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Fix the parsing of the .fini_array in the dynamic linker (it should happen in reverse order).

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Also add a small design overview document for the linker. The latter contains details on
how the initialization/finalization is supposed to work.
This commit is contained in:
David 'Digit' Turner
2009-05-18 14:37:41 +02:00
parent e5446feb21
commit 8215679b35
2 changed files with 148 additions and 24 deletions
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58
linker/linker.c
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@@ -1248,13 +1248,38 @@ static int reloc_library(soinfo *si, Elf32_Rel *rel, unsigned count)
return 0;
}
static void call_array(unsigned *ctor, int count)
/* Please read the "Initialization and Termination functions" functions.
* of the linker design note in bionic/linker/README.TXT to understand
* what the following code is doing.
*
* The important things to remember are:
*
* DT_PREINIT_ARRAY must be called first for executables, and should
* not appear in shared libraries.
*
* DT_INIT should be called before DT_INIT_ARRAY if both are present
*
* DT_FINI should be called after DT_FINI_ARRAY if both are present
*
* DT_FINI_ARRAY must be parsed in reverse order.
*/
static void call_array(unsigned *ctor, int count, int reverse)
{
int n;
for(n = count; n > 0; n--){
TRACE("[ %5d Looking at ctor *0x%08x == 0x%08x ]\n", pid,
int n, inc = 1;
if (reverse) {
ctor += (count-1);
inc = -1;
}
for(n = count; n > 0; n--) {
TRACE("[ %5d Looking at %s *0x%08x == 0x%08x ]\n", pid,
reverse ? "dtor" : "ctor",
(unsigned)ctor, (unsigned)*ctor);
void (*func)() = (void (*)()) *ctor++;
void (*func)() = (void (*)()) *ctor;
ctor += inc;
if(((int) func == 0) || ((int) func == -1)) continue;
TRACE("[ %5d Calling func @ 0x%08x ]\n", pid, (unsigned)func);
func();
@@ -1263,17 +1288,11 @@ static void call_array(unsigned *ctor, int count)
static void call_constructors(soinfo *si)
{
/* TODO: THE ORIGINAL CODE SEEMED TO CALL THE INIT FUNCS IN THE WRONG ORDER.
* Old order: init, init_array, preinit_array..
* Correct order: preinit_array, init, init_array.
* Verify WHY.
*/
if (si->flags & FLAG_EXE) {
TRACE("[ %5d Calling preinit_array @ 0x%08x [%d] for '%s' ]\n",
pid, (unsigned)si->preinit_array, si->preinit_array_count,
si->name);
call_array(si->preinit_array, si->preinit_array_count);
call_array(si->preinit_array, si->preinit_array_count, 0);
TRACE("[ %5d Done calling preinit_array for '%s' ]\n", pid, si->name);
} else {
if (si->preinit_array) {
@@ -1283,11 +1302,6 @@ static void call_constructors(soinfo *si)
}
}
// If we have an init section, then we should call it now, to make sure
// that all the funcs in the .ctors section get run.
// Note: For ARM, we shouldn't have a .ctor section (should be empty)
// when we have an (pre)init_array section, but let's be compatible with
// old (non-eabi) binaries and try the _init (DT_INIT) anyway.
if (si->init_func) {
TRACE("[ %5d Calling init_func @ 0x%08x for '%s' ]\n", pid,
(unsigned)si->init_func, si->name);
@@ -1298,25 +1312,21 @@ static void call_constructors(soinfo *si)
if (si->init_array) {
TRACE("[ %5d Calling init_array @ 0x%08x [%d] for '%s' ]\n", pid,
(unsigned)si->init_array, si->init_array_count, si->name);
call_array(si->init_array, si->init_array_count);
call_array(si->init_array, si->init_array_count, 0);
TRACE("[ %5d Done calling init_array for '%s' ]\n", pid, si->name);
}
}
static void call_destructors(soinfo *si)
{
if (si->fini_array) {
TRACE("[ %5d Calling fini_array @ 0x%08x [%d] for '%s' ]\n", pid,
(unsigned)si->fini_array, si->fini_array_count, si->name);
call_array(si->fini_array, si->fini_array_count);
call_array(si->fini_array, si->fini_array_count, 1);
TRACE("[ %5d Done calling fini_array for '%s' ]\n", pid, si->name);
}
// If we have an fini section, then we should call it now, to make sure
// that all the funcs in the .dtors section get run.
// Note: For ARM, we shouldn't have a .dtor section (should be empty)
// when we have an fini_array section, but let's be compatible with
// old (non-eabi) binaries and try the _fini (DT_FINI) anyway.
if (si->fini_func) {
TRACE("[ %5d Calling fini_func @ 0x%08x for '%s' ]\n", pid,
(unsigned)si->fini_func, si->name);