glibc/sysdeps/generic/unwind-link.h
Florian Weimer 9fc813e1a3 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 existing backtrace implementations, it provides some
hardening based on pointer mangling.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
2021-03-01 15:58:01 +01:00

107 lines
3.2 KiB
C

/* Dynamic loading of the libgcc unwinder. Generic version.
Copyright (C) 2021 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>
#include <unwind-arch.h>
#if !UNWIND_LINK_FRAME_ADJUSTMENT
static inline void *
unwind_arch_adjustment (void *prev, void *addr)
{
return addr;
}
#endif
#ifdef SHARED
# 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 *, 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 */