modlib:Standardized module loading method

1. use '__attribute__((constructor))' mark initialize function 2. use '__attribute__((destructor))' mark uninitialize function 3. compile module with -fvisibility=hidden. use `__attribute__((visibility("default")))` mark is need export symbol.so not need module_initialize to initialize export symbol. Signed-off-by: anjiahao <[email protected]>
anjiahao1 · Oct 4, 2024 · 3641273 · 3641273
1 parent 0976258
commit 3641273
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Showing 10 changed files with 115 additions and 90 deletions.
diff --git a/include/elf.h b/include/elf.h
@@ -191,6 +191,7 @@
 #define SHF_WRITE          1
 #define SHF_ALLOC          2
 #define SHF_EXECINSTR      4
+#define SHF_INFO_LINK      0x40
 #define SHF_MASKPROC       0xf0000000
 
 /* Figure 4-16: Symbol Binding, ELF_ST_BIND */
@@ -211,6 +212,13 @@
 #define STT_LOPROC         13
 #define STT_HIPROC         15
 
+/* Table 7-21 ELF Symbol Visibility */
+
+#define STV_DEFAULT        0
+#define STV_INTERNAL       1
+#define STV_HIDDEN         2
+#define STV_PROTECTED      3
+
 /* Figure 5-2: Segment Types, p_type */
 
 #define PT_NULL            0

diff --git a/include/elf32.h b/include/elf32.h
@@ -36,25 +36,27 @@
  * Pre-processor Definitions
  ****************************************************************************/
 
-#define ELF_CLASS          ELFCLASS32
+#define ELF_CLASS              ELFCLASS32
 
-#define ELF32_ST_BIND(i)   ((i) >> 4)
-#define ELF32_ST_TYPE(i)   ((i) & 0xf)
-#define ELF32_ST_INFO(b,t) (((b) << 4) | ((t) & 0xf))
+#define ELF32_ST_BIND(i)       ((i) >> 4)
+#define ELF32_ST_TYPE(i)       ((i) & 0xf)
+#define ELF32_ST_INFO(b,t)     (((b) << 4) | ((t) & 0xf))
+#define ELF32_ST_VISIBILITY(o) ((o) & 0x3)
 
 /* Generic macro to abstract ELF32/ELF64 type/bind */
 
-#define ELF_ST_TYPE(a)     ELF32_ST_TYPE(a)
-#define ELF_ST_BIND(a)     ELF32_ST_BIND(a)
+#define ELF_ST_TYPE(a)         ELF32_ST_TYPE(a)
+#define ELF_ST_BIND(a)         ELF32_ST_BIND(a)
+#define ELF_ST_VISIBILITY(o)   ELF32_ST_VISIBILITY(o)
 
 /* Definitions for Elf32_Rel*::r_info */
 
-#define ELF32_R_SYM(i)     ((i) >> 8)
-#define ELF32_R_TYPE(i)    ((i) & 0xff)
-#define ELF32_R_INFO(s,t)  (((s)<< 8) | ((t) & 0xff))
+#define ELF32_R_SYM(i)         ((i) >> 8)
+#define ELF32_R_TYPE(i)        ((i) & 0xff)
+#define ELF32_R_INFO(s,t)      (((s)<< 8) | ((t) & 0xff))
 
-#define ELF_R_SYM(i)       ELF32_R_SYM(i)
-#define ELF_R_TYPE(i)      ELF32_R_TYPE(i)
+#define ELF_R_SYM(i)           ELF32_R_SYM(i)
+#define ELF_R_TYPE(i)          ELF32_R_TYPE(i)
 
 /****************************************************************************
  * Public Type Definitions

diff --git a/include/elf64.h b/include/elf64.h
@@ -36,27 +36,29 @@
  * Pre-processor Definitions
  ****************************************************************************/
 
-#define ELF_CLASS         ELFCLASS64
+#define ELF_CLASS              ELFCLASS64
 
 /* See ELF-64 Object File Format: Version 1.5 Draft 2 */
 
-#define ELF64_ST_BIND(i)     ((i) >> 4)
-#define ELF64_ST_TYPE(i)     ((i) & 0xf)
-#define ELF64_ST_INFO(b,t)   (((b) << 4) | ((t) & 0xf))
+#define ELF64_ST_BIND(i)       ((i) >> 4)
+#define ELF64_ST_TYPE(i)       ((i) & 0xf)
+#define ELF64_ST_INFO(b,t)     (((b) << 4) | ((t) & 0xf))
+#define ELF64_ST_VISIBILITY(o) ((o) & 0x3)
 
 /* Generic macro to abstract ELF32/ELF64 type/bind */
 
-#define ELF_ST_TYPE(a)       ELF64_ST_TYPE(a)
-#define ELF_ST_BIND(a)       ELF64_ST_BIND(a)
+#define ELF_ST_TYPE(a)         ELF64_ST_TYPE(a)
+#define ELF_ST_BIND(a)         ELF64_ST_BIND(a)
+#define ELF_ST_VISIBILITY(o)   ELF64_ST_VISIBILITY(o)
 
 /* Definitions for Elf64_Rel*::r_info */
 
-#define ELF64_R_SYM(i)       ((i) >> 32)
-#define ELF64_R_TYPE(i)      ((i) & 0xffffffffL)
-#define ELF64_R_INFO(s,t)    (((s)<< 32) + ((t) & 0xffffffffL))
+#define ELF64_R_SYM(i)         ((i) >> 32)
+#define ELF64_R_TYPE(i)        ((i) & 0xffffffffL)
+#define ELF64_R_INFO(s,t)      (((s)<< 32) + ((t) & 0xffffffffL))
 
-#define ELF_R_SYM(i)         ELF64_R_SYM(i)
-#define ELF_R_TYPE(i)        ELF64_R_TYPE(i)
+#define ELF_R_SYM(i)           ELF64_R_SYM(i)
+#define ELF_R_TYPE(i)          ELF64_R_TYPE(i)
 
 /****************************************************************************
  * Public Type Definitions

diff --git a/include/nuttx/lib/modlib.h b/include/nuttx/lib/modlib.h
@@ -154,9 +154,6 @@ struct module_s
   FAR struct module_s *flink;          /* Supports a singly linked list */
 #ifdef HAVE_MODLIB_NAMES
   char modname[MODLIB_NAMEMAX];        /* Module name */
-#endif
-#if defined(CONFIG_FS_PROCFS) && !defined(CONFIG_FS_PROCFS_EXCLUDE_MODULE)
-  mod_initializer_t initializer;       /* Module initializer function */
 #endif
   struct mod_info_s modinfo;           /* Module information */
   FAR void *textalloc;                 /* Allocated kernel text memory */

diff --git a/libs/libc/modlib/gnu-elf.ld b/libs/libc/modlib/gnu-elf.ld
@@ -33,6 +33,16 @@ SECTIONS
       _etext = . ;
     }
 
+  .init_array :
+    {
+      *(.init_array)
+    }
+
+  .fini_array :
+    {
+      *(.fini_array)
+    }
+
   .rodata :
     {
       _srodata = . ;

diff --git a/libs/libc/modlib/modlib_bind.c b/libs/libc/modlib/modlib_bind.c
@@ -814,32 +814,6 @@ static int modlib_relocatedyn(FAR struct module_s *modp,
         }
     }
 
-  /* Iterate through the dynamic symbol table looking for global symbols
-   * to put in our own symbol table for use with dlgetsym()
-   */
-
-  /* Relocate the entries in the table */
-
-  for (i = 0; i < symhdr->sh_size / sizeof(Elf_Sym); i++)
-    {
-      FAR Elf_Shdr *s = &loadinfo->shdr[sym[i].st_shndx];
-
-      if (sym[i].st_shndx != SHN_UNDEF)
-        {
-          if (s->sh_addr < loadinfo->datasec)
-            {
-              sym[i].st_value = sym[i].st_value + loadinfo->textalloc;
-            }
-          else
-            {
-              sym[i].st_value = sym[i].st_value -
-                                loadinfo->datasec + loadinfo->datastart;
-            }
-        }
-    }
-
-  ret = modlib_insertsymtab(modp, loadinfo, symhdr, sym);
-
   lib_free(sym);
   lib_free(rels);
   lib_free(dyn);
@@ -872,6 +846,8 @@ static int modlib_relocatedyn(FAR struct module_s *modp,
 int modlib_bind(FAR struct module_s *modp,
                 FAR struct mod_loadinfo_s *loadinfo)
 {
+  FAR Elf_Shdr *symhdr;
+  FAR Elf_Sym *sym;
   int ret;
   int i;
 
@@ -937,7 +913,8 @@ int modlib_bind(FAR struct module_s *modp,
            * relocate sections that were not loaded into memory.
            */
 
-          if ((loadinfo->shdr[infosec].sh_flags & SHF_ALLOC) == 0)
+          if ((loadinfo->shdr[i].sh_flags & SHF_ALLOC) == 0 &&
+              (loadinfo->shdr[i].sh_flags & SHF_INFO_LINK) == 0)
             {
               continue;
             }
@@ -952,6 +929,16 @@ int modlib_bind(FAR struct module_s *modp,
               case SHT_RELA:
                 ret = modlib_relocateadd(modp, loadinfo, i);
                 break;
+              case SHT_INIT_ARRAY:
+                loadinfo->initarr = loadinfo->shdr[i].sh_addr;
+                loadinfo->ninit = loadinfo->shdr[i].sh_size /
+                                  sizeof(uintptr_t);
+                break;
+              case SHT_FINI_ARRAY:
+                loadinfo->finiarr = loadinfo->shdr[i].sh_addr;
+                loadinfo->nfini = loadinfo->shdr[i].sh_size /
+                                  sizeof(uintptr_t);
+                break;
             }
         }
 
@@ -961,6 +948,37 @@ int modlib_bind(FAR struct module_s *modp,
         }
     }
 
+  symhdr = &loadinfo->shdr[loadinfo->symtabidx];
+  sym = lib_malloc(symhdr->sh_size);
+
+  ret = modlib_read(loadinfo, (FAR uint8_t *)sym, symhdr->sh_size,
+                    symhdr->sh_offset);
+
+  if (ret < 0)
+    {
+      berr("Failed to read symbol table\n");
+      lib_free(sym);
+      return ret;
+    }
+
+  for (i = 0; i < symhdr->sh_size / sizeof(Elf_Sym); i++)
+    {
+      FAR Elf_Shdr *s = &loadinfo->shdr[sym[i].st_shndx];
+
+      if (sym[i].st_shndx != SHN_UNDEF)
+        {
+          sym[i].st_value = sym[i].st_value + s->sh_addr;
+        }
+    }
+
+  ret = modlib_insertsymtab(modp, loadinfo, symhdr, sym);
+  lib_free(sym);
+  if (ret != 0)
+    {
+      binfo("Failed to export symbols program binary: %d\n", ret);
+      return ret;
+    }
+
   /* Ensure that the I and D caches are coherent before starting the newly
    * loaded module by cleaning the D cache (i.e., flushing the D cache
    * contents to memory and invalidating the I cache).

diff --git a/libs/libc/modlib/modlib_insert.c b/libs/libc/modlib/modlib_insert.c
@@ -105,21 +105,6 @@ static void modlib_dumploadinfo(FAR struct mod_loadinfo_s *loadinfo)
 #  define modlib_dumploadinfo(i)
 #endif
 
-/****************************************************************************
- * Name: modlib_dumpinitializer
- ****************************************************************************/
-
-#ifdef CONFIG_MODLIB_DUMPBUFFER
-static void modlib_dumpinitializer(mod_initializer_t initializer,
-                                   FAR struct mod_loadinfo_s *loadinfo)
-{
-  modlib_dumpbuffer("Initializer code", (FAR const uint8_t *)initializer,
-                    MIN(loadinfo->textsize - loadinfo->ehdr.e_entry, 512));
-}
-#else
-#  define modlib_dumpinitializer(b,l)
-#endif
-
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -154,7 +139,6 @@ FAR void *modlib_insert(FAR const char *filename, FAR const char *modname)
 {
   struct mod_loadinfo_s loadinfo;
   FAR struct module_s *modp;
-  mod_initializer_t initializer;
   FAR void (**array)(void);
   int ret;
   int i;
@@ -231,27 +215,11 @@ FAR void *modlib_insert(FAR const char *filename, FAR const char *modname)
   modp->datasize  = loadinfo.datasize;
 #endif
 
-  /* Get the module initializer entry point */
-
-  initializer = (mod_initializer_t)(loadinfo.textalloc +
-                                    loadinfo.ehdr.e_entry);
-#if defined(CONFIG_FS_PROCFS) && !defined(CONFIG_FS_PROCFS_EXCLUDE_MODULE)
-  modp->initializer = initializer;
-#endif
-  modlib_dumpinitializer(initializer, &loadinfo);
-
   /* Call the module initializer */
 
   switch (loadinfo.ehdr.e_type)
     {
       case ET_REL :
-          ret = initializer(&modp->modinfo);
-          if (ret < 0)
-            {
-              binfo("Failed to initialize the module: %d\n", ret);
-              goto errout_with_load;
-            }
-          break;
       case ET_DYN :
 
           /* Process any preinit_array entries */
@@ -296,4 +264,3 @@ FAR void *modlib_insert(FAR const char *filename, FAR const char *modname)
   set_errno(-ret);
   return NULL;
 }
-
diff --git a/libs/libc/modlib/modlib_remove.c b/libs/libc/modlib/modlib_remove.c
@@ -53,7 +53,9 @@
 int modlib_remove(FAR void *handle)
 {
   FAR struct module_s *modp = (FAR struct module_s *)handle;
+  FAR void (**array)(void);
   int ret;
+  int i;
 
   DEBUGASSERT(modp != NULL);
 
@@ -83,6 +85,12 @@ int modlib_remove(FAR void *handle)
 
   /* Is there an uninitializer? */
 
+  array = (FAR void (**)(void))modp->finiarr;
+  for (i = 0; i < modp->nfini; i++)
+    {
+      array[i]();
+    }
+
   if (modp->modinfo.uninitializer != NULL)
     {
       /* Try to uninitialize the module */
@@ -97,11 +105,12 @@ int modlib_remove(FAR void *handle)
           goto errout_with_lock;
         }
 
+      modlib_freesymtab(modp);
+
       /* Nullify so that the uninitializer cannot be called again */
 
       modp->modinfo.uninitializer = NULL;
 #if defined(CONFIG_FS_PROCFS) && !defined(CONFIG_FS_PROCFS_EXCLUDE_MODULE)
-      modp->initializer           = NULL;
       modp->modinfo.arg           = NULL;
       modp->modinfo.exports       = NULL;
       modp->modinfo.nexports      = 0;

diff --git a/libs/libc/modlib/modlib_symbols.c b/libs/libc/modlib/modlib_symbols.c
@@ -495,8 +495,13 @@ int modlib_insertsymtab(FAR struct module_s *modp,
   nsym = shdr->sh_size / sizeof(Elf_Sym);
   for (i = 0, symcount = 0; i < nsym; i++)
     {
-      if (sym[i].st_name != 0)
+      if (sym[i].st_name != 0 &&
+          ELF_ST_BIND(sym[i].st_info) == STB_GLOBAL &&
+          ELF_ST_TYPE(sym[i].st_info) != STT_NOTYPE &&
+          ELF_ST_VISIBILITY(sym[i].st_other) == STV_DEFAULT)
+        {
           symcount++;
+        }
     }
 
   if (symcount > 0)
@@ -511,7 +516,10 @@ int modlib_insertsymtab(FAR struct module_s *modp,
           modp->modinfo.nexports = symcount;
           for (i = 0, j = 0; i < nsym; i++)
             {
-              if (sym[i].st_name != 0)
+              if (sym[i].st_name != 0 &&
+                  ELF_ST_BIND(sym[i].st_info) == STB_GLOBAL &&
+                  ELF_ST_TYPE(sym[i].st_info) != STT_NOTYPE &&
+                  ELF_ST_VISIBILITY(sym[i].st_other) == STV_DEFAULT)
                 {
                   ret = modlib_symname(loadinfo, &sym[i], strtab->sh_offset);
                   if (ret < 0)
@@ -528,6 +536,10 @@ int modlib_insertsymtab(FAR struct module_s *modp,
                   j++;
                 }
             }
+
+#ifdef CONFIG_SYMTAB_ORDEREDBYNAME
+          symtab_sortbyname(symbol, symcount);
+#endif
         }
       else
         {

diff --git a/sched/module/mod_procfs.c b/sched/module/mod_procfs.c
@@ -137,8 +137,8 @@ static int modprocfs_callback(FAR struct module_s *modp, FAR void *arg)
   priv = (FAR struct modprocfs_file_s *)arg;
 
   linesize = snprintf(priv->line, MOD_LINELEN,
-                      "%s,%p,%p,%p,%u,%p,%lu,%p,%lu\n",
-                      modp->modname, modp->initializer,
+                      "%s,%p,%p,%u,%p,%lu,%p,%lu\n",
+                      modp->modname,
                       modp->modinfo.uninitializer, modp->modinfo.arg,
                       modp->modinfo.nexports,
                       modp->textalloc,