elf: Introduce to _dl_call_fini
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Commit Message
This consolidates the destructor invocations from _dl_fini and
dlclose. Remove the micro-optimization that avoids
calling _dl_call_fini if they are no destructors (as dlclose is quite
expensive anyway).
---
elf/Makefile | 1 +
elf/dl-call_fini.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++
elf/dl-close.c | 42 +-------------------------------------
elf/dl-fini.c | 38 +----------------------------------
sysdeps/generic/ldsodefs.h | 8 ++++++++
5 files changed, 61 insertions(+), 78 deletions(-)
base-commit: 264db94040c463d9bc356101595d89335586875e
Comments
On Okt 13 2022, Florian Weimer via Libc-alpha wrote:
> This consolidates the destructor invocations from _dl_fini and
> dlclose. Remove the micro-optimization that avoids
> calling _dl_call_fini if they are no destructors (as dlclose is quite
> expensive anyway).
This also changes whether to print the debug message.
> @@ -53,6 +53,7 @@ routines = \
> # profiled libraries.
> dl-routines = \
> dl-call-libc-early-init \
> + dl-call_fini \
Convention is to use dashes in file names.
* Andreas Schwab:
> On Okt 13 2022, Florian Weimer via Libc-alpha wrote:
>
>> This consolidates the destructor invocations from _dl_fini and
>> dlclose. Remove the micro-optimization that avoids
>> calling _dl_call_fini if they are no destructors (as dlclose is quite
>> expensive anyway).
>
> This also changes whether to print the debug message.
I've added, ?The debug log message is now printed unconditionally.?
The change is practically invisible because crtbegin*.o from GCC has a
destructor.
>> @@ -53,6 +53,7 @@ routines = \
>> # profiled libraries.
>> dl-routines = \
>> dl-call-libc-early-init \
>> + dl-call_fini \
>
> Convention is to use dashes in file names.
I think we tend to use the underscore if it matches the symbol name
verbatim (perhaps without the _dl_ prefix).
Thanks,
Florian
On 13/10/22 08:35, Florian Weimer via Libc-alpha wrote:
> This consolidates the destructor invocations from _dl_fini and
> dlclose. Remove the micro-optimization that avoids
> calling _dl_call_fini if they are no destructors (as dlclose is quite
> expensive anyway).
>
LGTM, I think the debug message change should be ok. Some comment on the old
code you refactored.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
> ---
> elf/Makefile | 1 +
> elf/dl-call_fini.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++
> elf/dl-close.c | 42 +-------------------------------------
> elf/dl-fini.c | 38 +----------------------------------
> sysdeps/generic/ldsodefs.h | 8 ++++++++
> 5 files changed, 61 insertions(+), 78 deletions(-)
>
> diff --git a/elf/Makefile b/elf/Makefile
> index 7b50ccc07a..86c960cf8a 100644
> --- a/elf/Makefile
> +++ b/elf/Makefile
> @@ -53,6 +53,7 @@ routines = \
> # profiled libraries.
> dl-routines = \
> dl-call-libc-early-init \
> + dl-call_fini \
> dl-close \
> dl-debug \
> dl-debug-symbols \
> diff --git a/elf/dl-call_fini.c b/elf/dl-call_fini.c
> new file mode 100644
> index 0000000000..383dfd093e
> --- /dev/null
> +++ b/elf/dl-call_fini.c
> @@ -0,0 +1,50 @@
> +/* Invoke DT_FINI and DT_FINI_ARRAY callbacks.
> + Copyright (C) 1996-2022 Free Software Foundation, Inc.
> + This file is part of the GNU C Library.
> +
> + The GNU C Library is free software; you can redistribute it and/or
> + modify it under the terms of the GNU Lesser General Public
> + License as published by the Free Software Foundation; either
> + version 2.1 of the License, or (at your option) any later version.
> +
> + The GNU C Library is distributed in the hope that it will be useful,
> + but WITHOUT ANY WARRANTY; without even the implied warranty of
> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + Lesser General Public License for more details.
> +
> + You should have received a copy of the GNU Lesser General Public
> + License along with the GNU C Library; if not, see
> + <https://www.gnu.org/licenses/>. */
> +
> +#include <ldsodefs.h>
> +#include <sysdep.h>
> +
> +void
> +_dl_call_fini (void *closure_map)
> +{
> + struct link_map *map = closure_map;
> +
> + /* When debugging print a message first. */
> + if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_IMPCALLS, 0))
Use __glibc_likely here (even though it is mostly a refactor).
> + _dl_debug_printf ("\ncalling fini: %s [%lu]\n\n", map->l_name, map->l_ns);
> +
> + /* Make sure nothing happens if we are called twice. */
> + map->l_init_called = 0;
> +
> + ElfW(Dyn) *fini_array = map->l_info[DT_FINI_ARRAY];
> + if (fini_array != NULL)
> + {
> + ElfW(Addr) *array = (ElfW(Addr) *) (map->l_addr
> + + fini_array->d_un.d_ptr);
> + unsigned int sz = (map->l_info[DT_FINI_ARRAYSZ]->d_un.d_val
> + / sizeof (ElfW(Addr)));
Shouldn't we use size_t here (since dl_val is Elf64_Xword)?
> +
> + while (sz-- > 0)
> + ((fini_t) array[sz]) ();
> + }
> +
> + /* Next try the old-style destructor. */
> + ElfW(Dyn) *fini = map->l_info[DT_FINI];
> + if (fini != NULL)
> + DL_CALL_DT_FINI (map, ((void *) map->l_addr + fini->d_un.d_ptr));
> +}
> diff --git a/elf/dl-close.c b/elf/dl-close.c
> index bcd6e206e9..14deca2e2b 100644
> --- a/elf/dl-close.c
> +++ b/elf/dl-close.c
> @@ -36,11 +36,6 @@
>
> #include <dl-unmap-segments.h>
>
> -
> -/* Type of the constructor functions. */
> -typedef void (*fini_t) (void);
> -
> -
> /* Special l_idx value used to indicate which objects remain loaded. */
> #define IDX_STILL_USED -1
>
> @@ -110,31 +105,6 @@ remove_slotinfo (size_t idx, struct dtv_slotinfo_list *listp, size_t disp,
> return false;
> }
>
> -/* Invoke dstructors for CLOSURE (a struct link_map *). Called with
> - exception handling temporarily disabled, to make errors fatal. */
> -static void
> -call_destructors (void *closure)
> -{
> - struct link_map *map = closure;
> -
> - if (map->l_info[DT_FINI_ARRAY] != NULL)
> - {
> - ElfW(Addr) *array =
> - (ElfW(Addr) *) (map->l_addr
> - + map->l_info[DT_FINI_ARRAY]->d_un.d_ptr);
> - unsigned int sz = (map->l_info[DT_FINI_ARRAYSZ]->d_un.d_val
> - / sizeof (ElfW(Addr)));
> -
> - while (sz-- > 0)
> - ((fini_t) array[sz]) ();
> - }
> -
> - /* Next try the old-style destructor. */
> - if (map->l_info[DT_FINI] != NULL)
> - DL_CALL_DT_FINI (map, ((void *) map->l_addr
> - + map->l_info[DT_FINI]->d_un.d_ptr));
> -}
> -
> void
> _dl_close_worker (struct link_map *map, bool force)
> {
Ok.
> @@ -280,17 +250,7 @@ _dl_close_worker (struct link_map *map, bool force)
> half-cooked objects. Temporarily disable exception
> handling, so that errors are fatal. */
> if (imap->l_init_called)
> - {
> - /* When debugging print a message first. */
> - if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_IMPCALLS,
> - 0))
> - _dl_debug_printf ("\ncalling fini: %s [%lu]\n\n",
> - imap->l_name, nsid);
> -
> - if (imap->l_info[DT_FINI_ARRAY] != NULL
> - || imap->l_info[DT_FINI] != NULL)
> - _dl_catch_exception (NULL, call_destructors, imap);
> - }
> + _dl_catch_exception (NULL, _dl_call_fini, imap);
>
> #ifdef SHARED
> /* Auditing checkpoint: we remove an object. */
Ok.
> diff --git a/elf/dl-fini.c b/elf/dl-fini.c
> index 030b1fcbcd..50ff94db16 100644
> --- a/elf/dl-fini.c
> +++ b/elf/dl-fini.c
> @@ -21,11 +21,6 @@
> #include <ldsodefs.h>
> #include <elf-initfini.h>
>
> -
> -/* Type of the constructor functions. */
> -typedef void (*fini_t) (void);
> -
> -
> void
> _dl_fini (void)
> {
> @@ -116,38 +111,7 @@ _dl_fini (void)
>
> if (l->l_init_called)
> {
> - /* Make sure nothing happens if we are called twice. */
> - l->l_init_called = 0;
> -
> - /* Is there a destructor function? */
> - if (l->l_info[DT_FINI_ARRAY] != NULL
> - || (ELF_INITFINI && l->l_info[DT_FINI] != NULL))
> - {
> - /* When debugging print a message first. */
> - if (__builtin_expect (GLRO(dl_debug_mask)
> - & DL_DEBUG_IMPCALLS, 0))
> - _dl_debug_printf ("\ncalling fini: %s [%lu]\n\n",
> - DSO_FILENAME (l->l_name),
> - ns);
> -
> - /* First see whether an array is given. */
> - if (l->l_info[DT_FINI_ARRAY] != NULL)
> - {
> - ElfW(Addr) *array =
> - (ElfW(Addr) *) (l->l_addr
> - + l->l_info[DT_FINI_ARRAY]->d_un.d_ptr);
> - unsigned int i = (l->l_info[DT_FINI_ARRAYSZ]->d_un.d_val
> - / sizeof (ElfW(Addr)));
> - while (i-- > 0)
> - ((fini_t) array[i]) ();
> - }
> -
> - /* Next try the old-style destructor. */
> - if (ELF_INITFINI && l->l_info[DT_FINI] != NULL)
> - DL_CALL_DT_FINI
> - (l, l->l_addr + l->l_info[DT_FINI]->d_un.d_ptr);
> - }
> -
> + _dl_call_fini (l);
> #ifdef SHARED
> /* Auditing checkpoint: another object closed. */
> _dl_audit_objclose (l);
Ok.
> diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
> index 6b256b8388..c2627fced7 100644
> --- a/sysdeps/generic/ldsodefs.h
> +++ b/sysdeps/generic/ldsodefs.h
> @@ -105,6 +105,9 @@ typedef struct link_map *lookup_t;
> DT_PREINIT_ARRAY. */
> typedef void (*dl_init_t) (int, char **, char **);
>
> +/* Type of a constructor function, in DT_FINI, DT_FINI_ARRAY. */
> +typedef void (*fini_t) (void);
> +
> /* On some architectures a pointer to a function is not just a pointer
> to the actual code of the function but rather an architecture
> specific descriptor. */
> @@ -1048,6 +1051,11 @@ extern void _dl_init (struct link_map *main_map, int argc, char **argv,
> initializer functions have completed. */
> extern void _dl_fini (void) attribute_hidden;
>
> +/* Invoke the DT_FINI_ARRAY and DT_FINI destructors for MAP, which
> + must be a struct link_map *. Can be used as an argument to
> + _dl_catch_exception. */
> +void _dl_call_fini (void *map) attribute_hidden;
> +
> /* Sort array MAPS according to dependencies of the contained objects.
> If FORCE_FIRST, MAPS[0] keeps its place even if the dependencies
> say otherwise. */
>
> base-commit: 264db94040c463d9bc356101595d89335586875e
>
Ok.
* Adhemerval Zanella Netto:
> On 13/10/22 08:35, Florian Weimer via Libc-alpha wrote:
>> This consolidates the destructor invocations from _dl_fini and
>> dlclose. Remove the micro-optimization that avoids
>> calling _dl_call_fini if they are no destructors (as dlclose is quite
>> expensive anyway).
>>
>
> LGTM, I think the debug message change should be ok. Some comment on
> the old code you refactored.
Should I fix this and repost? Reviewed-by: plus suggestions is kind of
confusing. 8-)
Thanks,
Florian
On 21/10/22 15:24, Florian Weimer wrote:
> * Adhemerval Zanella Netto:
>
>> On 13/10/22 08:35, Florian Weimer via Libc-alpha wrote:
>>> This consolidates the destructor invocations from _dl_fini and
>>> dlclose. Remove the micro-optimization that avoids
>>> calling _dl_call_fini if they are no destructors (as dlclose is quite
>>> expensive anyway).
>>>
>>
>> LGTM, I think the debug message change should be ok. Some comment on
>> the old code you refactored.
>
> Should I fix this and repost? Reviewed-by: plus suggestions is kind of
> confusing. 8-)
Right it was indeed confusing from my part. I think if you are ok with the
suggestions I don't think it is required to repost.
@@ -53,6 +53,7 @@ routines = \
# profiled libraries.
dl-routines = \
dl-call-libc-early-init \
+ dl-call_fini \
dl-close \
dl-debug \
dl-debug-symbols \
new file mode 100644
@@ -0,0 +1,50 @@
+/* Invoke DT_FINI and DT_FINI_ARRAY callbacks.
+ Copyright (C) 1996-2022 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <ldsodefs.h>
+#include <sysdep.h>
+
+void
+_dl_call_fini (void *closure_map)
+{
+ struct link_map *map = closure_map;
+
+ /* When debugging print a message first. */
+ if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_IMPCALLS, 0))
+ _dl_debug_printf ("\ncalling fini: %s [%lu]\n\n", map->l_name, map->l_ns);
+
+ /* Make sure nothing happens if we are called twice. */
+ map->l_init_called = 0;
+
+ ElfW(Dyn) *fini_array = map->l_info[DT_FINI_ARRAY];
+ if (fini_array != NULL)
+ {
+ ElfW(Addr) *array = (ElfW(Addr) *) (map->l_addr
+ + fini_array->d_un.d_ptr);
+ unsigned int sz = (map->l_info[DT_FINI_ARRAYSZ]->d_un.d_val
+ / sizeof (ElfW(Addr)));
+
+ while (sz-- > 0)
+ ((fini_t) array[sz]) ();
+ }
+
+ /* Next try the old-style destructor. */
+ ElfW(Dyn) *fini = map->l_info[DT_FINI];
+ if (fini != NULL)
+ DL_CALL_DT_FINI (map, ((void *) map->l_addr + fini->d_un.d_ptr));
+}
@@ -36,11 +36,6 @@
#include <dl-unmap-segments.h>
-
-/* Type of the constructor functions. */
-typedef void (*fini_t) (void);
-
-
/* Special l_idx value used to indicate which objects remain loaded. */
#define IDX_STILL_USED -1
@@ -110,31 +105,6 @@ remove_slotinfo (size_t idx, struct dtv_slotinfo_list *listp, size_t disp,
return false;
}
-/* Invoke dstructors for CLOSURE (a struct link_map *). Called with
- exception handling temporarily disabled, to make errors fatal. */
-static void
-call_destructors (void *closure)
-{
- struct link_map *map = closure;
-
- if (map->l_info[DT_FINI_ARRAY] != NULL)
- {
- ElfW(Addr) *array =
- (ElfW(Addr) *) (map->l_addr
- + map->l_info[DT_FINI_ARRAY]->d_un.d_ptr);
- unsigned int sz = (map->l_info[DT_FINI_ARRAYSZ]->d_un.d_val
- / sizeof (ElfW(Addr)));
-
- while (sz-- > 0)
- ((fini_t) array[sz]) ();
- }
-
- /* Next try the old-style destructor. */
- if (map->l_info[DT_FINI] != NULL)
- DL_CALL_DT_FINI (map, ((void *) map->l_addr
- + map->l_info[DT_FINI]->d_un.d_ptr));
-}
-
void
_dl_close_worker (struct link_map *map, bool force)
{
@@ -280,17 +250,7 @@ _dl_close_worker (struct link_map *map, bool force)
half-cooked objects. Temporarily disable exception
handling, so that errors are fatal. */
if (imap->l_init_called)
- {
- /* When debugging print a message first. */
- if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_IMPCALLS,
- 0))
- _dl_debug_printf ("\ncalling fini: %s [%lu]\n\n",
- imap->l_name, nsid);
-
- if (imap->l_info[DT_FINI_ARRAY] != NULL
- || imap->l_info[DT_FINI] != NULL)
- _dl_catch_exception (NULL, call_destructors, imap);
- }
+ _dl_catch_exception (NULL, _dl_call_fini, imap);
#ifdef SHARED
/* Auditing checkpoint: we remove an object. */
@@ -21,11 +21,6 @@
#include <ldsodefs.h>
#include <elf-initfini.h>
-
-/* Type of the constructor functions. */
-typedef void (*fini_t) (void);
-
-
void
_dl_fini (void)
{
@@ -116,38 +111,7 @@ _dl_fini (void)
if (l->l_init_called)
{
- /* Make sure nothing happens if we are called twice. */
- l->l_init_called = 0;
-
- /* Is there a destructor function? */
- if (l->l_info[DT_FINI_ARRAY] != NULL
- || (ELF_INITFINI && l->l_info[DT_FINI] != NULL))
- {
- /* When debugging print a message first. */
- if (__builtin_expect (GLRO(dl_debug_mask)
- & DL_DEBUG_IMPCALLS, 0))
- _dl_debug_printf ("\ncalling fini: %s [%lu]\n\n",
- DSO_FILENAME (l->l_name),
- ns);
-
- /* First see whether an array is given. */
- if (l->l_info[DT_FINI_ARRAY] != NULL)
- {
- ElfW(Addr) *array =
- (ElfW(Addr) *) (l->l_addr
- + l->l_info[DT_FINI_ARRAY]->d_un.d_ptr);
- unsigned int i = (l->l_info[DT_FINI_ARRAYSZ]->d_un.d_val
- / sizeof (ElfW(Addr)));
- while (i-- > 0)
- ((fini_t) array[i]) ();
- }
-
- /* Next try the old-style destructor. */
- if (ELF_INITFINI && l->l_info[DT_FINI] != NULL)
- DL_CALL_DT_FINI
- (l, l->l_addr + l->l_info[DT_FINI]->d_un.d_ptr);
- }
-
+ _dl_call_fini (l);
#ifdef SHARED
/* Auditing checkpoint: another object closed. */
_dl_audit_objclose (l);
@@ -105,6 +105,9 @@ typedef struct link_map *lookup_t;
DT_PREINIT_ARRAY. */
typedef void (*dl_init_t) (int, char **, char **);
+/* Type of a constructor function, in DT_FINI, DT_FINI_ARRAY. */
+typedef void (*fini_t) (void);
+
/* On some architectures a pointer to a function is not just a pointer
to the actual code of the function but rather an architecture
specific descriptor. */
@@ -1048,6 +1051,11 @@ extern void _dl_init (struct link_map *main_map, int argc, char **argv,
initializer functions have completed. */
extern void _dl_fini (void) attribute_hidden;
+/* Invoke the DT_FINI_ARRAY and DT_FINI destructors for MAP, which
+ must be a struct link_map *. Can be used as an argument to
+ _dl_catch_exception. */
+void _dl_call_fini (void *map) attribute_hidden;
+
/* Sort array MAPS according to dependencies of the contained objects.
If FORCE_FIRST, MAPS[0] keeps its place even if the dependencies
say otherwise. */