Commit afba19d9 authored by Adrian Hunter's avatar Adrian Hunter Committed by Arnaldo Carvalho de Melo
Browse files

perf symbols: Workaround objdump difficulties with kcore 



The objdump tool fails to annotate module symbols when looking at kcore.

Workaround this by extracting object code from kcore and putting it in a
temporary file for objdump to use instead.

The temporary file is created to look like kcore but contains only the
function being disassembled.

Signed-off-by: default avatarAdrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1381320078-16497-3-git-send-email-adrian.hunter@intel.com


[ Renamed 'index' to 'idx' to avoid shadowing string.h's 'index' in Fedora 12,
  Replace local with variable length with malloc/free to fix build in Fedora 12 ]
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 52afdaf9

tools/perf/util/annotate.c

+21 −0
Original line number Diff line number Diff line
@@ -879,6 +879,8 @@ int symbol__annotate(struct symbol *sym, struct map *map, size_t privsize) 
	FILE *file;

	int err = 0;

	char symfs_filename[PATH_MAX];

	struct kcore_extract kce;

	bool delete_extract = false;



	if (filename) {

		snprintf(symfs_filename, sizeof(symfs_filename), "%s%s",
@@ -940,6 +942,23 @@ fallback: 
	pr_debug("annotating [%p] %30s : [%p] %30s\n",

		 dso, dso->long_name, sym, sym->name);



	if (dso__is_kcore(dso)) {

		kce.kcore_filename = symfs_filename;

		kce.addr = map__rip_2objdump(map, sym->start);

		kce.offs = sym->start;

		kce.len = sym->end + 1 - sym->start;

		if (!kcore_extract__create(&kce)) {

			delete_extract = true;

			strlcpy(symfs_filename, kce.extract_filename,

				sizeof(symfs_filename));

			if (free_filename) {

				free(filename);

				free_filename = false;

			}

			filename = symfs_filename;

		}

	}



	snprintf(command, sizeof(command),

		 "%s %s%s --start-address=0x%016" PRIx64

		 " --stop-address=0x%016" PRIx64
@@ -972,6 +991,8 @@ fallback: 


	pclose(file);

out_free_filename:

	if (delete_extract)

		kcore_extract__delete(&kce);

	if (free_filename)

		free(filename);

	return err;

tools/perf/util/symbol-elf.c

+229 −0
Original line number Diff line number Diff line
@@ -1018,6 +1018,235 @@ int file__read_maps(int fd, bool exe, mapfn_t mapfn, void *data, 
	return err;

}



static int copy_bytes(int from, off_t from_offs, int to, off_t to_offs, u64 len)

{

	ssize_t r;

	size_t n;

	int err = -1;

	char *buf = malloc(page_size);



	if (buf == NULL)

		return -1;



	if (lseek(to, to_offs, SEEK_SET) != to_offs)

		goto out;



	if (lseek(from, from_offs, SEEK_SET) != from_offs)

		goto out;



	while (len) {

		n = page_size;

		if (len < n)

			n = len;

		/* Use read because mmap won't work on proc files */

		r = read(from, buf, n);

		if (r < 0)

			goto out;

		if (!r)

			break;

		n = r;

		r = write(to, buf, n);

		if (r < 0)

			goto out;

		if ((size_t)r != n)

			goto out;

		len -= n;

	}



	err = 0;

out:

	free(buf);

	return err;

}



struct kcore {

	int fd;

	int elfclass;

	Elf *elf;

	GElf_Ehdr ehdr;

};



static int kcore__open(struct kcore *kcore, const char *filename)

{

	GElf_Ehdr *ehdr;



	kcore->fd = open(filename, O_RDONLY);

	if (kcore->fd == -1)

		return -1;



	kcore->elf = elf_begin(kcore->fd, ELF_C_READ, NULL);

	if (!kcore->elf)

		goto out_close;



	kcore->elfclass = gelf_getclass(kcore->elf);

	if (kcore->elfclass == ELFCLASSNONE)

		goto out_end;



	ehdr = gelf_getehdr(kcore->elf, &kcore->ehdr);

	if (!ehdr)

		goto out_end;



	return 0;



out_end:

	elf_end(kcore->elf);

out_close:

	close(kcore->fd);

	return -1;

}



static int kcore__init(struct kcore *kcore, char *filename, int elfclass,

		       bool temp)

{

	GElf_Ehdr *ehdr;



	kcore->elfclass = elfclass;



	if (temp)

		kcore->fd = mkstemp(filename);

	else

		kcore->fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0400);

	if (kcore->fd == -1)

		return -1;



	kcore->elf = elf_begin(kcore->fd, ELF_C_WRITE, NULL);

	if (!kcore->elf)

		goto out_close;



	if (!gelf_newehdr(kcore->elf, elfclass))

		goto out_end;



	ehdr = gelf_getehdr(kcore->elf, &kcore->ehdr);

	if (!ehdr)

		goto out_end;



	return 0;



out_end:

	elf_end(kcore->elf);

out_close:

	close(kcore->fd);

	unlink(filename);

	return -1;

}



static void kcore__close(struct kcore *kcore)

{

	elf_end(kcore->elf);

	close(kcore->fd);

}



static int kcore__copy_hdr(struct kcore *from, struct kcore *to, size_t count)

{

	GElf_Ehdr *ehdr = &to->ehdr;

	GElf_Ehdr *kehdr = &from->ehdr;



	memcpy(ehdr->e_ident, kehdr->e_ident, EI_NIDENT);

	ehdr->e_type      = kehdr->e_type;

	ehdr->e_machine   = kehdr->e_machine;

	ehdr->e_version   = kehdr->e_version;

	ehdr->e_entry     = 0;

	ehdr->e_shoff     = 0;

	ehdr->e_flags     = kehdr->e_flags;

	ehdr->e_phnum     = count;

	ehdr->e_shentsize = 0;

	ehdr->e_shnum     = 0;

	ehdr->e_shstrndx  = 0;



	if (from->elfclass == ELFCLASS32) {

		ehdr->e_phoff     = sizeof(Elf32_Ehdr);

		ehdr->e_ehsize    = sizeof(Elf32_Ehdr);

		ehdr->e_phentsize = sizeof(Elf32_Phdr);

	} else {

		ehdr->e_phoff     = sizeof(Elf64_Ehdr);

		ehdr->e_ehsize    = sizeof(Elf64_Ehdr);

		ehdr->e_phentsize = sizeof(Elf64_Phdr);

	}



	if (!gelf_update_ehdr(to->elf, ehdr))

		return -1;



	if (!gelf_newphdr(to->elf, count))

		return -1;



	return 0;

}



static int kcore__add_phdr(struct kcore *kcore, int idx, off_t offset,

			   u64 addr, u64 len)

{

	GElf_Phdr gphdr;

	GElf_Phdr *phdr;



	phdr = gelf_getphdr(kcore->elf, idx, &gphdr);

	if (!phdr)

		return -1;



	phdr->p_type	= PT_LOAD;

	phdr->p_flags	= PF_R | PF_W | PF_X;

	phdr->p_offset	= offset;

	phdr->p_vaddr	= addr;

	phdr->p_paddr	= 0;

	phdr->p_filesz	= len;

	phdr->p_memsz	= len;

	phdr->p_align	= page_size;



	if (!gelf_update_phdr(kcore->elf, idx, phdr))

		return -1;



	return 0;

}



static off_t kcore__write(struct kcore *kcore)

{

	return elf_update(kcore->elf, ELF_C_WRITE);

}



int kcore_extract__create(struct kcore_extract *kce)

{

	struct kcore kcore;

	struct kcore extract;

	size_t count = 1;

	int idx = 0, err = -1;

	off_t offset = page_size, sz;



	if (kcore__open(&kcore, kce->kcore_filename))

		return -1;



	strcpy(kce->extract_filename, PERF_KCORE_EXTRACT);

	if (kcore__init(&extract, kce->extract_filename, kcore.elfclass, true))

		goto out_kcore_close;



	if (kcore__copy_hdr(&kcore, &extract, count))

		goto out_extract_close;



	if (kcore__add_phdr(&extract, idx, offset, kce->addr, kce->len))

		goto out_extract_close;



	sz = kcore__write(&extract);

	if (sz < 0 || sz > offset)

		goto out_extract_close;



	if (copy_bytes(kcore.fd, kce->offs, extract.fd, offset, kce->len))

		goto out_extract_close;



	err = 0;



out_extract_close:

	kcore__close(&extract);

	if (err)

		unlink(kce->extract_filename);

out_kcore_close:

	kcore__close(&kcore);



	return err;

}



void kcore_extract__delete(struct kcore_extract *kce)

{

	unlink(kce->extract_filename);

}



void symbol__elf_init(void)

{

	elf_version(EV_CURRENT);

tools/perf/util/symbol-minimal.c

+9 −0
Original line number Diff line number Diff line
@@ -308,6 +308,15 @@ int file__read_maps(int fd __maybe_unused, bool exe __maybe_unused, 
	return -1;

}



int kcore_extract__create(struct kcore_extract *kce __maybe_unused)

{

	return -1;

}



void kcore_extract__delete(struct kcore_extract *kce __maybe_unused)

{

}



void symbol__elf_init(void)

{

}

tools/perf/util/symbol.h

+14 −0
Original line number Diff line number Diff line
@@ -256,4 +256,18 @@ typedef int (*mapfn_t)(u64 start, u64 len, u64 pgoff, void *data); 
int file__read_maps(int fd, bool exe, mapfn_t mapfn, void *data,

		    bool *is_64_bit);



#define PERF_KCORE_EXTRACT "/tmp/perf-kcore-XXXXXX"



struct kcore_extract {

	char *kcore_filename;

	u64 addr;

	u64 offs;

	u64 len;

	char extract_filename[sizeof(PERF_KCORE_EXTRACT)];

	int fd;

};



int kcore_extract__create(struct kcore_extract *kce);

void kcore_extract__delete(struct kcore_extract *kce);



#endif /* __PERF_SYMBOL */

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