Commit 2e538c4a authored by Arnaldo Carvalho de Melo's avatar Arnaldo Carvalho de Melo Committed by Ingo Molnar
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perf tools: Improve kernel/modules symbol lookup 



This removes the ovelapping of vmlinux addresses with modules,
using the ELF section name when using --vmlinux and creating a
unique DSO name when using /proc/kallsyms ([kernel].N).

This is done by creating multiple 'struct map' instances for
address ranges backed by DSOs that have just the symbols for that
range and a name that is derived from the ELF section name.o

Now it is possible to ask for just the symbols in some particular
kernel section:

$ perf report -m --vmlinux ../build/tip-recvmmsg/vmlinux \
	--dsos [kernel].vsyscall_fn | head -15
    52.73%             Xorg  [.] vread_hpet
    18.61%          firefox  [.] vread_hpet
    14.50%     npviewer.bin  [.] vread_hpet
     6.83%           compiz  [.] vread_hpet
     5.73%         glxgears  [.] vread_hpet
     0.63%             java  [.] vread_hpet
     0.30%   gnome-terminal  [.] vread_hpet
     0.23%             perf  [.] vread_hpet
     0.18%            xchat  [.] vread_hpet
$

Now we don't have to first lookup the list of modules and then, if
it fails, vmlinux symbols, its just a simple lookup for the map
then the symbols, just like for threads.

Reports generated using /proc/kallsyms and --vmlinux should provide
the same results, modulo the DSO name for sections other than
".text".

But they don't right now because things like:

 ffffffff81011c20-ffffffff81012068 system_call
 ffffffff81011c30-ffffffff81011c9b system_call_after_swapgs
 ffffffff81011c9c-ffffffff81011cb6 system_call_fastpath
 ffffffff81011cb7-ffffffff81011cbb ret_from_sys_call

I.e. overlapping symbols, again some ASM special case that we have
to fixup.

Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <1254934136-8503-1-git-send-email-acme@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent da21d1b5

tools/perf/util/symbol.c

+201 −87
Original line number Diff line number Diff line
@@ -26,27 +26,35 @@ enum dso_origin { 


static void dsos__add(struct dso *dso);

static struct dso *dsos__find(const char *name);

static struct map *map__new2(u64 start, struct dso *dso);

static void kernel_maps__insert(struct map *map);



static struct rb_root kernel_maps;



static void dso__set_symbols_end(struct dso *self)

static void dso__fixup_sym_end(struct dso *self)

{

	struct rb_node *nd, *prevnd = rb_first(&self->syms);

	struct symbol *curr, *prev;



	if (prevnd == NULL)

		return;



	curr = rb_entry(prevnd, struct symbol, rb_node);



	for (nd = rb_next(prevnd); nd; nd = rb_next(nd)) {

		struct symbol *prev = rb_entry(prevnd, struct symbol, rb_node),

			      *curr = rb_entry(nd, struct symbol, rb_node);

		prev = curr;

		curr = rb_entry(nd, struct symbol, rb_node);



		if (prev->end == prev->start)

			prev->end = curr->start - 1;

		prevnd = nd;

	}



	/* Last entry */

	if (curr->end == curr->start)

		curr->end = roundup(curr->start, 4096);

}



static void kernel_maps__fixup_sym_end(void)

static void kernel_maps__fixup_end(void)

{

	struct map *prev, *curr;

	struct rb_node *nd, *prevnd = rb_first(&kernel_maps);
@@ -55,13 +63,17 @@ static void kernel_maps__fixup_sym_end(void) 
		return;



	curr = rb_entry(prevnd, struct map, rb_node);

	dso__set_symbols_end(curr->dso);



	for (nd = rb_next(prevnd); nd; nd = rb_next(nd)) {

		prev = curr;

		curr = rb_entry(nd, struct map, rb_node);

		prev->end = curr->start - 1;

		dso__set_symbols_end(curr->dso);

	}



	nd = rb_last(&curr->dso->syms);

	if (nd) {

		struct symbol *sym = rb_entry(nd, struct symbol, rb_node);

		curr->end = sym->end;

	}

}
@@ -200,13 +212,16 @@ size_t dso__fprintf(struct dso *self, FILE *fp) 
	return ret;

}



static int maps__load_kallsyms(symbol_filter_t filter, int use_modules, int v)

/*

 * Loads the function entries in /proc/kallsyms into kernel_map->dso,

 * so that we can in the next step set the symbol ->end address and then

 * call kernel_maps__split_kallsyms.

 */

static int kernel_maps__load_all_kallsyms(int v)

{

	struct map *map = kernel_map;

	char *line = NULL;

	size_t n;

	FILE *file = fopen("/proc/kallsyms", "r");

	int count = 0;



	if (file == NULL)

		goto out_failure;
@@ -216,7 +231,7 @@ static int maps__load_kallsyms(symbol_filter_t filter, int use_modules, int v) 
		struct symbol *sym;

		int line_len, len;

		char symbol_type;

		char *module, *symbol_name;

		char *symbol_name;



		line_len = getline(&line, &n, file);

		if (line_len < 0)
@@ -241,20 +256,55 @@ static int maps__load_kallsyms(symbol_filter_t filter, int use_modules, int v) 
			continue;



		symbol_name = line + len + 2;

		module = strchr(symbol_name, '\t');

		if (module) {

			char *module_name_end;

		/*

		 * Will fix up the end later, when we have all symbols sorted.

		 */

		sym = symbol__new(start, 0, symbol_name,

				  kernel_map->dso->sym_priv_size, v);



		if (sym == NULL)

			goto out_delete_line;



		dso__insert_symbol(kernel_map->dso, sym);

	}



	free(line);

	fclose(file);



	return 0;



out_delete_line:

	free(line);

out_failure:

	return -1;

}



/*

 * Split the symbols into maps, making sure there are no overlaps, i.e. the

 * kernel range is broken in several maps, named [kernel].N, as we don't have

 * the original ELF section names vmlinux have.

 */

static int kernel_maps__split_kallsyms(symbol_filter_t filter, int use_modules)

{

	struct map *map = kernel_map;

	struct symbol *pos;

	int count = 0;

	struct rb_node *next = rb_first(&kernel_map->dso->syms);

	int kernel_range = 0;



	while (next) {

		char *module;



		pos = rb_entry(next, struct symbol, rb_node);

		next = rb_next(&pos->rb_node);



		module = strchr(pos->name, '\t');

		if (module) {

			if (!use_modules)

				continue;

			*module = '\0';

			module = strchr(module + 1, '[');

			if (!module)

				continue;

			module_name_end = strchr(module + 1, ']');

			if (!module_name_end)

				continue;

			*(module_name_end + 1) = '\0';

				goto delete_symbol;



			*module++ = '\0';



			if (strcmp(map->dso->name, module)) {

				map = kernel_maps__find_by_dso_name(module);

				if (!map) {
@@ -263,50 +313,77 @@ static int maps__load_kallsyms(symbol_filter_t filter, int use_modules, int v) 
					return -1;

				}

			}

			start = map->map_ip(map, start);

		} else

			map = kernel_map;

			/*

		 * Well fix up the end later, when we have all sorted.

			 * So that we look just like we get from .ko files,

			 * i.e. not prelinked, relative to map->start.

			 */

		sym = symbol__new(start, 0, symbol_name,

				  map->dso->sym_priv_size, v);

			pos->start = map->map_ip(map, pos->start);

			pos->end   = map->map_ip(map, pos->end);

		} else if (map != kernel_map) {

			char dso_name[PATH_MAX];

			struct dso *dso;



		if (sym == NULL)

			goto out_delete_line;

			snprintf(dso_name, sizeof(dso_name), "[kernel].%d",

				 kernel_range++);



		if (filter && filter(map, sym))

			symbol__delete(sym, map->dso->sym_priv_size);

		else {

			dso__insert_symbol(map->dso, sym);

			count++;

			dso = dso__new(dso_name,

				       kernel_map->dso->sym_priv_size);

			if (dso == NULL)

				return -1;



			map = map__new2(pos->start, dso);

			if (map == NULL) {

				dso__delete(dso);

				return -1;

			}



			map->map_ip = vdso__map_ip;

			kernel_maps__insert(map);

			++kernel_range;

		}



	free(line);

	fclose(file);

		if (filter && filter(map, pos)) {

delete_symbol:

			rb_erase(&pos->rb_node, &kernel_map->dso->syms);

			symbol__delete(pos, kernel_map->dso->sym_priv_size);

		} else {

			if (map != kernel_map) {

				rb_erase(&pos->rb_node, &kernel_map->dso->syms);

				dso__insert_symbol(map->dso, pos);

			}

			count++;

		}

	}



	return count;

}



out_delete_line:

	free(line);

out_failure:



static int kernel_maps__load_kallsyms(symbol_filter_t filter,

				      int use_modules, int v)

{

	if (kernel_maps__load_all_kallsyms(v))

		return -1;



	dso__fixup_sym_end(kernel_map->dso);



	return kernel_maps__split_kallsyms(filter, use_modules);

}



static size_t kernel_maps__fprintf(FILE *fp)

static size_t kernel_maps__fprintf(FILE *fp, int v)

{

	size_t printed = fprintf(stderr, "Kernel maps:\n");

	struct rb_node *nd;



	printed += map__fprintf(kernel_map, fp);

	printed += dso__fprintf(kernel_map->dso, fp);



	for (nd = rb_first(&kernel_maps); nd; nd = rb_next(nd)) {

		struct map *pos = rb_entry(nd, struct map, rb_node);



		printed += fprintf(fp, "Map:");

		printed += map__fprintf(pos, fp);

		if (v > 1) {

			printed += dso__fprintf(pos->dso, fp);

			printed += fprintf(fp, "--\n");

		}

	}



	return printed + fprintf(stderr, "END kernel maps\n");
@@ -594,6 +671,9 @@ static int dso__load_sym(struct dso *self, struct map *map, const char *name, 
			 int fd, symbol_filter_t filter, int kernel,

			 int kmodule, int v)

{

	struct map *curr_map = map;

	struct dso *curr_dso = self;

	size_t dso_name_len = strlen(self->short_name);

	Elf_Data *symstrs, *secstrs;

	uint32_t nr_syms;

	int err = -1;
@@ -660,10 +740,9 @@ static int dso__load_sym(struct dso *self, struct map *map, const char *name, 
	elf_symtab__for_each_symbol(syms, nr_syms, idx, sym) {

		struct symbol *f;

		const char *elf_name;

		char *demangled;

		char *demangled = NULL;

		int is_label = elf_sym__is_label(&sym);

		const char *section_name;

		u64 sh_offset = 0;



		if (!is_label && !elf_sym__is_function(&sym))

			continue;
@@ -677,14 +756,51 @@ static int dso__load_sym(struct dso *self, struct map *map, const char *name, 
		if (is_label && !elf_sec__is_text(&shdr, secstrs))

			continue;



		elf_name = elf_sym__name(&sym, symstrs);

		section_name = elf_sec__name(&shdr, secstrs);



		if ((kernel || kmodule)) {

			if (strstr(section_name, ".init"))

				sh_offset = shdr.sh_offset;

		if (kernel || kmodule) {

			char dso_name[PATH_MAX];



			if (strcmp(section_name,

				   curr_dso->short_name + dso_name_len) == 0)

				goto new_symbol;



			if (strcmp(section_name, ".text") == 0) {

				curr_map = map;

				curr_dso = self;

				goto new_symbol;

			}



			snprintf(dso_name, sizeof(dso_name),

				 "%s%s", self->short_name, section_name);



			curr_map = kernel_maps__find_by_dso_name(dso_name);

			if (curr_map == NULL) {

				u64 start = sym.st_value;



				if (kmodule)

					start += map->start + shdr.sh_offset;



				curr_dso = dso__new(dso_name, self->sym_priv_size);

				if (curr_dso == NULL)

					goto out_elf_end;

				curr_map = map__new2(start, curr_dso);

				if (curr_map == NULL) {

					dso__delete(curr_dso);

					goto out_elf_end;

				}

				curr_map->map_ip = vdso__map_ip;

				curr_dso->origin = DSO__ORIG_KERNEL;

				kernel_maps__insert(curr_map);

				dsos__add(curr_dso);

			} else

				curr_dso = curr_map->dso;



			goto new_symbol;

		}



		if (self->adjust_symbols) {

		if (curr_dso->adjust_symbols) {

			if (v > 2)

				printf("adjusting symbol: st_value: %Lx sh_addr: %Lx sh_offset: %Lx\n",

					(u64)sym.st_value, (u64)shdr.sh_addr, (u64)shdr.sh_offset);
@@ -696,25 +812,29 @@ static int dso__load_sym(struct dso *self, struct map *map, const char *name, 
		 * DWARF DW_compile_unit has this, but we don't always have access

		 * to it...

		 */

		elf_name = elf_sym__name(&sym, symstrs);

		demangled = bfd_demangle(NULL, elf_name, DMGL_PARAMS | DMGL_ANSI);

		if (demangled != NULL)

			elf_name = demangled;



		f = symbol__new(sym.st_value + sh_offset, sym.st_size, elf_name,

				self->sym_priv_size, v);

new_symbol:

		f = symbol__new(sym.st_value, sym.st_size, elf_name,

				curr_dso->sym_priv_size, v);

		free(demangled);

		if (!f)

			goto out_elf_end;



		if (filter && filter(map, f))

			symbol__delete(f, self->sym_priv_size);

		if (filter && filter(curr_map, f))

			symbol__delete(f, curr_dso->sym_priv_size);

		else {

			dso__insert_symbol(self, f);

			dso__insert_symbol(curr_dso, f);

			nr++;

		}

	}



	/*

	 * For misannotated, zeroed, ASM function sizes.

	 */

	if (nr > 0)

		dso__fixup_sym_end(self);

	err = nr;

out_elf_end:

	elf_end(elf);
@@ -883,27 +1003,17 @@ static void kernel_maps__insert(struct map *map) 


struct symbol *kernel_maps__find_symbol(u64 ip, struct map **mapp)

{

	/*

	 * We can't have kernel_map in kernel_maps because it spans an address

	 * space that includes the modules. The right way to fix this is to

	 * create several maps, so that we don't have overlapping ranges with

	 * modules. For now lets look first on the kernel dso.

	 */

	struct map *map = maps__find(&kernel_maps, ip);

	struct symbol *sym;



	if (mapp)

		*mapp = map;



	if (map) {

		ip = map->map_ip(map, ip);

		sym = map->dso->find_symbol(map->dso, ip);

	} else {

		map = kernel_map;

		sym = map->dso->find_symbol(map->dso, ip);

		return map->dso->find_symbol(map->dso, ip);

	}



	if (mapp)

		*mapp = map;



	return sym;

	return NULL;

}



struct map *kernel_maps__find_by_dso_name(const char *name)
@@ -994,6 +1104,14 @@ static int dsos__load_modules_sym_dir(char *dirname, 
			last = rb_last(&map->dso->syms);

			if (last) {

				struct symbol *sym;

				/*

				 * We do this here as well, even having the

				 * symbol size found in the symtab because

				 * misannotated ASM symbols may have the size

				 * set to zero.

				 */

				dso__fixup_sym_end(map->dso);



				sym = rb_entry(last, struct symbol, rb_node);

				map->end = map->start + sym->end;

			}
@@ -1163,17 +1281,11 @@ int dsos__load_kernel(const char *vmlinux, unsigned int sym_priv_size, 
	}



	if (err <= 0)

		err = maps__load_kallsyms(filter, use_modules, v);

		err = kernel_maps__load_kallsyms(filter, use_modules, v);



	if (err > 0) {

		struct rb_node *node = rb_first(&dso->syms);

		struct symbol *sym = rb_entry(node, struct symbol, rb_node);

		/*

		 * Now that we have all sorted out, just set the ->end of all

		 * symbols that still don't have it.

		 */

		dso__set_symbols_end(dso);

		kernel_maps__fixup_sym_end();



		kernel_map->start = sym->start;

		node = rb_last(&dso->syms);
@@ -1181,14 +1293,16 @@ int dsos__load_kernel(const char *vmlinux, unsigned int sym_priv_size, 
		kernel_map->end = sym->end;



		dso->origin = DSO__ORIG_KERNEL;

		kernel_maps__insert(kernel_map);

		/*

		 * XXX See kernel_maps__find_symbol comment

		 * kernel_maps__insert(kernel_map)

		 * Now that we have all sorted out, just set the ->end of all

		 * maps:

		 */

		kernel_maps__fixup_end();

		dsos__add(dso);



		if (v > 0)

			kernel_maps__fprintf(stderr);

			kernel_maps__fprintf(stderr, v);

	}



	return err;

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