Date: Thu, 6 Mar 2003 18:16:40 -0800 From: Arun Sharma <arun.sharma@intel.com> To: freebsd-ia64@freebsd.org Cc: jdp@freebsd.org Subject: Review fix for ia64/48024 Message-ID: <200303070216.h272Gev29185@unix-os.sc.intel.com>
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The following changes are proposed to: rtld-elf
- factor out alloc_fptrs into a function of its own
- update the fptrs array of the defining object rather than the
referencing object
- We use the same algorithm to index fptrs array now in
make_function_pointer and reloc_non_plt_obj.
Issues:
- Is it possible to make an out of bounds access to the fptr array ?
-Arun
--- ia64/reloc.c- Fri Mar 7 02:06:30 2003
+++ ia64/reloc.c Fri Mar 7 02:06:16 2003
@@ -77,6 +77,31 @@
static struct fptr *next_fptr = &first_chunk.fptrs[0];
static struct fptr *last_fptr = &first_chunk.fptrs[FPTR_CHUNK_SIZE];
+static struct fptr **
+alloc_fptrs(const Obj_Entry *obj, Obj_Entry *obj_rtld)
+{
+ struct fptr **fptrs;
+ int fbytes = obj->nchains * sizeof(struct fptr *);
+
+ /*
+ * When relocating rtld itself, we need to avoid using malloc.
+ */
+ if (obj == obj_rtld) {
+ fptrs = mmap(NULL, fbytes, PROT_READ|PROT_WRITE,
+ MAP_ANON, -1, 0);
+ if (fptrs == MAP_FAILED)
+ fptrs = NULL;
+ } else {
+ fptrs = (struct fptr **)
+ malloc(obj->nchains * sizeof(struct fptr *));
+ }
+
+ if (fptrs != NULL)
+ memset(fptrs, 0, fbytes);
+
+ return fptrs;
+}
+
/*
* We use static storage initially so that we don't have to call
* malloc during init_rtld().
@@ -101,8 +126,9 @@
/* Relocate a non-PLT object with addend. */
static int
reloc_non_plt_obj(Obj_Entry *obj_rtld, Obj_Entry *obj, const Elf_Rela *rela,
- SymCache *cache, struct fptr **fptrs)
+ SymCache *cache)
{
+ struct fptr **fptrs;
Elf_Addr *where = (Elf_Addr *) (obj->relocbase + rela->r_offset);
switch (ELF_R_TYPE(rela->r_info)) {
@@ -135,9 +161,7 @@
/*
* We have to make sure that all @fptr references to
* the same function are identical so that code can
- * compare function pointers. We actually only bother
- * to ensure this within a single object. If the
- * caller's alloca failed, we don't even ensure that.
+ * compare function pointers.
*/
const Elf_Sym *def;
const Obj_Entry *defobj;
@@ -150,18 +174,28 @@
return -1;
if (def->st_shndx != SHN_UNDEF) {
+ int index;
target = (Elf_Addr)(defobj->relocbase + def->st_value);
gp = (Elf_Addr)defobj->pltgot;
+ fptrs = defobj->priv;
+ index = def - defobj->symtab;
+
+ if (!fptrs) {
+ /* Need to allocate one */
+ fptrs = alloc_fptrs(defobj, obj_rtld);
+ if (fptrs)
+ ((Obj_Entry*) defobj)->priv = fptrs;
+ }
/*
* Find the @fptr, using fptrs as a helper.
*/
if (fptrs)
- fptr = fptrs[ELF_R_SYM(rela->r_info)];
+ fptr = fptrs[index];
if (!fptr) {
fptr = alloc_fptr(target, gp);
if (fptrs)
- fptrs[ELF_R_SYM(rela->r_info)] = fptr;
+ fptrs[index] = fptr;
}
} else
fptr = NULL;
@@ -221,7 +255,6 @@
SymCache *cache;
struct fptr **fptrs;
int bytes = obj->nchains * sizeof(SymCache);
- int fbytes = obj->nchains * sizeof(struct fptr *);
int r = -1;
/*
@@ -234,21 +267,9 @@
if (cache != NULL)
memset(cache, 0, bytes);
- /*
- * When relocating rtld itself, we need to avoid using malloc.
- */
- if (obj == obj_rtld) {
- fptrs = mmap(NULL, fbytes, PROT_READ|PROT_WRITE,
- MAP_ANON, -1, 0);
- if (fptrs == MAP_FAILED)
- fptrs = NULL;
- } else {
- fptrs = (struct fptr **)
- malloc(obj->nchains * sizeof(struct fptr *));
- }
+ fptrs = alloc_fptrs(obj, obj_rtld);
if (fptrs == NULL)
goto done;
- memset(fptrs, 0, fbytes);
/* Perform relocations without addend if there are any: */
rellim = (const Elf_Rel *) ((caddr_t) obj->rel + obj->relsize);
@@ -258,14 +279,14 @@
locrela.r_info = rel->r_info;
locrela.r_offset = rel->r_offset;
locrela.r_addend = 0;
- if (reloc_non_plt_obj(obj_rtld, obj, &locrela, cache, fptrs))
+ if (reloc_non_plt_obj(obj_rtld, obj, &locrela, cache))
goto done;
}
/* Perform relocations with addend if there are any: */
relalim = (const Elf_Rela *) ((caddr_t) obj->rela + obj->relasize);
for (rela = obj->rela; obj->rela != NULL && rela < relalim; rela++) {
- if (reloc_non_plt_obj(obj_rtld, obj, rela, cache, fptrs))
+ if (reloc_non_plt_obj(obj_rtld, obj, rela, cache))
goto done;
}
@@ -290,10 +311,12 @@
if (cache)
munmap(cache, bytes);
if (fptrs) {
- if (obj == obj_rtld)
+ if (obj == obj_rtld) {
+ int fbytes = obj->nchains * sizeof(struct fptr *);
munmap(fptrs, fbytes);
- else
+ } else {
free(fptrs);
+ }
}
return (r);
}
@@ -449,9 +472,9 @@
* dlsym("dlopen"). Actually, I'm not sure it can ever
* happen.
*/
- fptrs = (struct fptr **)
- malloc(obj->nchains * sizeof(struct fptr *));
- memset(fptrs, 0, obj->nchains * sizeof(struct fptr *));
+
+ /* assume obj != obj_rtld */
+ fptrs = alloc_fptrs((Obj_Entry *) obj, NULL);
((Obj_Entry*) obj)->priv = fptrs;
}
if (!fptrs[index]) {
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