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* [glibc/fw/unwind-link] Implement <unwind-link.h> for dynamically loading the libgcc_s unwinder
@ 2020-02-10 17:08 Florian Weimer
0 siblings, 0 replies; 3+ messages in thread
From: Florian Weimer @ 2020-02-10 17:08 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=01b41a99850200248e385e7fd9abee899ed75777
commit 01b41a99850200248e385e7fd9abee899ed75777
Author: Florian Weimer <fweimer@redhat.com>
Date: Mon Feb 10 14:23:16 2020 +0100
Implement <unwind-link.h> for dynamically loading the libgcc_s unwinder
This will be used to consolidate the libgcc_s access for backtrace
and pthread_cancel.
Unlike the backtrace implementations, it provides some hardening
based on pointer mangling.
Diff:
---
malloc/set-freeres.c | 5 ++
misc/Makefile | 2 +-
misc/Versions | 1 +
misc/unwind-link.c | 114 +++++++++++++++++++++++++++++
sysdeps/arm/unwind-link.h | 33 +++++++++
sysdeps/generic/unwind-link.h | 85 +++++++++++++++++++++
sysdeps/i386/unwind-link.h | 31 ++++++++
sysdeps/unix/sysv/linux/ia64/unwind-link.h | 31 ++++++++
8 files changed, 301 insertions(+), 1 deletion(-)
diff --git a/malloc/set-freeres.c b/malloc/set-freeres.c
index aa80eb6..a80cd30 100644
--- a/malloc/set-freeres.c
+++ b/malloc/set-freeres.c
@@ -19,6 +19,7 @@
#include <stdlib.h>
#include <set-hooks.h>
#include <libc-internal.h>
+#include <unwind-link.h>
#include "../libio/libioP.h"
@@ -56,6 +57,10 @@ __libc_freeres (void)
if (&__libpthread_freeres != NULL)
__libpthread_freeres ();
+#ifdef SHARED
+ __libc_unwind_link_freeres ();
+#endif
+
for (p = symbol_set_first_element (__libc_freeres_ptrs);
!symbol_set_end_p (__libc_freeres_ptrs, p); ++p)
free (*p);
diff --git a/misc/Makefile b/misc/Makefile
index e046598..aae5241 100644
--- a/misc/Makefile
+++ b/misc/Makefile
@@ -72,7 +72,7 @@ routines := brk sbrk sstk ioctl \
fgetxattr flistxattr fremovexattr fsetxattr getxattr \
listxattr lgetxattr llistxattr lremovexattr lsetxattr \
removexattr setxattr getauxval ifunc-impl-list makedev \
- allocate_once
+ allocate_once unwind-link
generated += tst-error1.mtrace tst-error1-mem.out \
tst-allocate_once.mtrace tst-allocate_once-mem.out
diff --git a/misc/Versions b/misc/Versions
index e749582..a9cfe3b 100644
--- a/misc/Versions
+++ b/misc/Versions
@@ -169,5 +169,6 @@ libc {
__mmap; __munmap; __mprotect;
__sched_get_priority_min; __sched_get_priority_max;
__libc_allocate_once_slow;
+ __libc_unwind_link_get;
}
}
diff --git a/misc/unwind-link.c b/misc/unwind-link.c
new file mode 100644
index 0000000..b0d5a70
--- /dev/null
+++ b/misc/unwind-link.c
@@ -0,0 +1,114 @@
+/* Dynamic loading of the libgcc unwinder.
+ Copyright (C) 2020 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/>. */
+
+#ifdef SHARED
+
+#include <allocate_once.h>
+#include <assert.h>
+#include <dlfcn.h>
+#include <gnu/lib-names.h>
+#include <unwind-link.h>
+
+/* Used by allocate_one. */
+static void *place;
+
+/* Open libgcc_s and look up the symbols required by glibc. */
+static void *
+allocate_link (void *closure)
+{
+ struct unwind_link *result = malloc (sizeof (*result));
+ if (result == NULL)
+ return NULL;
+
+ result->libgcc_handle = __libc_dlopen (LIBGCC_S_SO);
+ if (result->libgcc_handle == NULL)
+ {
+ /* Assume that this is a transient failure. */
+ free (result);
+ return NULL;
+ }
+
+ result->ptr__Unwind_Backtrace
+ = __libc_dlsym (result->libgcc_handle, "_Unwind_Backtrace");
+ result->ptr__Unwind_ForcedUnwind
+ = __libc_dlsym (result->libgcc_handle, "_Unwind_ForcedUnwind");
+ result->ptr__Unwind_GetCFA
+ = __libc_dlsym (result->libgcc_handle, "_Unwind_GetCFA");
+#ifndef UNWIND_LINK_NO_GETIP
+ result->ptr__Unwind_GetIP
+ = __libc_dlsym (result->libgcc_handle, "_Unwind_GetIP");
+#endif
+ result->ptr__Unwind_Resume
+ = __libc_dlsym (result->libgcc_handle, "_Unwind_Resume");
+ result->ptr_personality
+ = __libc_dlsym (result->libgcc_handle, "__gcc_personality_v0");
+#ifdef UNWIND_LINK_EXTRA_INIT
+ UNWIND_LINK_EXTRA_INIT
+#endif
+
+ /* If a symbol is missing, libgcc_s has somehow been corrupted. */
+ assert (result->ptr__Unwind_Backtrace != NULL);
+ assert (result->ptr__Unwind_ForcedUnwind != NULL);
+ assert (result->ptr__Unwind_GetCFA != NULL);
+#ifndef UNWIND_LINK_NO_GETIP
+ assert (result->ptr__Unwind_GetIP != NULL);
+#endif
+ assert (result->ptr__Unwind_Resume != NULL);
+ assert (result->ptr_personality != NULL);
+
+#ifdef PTR_MANGLE
+ PTR_MANGLE (result->ptr__Unwind_Backtrace);
+ PTR_MANGLE (result->ptr__Unwind_ForcedUnwind);
+ PTR_MANGLE (result->ptr__Unwind_GetCFA);
+# ifndef UNWIND_LINK_NO_GETIP
+ PTR_MANGLE (result->ptr__Unwind_GetIP);
+# endif
+ PTR_MANGLE (result->ptr__Unwind_Resume);
+ PTR_MANGLE (result->ptr_personality);
+#endif
+
+ return result;
+}
+
+/* Deallocate the object after the race was lost. */
+static void
+deallocate_link (void *closure, void *result)
+{
+ struct unwind_link *link = result;
+ __libc_dlclose (link->libgcc_handle);
+ free (link);
+}
+
+struct unwind_link *
+__libc_unwind_link_get (void)
+{
+ return allocate_once (&place, allocate_link, deallocate_link, NULL);
+}
+libc_hidden_def (__libc_unwind_link_get)
+
+void __libc_freeres_fn_section
+__libc_unwind_link_freeres (void)
+{
+ if (place != NULL)
+ {
+ deallocate_link (NULL, place);
+ place = NULL;
+ }
+}
+
+#endif /* SHARED */
diff --git a/sysdeps/arm/unwind-link.h b/sysdeps/arm/unwind-link.h
new file mode 100644
index 0000000..2372bd8
--- /dev/null
+++ b/sysdeps/arm/unwind-link.h
@@ -0,0 +1,33 @@
+/* Dynamic loading of the libgcc unwinder. Arm overrides.
+ Copyright (C) 2020 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 _UNWIND_LINK_H
+
+/* On arm, _Unwind_GetIP is a macro. */
+#define UNWIND_LINK_NO_GETIP
+#define UNWIND_LINK_EXTRA_FIELDS \
+ __typeof (_Unwind_VRS_Get) *ptr__Unwind_VRS_Get;
+#define UNWIND_LINK_EXTRA_INIT \
+ result->ptr__Unwind_VRS_Get \
+ = __libc_dlsym (result->libgcc_handle, "_Unwind_VRS_Get"); \
+ assert (result->ptr__Unwind_VRS_Get != NULL); \
+ PTR_MANGLE (result->ptr__Unwind_VRS_Get);
+
+#include <sysdeps/generic/unwind-link.h>
+
+#endif /* _UNWIND_LINK_H */
diff --git a/sysdeps/generic/unwind-link.h b/sysdeps/generic/unwind-link.h
new file mode 100644
index 0000000..4fca352
--- /dev/null
+++ b/sysdeps/generic/unwind-link.h
@@ -0,0 +1,85 @@
+/* Dynamic loading of the libgcc unwinder. Generic version.
+ Copyright (C) 2020 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 _UNWIND_LINK_H
+#define _UNWIND_LINK_H
+
+#include <unwind.h>
+
+#ifdef SHARED
+
+#include <sysdep.h>
+#include <unwind-resume.h>
+
+struct unwind_link
+{
+ void *libgcc_handle;
+ __typeof (_Unwind_Backtrace) *ptr__Unwind_Backtrace;
+ __typeof (_Unwind_ForcedUnwind) *ptr__Unwind_ForcedUnwind;
+ __typeof (_Unwind_GetCFA) *ptr__Unwind_GetCFA;
+# ifndef UNWIND_LINK_NO_GETIP
+ __typeof (_Unwind_GetIP) *ptr__Unwind_GetIP;
+# endif
+ __typeof (_Unwind_Resume) *ptr__Unwind_Resume;
+ _Unwind_Reason_Code (*ptr_personality) PERSONALITY_PROTO;
+# ifdef UNWIND_LINK_EXTRA_FIELDS
+ UNWIND_LINK_EXTRA_FIELDS
+# endif
+};
+
+/* Return a pointer to the implementation, or NULL on failure. */
+struct unwind_link *__libc_unwind_link_get (void);
+libc_hidden_proto (__libc_unwind_link_get)
+
+/* UNWIND_LINK_CALL invokes the stored function pointer NAME via the
+ cached unwind link OBJ (which was previously returned by
+ __libc_unwind_link_get). */
+# ifdef PTR_DEMANGLE
+# define UNWIND_LINK_CALL(obj, name, ...) \
+ ({ \
+ __typeof ((obj)->ptr_##name) __unwind_fptr = (obj)->ptr_##name; \
+ PTR_DEMANGLE (__unwind_fptr); \
+ __unwind_fptr (__VA_ARGS__); \
+ })
+# else /* !PTR_DEMANGLE */
+# define UNWIND_LINK_CALL(obj, name, ...) ((obj)->ptr_##name (__VA_ARGS__))
+# endif
+
+/* Called from __libc_freeres. */
+void __libc_unwind_link_freeres (void) attribute_hidden;
+
+#else /* !SHARED */
+
+/* Dummy implementation so that the code can be shared with the SHARED
+ version. */
+struct unwind_link;
+static inline struct unwind_link *
+__libc_unwind_link_get (void)
+{
+ /* Return something that is not a null pointer, so that error checks
+ succeed. */
+ return (struct unwind_link *) 1;
+}
+
+/* Directly call the static implementation. */
+# define UNWIND_LINK_CALL(obj, name, ...) \
+ ((void) (obj), (name (__VA_ARGS__)))
+
+#endif /* !SHARED */
+
+#endif /* _UNWIND_LINK_H */
diff --git a/sysdeps/i386/unwind-link.h b/sysdeps/i386/unwind-link.h
new file mode 100644
index 0000000..ef5999f
--- /dev/null
+++ b/sysdeps/i386/unwind-link.h
@@ -0,0 +1,31 @@
+/* Dynamic loading of the libgcc unwinder. i386 overrides.
+ Copyright (C) 2020 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 _UNWIND_LINK_H
+
+#define UNWIND_LINK_EXTRA_FIELDS \
+ __typeof (_Unwind_GetGR) *ptr__Unwind_GetGR;
+#define UNWIND_LINK_EXTRA_INIT \
+ result->ptr__Unwind_GetGR \
+ = __libc_dlsym (result->libgcc_handle, "_Unwind_GetGR"); \
+ assert (result->ptr__Unwind_GetGR != NULL); \
+ PTR_MANGLE (result->ptr__Unwind_GetGR);
+
+#include <sysdeps/generic/unwind-link.h>
+
+#endif /* _UNWIND_LINK_H */
diff --git a/sysdeps/unix/sysv/linux/ia64/unwind-link.h b/sysdeps/unix/sysv/linux/ia64/unwind-link.h
new file mode 100644
index 0000000..32dd74b
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/ia64/unwind-link.h
@@ -0,0 +1,31 @@
+/* Dynamic loading of the libgcc unwinder. ia64 overrides.
+ Copyright (C) 2020 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 _UNWIND_LINK_H
+
+#define UNWIND_LINK_EXTRA_FIELDS \
+ __typeof (_Unwind_GetBSP) *ptr__Unwind_GetBSP;
+#define UNWIND_LINK_EXTRA_INIT \
+ result->ptr__Unwind_GetBSP \
+ = __libc_dlsym (result->libgcc_handle, "_Unwind_GetBSP"); \
+ assert (result->ptr__Unwind_GetBSP != NULL); \
+ PTR_MANGLE (result->ptr__Unwind_GetBSP);
+
+#include <sysdeps/generic/unwind-link.h>
+
+#endif /* _UNWIND_LINK_H */
^ permalink raw reply [flat|nested] 3+ messages in thread
* [glibc/fw/unwind-link] Implement <unwind-link.h> for dynamically loading the libgcc_s unwinder
@ 2020-02-13 16:22 Florian Weimer
0 siblings, 0 replies; 3+ messages in thread
From: Florian Weimer @ 2020-02-13 16:22 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=030c3e22e6b32b890d78c5b3ee7c3023a3013c94
commit 030c3e22e6b32b890d78c5b3ee7c3023a3013c94
Author: Florian Weimer <fweimer@redhat.com>
Date: Thu Feb 13 17:05:50 2020 +0100
Implement <unwind-link.h> for dynamically loading the libgcc_s unwinder
This will be used to consolidate the libgcc_s access for backtrace
and pthread_cancel.
Unlike the backtrace implementations, it provides some hardening
based on pointer mangling.
Diff:
---
malloc/set-freeres.c | 5 +
misc/Makefile | 2 +-
misc/Versions | 1 +
misc/unwind-link.c | 149 +++++++++++++++++++++++++++
sysdeps/alpha/arch-unwind-link.h | 27 +++++
sysdeps/arm/arch-unwind-link.h | 34 ++++++
sysdeps/generic/arch-unwind-link.h | 32 ++++++
sysdeps/generic/unwind-link.h | 99 ++++++++++++++++++
sysdeps/i386/arch-unwind-link.h | 38 +++++++
sysdeps/ia64/arch-unwind-link.h | 31 ++++++
sysdeps/m68k/arch-unwind-link.h | 34 ++++++
sysdeps/m68k/m680x0/arch-unwind-link.h | 26 +++++
sysdeps/mach/hurd/fork.c | 3 +
sysdeps/mips/arch-unwind-link.h | 27 +++++
sysdeps/nptl/fork.c | 3 +
sysdeps/powerpc/powerpc32/arch-unwind-link.h | 27 +++++
sysdeps/s390/arch-unwind-link.h | 27 +++++
sysdeps/sh/arch-unwind-link.h | 27 +++++
sysdeps/sparc/arch-unwind-link.h | 27 +++++
19 files changed, 618 insertions(+), 1 deletion(-)
diff --git a/malloc/set-freeres.c b/malloc/set-freeres.c
index aa80eb6..a80cd30 100644
--- a/malloc/set-freeres.c
+++ b/malloc/set-freeres.c
@@ -19,6 +19,7 @@
#include <stdlib.h>
#include <set-hooks.h>
#include <libc-internal.h>
+#include <unwind-link.h>
#include "../libio/libioP.h"
@@ -56,6 +57,10 @@ __libc_freeres (void)
if (&__libpthread_freeres != NULL)
__libpthread_freeres ();
+#ifdef SHARED
+ __libc_unwind_link_freeres ();
+#endif
+
for (p = symbol_set_first_element (__libc_freeres_ptrs);
!symbol_set_end_p (__libc_freeres_ptrs, p); ++p)
free (*p);
diff --git a/misc/Makefile b/misc/Makefile
index e046598..aae5241 100644
--- a/misc/Makefile
+++ b/misc/Makefile
@@ -72,7 +72,7 @@ routines := brk sbrk sstk ioctl \
fgetxattr flistxattr fremovexattr fsetxattr getxattr \
listxattr lgetxattr llistxattr lremovexattr lsetxattr \
removexattr setxattr getauxval ifunc-impl-list makedev \
- allocate_once
+ allocate_once unwind-link
generated += tst-error1.mtrace tst-error1-mem.out \
tst-allocate_once.mtrace tst-allocate_once-mem.out
diff --git a/misc/Versions b/misc/Versions
index e749582..a9cfe3b 100644
--- a/misc/Versions
+++ b/misc/Versions
@@ -169,5 +169,6 @@ libc {
__mmap; __munmap; __mprotect;
__sched_get_priority_min; __sched_get_priority_max;
__libc_allocate_once_slow;
+ __libc_unwind_link_get;
}
}
diff --git a/misc/unwind-link.c b/misc/unwind-link.c
new file mode 100644
index 0000000..49076f8
--- /dev/null
+++ b/misc/unwind-link.c
@@ -0,0 +1,149 @@
+/* Dynamic loading of the libgcc unwinder.
+ Copyright (C) 2020 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/>. */
+
+#ifdef SHARED
+
+#include <assert.h>
+#include <dlfcn.h>
+#include <gnu/lib-names.h>
+#include <unwind-link.h>
+#include <libc-lock.h>
+
+/* Statically allocate the object, so that we do not have to deal with
+ malloc failure. __libc_unwind_link_get must not fail if libgcc_s
+ has already been loaded by other means. */
+static struct unwind_link global;
+
+/* dlopen handle. Also used for the double-checked locking idiom. */
+static void *global_libgcc_handle;
+
+/* We cannot use __libc_once because the pthread_once implementation
+ may depend on unwinding. */
+__libc_lock_define (static, lock);
+
+struct unwind_link *
+__libc_unwind_link_get (void)
+{
+ /* Double-checked locking idiom. Synchronizes with the release MO
+ store at the end of this function. */
+ if (atomic_load_acquire (&global_libgcc_handle) != NULL)
+ return &global;
+
+ /* Initialize a copy of the data, so that we do not need about
+ unlocking in case the dynamic loader somehow triggers
+ unwinding. */
+ void *local_libgcc_handle = __libc_dlopen (LIBGCC_S_SO);
+ if (local_libgcc_handle == NULL)
+ {
+ __libc_lock_unlock (lock);
+ return NULL;
+ }
+
+ struct unwind_link local;
+ local.ptr__Unwind_Backtrace
+ = __libc_dlsym (local_libgcc_handle, "_Unwind_Backtrace");
+ local.ptr__Unwind_ForcedUnwind
+ = __libc_dlsym (local_libgcc_handle, "_Unwind_ForcedUnwind");
+ local.ptr__Unwind_GetCFA
+ = __libc_dlsym (local_libgcc_handle, "_Unwind_GetCFA");
+#if UNWIND_LINK_GETIP
+ local.ptr__Unwind_GetIP
+ = __libc_dlsym (local_libgcc_handle, "_Unwind_GetIP");
+#endif
+ local.ptr__Unwind_Resume
+ = __libc_dlsym (local_libgcc_handle, "_Unwind_Resume");
+#if UNWIND_LINK_FRAME_STATE_FOR
+ local.ptr___frame_state_for
+ = __libc_dlsym (local_libgcc_handle, "__frame_state_for");
+#endif
+ local.ptr_personality
+ = __libc_dlsym (local_libgcc_handle, "__gcc_personality_v0");
+ UNWIND_LINK_EXTRA_INIT
+
+ /* If a symbol is missing, libgcc_s has somehow been corrupted. */
+ assert (local.ptr__Unwind_Backtrace != NULL);
+ assert (local.ptr__Unwind_ForcedUnwind != NULL);
+ assert (local.ptr__Unwind_GetCFA != NULL);
+#if UNWIND_LINK_GETIP
+ assert (local.ptr__Unwind_GetIP != NULL);
+#endif
+ assert (local.ptr__Unwind_Resume != NULL);
+ assert (local.ptr_personality != NULL);
+
+#ifdef PTR_MANGLE
+ PTR_MANGLE (local.ptr__Unwind_Backtrace);
+ PTR_MANGLE (local.ptr__Unwind_ForcedUnwind);
+ PTR_MANGLE (local.ptr__Unwind_GetCFA);
+# if UNWIND_LINK_GETIP
+ PTR_MANGLE (local.ptr__Unwind_GetIP);
+# endif
+ PTR_MANGLE (local.ptr__Unwind_Resume);
+# if UNWIND_LINK_FRAME_STATE_FOR
+ PTR_MANGLE (local.ptr___frame_state_for);
+# endif
+ PTR_MANGLE (local.ptr_personality);
+#endif
+
+ __libc_lock_lock (lock);
+ if (atomic_load_relaxed (&global_libgcc_handle) != NULL)
+ /* This thread lost the race. Clean up. */
+ __libc_dlclose (local_libgcc_handle);
+ else
+ {
+ global = local;
+
+ /* Completes the double-checked locking idiom. */
+ atomic_store_release (&global_libgcc_handle, local_libgcc_handle);
+ }
+
+ __libc_lock_unlock (lock);
+ return &global;
+}
+libc_hidden_def (__libc_unwind_link_get)
+
+void
+__libc_unwind_link_after_fork (void)
+{
+ if (__libc_lock_trylock (lock) == 0)
+ /* The lock was not acquired during the fork. This covers both
+ the initialized and uninitialized case. */
+ __libc_lock_unlock (lock);
+ else
+ {
+ /* Initialization was in progress in another thread.
+ Reinitialize the lock. */
+ __libc_lock_init (lock);
+ global_libgcc_handle = NULL;
+ }
+}
+
+void __libc_freeres_fn_section
+__libc_unwind_link_freeres (void)
+{
+ if (__libc_lock_trylock (lock) == 0)
+ {
+ if (global_libgcc_handle != NULL)
+ {
+ __libc_dlclose (global_libgcc_handle );
+ global_libgcc_handle = NULL;
+ }
+ __libc_lock_unlock (lock);
+ }
+}
+
+#endif /* SHARED */
diff --git a/sysdeps/alpha/arch-unwind-link.h b/sysdeps/alpha/arch-unwind-link.h
new file mode 100644
index 0000000..998e47c
--- /dev/null
+++ b/sysdeps/alpha/arch-unwind-link.h
@@ -0,0 +1,27 @@
+/* Dynamic loading of the libgcc unwinder. alpha customization.
+ Copyright (C) 2020 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 _ARCH_UNWIND_LINK_H
+#define _ARCH_UNWIND_LINK_H
+
+#define UNWIND_LINK_GETIP 1
+#define UNWIND_LINK_FRAME_STATE_FOR 1
+#define UNWIND_LINK_EXTRA_FIELDS
+#define UNWIND_LINK_EXTRA_INIT
+
+#endif /* _ARCH_UNWIND_LINK_H */
diff --git a/sysdeps/arm/arch-unwind-link.h b/sysdeps/arm/arch-unwind-link.h
new file mode 100644
index 0000000..b16a94e
--- /dev/null
+++ b/sysdeps/arm/arch-unwind-link.h
@@ -0,0 +1,34 @@
+/* Dynamic loading of the libgcc unwinder. Arm customization.
+ Copyright (C) 2020 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 _ARCH_UNWIND_LINK_H
+#define _ARCH_UNWIND_LINK_H
+
+/* On arm, _Unwind_GetIP is a macro. */
+#define UNWIND_LINK_GETIP 0
+
+#define UNWIND_LINK_FRAME_STATE_FOR 0
+#define UNWIND_LINK_EXTRA_FIELDS \
+ __typeof (_Unwind_VRS_Get) *ptr__Unwind_VRS_Get;
+#define UNWIND_LINK_EXTRA_INIT \
+ local.ptr__Unwind_VRS_Get \
+ = __libc_dlsym (local_libgcc_handle, "_Unwind_VRS_Get"); \
+ assert (local.ptr__Unwind_VRS_Get != NULL); \
+ PTR_MANGLE (local.ptr__Unwind_VRS_Get);
+
+#endif /* _ARCH_UNWIND_LINK_H */
diff --git a/sysdeps/generic/arch-unwind-link.h b/sysdeps/generic/arch-unwind-link.h
new file mode 100644
index 0000000..efc2292
--- /dev/null
+++ b/sysdeps/generic/arch-unwind-link.h
@@ -0,0 +1,32 @@
+/* Dynamic loading of the libgcc unwinder. Generic version of parameters.
+ Copyright (C) 2020 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 _ARCH_UNWIND_LINK_H
+#define _ARCH_UNWIND_LINK_H
+
+/* The _Unwind_GetIP function is supported. */
+#define UNWIND_LINK_GETIP 1
+
+/* The __frame_state_for is needed and re-exported from glibc. */
+#define UNWIND_LINK_FRAME_STATE_FOR 0
+
+/* There are no extra fields in struct unwind_link. */
+#define UNWIND_LINK_EXTRA_FIELDS
+#define UNWIND_LINK_EXTRA_INIT
+
+#endif /* _ARCH_UNWIND_LINK_H */
diff --git a/sysdeps/generic/unwind-link.h b/sysdeps/generic/unwind-link.h
new file mode 100644
index 0000000..9e6e134
--- /dev/null
+++ b/sysdeps/generic/unwind-link.h
@@ -0,0 +1,99 @@
+/* Dynamic loading of the libgcc unwinder. Generic version.
+ Copyright (C) 2020 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 _UNWIND_LINK_H
+#define _UNWIND_LINK_H
+
+#include <unwind.h>
+
+#ifdef SHARED
+
+#include <arch-unwind-link.h>
+#include <sysdep.h>
+#include <unwind-resume.h>
+
+#if UNWIND_LINK_FRAME_STATE_FOR
+struct frame_state;
+#endif
+
+struct unwind_link
+{
+ __typeof (_Unwind_Backtrace) *ptr__Unwind_Backtrace;
+ __typeof (_Unwind_ForcedUnwind) *ptr__Unwind_ForcedUnwind;
+ __typeof (_Unwind_GetCFA) *ptr__Unwind_GetCFA;
+# if UNWIND_LINK_GETIP
+ __typeof (_Unwind_GetIP) *ptr__Unwind_GetIP;
+# endif
+ __typeof (_Unwind_Resume) *ptr__Unwind_Resume;
+#if UNWIND_LINK_FRAME_STATE_FOR
+ struct frame_state *(*ptr___frame_state_for)(void *pc, struct frame_state *);
+#endif
+ _Unwind_Reason_Code (*ptr_personality) PERSONALITY_PROTO;
+ UNWIND_LINK_EXTRA_FIELDS
+};
+
+/* Return a pointer to the implementation, or NULL on failure. */
+struct unwind_link *__libc_unwind_link_get (void);
+libc_hidden_proto (__libc_unwind_link_get)
+
+/* UNWIND_LINK_PTR returns the stored function pointer NAME from the
+ cached unwind link OBJ (which was previously returned by
+ __libc_unwind_link_get). */
+# ifdef PTR_DEMANGLE
+# define UNWIND_LINK_PTR(obj, name, ...) \
+ ({ \
+ __typeof ((obj)->ptr_##name) __unwind_fptr = (obj)->ptr_##name; \
+ PTR_DEMANGLE (__unwind_fptr); \
+ __unwind_fptr; \
+ })
+# else /* !PTR_DEMANGLE */
+# define UNWIND_LINK_PTR(obj, name, ...) ((obj)->ptr_##name)
+# endif
+
+/* Called from fork, in the new subprocess. */
+void __libc_unwind_link_after_fork (void);
+
+/* Called from __libc_freeres. */
+void __libc_unwind_link_freeres (void) attribute_hidden;
+
+#else /* !SHARED */
+
+/* Dummy implementation so that the code can be shared with the SHARED
+ version. */
+struct unwind_link;
+static inline struct unwind_link *
+__libc_unwind_link_get (void)
+{
+ /* Return something that is not a null pointer, so that error checks
+ succeed. */
+ return (struct unwind_link *) 1;
+}
+
+/* Directly call the static implementation. */
+# define UNWIND_LINK_PTR(obj, name, ...) \
+ ((void) (obj), &name)
+
+static inline void
+__libc_unwind_link_after_fork (void)
+{
+ /* No need to clean up if the unwinder is statically linked. */
+}
+
+#endif /* !SHARED */
+
+#endif /* _UNWIND_LINK_H */
diff --git a/sysdeps/i386/arch-unwind-link.h b/sysdeps/i386/arch-unwind-link.h
new file mode 100644
index 0000000..bc9c3a1
--- /dev/null
+++ b/sysdeps/i386/arch-unwind-link.h
@@ -0,0 +1,38 @@
+/* Dynamic loading of the libgcc unwinder. i386 customization.
+ Copyright (C) 2020 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 _ARCH_UNWIND_LINK_H
+#define _ARCH_UNWIND_LINK_H
+
+#define UNWIND_LINK_GETIP 1
+#define UNWIND_LINK_FRAME_STATE_FOR 1
+#define UNWIND_LINK_EXTRA_FIELDS \
+ __typeof (_Unwind_GetGR) *ptr__Unwind_GetGR;
+#define UNWIND_LINK_EXTRA_INIT_SHARED \
+ local.ptr__Unwind_GetGR \
+ = __libc_dlsym (local_libgcc_handle, "_Unwind_GetGR"); \
+ assert (local.ptr__Unwind_GetGR != NULL);
+#ifdef PTR_MANGLE
+# define UNWIND_LINK_EXTRA_INIT \
+ UNWIND_LINK_EXTRA_INIT_SHARED \
+ PTR_MANGLE (local.ptr__Unwind_GetGR);
+#else
+# define UNWIND_LINK_EXTRA_INIT UNWIND_LINK_EXTRA_INIT_SHARED
+#endif
+
+#endif /* _ARCH_UNWIND_LINK_H */
diff --git a/sysdeps/ia64/arch-unwind-link.h b/sysdeps/ia64/arch-unwind-link.h
new file mode 100644
index 0000000..570b711
--- /dev/null
+++ b/sysdeps/ia64/arch-unwind-link.h
@@ -0,0 +1,31 @@
+/* Dynamic loading of the libgcc unwinder. ia64 customization.
+ Copyright (C) 2020 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 _ARCH_UNWIND_LINK_H
+
+#define UNWIND_LINK_GETIP 1
+#define UNWIND_LINK_FRAME_STATE_FOR 1
+#define UNWIND_LINK_EXTRA_FIELDS \
+ __typeof (_Unwind_GetBSP) *ptr__Unwind_GetBSP;
+#define UNWIND_LINK_EXTRA_INIT \
+ local.ptr__Unwind_GetBSP \
+ = __libc_dlsym (local_libgcc_handle, "_Unwind_GetBSP"); \
+ assert (local.ptr__Unwind_GetBSP != NULL); \
+ PTR_MANGLE (local.ptr__Unwind_GetBSP);
+
+#endif /* _ARCH_UNWIND_LINK_H */
diff --git a/sysdeps/m68k/arch-unwind-link.h b/sysdeps/m68k/arch-unwind-link.h
new file mode 100644
index 0000000..e010514
--- /dev/null
+++ b/sysdeps/m68k/arch-unwind-link.h
@@ -0,0 +1,34 @@
+/* Dynamic loading of the libgcc unwinder. m68k customization.
+ Copyright (C) 2020 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 _ARCH_UNWIND_LINK_H
+#define _ARCH_UNWIND_LINK_H
+
+#define UNWIND_LINK_GETIP 1
+#define UNWIND_LINK_EXTRA_FIELDS \
+ __typeof (_Unwind_GetGR) *ptr__Unwind_GetGR;
+#define UNWIND_LINK_EXTRA_INIT \
+ local.ptr__Unwind_GetGR \
+ = __libc_dlsym (local_libgcc_handle, "_Unwind_GetGR"); \
+ assert (local.ptr__Unwind_GetGR != NULL); \
+ PTR_MANGLE (local.ptr__Unwind_GetGR);
+
+/* This is overriden by the m680x0 variant. */
+#define UNWIND_LINK_FRAME_STATE_FOR 0
+
+#endif /* _ARCH_UNWIND_LINK_H */
diff --git a/sysdeps/m68k/m680x0/arch-unwind-link.h b/sysdeps/m68k/m680x0/arch-unwind-link.h
new file mode 100644
index 0000000..1adbf23
--- /dev/null
+++ b/sysdeps/m68k/m680x0/arch-unwind-link.h
@@ -0,0 +1,26 @@
+/* Dynamic loading of the libgcc unwinder. Baseline m68k customization.
+ Copyright (C) 2020 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 _ARCH_UNWIND_LINK_H
+
+#include <sysdeps/m68k/arch-unwind-link.h>
+
+#undef UNWIND_LINK_FRAME_STATE_FOR
+#define UNWIND_LINK_FRAME_STATE_FOR 1
+
+#endif /* _ARCH_UNWIND_LINK_H */
diff --git a/sysdeps/mach/hurd/fork.c b/sysdeps/mach/hurd/fork.c
index 3278306..1d4819e 100644
--- a/sysdeps/mach/hurd/fork.c
+++ b/sysdeps/mach/hurd/fork.c
@@ -28,6 +28,7 @@
#include "hurdmalloc.h" /* XXX */
#include <tls.h>
#include <malloc/malloc-internal.h>
+#include <unwind-link.h>
#undef __fork
@@ -662,6 +663,8 @@ __fork (void)
__sigemptyset (&_hurd_global_sigstate->pending);
__sigemptyset (&ss->pending);
+ __libc_unwind_link_after_fork ();
+
/* Release malloc locks. */
_hurd_malloc_fork_child ();
call_function_static_weak (__malloc_fork_unlock_child);
diff --git a/sysdeps/mips/arch-unwind-link.h b/sysdeps/mips/arch-unwind-link.h
new file mode 100644
index 0000000..9835c0f
--- /dev/null
+++ b/sysdeps/mips/arch-unwind-link.h
@@ -0,0 +1,27 @@
+/* Dynamic loading of the libgcc unwinder. MIPS customization.
+ Copyright (C) 2020 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 _ARCH_UNWIND_LINK_H
+#define _ARCH_UNWIND_LINK_H
+
+#define UNWIND_LINK_GETIP 1
+#define UNWIND_LINK_FRAME_STATE_FOR 1
+#define UNWIND_LINK_EXTRA_FIELDS
+#define UNWIND_LINK_EXTRA_INIT
+
+#endif /* _ARCH_UNWIND_LINK_H */
diff --git a/sysdeps/nptl/fork.c b/sysdeps/nptl/fork.c
index f5cf88d..19e8381 100644
--- a/sysdeps/nptl/fork.c
+++ b/sysdeps/nptl/fork.c
@@ -32,6 +32,7 @@
#include <arch-fork.h>
#include <futex-internal.h>
#include <malloc/malloc-internal.h>
+#include <unwind-link.h>
static void
fresetlockfiles (void)
@@ -112,6 +113,8 @@ __libc_fork (void)
/* Reset the lock state in the multi-threaded case. */
if (multiple_threads)
{
+ __libc_unwind_link_after_fork ();
+
/* Release malloc locks. */
call_function_static_weak (__malloc_fork_unlock_child);
diff --git a/sysdeps/powerpc/powerpc32/arch-unwind-link.h b/sysdeps/powerpc/powerpc32/arch-unwind-link.h
new file mode 100644
index 0000000..6a87daa
--- /dev/null
+++ b/sysdeps/powerpc/powerpc32/arch-unwind-link.h
@@ -0,0 +1,27 @@
+/* Dynamic loading of the libgcc unwinder. powerpc customization.
+ Copyright (C) 2020 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 _ARCH_UNWIND_LINK_H
+#define _ARCH_UNWIND_LINK_H
+
+#define UNWIND_LINK_GETIP 1
+#define UNWIND_LINK_FRAME_STATE_FOR 1
+#define UNWIND_LINK_EXTRA_FIELDS
+#define UNWIND_LINK_EXTRA_INIT
+
+#endif /* _ARCH_UNWIND_LINK_H */
diff --git a/sysdeps/s390/arch-unwind-link.h b/sysdeps/s390/arch-unwind-link.h
new file mode 100644
index 0000000..c50b7f2
--- /dev/null
+++ b/sysdeps/s390/arch-unwind-link.h
@@ -0,0 +1,27 @@
+/* Dynamic loading of the libgcc unwinder. S/390 customization.
+ Copyright (C) 2020 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 _ARCH_UNWIND_LINK_H
+#define _ARCH_UNWIND_LINK_H
+
+#define UNWIND_LINK_GETIP 1
+#define UNWIND_LINK_FRAME_STATE_FOR 1
+#define UNWIND_LINK_EXTRA_FIELDS
+#define UNWIND_LINK_EXTRA_INIT
+
+#endif /* _ARCH_UNWIND_LINK_H */
diff --git a/sysdeps/sh/arch-unwind-link.h b/sysdeps/sh/arch-unwind-link.h
new file mode 100644
index 0000000..519c224
--- /dev/null
+++ b/sysdeps/sh/arch-unwind-link.h
@@ -0,0 +1,27 @@
+/* Dynamic loading of the libgcc unwinder. SH customization.
+ Copyright (C) 2020 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 _ARCH_UNWIND_LINK_H
+#define _ARCH_UNWIND_LINK_H
+
+#define UNWIND_LINK_GETIP 1
+#define UNWIND_LINK_FRAME_STATE_FOR 1
+#define UNWIND_LINK_EXTRA_FIELDS
+#define UNWIND_LINK_EXTRA_INIT
+
+#endif /* _ARCH_UNWIND_LINK_H */
diff --git a/sysdeps/sparc/arch-unwind-link.h b/sysdeps/sparc/arch-unwind-link.h
new file mode 100644
index 0000000..4b7e2f1
--- /dev/null
+++ b/sysdeps/sparc/arch-unwind-link.h
@@ -0,0 +1,27 @@
+/* Dynamic loading of the libgcc unwinder. SPARC customization.
+ Copyright (C) 2020 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 _ARCH_UNWIND_LINK_H
+#define _ARCH_UNWIND_LINK_H
+
+#define UNWIND_LINK_GETIP 1
+#define UNWIND_LINK_FRAME_STATE_FOR 1
+#define UNWIND_LINK_EXTRA_FIELDS
+#define UNWIND_LINK_EXTRA_INIT
+
+#endif /* _ARCH_UNWIND_LINK_H */
^ permalink raw reply [flat|nested] 3+ messages in thread
* [glibc/fw/unwind-link] Implement <unwind-link.h> for dynamically loading the libgcc_s unwinder
@ 2020-02-13 10:45 Florian Weimer
0 siblings, 0 replies; 3+ messages in thread
From: Florian Weimer @ 2020-02-13 10:45 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=9105752b516e96a3dbcc7f871f4dc48ac304aa26
commit 9105752b516e96a3dbcc7f871f4dc48ac304aa26
Author: Florian Weimer <fweimer@redhat.com>
Date: Tue Feb 11 10:14:58 2020 +0100
Implement <unwind-link.h> for dynamically loading the libgcc_s unwinder
This will be used to consolidate the libgcc_s access for backtrace
and pthread_cancel.
Unlike the backtrace implementations, it provides some hardening
based on pointer mangling.
Diff:
---
malloc/set-freeres.c | 5 +
misc/Makefile | 2 +-
misc/Versions | 1 +
misc/unwind-link.c | 149 +++++++++++++++++++++++++++
sysdeps/alpha/arch-unwind-link.h | 27 +++++
sysdeps/arm/arch-unwind-link.h | 34 ++++++
sysdeps/generic/arch-unwind-link.h | 32 ++++++
sysdeps/generic/unwind-link.h | 99 ++++++++++++++++++
sysdeps/i386/arch-unwind-link.h | 38 +++++++
sysdeps/ia64/arch-unwind-link.h | 31 ++++++
sysdeps/m68k/arch-unwind-link.h | 34 ++++++
sysdeps/m68k/m680x0/arch-unwind-link.h | 26 +++++
sysdeps/mach/hurd/fork.c | 3 +
sysdeps/mips/arch-unwind-link.h | 27 +++++
sysdeps/nptl/fork.c | 3 +
sysdeps/powerpc/powerpc32/arch-unwind-link.h | 27 +++++
sysdeps/s390/arch-unwind-link.h | 27 +++++
sysdeps/sparc/arch-unwind-link.h | 27 +++++
18 files changed, 591 insertions(+), 1 deletion(-)
diff --git a/malloc/set-freeres.c b/malloc/set-freeres.c
index aa80eb6..a80cd30 100644
--- a/malloc/set-freeres.c
+++ b/malloc/set-freeres.c
@@ -19,6 +19,7 @@
#include <stdlib.h>
#include <set-hooks.h>
#include <libc-internal.h>
+#include <unwind-link.h>
#include "../libio/libioP.h"
@@ -56,6 +57,10 @@ __libc_freeres (void)
if (&__libpthread_freeres != NULL)
__libpthread_freeres ();
+#ifdef SHARED
+ __libc_unwind_link_freeres ();
+#endif
+
for (p = symbol_set_first_element (__libc_freeres_ptrs);
!symbol_set_end_p (__libc_freeres_ptrs, p); ++p)
free (*p);
diff --git a/misc/Makefile b/misc/Makefile
index e046598..aae5241 100644
--- a/misc/Makefile
+++ b/misc/Makefile
@@ -72,7 +72,7 @@ routines := brk sbrk sstk ioctl \
fgetxattr flistxattr fremovexattr fsetxattr getxattr \
listxattr lgetxattr llistxattr lremovexattr lsetxattr \
removexattr setxattr getauxval ifunc-impl-list makedev \
- allocate_once
+ allocate_once unwind-link
generated += tst-error1.mtrace tst-error1-mem.out \
tst-allocate_once.mtrace tst-allocate_once-mem.out
diff --git a/misc/Versions b/misc/Versions
index e749582..a9cfe3b 100644
--- a/misc/Versions
+++ b/misc/Versions
@@ -169,5 +169,6 @@ libc {
__mmap; __munmap; __mprotect;
__sched_get_priority_min; __sched_get_priority_max;
__libc_allocate_once_slow;
+ __libc_unwind_link_get;
}
}
diff --git a/misc/unwind-link.c b/misc/unwind-link.c
new file mode 100644
index 0000000..49076f8
--- /dev/null
+++ b/misc/unwind-link.c
@@ -0,0 +1,149 @@
+/* Dynamic loading of the libgcc unwinder.
+ Copyright (C) 2020 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/>. */
+
+#ifdef SHARED
+
+#include <assert.h>
+#include <dlfcn.h>
+#include <gnu/lib-names.h>
+#include <unwind-link.h>
+#include <libc-lock.h>
+
+/* Statically allocate the object, so that we do not have to deal with
+ malloc failure. __libc_unwind_link_get must not fail if libgcc_s
+ has already been loaded by other means. */
+static struct unwind_link global;
+
+/* dlopen handle. Also used for the double-checked locking idiom. */
+static void *global_libgcc_handle;
+
+/* We cannot use __libc_once because the pthread_once implementation
+ may depend on unwinding. */
+__libc_lock_define (static, lock);
+
+struct unwind_link *
+__libc_unwind_link_get (void)
+{
+ /* Double-checked locking idiom. Synchronizes with the release MO
+ store at the end of this function. */
+ if (atomic_load_acquire (&global_libgcc_handle) != NULL)
+ return &global;
+
+ /* Initialize a copy of the data, so that we do not need about
+ unlocking in case the dynamic loader somehow triggers
+ unwinding. */
+ void *local_libgcc_handle = __libc_dlopen (LIBGCC_S_SO);
+ if (local_libgcc_handle == NULL)
+ {
+ __libc_lock_unlock (lock);
+ return NULL;
+ }
+
+ struct unwind_link local;
+ local.ptr__Unwind_Backtrace
+ = __libc_dlsym (local_libgcc_handle, "_Unwind_Backtrace");
+ local.ptr__Unwind_ForcedUnwind
+ = __libc_dlsym (local_libgcc_handle, "_Unwind_ForcedUnwind");
+ local.ptr__Unwind_GetCFA
+ = __libc_dlsym (local_libgcc_handle, "_Unwind_GetCFA");
+#if UNWIND_LINK_GETIP
+ local.ptr__Unwind_GetIP
+ = __libc_dlsym (local_libgcc_handle, "_Unwind_GetIP");
+#endif
+ local.ptr__Unwind_Resume
+ = __libc_dlsym (local_libgcc_handle, "_Unwind_Resume");
+#if UNWIND_LINK_FRAME_STATE_FOR
+ local.ptr___frame_state_for
+ = __libc_dlsym (local_libgcc_handle, "__frame_state_for");
+#endif
+ local.ptr_personality
+ = __libc_dlsym (local_libgcc_handle, "__gcc_personality_v0");
+ UNWIND_LINK_EXTRA_INIT
+
+ /* If a symbol is missing, libgcc_s has somehow been corrupted. */
+ assert (local.ptr__Unwind_Backtrace != NULL);
+ assert (local.ptr__Unwind_ForcedUnwind != NULL);
+ assert (local.ptr__Unwind_GetCFA != NULL);
+#if UNWIND_LINK_GETIP
+ assert (local.ptr__Unwind_GetIP != NULL);
+#endif
+ assert (local.ptr__Unwind_Resume != NULL);
+ assert (local.ptr_personality != NULL);
+
+#ifdef PTR_MANGLE
+ PTR_MANGLE (local.ptr__Unwind_Backtrace);
+ PTR_MANGLE (local.ptr__Unwind_ForcedUnwind);
+ PTR_MANGLE (local.ptr__Unwind_GetCFA);
+# if UNWIND_LINK_GETIP
+ PTR_MANGLE (local.ptr__Unwind_GetIP);
+# endif
+ PTR_MANGLE (local.ptr__Unwind_Resume);
+# if UNWIND_LINK_FRAME_STATE_FOR
+ PTR_MANGLE (local.ptr___frame_state_for);
+# endif
+ PTR_MANGLE (local.ptr_personality);
+#endif
+
+ __libc_lock_lock (lock);
+ if (atomic_load_relaxed (&global_libgcc_handle) != NULL)
+ /* This thread lost the race. Clean up. */
+ __libc_dlclose (local_libgcc_handle);
+ else
+ {
+ global = local;
+
+ /* Completes the double-checked locking idiom. */
+ atomic_store_release (&global_libgcc_handle, local_libgcc_handle);
+ }
+
+ __libc_lock_unlock (lock);
+ return &global;
+}
+libc_hidden_def (__libc_unwind_link_get)
+
+void
+__libc_unwind_link_after_fork (void)
+{
+ if (__libc_lock_trylock (lock) == 0)
+ /* The lock was not acquired during the fork. This covers both
+ the initialized and uninitialized case. */
+ __libc_lock_unlock (lock);
+ else
+ {
+ /* Initialization was in progress in another thread.
+ Reinitialize the lock. */
+ __libc_lock_init (lock);
+ global_libgcc_handle = NULL;
+ }
+}
+
+void __libc_freeres_fn_section
+__libc_unwind_link_freeres (void)
+{
+ if (__libc_lock_trylock (lock) == 0)
+ {
+ if (global_libgcc_handle != NULL)
+ {
+ __libc_dlclose (global_libgcc_handle );
+ global_libgcc_handle = NULL;
+ }
+ __libc_lock_unlock (lock);
+ }
+}
+
+#endif /* SHARED */
diff --git a/sysdeps/alpha/arch-unwind-link.h b/sysdeps/alpha/arch-unwind-link.h
new file mode 100644
index 0000000..998e47c
--- /dev/null
+++ b/sysdeps/alpha/arch-unwind-link.h
@@ -0,0 +1,27 @@
+/* Dynamic loading of the libgcc unwinder. alpha customization.
+ Copyright (C) 2020 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 _ARCH_UNWIND_LINK_H
+#define _ARCH_UNWIND_LINK_H
+
+#define UNWIND_LINK_GETIP 1
+#define UNWIND_LINK_FRAME_STATE_FOR 1
+#define UNWIND_LINK_EXTRA_FIELDS
+#define UNWIND_LINK_EXTRA_INIT
+
+#endif /* _ARCH_UNWIND_LINK_H */
diff --git a/sysdeps/arm/arch-unwind-link.h b/sysdeps/arm/arch-unwind-link.h
new file mode 100644
index 0000000..b16a94e
--- /dev/null
+++ b/sysdeps/arm/arch-unwind-link.h
@@ -0,0 +1,34 @@
+/* Dynamic loading of the libgcc unwinder. Arm customization.
+ Copyright (C) 2020 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 _ARCH_UNWIND_LINK_H
+#define _ARCH_UNWIND_LINK_H
+
+/* On arm, _Unwind_GetIP is a macro. */
+#define UNWIND_LINK_GETIP 0
+
+#define UNWIND_LINK_FRAME_STATE_FOR 0
+#define UNWIND_LINK_EXTRA_FIELDS \
+ __typeof (_Unwind_VRS_Get) *ptr__Unwind_VRS_Get;
+#define UNWIND_LINK_EXTRA_INIT \
+ local.ptr__Unwind_VRS_Get \
+ = __libc_dlsym (local_libgcc_handle, "_Unwind_VRS_Get"); \
+ assert (local.ptr__Unwind_VRS_Get != NULL); \
+ PTR_MANGLE (local.ptr__Unwind_VRS_Get);
+
+#endif /* _ARCH_UNWIND_LINK_H */
diff --git a/sysdeps/generic/arch-unwind-link.h b/sysdeps/generic/arch-unwind-link.h
new file mode 100644
index 0000000..efc2292
--- /dev/null
+++ b/sysdeps/generic/arch-unwind-link.h
@@ -0,0 +1,32 @@
+/* Dynamic loading of the libgcc unwinder. Generic version of parameters.
+ Copyright (C) 2020 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 _ARCH_UNWIND_LINK_H
+#define _ARCH_UNWIND_LINK_H
+
+/* The _Unwind_GetIP function is supported. */
+#define UNWIND_LINK_GETIP 1
+
+/* The __frame_state_for is needed and re-exported from glibc. */
+#define UNWIND_LINK_FRAME_STATE_FOR 0
+
+/* There are no extra fields in struct unwind_link. */
+#define UNWIND_LINK_EXTRA_FIELDS
+#define UNWIND_LINK_EXTRA_INIT
+
+#endif /* _ARCH_UNWIND_LINK_H */
diff --git a/sysdeps/generic/unwind-link.h b/sysdeps/generic/unwind-link.h
new file mode 100644
index 0000000..9e6e134
--- /dev/null
+++ b/sysdeps/generic/unwind-link.h
@@ -0,0 +1,99 @@
+/* Dynamic loading of the libgcc unwinder. Generic version.
+ Copyright (C) 2020 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 _UNWIND_LINK_H
+#define _UNWIND_LINK_H
+
+#include <unwind.h>
+
+#ifdef SHARED
+
+#include <arch-unwind-link.h>
+#include <sysdep.h>
+#include <unwind-resume.h>
+
+#if UNWIND_LINK_FRAME_STATE_FOR
+struct frame_state;
+#endif
+
+struct unwind_link
+{
+ __typeof (_Unwind_Backtrace) *ptr__Unwind_Backtrace;
+ __typeof (_Unwind_ForcedUnwind) *ptr__Unwind_ForcedUnwind;
+ __typeof (_Unwind_GetCFA) *ptr__Unwind_GetCFA;
+# if UNWIND_LINK_GETIP
+ __typeof (_Unwind_GetIP) *ptr__Unwind_GetIP;
+# endif
+ __typeof (_Unwind_Resume) *ptr__Unwind_Resume;
+#if UNWIND_LINK_FRAME_STATE_FOR
+ struct frame_state *(*ptr___frame_state_for)(void *pc, struct frame_state *);
+#endif
+ _Unwind_Reason_Code (*ptr_personality) PERSONALITY_PROTO;
+ UNWIND_LINK_EXTRA_FIELDS
+};
+
+/* Return a pointer to the implementation, or NULL on failure. */
+struct unwind_link *__libc_unwind_link_get (void);
+libc_hidden_proto (__libc_unwind_link_get)
+
+/* UNWIND_LINK_PTR returns the stored function pointer NAME from the
+ cached unwind link OBJ (which was previously returned by
+ __libc_unwind_link_get). */
+# ifdef PTR_DEMANGLE
+# define UNWIND_LINK_PTR(obj, name, ...) \
+ ({ \
+ __typeof ((obj)->ptr_##name) __unwind_fptr = (obj)->ptr_##name; \
+ PTR_DEMANGLE (__unwind_fptr); \
+ __unwind_fptr; \
+ })
+# else /* !PTR_DEMANGLE */
+# define UNWIND_LINK_PTR(obj, name, ...) ((obj)->ptr_##name)
+# endif
+
+/* Called from fork, in the new subprocess. */
+void __libc_unwind_link_after_fork (void);
+
+/* Called from __libc_freeres. */
+void __libc_unwind_link_freeres (void) attribute_hidden;
+
+#else /* !SHARED */
+
+/* Dummy implementation so that the code can be shared with the SHARED
+ version. */
+struct unwind_link;
+static inline struct unwind_link *
+__libc_unwind_link_get (void)
+{
+ /* Return something that is not a null pointer, so that error checks
+ succeed. */
+ return (struct unwind_link *) 1;
+}
+
+/* Directly call the static implementation. */
+# define UNWIND_LINK_PTR(obj, name, ...) \
+ ((void) (obj), &name)
+
+static inline void
+__libc_unwind_link_after_fork (void)
+{
+ /* No need to clean up if the unwinder is statically linked. */
+}
+
+#endif /* !SHARED */
+
+#endif /* _UNWIND_LINK_H */
diff --git a/sysdeps/i386/arch-unwind-link.h b/sysdeps/i386/arch-unwind-link.h
new file mode 100644
index 0000000..bc9c3a1
--- /dev/null
+++ b/sysdeps/i386/arch-unwind-link.h
@@ -0,0 +1,38 @@
+/* Dynamic loading of the libgcc unwinder. i386 customization.
+ Copyright (C) 2020 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 _ARCH_UNWIND_LINK_H
+#define _ARCH_UNWIND_LINK_H
+
+#define UNWIND_LINK_GETIP 1
+#define UNWIND_LINK_FRAME_STATE_FOR 1
+#define UNWIND_LINK_EXTRA_FIELDS \
+ __typeof (_Unwind_GetGR) *ptr__Unwind_GetGR;
+#define UNWIND_LINK_EXTRA_INIT_SHARED \
+ local.ptr__Unwind_GetGR \
+ = __libc_dlsym (local_libgcc_handle, "_Unwind_GetGR"); \
+ assert (local.ptr__Unwind_GetGR != NULL);
+#ifdef PTR_MANGLE
+# define UNWIND_LINK_EXTRA_INIT \
+ UNWIND_LINK_EXTRA_INIT_SHARED \
+ PTR_MANGLE (local.ptr__Unwind_GetGR);
+#else
+# define UNWIND_LINK_EXTRA_INIT UNWIND_LINK_EXTRA_INIT_SHARED
+#endif
+
+#endif /* _ARCH_UNWIND_LINK_H */
diff --git a/sysdeps/ia64/arch-unwind-link.h b/sysdeps/ia64/arch-unwind-link.h
new file mode 100644
index 0000000..570b711
--- /dev/null
+++ b/sysdeps/ia64/arch-unwind-link.h
@@ -0,0 +1,31 @@
+/* Dynamic loading of the libgcc unwinder. ia64 customization.
+ Copyright (C) 2020 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 _ARCH_UNWIND_LINK_H
+
+#define UNWIND_LINK_GETIP 1
+#define UNWIND_LINK_FRAME_STATE_FOR 1
+#define UNWIND_LINK_EXTRA_FIELDS \
+ __typeof (_Unwind_GetBSP) *ptr__Unwind_GetBSP;
+#define UNWIND_LINK_EXTRA_INIT \
+ local.ptr__Unwind_GetBSP \
+ = __libc_dlsym (local_libgcc_handle, "_Unwind_GetBSP"); \
+ assert (local.ptr__Unwind_GetBSP != NULL); \
+ PTR_MANGLE (local.ptr__Unwind_GetBSP);
+
+#endif /* _ARCH_UNWIND_LINK_H */
diff --git a/sysdeps/m68k/arch-unwind-link.h b/sysdeps/m68k/arch-unwind-link.h
new file mode 100644
index 0000000..e010514
--- /dev/null
+++ b/sysdeps/m68k/arch-unwind-link.h
@@ -0,0 +1,34 @@
+/* Dynamic loading of the libgcc unwinder. m68k customization.
+ Copyright (C) 2020 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 _ARCH_UNWIND_LINK_H
+#define _ARCH_UNWIND_LINK_H
+
+#define UNWIND_LINK_GETIP 1
+#define UNWIND_LINK_EXTRA_FIELDS \
+ __typeof (_Unwind_GetGR) *ptr__Unwind_GetGR;
+#define UNWIND_LINK_EXTRA_INIT \
+ local.ptr__Unwind_GetGR \
+ = __libc_dlsym (local_libgcc_handle, "_Unwind_GetGR"); \
+ assert (local.ptr__Unwind_GetGR != NULL); \
+ PTR_MANGLE (local.ptr__Unwind_GetGR);
+
+/* This is overriden by the m680x0 variant. */
+#define UNWIND_LINK_FRAME_STATE_FOR 0
+
+#endif /* _ARCH_UNWIND_LINK_H */
diff --git a/sysdeps/m68k/m680x0/arch-unwind-link.h b/sysdeps/m68k/m680x0/arch-unwind-link.h
new file mode 100644
index 0000000..1adbf23
--- /dev/null
+++ b/sysdeps/m68k/m680x0/arch-unwind-link.h
@@ -0,0 +1,26 @@
+/* Dynamic loading of the libgcc unwinder. Baseline m68k customization.
+ Copyright (C) 2020 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 _ARCH_UNWIND_LINK_H
+
+#include <sysdeps/m68k/arch-unwind-link.h>
+
+#undef UNWIND_LINK_FRAME_STATE_FOR
+#define UNWIND_LINK_FRAME_STATE_FOR 1
+
+#endif /* _ARCH_UNWIND_LINK_H */
diff --git a/sysdeps/mach/hurd/fork.c b/sysdeps/mach/hurd/fork.c
index 3278306..1d4819e 100644
--- a/sysdeps/mach/hurd/fork.c
+++ b/sysdeps/mach/hurd/fork.c
@@ -28,6 +28,7 @@
#include "hurdmalloc.h" /* XXX */
#include <tls.h>
#include <malloc/malloc-internal.h>
+#include <unwind-link.h>
#undef __fork
@@ -662,6 +663,8 @@ __fork (void)
__sigemptyset (&_hurd_global_sigstate->pending);
__sigemptyset (&ss->pending);
+ __libc_unwind_link_after_fork ();
+
/* Release malloc locks. */
_hurd_malloc_fork_child ();
call_function_static_weak (__malloc_fork_unlock_child);
diff --git a/sysdeps/mips/arch-unwind-link.h b/sysdeps/mips/arch-unwind-link.h
new file mode 100644
index 0000000..9835c0f
--- /dev/null
+++ b/sysdeps/mips/arch-unwind-link.h
@@ -0,0 +1,27 @@
+/* Dynamic loading of the libgcc unwinder. MIPS customization.
+ Copyright (C) 2020 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 _ARCH_UNWIND_LINK_H
+#define _ARCH_UNWIND_LINK_H
+
+#define UNWIND_LINK_GETIP 1
+#define UNWIND_LINK_FRAME_STATE_FOR 1
+#define UNWIND_LINK_EXTRA_FIELDS
+#define UNWIND_LINK_EXTRA_INIT
+
+#endif /* _ARCH_UNWIND_LINK_H */
diff --git a/sysdeps/nptl/fork.c b/sysdeps/nptl/fork.c
index f5cf88d..19e8381 100644
--- a/sysdeps/nptl/fork.c
+++ b/sysdeps/nptl/fork.c
@@ -32,6 +32,7 @@
#include <arch-fork.h>
#include <futex-internal.h>
#include <malloc/malloc-internal.h>
+#include <unwind-link.h>
static void
fresetlockfiles (void)
@@ -112,6 +113,8 @@ __libc_fork (void)
/* Reset the lock state in the multi-threaded case. */
if (multiple_threads)
{
+ __libc_unwind_link_after_fork ();
+
/* Release malloc locks. */
call_function_static_weak (__malloc_fork_unlock_child);
diff --git a/sysdeps/powerpc/powerpc32/arch-unwind-link.h b/sysdeps/powerpc/powerpc32/arch-unwind-link.h
new file mode 100644
index 0000000..6a87daa
--- /dev/null
+++ b/sysdeps/powerpc/powerpc32/arch-unwind-link.h
@@ -0,0 +1,27 @@
+/* Dynamic loading of the libgcc unwinder. powerpc customization.
+ Copyright (C) 2020 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 _ARCH_UNWIND_LINK_H
+#define _ARCH_UNWIND_LINK_H
+
+#define UNWIND_LINK_GETIP 1
+#define UNWIND_LINK_FRAME_STATE_FOR 1
+#define UNWIND_LINK_EXTRA_FIELDS
+#define UNWIND_LINK_EXTRA_INIT
+
+#endif /* _ARCH_UNWIND_LINK_H */
diff --git a/sysdeps/s390/arch-unwind-link.h b/sysdeps/s390/arch-unwind-link.h
new file mode 100644
index 0000000..c50b7f2
--- /dev/null
+++ b/sysdeps/s390/arch-unwind-link.h
@@ -0,0 +1,27 @@
+/* Dynamic loading of the libgcc unwinder. S/390 customization.
+ Copyright (C) 2020 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 _ARCH_UNWIND_LINK_H
+#define _ARCH_UNWIND_LINK_H
+
+#define UNWIND_LINK_GETIP 1
+#define UNWIND_LINK_FRAME_STATE_FOR 1
+#define UNWIND_LINK_EXTRA_FIELDS
+#define UNWIND_LINK_EXTRA_INIT
+
+#endif /* _ARCH_UNWIND_LINK_H */
diff --git a/sysdeps/sparc/arch-unwind-link.h b/sysdeps/sparc/arch-unwind-link.h
new file mode 100644
index 0000000..4b7e2f1
--- /dev/null
+++ b/sysdeps/sparc/arch-unwind-link.h
@@ -0,0 +1,27 @@
+/* Dynamic loading of the libgcc unwinder. SPARC customization.
+ Copyright (C) 2020 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 _ARCH_UNWIND_LINK_H
+#define _ARCH_UNWIND_LINK_H
+
+#define UNWIND_LINK_GETIP 1
+#define UNWIND_LINK_FRAME_STATE_FOR 1
+#define UNWIND_LINK_EXTRA_FIELDS
+#define UNWIND_LINK_EXTRA_INIT
+
+#endif /* _ARCH_UNWIND_LINK_H */
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2020-02-13 16:22 UTC | newest]
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2020-02-10 17:08 [glibc/fw/unwind-link] Implement <unwind-link.h> for dynamically loading the libgcc_s unwinder Florian Weimer
2020-02-13 10:45 Florian Weimer
2020-02-13 16:22 Florian Weimer
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