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elf: Add <dl-debug.h> 

Add <dl-debug.h> to setup debugging entry in PT_DYNAMIC segment to support
DT_DEBUG, DT_MIPS_RLD_MAP_REL and DT_MIPS_RLD_MAP.

Tested on x86-64, x32 and i686 as well as with build-many-glibcs.py.
This commit is contained in:
H.J. Lu 2021-12-09 18:24:37 -08:00
parent bd1616c6be
commit 9288c92d00
5 changed files with 80 additions and 33 deletions
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11
elf/dl-reloc-static-pie.c
View File

@ -24,6 +24,7 @@
#include <ldsodefs.h>
#include <dl-machine.h>
#include <dl-debug.h>
#define RESOLVE_MAP(map, scope, sym, version, flags) map
#include "dynamic-link.h"
@ -68,14 +69,6 @@ _dl_relocate_static_pie (void)
/* Set up debugging before the debugger is notified for the first
time. */
# ifdef ELF_MACHINE_DEBUG_SETUP
/* Some machines (e.g. MIPS) don't use DT_DEBUG in this way. */
ELF_MACHINE_DEBUG_SETUP (main_map, r);
# else
if (main_map->l_info[DT_DEBUG] != NULL)
/* There is a DT_DEBUG entry in the dynamic section. Fill it in
with the run-time address of the r_debug structure */
main_map->l_info[DT_DEBUG]->d_un.d_ptr = (ElfW(Addr)) r;
# endif
elf_setup_debug_entry (main_map, r);
}
#endif

13
elf/rtld.c
View File

@ -63,6 +63,9 @@
#define RESOLVE_MAP(map, scope, sym, version, flags) map
#include "dynamic-link.h"
/* Must include after <dl-machine.h> for DT_MIPS definition. */
#include <dl-debug.h>
/* Only enables rtld profiling for architectures which provides non generic
hp-timing support. The generic support requires either syscall
(clock_gettime), which will incur in extra overhead on loading time.
@ -1776,15 +1779,7 @@ dl_main (const ElfW(Phdr) *phdr,
size_t count_modids = _dl_count_modids ();
/* Set up debugging before the debugger is notified for the first time. */
#ifdef ELF_MACHINE_DEBUG_SETUP
/* Some machines (e.g. MIPS) don't use DT_DEBUG in this way. */
ELF_MACHINE_DEBUG_SETUP (main_map, r);
#else
if (main_map->l_info[DT_DEBUG] != NULL)
/* There is a DT_DEBUG entry in the dynamic section. Fill it in
with the run-time address of the r_debug structure */
main_map->l_info[DT_DEBUG]->d_un.d_ptr = (ElfW(Addr)) r;
#endif
elf_setup_debug_entry (main_map, r);
/* We start adding objects. */
r->r_state = RT_ADD;

33
sysdeps/generic/dl-debug.h Normal file
View File

@ -0,0 +1,33 @@
/* Debugging support. Generic version.
Copyright (C) 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/>. */
#ifndef _DL_DEBUG_H
#define _DL_DEBUG_H
/* There is a DT_DEBUG entry in the dynamic section. Fill it in with the
run-time address of the r_debug structure */
static inline void
__attribute ((always_inline))
elf_setup_debug_entry (struct link_map *l, struct r_debug *r)
{
if (l->l_info[DT_DEBUG] != NULL)
l->l_info[DT_DEBUG]->d_un.d_ptr = (ElfW(Addr)) r;
}
#endif /* _DL_DEBUG_H */

41
sysdeps/mips/dl-debug.h Normal file
View File

@ -0,0 +1,41 @@
/* Debugging support. MIPS version.
Copyright (C) 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/>. */
#ifndef _DL_DEBUG_H
#define _DL_DEBUG_H
/* If there is a DT_MIPS_RLD_MAP_REL or DT_MIPS_RLD_MAP entry in the
dynamic section, fill in the debug map pointer with the run-time
address of the r_debug structure. */
static inline void
__attribute ((always_inline))
elf_setup_debug_entry (struct link_map *l, struct r_debug *r)
{
if (l->l_info[DT_MIPS (RLD_MAP_REL)] != NULL)
{
char *ptr = (char *) l->l_info[DT_MIPS (RLD_MAP_REL)];
ptr += l->l_info[DT_MIPS (RLD_MAP_REL)]->d_un.d_val;
*(ElfW(Addr) *) ptr = (ElfW(Addr)) r;
}
else if (l->l_info[DT_MIPS (RLD_MAP)] != NULL)
*(ElfW(Addr) *) (l->l_info[DT_MIPS (RLD_MAP)]->d_un.d_ptr)
= (ElfW(Addr)) r;
}
#endif /* _DL_DEBUG_H */

15
sysdeps/mips/dl-machine.h
View File

@ -65,21 +65,6 @@
in l_info array. */
#define DT_MIPS(x) (DT_MIPS_##x - DT_LOPROC + DT_NUM)
/* If there is a DT_MIPS_RLD_MAP_REL or DT_MIPS_RLD_MAP entry in the dynamic
section, fill in the debug map pointer with the run-time address of the
r_debug structure. */
#define ELF_MACHINE_DEBUG_SETUP(l,r) \
do { if ((l)->l_info[DT_MIPS (RLD_MAP_REL)]) \
{ \
char *ptr = (char *)(l)->l_info[DT_MIPS (RLD_MAP_REL)]; \
ptr += (l)->l_info[DT_MIPS (RLD_MAP_REL)]->d_un.d_val; \
*(ElfW(Addr) *)ptr = (ElfW(Addr)) (r); \
} \
else if ((l)->l_info[DT_MIPS (RLD_MAP)]) \
*(ElfW(Addr) *)((l)->l_info[DT_MIPS (RLD_MAP)]->d_un.d_ptr) = \
(ElfW(Addr)) (r); \
} while (0)
#if ((defined __mips_nan2008 && !defined HAVE_MIPS_NAN2008) \
|| (!defined __mips_nan2008 && defined HAVE_MIPS_NAN2008))
# error "Configuration inconsistency: __mips_nan2008 != HAVE_MIPS_NAN2008, overridden CFLAGS?"