This patch solves a problem in dladdr caused by the wrong value

of elf_resolve's loadaddr field for the main application.

Signed-off-by: Filippo Arcidiacono <filippo.arcidiacono@st.com>
Signed-off-by: Carmelo Amoroso <carmelo.amoroso@st.com>

ldso/include/dl-defs.h

@@ -168,8 +168,8 @@ typedef struct {
  */
 #ifndef DL_ADDR_IN_LOADADDR
 # define DL_ADDR_IN_LOADADDR(ADDR, TPNT, TFROM) \
-	((void*)(TPNT)->loadaddr < (void*)(ADDR) \
-	 && (!(TFROM) || (TFROM)->loadaddr < (TPNT)->loadaddr))
+	((void*)(TPNT)->mapaddr < (void*)(ADDR) \
+	 && (!(TFROM) || (TFROM)->mapaddr < (TPNT)->mapaddr))
 #endif
 
 /* This is called from dladdr() to give targets that use function descriptors

ldso/include/dl-hash.h

@@ -34,6 +34,7 @@ struct elf_resolve {
   struct elf_resolve * next;
   struct elf_resolve * prev;
   /* Nothing after this address is used by gdb. */
+  DL_LOADADDR_TYPE mapaddr;    /* Address at which ELF segments (either main app and DSO) are mapped into */
   enum {elf_lib, elf_executable,program_interpreter, loaded_file} libtype;
   struct dyn_elf * symbol_scope;
   unsigned short usage_count;

ldso/ldso/dl-hash.c

@@ -152,7 +152,7 @@ struct elf_resolve *_dl_add_elf_hash_table(const char *libname,
 		hash_addr += tpnt->nbucket;
 		tpnt->chains = hash_addr;
 	}
-	tpnt->loadaddr = loadaddr;
+	tpnt->loadaddr = tpnt->mapaddr = loadaddr;
 	for (i = 0; i < DYNAMIC_SIZE; i++)
 		tpnt->dynamic_info[i] = dynamic_info[i];
 	return tpnt;

ldso/ldso/ldso.c

@@ -135,6 +135,7 @@ void _dl_get_ready_to_run(struct elf_resolve *tpnt, DL_LOADADDR_TYPE load_addr,
 			  char **argv
 			  DL_GET_READY_TO_RUN_EXTRA_PARMS)
 {
+	DL_LOADADDR_TYPE app_loadaddr = NULL;
 	ElfW(Phdr) *ppnt;
 	ElfW(Dyn) *dpnt;
 	char *lpntstr;
@@ -276,6 +277,9 @@ void _dl_get_ready_to_run(struct elf_resolve *tpnt, DL_LOADADDR_TYPE load_addr,
 			relro_addr = ppnt->p_vaddr;
 			relro_size = ppnt->p_memsz;
 		}
+		if (!app_loadaddr && (ppnt->p_type == PT_LOAD)) {
+			app_loadaddr = ppnt->p_vaddr;
+		}
 		if (ppnt->p_type == PT_DYNAMIC) {
 			dpnt = (ElfW(Dyn) *) DL_RELOC_ADDR(app_tpnt->loadaddr, ppnt->p_vaddr);
 			_dl_parse_dynamic_info(dpnt, app_tpnt->dynamic_info, debug_addr, app_tpnt->loadaddr);
@@ -322,6 +326,7 @@ void _dl_get_ready_to_run(struct elf_resolve *tpnt, DL_LOADADDR_TYPE load_addr,
 			_dl_symbol_tables = rpnt = (struct dyn_elf *) _dl_malloc(sizeof(struct dyn_elf));
 			_dl_memset(rpnt, 0, sizeof(struct dyn_elf));
 			rpnt->dyn = _dl_loaded_modules;
+			app_tpnt->mapaddr = app_loadaddr;
 			app_tpnt->rtld_flags = unlazy | RTLD_GLOBAL;
 			app_tpnt->usage_count++;
 			app_tpnt->symbol_scope = _dl_symbol_tables;

ldso/libdl/libdl.c

@@ -739,13 +739,40 @@ int dladdr(const void *__address, Dl_info * __info)
 		char *strtab;
 		ElfW(Sym) *symtab;
 		unsigned int hn, si, sn, sf;
-		ElfW(Addr) sa;
+		ElfW(Addr) sa = 0;
+
+		/* Set the info for the object the address lies in */
+		__info->dli_fname = pelf->libname;
+		__info->dli_fbase = (void *) DL_LOADADDR_BASE(pelf->mapaddr);
 
-		sa = 0;
 		symtab = (ElfW(Sym) *) (pelf->dynamic_info[DT_SYMTAB]);
 		strtab = (char *) (pelf->dynamic_info[DT_STRTAB]);
 
 		sf = sn = 0;
+
+#ifdef __LDSO_GNU_HASH_SUPPORT__
+		if (pelf->l_gnu_bitmask) {
+			for (hn = 0; hn < pelf->nbucket; hn++) {
+				si = pelf->l_gnu_buckets[hn];
+				if (!si)
+					continue;
+
+				const Elf32_Word *hasharr = &pelf->l_gnu_chain_zero[si];
+				do {
+					ElfW(Addr) symbol_addr;
+
+					symbol_addr = (ElfW(Addr)) pelf->loadaddr + symtab[si].st_value;
+					if (symbol_addr <= (ElfW(Addr))__address && (!sf || sa < symbol_addr)) {
+						sa = symbol_addr;
+						sn = si;
+						sf = 1;
+					}
+					_dl_if_debug_print("Symbol \"%s\" at %p\n", strtab + symtab[si].st_name, symbol_addr);
+					++si;
+				} while ((*hasharr++ & 1u) == 0);
+			}
+		} else
+#endif
 		for (hn = 0; hn < pelf->nbucket; hn++) {
 			for (si = pelf->elf_buckets[hn]; si; si = pelf->chains[si]) {
 				ElfW(Addr) symbol_addr;
@@ -763,10 +790,14 @@ int dladdr(const void *__address, Dl_info * __info)
 		}
 
 		if (sf) {
-			__info->dli_fname = pelf->libname;
-			__info->dli_fbase = (void *) DL_LOADADDR_BASE(pelf->loadaddr);
+			/* A nearest symbol has been found; fill the entries */
 			__info->dli_sname = strtab + symtab[sn].st_name;
 			__info->dli_saddr = (void *)sa;
+		} else {
+			/* No symbol found, fill entries with NULL value,
+			only the containing object will be returned. */
+			__info->dli_sname = NULL;
+			__info->dli_saddr = NULL;
 		}
 		return 1;
 	}