elf: support dynamic symbol table lookup

[lttng-tools.git] / src / common / lttng-elf.c

diff --git a/src/common/lttng-elf.c b/src/common/lttng-elf.c
index f5702ae453f4df08625ced8e5cdcf82367b6c502..52e05f0c6fe825f60a465aabe49d39f653140e88 100644 (file)
--- a/src/common/lttng-elf.c
+++ b/src/common/lttng-elf.c
@@ -38,6 +38,8 @@
 #define TEXT_SECTION_NAME      ".text"
 #define SYMBOL_TAB_SECTION_NAME ".symtab"
 #define STRING_TAB_SECTION_NAME ".strtab"
+#define DYNAMIC_SYMBOL_TAB_SECTION_NAME ".dynsym"
+#define DYNAMIC_STRING_TAB_SECTION_NAME ".dynstr"
 #define NOTE_STAPSDT_SECTION_NAME ".note.stapsdt"
 #define NOTE_STAPSDT_NAME "stapsdt"
 #define NOTE_STAPSDT_TYPE 3
@@ -736,6 +738,7 @@ int lttng_elf_get_symbol_offset(int fd, char *symbol, uint64_t *offset)
        char *curr_sym_str = NULL;
        char *symbol_table_data = NULL;
        char *string_table_data = NULL;
+       char *string_table_name = NULL;
        struct lttng_elf_shdr *symtab_hdr = NULL;
        struct lttng_elf_shdr *strtab_hdr = NULL;
        struct lttng_elf *elf = NULL;
@@ -751,14 +754,29 @@ int lttng_elf_get_symbol_offset(int fd, char *symbol, uint64_t *offset)
                goto end;
        }
 
-       /* Get the symbol table section header. */
+       /*
+        * The .symtab section might not exist on stripped binaries.
+        * Try to get the symbol table section header first. If it's absent,
+        * try to get the dynamic symbol table. All symbols in the dynamic
+        * symbol tab are in the (normal) symbol table if it exists.
+        */
        ret = lttng_elf_get_section_hdr_by_name(elf, SYMBOL_TAB_SECTION_NAME,
                        &symtab_hdr);
        if (ret) {
-               DBG("Cannot get ELF Symbol Table section.");
-               ret = LTTNG_ERR_ELF_PARSING;
-               goto destroy_elf;
+               DBG("Cannot get ELF Symbol Table section. Trying to get ELF Dynamic Symbol Table section.");
+               /* Get the dynamic symbol table section header. */
+               ret = lttng_elf_get_section_hdr_by_name(elf, DYNAMIC_SYMBOL_TAB_SECTION_NAME,
+                               &symtab_hdr);
+               if (ret) {
+                       DBG("Cannot get ELF Symbol Table nor Dynamic Symbol Table sections.");
+                       ret = LTTNG_ERR_ELF_PARSING;
+                       goto destroy_elf;
+               }
+               string_table_name = DYNAMIC_STRING_TAB_SECTION_NAME;
+       } else {
+               string_table_name = STRING_TAB_SECTION_NAME;
        }
+
        /* Get the data associated with the symbol table section. */
        symbol_table_data = lttng_elf_get_section_data(elf, symtab_hdr);
        if (symbol_table_data == NULL) {
@@ -768,7 +786,7 @@ int lttng_elf_get_symbol_offset(int fd, char *symbol, uint64_t *offset)
        }
 
        /* Get the string table section header. */
-       ret = lttng_elf_get_section_hdr_by_name(elf, STRING_TAB_SECTION_NAME,
+       ret = lttng_elf_get_section_hdr_by_name(elf, string_table_name,
                        &strtab_hdr);
        if (ret) {
                DBG("Cannot get ELF string table section.");