[ktap] [PATCH 1/3] symbol: replace find_symbol() by get_dso_symbols()
- From: Azat Khuzhin <a3at.mail@xxxxxxxxx>
- To: ktap@xxxxxxxxxxxxx
- Date: Wed, 13 Nov 2013 23:13:35 +0400
Old find_symbol() just find symbol by name, the new one
get_dso_symbols() will return all symbols/notes.
And user of this functions, will match name/pattern by itself.
For now get_dso_symbols() used like find_symbol(), this behaviour will
be changed in next patches.
Signed-off-by: Azat Khuzhin <a3at.mail@xxxxxxxxx>
---
userspace/eventdef.c | 13 ++++++-
userspace/symbol.c | 105 +++++++++++++++++++++++++++++++++++++++++----------
userspace/symbol.h | 25 +++++++++---
3 files changed, 117 insertions(+), 26 deletions(-)
diff --git a/userspace/eventdef.c b/userspace/eventdef.c
index 748ca10..13703c6 100644
--- a/userspace/eventdef.c
+++ b/userspace/eventdef.c
@@ -333,6 +333,8 @@ static char *parse_events_resolve_symbol(char *event, int
type)
{
char *colon, *end, *tail, *binary, *symbol;
vaddr_t symbol_address;
+ struct dso_symbol *symbols = NULL;
+ size_t symbols_count, i;
colon = strchr(event, ':');
if (!colon)
@@ -357,7 +359,16 @@ static char *parse_events_resolve_symbol(char *event, int
type)
symbol = strdup(colon + 1 /* skip ":" */);
}
- symbol_address = find_symbol(binary, symbol, type);
+ symbols_count = get_dso_symbols(&symbols, binary, type);
+ for (i = 0; i < symbols_count; ++i) {
+ if (strcmp(symbols[i].name, symbol))
+ continue;
+
+ symbol_address = symbols[i].addr;
+ break;
+ }
+ free_dso_symbols(symbols, symbols_count);
+
if (symbol_address) {
verbose_printf("symbol %s resolved to 0x%lx\n",
event, symbol_address);
diff --git a/userspace/symbol.c b/userspace/symbol.c
index 1df20f9..f3d5fc6 100644
--- a/userspace/symbol.c
+++ b/userspace/symbol.c
@@ -75,21 +75,59 @@ static vaddr_t find_load_address(Elf *elf)
return address;
}
-static vaddr_t search_symbol(Elf *elf, const char *symbol)
+void free_dso_symbols(struct dso_symbol *symbols, size_t symbols_count)
+{
+ size_t i;
+ for (i = 0; i < symbols_count; ++i) {
+ free(symbols[i].name);
+ }
+
+ free(symbols);
+}
+
+/**
+ * libc have about ~2000 symbols.
+ */
+#define SYMBOLS_COUNT 3000
+
+/**
+ * realloc() and free() on failure
+ *
+ * TODO: allocation by chunks
+ */
+static struct dso_symbol *
+realloc_symbols(struct dso_symbol *symbols, size_t symbols_count)
+{
+ struct dso_symbol *new;
+
+ new = realloc(symbols, sizeof(*symbols) * symbols_count);
+
+ if (!new && symbols)
+ free_dso_symbols(symbols, symbols_count);
+
+ return new;
+}
+
+static size_t elf_symbols(GElf_Shdr shdr)
+{
+ return shdr.sh_size / shdr.sh_entsize;
+}
+
+static size_t dso_symbols(struct dso_symbol **symbols, Elf *elf)
{
Elf_Data *elf_data = NULL;
Elf_Scn *scn = NULL;
GElf_Sym sym;
GElf_Shdr shdr;
+ size_t symbols_count = 0;
vaddr_t load_address = find_load_address(elf);
if (!load_address)
- return 0;
+ return symbols_count;
while ((scn = elf_nextscn(elf, scn))) {
- int i, symbols;
- char *current_symbol;
+ int i;
gelf_getshdr(scn, &shdr);
@@ -97,21 +135,31 @@ static vaddr_t search_symbol(Elf *elf, const char *symbol)
continue;
elf_data = elf_getdata(scn, elf_data);
- symbols = shdr.sh_size / shdr.sh_entsize;
- for (i = 0; i < symbols; i++) {
+ for (i = 0; i < elf_symbols(shdr); i++) {
+ char *name;
+ struct dso_symbol symbol;
+
gelf_getsym(elf_data, i, &sym);
if (GELF_ST_TYPE(sym.st_info) != STT_FUNC)
continue;
- current_symbol = elf_strptr(elf, shdr.sh_link,
sym.st_name);
- if (!strcmp(current_symbol, symbol))
- return sym.st_value - load_address;
+ ++symbols_count;
+ *symbols = realloc_symbols(*symbols, symbols_count);
+ if (!*symbols) {
+ symbols_count = 0;
+ break;
+ }
+
+ name = elf_strptr(elf, shdr.sh_link, sym.st_name);
+ symbol.name = strdup(name);
+ symbol.addr = sym.st_value - load_address;
+ memcpy(&(*symbols)[symbols_count - 1], &symbol,
sizeof(symbol));
}
}
- return 0;
+ return symbols_count;
}
#define SDT_NOTE_TYPE 3
@@ -172,7 +220,7 @@ static const char *sdt_note_data(const Elf_Data *data,
size_t off)
return ((data->d_buf) + off);
}
-static vaddr_t search_stapsdt_note(Elf *elf, const char *note)
+static size_t dso_sdt_notes(struct dso_symbol **symbols, Elf *elf)
{
GElf_Ehdr ehdr;
Elf_Scn *scn = NULL;
@@ -182,7 +230,9 @@ static vaddr_t search_stapsdt_note(Elf *elf, const char
*note)
size_t next;
GElf_Nhdr nhdr;
size_t name_off, desc_off, offset;
+
vaddr_t vaddr = 0;
+ size_t symbols_count = 0;
if (gelf_getehdr(elf, &ehdr) == NULL)
return 0;
@@ -205,6 +255,7 @@ static vaddr_t search_stapsdt_note(Elf *elf, const char
*note)
(next = gelf_getnote(data, offset, &nhdr, &name_off,
&desc_off)) > 0;
offset = next) {
const char *name;
+ struct dso_symbol symbol;
if (nhdr.n_namesz != sizeof(SDT_NOTE_NAME) ||
memcmp(data->d_buf + name_off, SDT_NOTE_NAME,
@@ -212,37 +263,51 @@ static vaddr_t search_stapsdt_note(Elf *elf, const char
*note)
continue;
name = sdt_note_name(elf, &nhdr, sdt_note_data(data, desc_off));
- if (!name || strcmp(name, note))
+ if (!name)
continue;
vaddr = sdt_note_addr(elf, sdt_note_data(data, desc_off),
nhdr.n_descsz, nhdr.n_type);
+ if (!vaddr)
+ continue;
+
+ ++symbols_count;
+ *symbols = realloc_symbols(*symbols, symbols_count);
+ if (!*symbols) {
+ symbols_count = 0;
+ break;
+ }
+
+ symbol.name = strdup(name);
+ symbol.addr = vaddr;
+ memcpy(&(*symbols)[symbols_count - 1], &symbol, sizeof(symbol));
}
- return vaddr;
+ return symbols_count;
}
-vaddr_t find_symbol(const char *exec, const char *symbol, int type)
+size_t get_dso_symbols(struct dso_symbol **symbols, const char *exec, int type)
{
- vaddr_t vaddr = 0;
+ size_t symbols_count = 0;
+
Elf *elf;
int fd;
if (elf_version(EV_CURRENT) == EV_NONE)
- return vaddr;
+ return symbols_count;
fd = open(exec, O_RDONLY);
if (fd < 0)
- return vaddr;
+ return symbols_count;
elf = elf_begin(fd, ELF_C_READ, NULL);
if (elf) {
switch (type) {
case FIND_SYMBOL:
- vaddr = search_symbol(elf, symbol);
+ symbols_count = dso_symbols(symbols, elf);
break;
case FIND_STAPSDT_NOTE:
- vaddr = search_stapsdt_note(elf, symbol);
+ symbols_count = dso_sdt_notes(symbols, elf);
break;
}
@@ -250,5 +315,5 @@ vaddr_t find_symbol(const char *exec, const char *symbol,
int type)
}
close(fd);
- return vaddr;
+ return symbols_count;
}
diff --git a/userspace/symbol.h b/userspace/symbol.h
index 558d5fe..e4ac8a7 100644
--- a/userspace/symbol.h
+++ b/userspace/symbol.h
@@ -1,5 +1,5 @@
/*
- * symbol.h
+ * symbol.h - extract symbols from DSO.
*
* This file is part of ktap by Jovi Zhangwei.
*
@@ -23,14 +23,29 @@
#define FIND_SYMBOL 1
#define FIND_STAPSDT_NOTE 2
+struct dso_symbol;
+
#ifndef NO_LIBELF
+
#include <gelf.h>
+#include <sys/queue.h>
+
typedef GElf_Addr vaddr_t;
+struct dso_symbol
+{
+ char *name;
+ vaddr_t addr;
+};
+
/**
- * Find symbol in DSO
- *
- * @return 0 on failure, otherwise address of symbol.
+ * free() symbols and it's names
+ */
+void free_dso_symbols(struct dso_symbol *symbols, size_t symbols_count);
+/**
+ * @return all symbols and notes in DSO.
+ * (You must call free_dso_symbols() at end.)
*/
-vaddr_t find_symbol(const char *exec, const char *symbol, int type);
+size_t get_dso_symbols(struct dso_symbol **symbols, const char *exec, int
type);
+
#endif
--
1.8.4.rc3
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