From: Florian Weimer <fw@deneb.enyo.de>
To: libc-alpha@sourceware.org
Subject: [PATCH] elf: Add initial flag argument to __libc_early_init
Date: Mon, 27 Apr 2020 14:31:21 +0200 [thread overview]
Message-ID: <87a72xxg86.fsf@mid.deneb.enyo.de> (raw)
The rseq initialization should happen only for the libc in the base
namespace (in the dynamic case) or the statically linked libc. The
__libc_multiple_libcs flag does not quite cover this case at present,
so this commit introduces a flag argument to __libc_early_init,
indicating whether the libc being libc is the primary one (of the main
program).
Tested on i686-linux-gnu and x86_64-linux-gnu (although the new flag
is currently not used).
-----
csu/libc-start.c | 3 ++-
elf/dl-call-libc-early-init.c | 4 ++--
elf/dl-open.c | 17 +++++++++++++++--
elf/libc-early-init.h | 11 +++++++----
elf/libc_early_init.c | 2 +-
elf/rtld.c | 6 ++++--
6 files changed, 31 insertions(+), 12 deletions(-)
diff --git a/csu/libc-start.c b/csu/libc-start.c
index ccc743c9d1..4005caf84a 100644
--- a/csu/libc-start.c
+++ b/csu/libc-start.c
@@ -23,6 +23,7 @@
#include <exit-thread.h>
#include <libc-internal.h>
#include <elf/libc-early-init.h>
+#include <stdbool.h>
#include <elf/dl-tunables.h>
@@ -241,7 +242,7 @@ LIBC_START_MAIN (int (*main) (int, char **, char ** MAIN_AUXVEC_DECL),
#ifndef SHARED
/* Perform early initialization. In the shared case, this function
is called from the dynamic loader as early as possible. */
- __libc_early_init ();
+ __libc_early_init (true);
/* Call the initializer of the libc. This is only needed here if we
are compiling for the static library in which case we haven't
diff --git a/elf/dl-call-libc-early-init.c b/elf/dl-call-libc-early-init.c
index 41e9ad9aad..9a84680a1c 100644
--- a/elf/dl-call-libc-early-init.c
+++ b/elf/dl-call-libc-early-init.c
@@ -23,7 +23,7 @@
#include <stddef.h>
void
-_dl_call_libc_early_init (struct link_map *libc_map)
+_dl_call_libc_early_init (struct link_map *libc_map, _Bool initial)
{
/* There is nothing to do if we did not actually load libc.so. */
if (libc_map == NULL)
@@ -37,5 +37,5 @@ _dl_call_libc_early_init (struct link_map *libc_map)
assert (sym != NULL);
__typeof (__libc_early_init) *early_init
= DL_SYMBOL_ADDRESS (libc_map, sym);
- early_init ();
+ early_init (initial);
}
diff --git a/elf/dl-open.c b/elf/dl-open.c
index ac7ab495e4..7bf1144e93 100644
--- a/elf/dl-open.c
+++ b/elf/dl-open.c
@@ -748,9 +748,22 @@ dl_open_worker (void *a)
LIBC_PROBE (reloc_complete, 3, args->nsid, r, new);
/* If libc.so was not there before, attempt to call its early
- initialization routine. */
+ initialization routine. Indicate to the initialization routine
+ whether thie libc being initialized is the one in the base
+ namespace. */
if (!args->libc_already_loaded)
- _dl_call_libc_early_init (GL(dl_ns)[args->nsid].libc_map);
+ {
+ struct link_map *libc_map = GL(dl_ns)[args->nsid].libc_map;
+#ifdef SHARED
+ bool initial = libc_map->l_ns == LM_ID_BASE;
+#else
+ /* In the static case, there is only one namespace, but it
+ contains a secondary libc (the primary libc is statically
+ linked). */
+ bool initial = false;
+#endif
+ _dl_call_libc_early_init (libc_map, initial);
+ }
#ifndef SHARED
DL_STATIC_INIT (new);
diff --git a/elf/libc-early-init.h b/elf/libc-early-init.h
index 5185fa8895..8f7836dcea 100644
--- a/elf/libc-early-init.h
+++ b/elf/libc-early-init.h
@@ -22,14 +22,17 @@
struct link_map;
/* If LIBC_MAP is not NULL, look up the __libc_early_init symbol in it
- and call this function. */
-void _dl_call_libc_early_init (struct link_map *libc_map) attribute_hidden;
+ and call this function, with INITIAL as the argument. */
+void _dl_call_libc_early_init (struct link_map *libc_map, _Bool initial)
+ attribute_hidden;
/* In the shared case, this function is defined in libc.so and invoked
from ld.so (or on the fist static dlopen) after complete relocation
of a new loaded libc.so, but before user-defined ELF constructors
run. In the static case, this function is called directly from the
- startup code. */
-void __libc_early_init (void);
+ startup code. If INITIAL is true, the libc being initialized is
+ the libc for the main program. INITIAL is false for libcs loaded
+ for audit modules, dlmopen, and static dlopen. */
+void __libc_early_init (_Bool initial);
#endif /* _LIBC_EARLY_INIT_H */
diff --git a/elf/libc_early_init.c b/elf/libc_early_init.c
index 7f4ca332b8..e6c64fb526 100644
--- a/elf/libc_early_init.c
+++ b/elf/libc_early_init.c
@@ -20,7 +20,7 @@
#include <libc-early-init.h>
void
-__libc_early_init (void)
+__libc_early_init (_Bool initial)
{
/* Initialize ctype data. */
__ctype_init ();
diff --git a/elf/rtld.c b/elf/rtld.c
index 0016db86a7..5ccc3c2dbb 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -2373,8 +2373,10 @@ ERROR: '%s': cannot process note segment.\n", _dl_argv[0]);
rtld_timer_accum (&relocate_time, start);
}
- /* Relocation is complete. Perform early libc initialization. */
- _dl_call_libc_early_init (GL(dl_ns)[LM_ID_BASE].libc_map);
+ /* Relocation is complete. Perform early libc initialization. This
+ is the initial libc, even if audit modules have been loaded with
+ other libcs. */
+ _dl_call_libc_early_init (GL(dl_ns)[LM_ID_BASE].libc_map, true);
/* Do any necessary cleanups for the startup OS interface code.
We do these now so that no calls are made after rtld re-relocation
next reply other threads:[~2020-04-27 12:31 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-27 12:31 Florian Weimer [this message]
2020-04-29 13:30 ` [PATCH] elf: Add initial flag argument to __libc_early_init Carlos O'Donell via Libc-alpha
-- strict thread matches above, loose matches on Subject: below --
2020-04-27 18:07 Mathieu Desnoyers via Libc-alpha
2020-04-27 19:06 ` Florian Weimer
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