xiaoxiang781216 commented on code in PR #20131:
URL: https://github.com/apache/nuttx/pull/20131#discussion_r4107770087
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libs/libc/elf/elf_remove.c:
##########
@@ -150,6 +167,24 @@ int libelf_uninit(FAR struct module_s *modp)
# endif
#endif
}
+ else if (modp->fdpic)
+ {
+ /* An FDPIC object placed its two segments separately. Free each
+ * one. If the text stayed on the media, it was never allocated,
+ * thus leave it.
+ */
+
+ if (modp->xipbase == 0)
+ {
+#if defined(CONFIG_ARCH_USE_TEXT_HEAP)
Review Comment:
`#ifdef CONFIG_ARCH_USE_TEXT_HEAP`
##########
libs/libc/elf/elf_remove.c:
##########
@@ -59,12 +63,17 @@ int libelf_uninit(FAR struct module_s *modp)
}
#endif
- /* Is there an uninitializer? */
+ /* Is there an uninitializer? Like the constructors, an FDPIC object's
+ * destructors reach its globals through its own data base, which the
+ * unloading thread does not carry.
+ */
+
+ gotbase = modp->fdpic ? modp->gotbase : 0;
array = (FAR void (**)(void))modp->finiarr;
for (i = 0; i < modp->nfini; i++)
{
- array[i]();
+ fdpic_call(array[i], gotbase);
Review Comment:
gotbase->modp->gotbase
##########
include/nuttx/fdpic.h:
##########
@@ -159,6 +159,34 @@ static inline void fdpic_invoke(uintptr_t arg,
}
}
+/****************************************************************************
+ * Name: fdpic_call
+ *
+ * Description:
+ * Call a function of a module the caller is not running in, such as a
+ * constructor of a module being loaded or a destructor of one being
+ * unloaded, with the data base that function needs.
+ *
+ * A zero base means the function is not a module's, or the caller already
+ * carries the right one, and it is called directly. A non-FDPIC object
+ * has a GOT too, so the caller decides which base to pass, not this.
+ *
+ * Input Parameters:
+ * fn - The function to call.
+ * got - The data base to enter it with, or zero.
+ *
+ ****************************************************************************/
+
+static inline void fdpic_call(CODE void (*fn)(void), uintptr_t got)
Review Comment:
should we pass arg like fdpic_invoke
##########
libs/libc/elf/elf_insert.c:
##########
@@ -414,7 +422,13 @@ FAR void *libelf_insert(FAR const char *filename, FAR
const char *modname)
modp->datasize = loadinfo.datasize;
#endif
- /* Call the module initializer */
+ /* Call the module initializer. An FDPIC object's constructors reach its
+ * globals through its own data base, which the loading thread does not
+ * carry; a non-FDPIC one runs on the base it is entered with, so it gets
+ * none of its own.
+ */
+
+ gotbase = loadinfo.fdpic ? loadinfo.gotbase : 0;
Review Comment:
ditto
##########
libs/libc/elf/elf_bind.c:
##########
@@ -733,6 +733,24 @@ static int libelf_relocatedyn(FAR struct module_s *modp,
case DT_PLTRELSZ:
reldata.relsz[I_PLT] = dyn[i].d_un.d_val;
break;
+ case DT_NEEDED:
Review Comment:
let's move to DT_NEEDED patch
##########
include/nuttx/lib/elf.h:
##########
@@ -190,6 +190,18 @@ struct module_s
uint16_t nsect; /* Number of entries in sectalloc array
*/
#endif
int dynamic; /* Module is a dynamic shared object */
+ bool fdpic; /* Module is an FDPIC object: its two
Review Comment:
remove?
##########
libs/libc/elf/elf_remove.c:
##########
@@ -59,12 +63,17 @@ int libelf_uninit(FAR struct module_s *modp)
}
#endif
- /* Is there an uninitializer? */
+ /* Is there an uninitializer? Like the constructors, an FDPIC object's
+ * destructors reach its globals through its own data base, which the
+ * unloading thread does not carry.
+ */
+
+ gotbase = modp->fdpic ? modp->gotbase : 0;
Review Comment:
why need? gotbase should be zero if fdpic equals false.
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