Addr addr; Dwarf_Die die_mem; int lineno; int ret; if (list_empty(&pf->lcache)) { /* Matching lazy line pattern */ ret = find_lazy_match_lines(&pf->lcache, pf->fname, pf->pp->lazy_line); if (ret <= 0) die("No matched lines found in %s.", pf->fname); } ret = dwarf_getsrclines(&pf->cu_die, &lines, &nlines); DIE_IF(ret != 0); for (i = 0; i < nlines; i++) { line = dwarf_onesrcline(lines, i); dwarf_lineno(line, &lineno); if (!line_list__has_line(&pf->lcache, lineno)) continue; /* TODO: Get fileno from line, but how? */ if (strtailcmp(dwarf_linesrc(line, NULL, NULL), pf->fname) != 0) continue; ret = dwarf_lineaddr(line, &addr); DIE_IF(ret != 0); if (sp_die) { /* Address filtering 1: does sp_die include addr? */ if (!dwarf_haspc(sp_die, addr)) continue; /* Address filtering 2: No child include addr? */ if (die_get_inlinefunc(sp_die, addr, &die_mem)) continue; } pr_debug("Probe line found: line[%d]:%d addr:0x%llx\n", (int)i, lineno, (unsigned long long)addr); pf->addr = addr; show_probe_point(sp_die, pf); /* Continuing, because target line might be inlined. */ } /* TODO: deallocate lines, but how? */ } static int probe_point_inline_cb(Dwarf_Die *in_die, void *data) { struct probe_finder *pf = (struct probe_finder *)data; struct probe_point *pp = pf->pp; if (pp->lazy_line) find_probe_point_lazy(in_die, pf); else { /* Get probe address */ pf->addr = die_get_entrypc(in_die); pf->addr += pp->offset; pr_debug("found inline addr: 0x%jx\n", (uintmax_t)pf->addr); show_probe_point(in_die, pf); } return DWARF_CB_OK; } /* Search function from function name */ static int probe_point_search_cb(Dwarf_Die *sp_die, void *data) { struct probe_finder *pf = (struct probe_finder *)data; struct probe_point *pp = pf->pp; /* Check tag and diename */ if (dwarf_tag(sp_die) != DW_TAG_subprogram || die_compare_name(sp_die, pp->function) != 0) return 0; pf->fname = dwarf_decl_file(sp_die); if (pp->line) { /* Function relative line */ dwarf_decl_line(sp_die, &pf->lno); pf->lno += pp->line; find_probe_point_by_line(pf); } else if (!dwarf_func_inline(sp_die)) { /* Real function */ if (pp->lazy_line) find_probe_point_lazy(sp_die, pf); else { pf->addr = die_get_entrypc(sp_die); pf->addr += pp->offset; /* TODO: Check the address in this function */ show_probe_point(sp_die, pf); } } else /* Inlined function: search instances */ dwarf_func_inline_instances(sp_die, probe_point_inline_cb, pf); return 1; /* Exit; no same symbol in this CU. */ } static void find_probe_point_by_func(struct probe_finder *pf) { dwarf_getfuncs(&pf->cu_die, probe_point_search_cb, pf, 0); } /* Find a probe point */ int find_probe_point(int fd, struct probe_point *pp) { struct probe_finder pf = {.pp = pp}; Dwarf_Off off, noff; size_t cuhl; Dwarf_Die *diep; Dwarf *dbg; dbg = dwarf_begin(fd, DWARF_C_READ); if (!dbg) return -ENOENT; pp->found = 0; off = 0; line_list__init(&pf.lcache); /* Loop on CUs (Compilation Unit) */ while (!dwarf_nextcu(dbg, off, &noff, &cuhl, NULL, NULL, NULL)) { /* Get the DIE(Debugging Information Entry) of this CU */ diep = dwarf_offdie(dbg, off + cuhl, &pf.cu_die); if (!diep) continue; /* Check if target file is included. */ if (pp->file) pf.fname = cu_find_realpath(&pf.cu_die, pp->file); else pf.fname = NULL; if (!pp->file || pf.fname) { if (pp->function) find_probe_point_by_func(&pf); else if (pp->lazy_line) find_probe_point_lazy(NULL, &pf); else { pf.lno = pp->line; find_probe_point_by_line(&pf); } } off = noff; } line_list__free(&pf.lcache); dwarf_end(dbg); return pp->found; } /* Find line range from its line number */ static void find_line_range_by_line(Dwarf_Die *sp_die, struct line_finder *lf) { Dwarf_Lines *lines; Dwarf_Line *line; size_t nlines, i; Dwarf_Addr addr; int lineno; int ret; const char *src; Dwarf_Die die_mem; line_list__init(&lf->lr->line_list); ret = dwarf_getsrclines(&lf->cu_die, &lines, &nlines); DIE_IF(ret != 0); for (i = 0; i < nlines; i++) { line = dwarf_onesrcline(lines, i); ret = dwarf_lineno(line, &lineno); DIE_IF(ret != 0); if (lf->lno_s > lineno || lf->lno_e < lineno) continue; if (sp_die) { /* Address filtering 1: does sp_die include addr? */ ret = dwarf_lineaddr(line, &addr); DIE_IF(ret != 0); if (!dwarf_haspc(sp_die, addr)) continue; /* Address filtering 2: No child include addr? */ if (die_get_inlinefunc(sp_die, addr, &die_mem)) continue; } /* TODO: Get fileno from line, but how? */ src = dwarf_linesrc(line, NULL, NULL); if (strtailcmp(src, lf->fname) != 0) continue; /* Copy real path */ if (!lf->lr->path) lf->lr->path = strdup(src); line_list__add_line(&lf->lr->line_list, (unsigned int)lineno); } /* Update status */ if (!list_empty(&lf->lr->line_list)) lf->found = 1; else { free(lf->lr->path); lf->lr->path = NULL; } } static int line_range_inline_cb(Dwarf_Die *in_die, void *data) { find_line_range_by_line(in_die, (struct line_finder *)data); return DWARF_CB_ABORT; /* No need to find other instances */ } /* Search function from function name */ static int line_range_search_cb(Dwarf_Die *sp_die, void *data) { struct line_finder *lf = (struct line_finder *)data; struct line_range *lr = lf->lr; if (dwarf_tag(sp_die) == DW_TAG_subprogram && die_compare_name(sp_die, lr->function) == 0) { lf->fname = dwarf_decl_file(sp_die); dwarf_decl_line(sp_die, &lr->offset); pr_debug("fname: %s, lineno:%d\n", lf->fname, lr->offset); lf->lno_s = lr->offset + lr->start; if (!lr->end) lf->lno_e = INT_MAX; else lf->lno_e = lr->offset + lr->end; lr->start = lf->lno_s; lr->end = lf->lno_e; if (dwarf_func_inline(sp_die)) dwarf_func_inline_instances(sp_die, line_range_inline_cb, lf); else find_line_range_by_line(sp_die, lf); return 1; } return 0; } static void find_line_range_by_func(struct line_finder *lf) { dwarf_getfuncs(&lf->cu_die, line_range_search_cb, lf, 0); } int find_line_range(int fd, struct line_range *lr) { struct line_finder lf = {.lr = lr, .found = 0}; int ret; Dwarf_Off off = 0, noff; size_t cuhl; Dwarf_Die *diep; Dwarf *dbg; dbg = dwarf_begin(fd, DWARF_C_READ); if (!dbg) return -ENOENT; /* Loop on CUs (Compilation Unit) */ while (!lf.found) { ret = dwarf_nextcu(dbg, off, &noff, &cuhl, NULL, NULL, NULL); if (ret != 0) break; /* Get the DIE(Debugging Information Entry) of this CU */ diep = dwarf_offdie(dbg, off + cuhl, &lf.cu_die); if (!diep) continue; /* Check if target file is included. */ if (lr->file) lf.fname = cu_find_realpath(&lf.cu_die, lr->file); else lf.fname = 0; if (!lr->file || lf.fname) { if (lr->function) find_line_range_by_func(&lf); else { lf.lno_s = lr->start; if (!lr->end) lf.lno_e = INT_MAX; else lf.lno_e = lr->end; find_line_range_by_line(NULL, &lf); } } off = noff; } pr_debug("path: %lx\n", (unsigned long)lr->path); dwarf_end(dbg); return lf.found; }