781 lines
19 KiB
C
781 lines
19 KiB
C
/* Subroutines needed for unwinding DWARF 2 format stack frame info
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for exception handling. */
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/* Compile this one with gcc. */
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/* Copyright (C) 1997, 1998, 1999, 2000 Free Software Foundation, Inc.
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Contributed by Jason Merrill <jason@cygnus.com>.
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This file is part of GNU CC.
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GNU CC is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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In addition to the permissions in the GNU General Public License, the
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Free Software Foundation gives you unlimited permission to link the
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compiled version of this file into combinations with other programs,
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and to distribute those combinations without any restriction coming
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from the use of this file. (The General Public License restrictions
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do apply in other respects; for example, they cover modification of
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the file, and distribution when not linked into a combine
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executable.)
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GNU CC is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU CC; see the file COPYING. If not, write to
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the Free Software Foundation, 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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/* It is incorrect to include config.h here, because this file is being
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compiled for the target, and hence definitions concerning only the host
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do not apply. */
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#include "tconfig.h"
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#include "tsystem.h"
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#include "defaults.h"
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#ifdef DWARF2_UNWIND_INFO
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#include "dwarf2.h"
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#include "frame.h"
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#include "gthr.h"
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#ifdef __GTHREAD_MUTEX_INIT
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static __gthread_mutex_t object_mutex = __GTHREAD_MUTEX_INIT;
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#else
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static __gthread_mutex_t object_mutex;
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#endif
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/* Don't use `fancy_abort' here even if config.h says to use it. */
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#ifdef abort
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#undef abort
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#endif
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/* Some types used by the DWARF 2 spec. */
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typedef int sword __attribute__ ((mode (SI)));
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typedef unsigned int uword __attribute__ ((mode (SI)));
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typedef unsigned int uaddr __attribute__ ((mode (pointer)));
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typedef int saddr __attribute__ ((mode (pointer)));
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typedef unsigned char ubyte;
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/* Terminology:
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CIE - Common Information Element
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FDE - Frame Descriptor Element
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There is one per function, and it describes where the function code
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is located, and what the register lifetimes and stack layout are
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within the function.
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The data structures are defined in the DWARF specfication, although
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not in a very readable way (see LITERATURE).
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Every time an exception is thrown, the code needs to locate the FDE
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for the current function, and starts to look for exception regions
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from that FDE. This works in a two-level search:
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a) in a linear search, find the shared image (i.e. DLL) containing
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the PC
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b) using the FDE table for that shared object, locate the FDE using
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binary search (which requires the sorting). */
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/* The first few fields of a CIE. The CIE_id field is 0 for a CIE,
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to distinguish it from a valid FDE. FDEs are aligned to an addressing
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unit boundary, but the fields within are unaligned. */
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struct dwarf_cie {
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uword length;
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sword CIE_id;
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ubyte version;
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char augmentation[0];
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} __attribute__ ((packed, aligned (__alignof__ (void *))));
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/* The first few fields of an FDE. */
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struct dwarf_fde {
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uword length;
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sword CIE_delta;
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void* pc_begin;
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uaddr pc_range;
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} __attribute__ ((packed, aligned (__alignof__ (void *))));
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typedef struct dwarf_fde fde;
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/* Objects to be searched for frame unwind info. */
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static struct object *objects;
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/* The information we care about from a CIE. */
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struct cie_info {
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char *augmentation;
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void *eh_ptr;
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int code_align;
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int data_align;
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unsigned ra_regno;
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};
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/* The current unwind state, plus a saved copy for DW_CFA_remember_state. */
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struct frame_state_internal
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{
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struct frame_state s;
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struct frame_state_internal *saved_state;
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};
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/* This is undefined below if we need it to be an actual function. */
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#define init_object_mutex_once()
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#if __GTHREADS
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#ifdef __GTHREAD_MUTEX_INIT_FUNCTION
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/* Helper for init_object_mutex_once. */
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static void
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init_object_mutex (void)
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{
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__GTHREAD_MUTEX_INIT_FUNCTION (&object_mutex);
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}
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/* Call this to arrange to initialize the object mutex. */
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#undef init_object_mutex_once
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static void
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init_object_mutex_once (void)
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{
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static __gthread_once_t once = __GTHREAD_ONCE_INIT;
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__gthread_once (&once, init_object_mutex);
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}
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#endif /* __GTHREAD_MUTEX_INIT_FUNCTION */
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#endif /* __GTHREADS */
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/* Decode the unsigned LEB128 constant at BUF into the variable pointed to
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by R, and return the new value of BUF. */
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static void *
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decode_uleb128 (unsigned char *buf, unsigned *r)
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{
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unsigned shift = 0;
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unsigned result = 0;
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while (1)
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{
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unsigned byte = *buf++;
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result |= (byte & 0x7f) << shift;
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if ((byte & 0x80) == 0)
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break;
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shift += 7;
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}
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*r = result;
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return buf;
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}
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/* Decode the signed LEB128 constant at BUF into the variable pointed to
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by R, and return the new value of BUF. */
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static void *
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decode_sleb128 (unsigned char *buf, int *r)
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{
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unsigned shift = 0;
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unsigned result = 0;
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unsigned byte;
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while (1)
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{
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byte = *buf++;
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result |= (byte & 0x7f) << shift;
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shift += 7;
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if ((byte & 0x80) == 0)
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break;
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}
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if (shift < (sizeof (*r) * 8) && (byte & 0x40) != 0)
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result |= - (1 << shift);
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*r = result;
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return buf;
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}
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/* Read unaligned data from the instruction buffer. */
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union unaligned {
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void *p;
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unsigned b2 __attribute__ ((mode (HI)));
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unsigned b4 __attribute__ ((mode (SI)));
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unsigned b8 __attribute__ ((mode (DI)));
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} __attribute__ ((packed));
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static inline void *
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read_pointer (void *p)
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{ union unaligned *up = p; return up->p; }
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static inline unsigned
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read_1byte (void *p)
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{ return *(unsigned char *)p; }
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static inline unsigned
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read_2byte (void *p)
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{ union unaligned *up = p; return up->b2; }
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static inline unsigned
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read_4byte (void *p)
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{ union unaligned *up = p; return up->b4; }
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static inline unsigned long
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read_8byte (void *p)
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{ union unaligned *up = p; return up->b8; }
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/* Ordering function for FDEs. Functions can't overlap, so we just compare
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their starting addresses. */
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static inline saddr
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fde_compare (fde *x, fde *y)
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{
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return (saddr)x->pc_begin - (saddr)y->pc_begin;
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}
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/* Return the address of the FDE after P. */
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static inline fde *
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next_fde (fde *p)
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{
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return (fde *)(((char *)p) + p->length + sizeof (p->length));
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}
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#include "frame.c"
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static size_t
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count_fdes (fde *this_fde)
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{
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size_t count;
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for (count = 0; this_fde->length != 0; this_fde = next_fde (this_fde))
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{
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/* Skip CIEs and linked once FDE entries. */
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if (this_fde->CIE_delta == 0 || this_fde->pc_begin == 0)
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continue;
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++count;
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}
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return count;
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}
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static void
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add_fdes (fde *this_fde, fde_accumulator *accu, void **beg_ptr, void **end_ptr)
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{
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void *pc_begin = *beg_ptr;
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void *pc_end = *end_ptr;
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for (; this_fde->length != 0; this_fde = next_fde (this_fde))
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{
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/* Skip CIEs and linked once FDE entries. */
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if (this_fde->CIE_delta == 0 || this_fde->pc_begin == 0)
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continue;
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fde_insert (accu, this_fde);
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if (this_fde->pc_begin < pc_begin)
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pc_begin = this_fde->pc_begin;
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if (this_fde->pc_begin + this_fde->pc_range > pc_end)
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pc_end = this_fde->pc_begin + this_fde->pc_range;
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}
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*beg_ptr = pc_begin;
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*end_ptr = pc_end;
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}
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/* search this fde table for the one containing the pc */
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static fde *
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search_fdes (fde *this_fde, void *pc)
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{
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for (; this_fde->length != 0; this_fde = next_fde (this_fde))
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{
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/* Skip CIEs and linked once FDE entries. */
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if (this_fde->CIE_delta == 0 || this_fde->pc_begin == 0)
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continue;
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if ((uaddr)((char *)pc - (char *)this_fde->pc_begin) < this_fde->pc_range)
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return this_fde;
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}
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return NULL;
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}
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/* Set up a sorted array of pointers to FDEs for a loaded object. We
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count up the entries before allocating the array because it's likely to
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be faster. We can be called multiple times, should we have failed to
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allocate a sorted fde array on a previous occasion. */
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static void
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frame_init (struct object* ob)
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{
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size_t count;
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fde_accumulator accu;
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void *pc_begin, *pc_end;
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fde **array;
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if (ob->pc_begin)
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count = ob->count;
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else if (ob->fde_array)
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{
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fde **p = ob->fde_array;
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for (count = 0; *p; ++p)
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count += count_fdes (*p);
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}
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else
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count = count_fdes (ob->fde_begin);
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ob->count = count;
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if (!start_fde_sort (&accu, count) && ob->pc_begin)
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return;
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pc_begin = (void*)(uaddr)-1;
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pc_end = 0;
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if (ob->fde_array)
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{
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fde **p = ob->fde_array;
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for (; *p; ++p)
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add_fdes (*p, &accu, &pc_begin, &pc_end);
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}
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else
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add_fdes (ob->fde_begin, &accu, &pc_begin, &pc_end);
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array = end_fde_sort (&accu, count);
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if (array)
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ob->fde_array = array;
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ob->pc_begin = pc_begin;
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ob->pc_end = pc_end;
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}
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/* Return a pointer to the FDE for the function containing PC. */
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static fde *
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find_fde (void *pc)
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{
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struct object *ob;
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size_t lo, hi;
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init_object_mutex_once ();
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__gthread_mutex_lock (&object_mutex);
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/* Linear search through the objects, to find the one containing the pc. */
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for (ob = objects; ob; ob = ob->next)
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{
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if (ob->pc_begin == 0)
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frame_init (ob);
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if (pc >= ob->pc_begin && pc < ob->pc_end)
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break;
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}
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if (ob == 0)
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{
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__gthread_mutex_unlock (&object_mutex);
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return 0;
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}
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if (!ob->fde_array || (void *)ob->fde_array == (void *)ob->fde_begin)
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frame_init (ob);
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if (ob->fde_array && (void *)ob->fde_array != (void *)ob->fde_begin)
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{
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__gthread_mutex_unlock (&object_mutex);
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/* Standard binary search algorithm. */
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for (lo = 0, hi = ob->count; lo < hi; )
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{
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size_t i = (lo + hi) / 2;
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fde *f = ob->fde_array[i];
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if (pc < f->pc_begin)
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hi = i;
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else if (pc >= f->pc_begin + f->pc_range)
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lo = i + 1;
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else
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return f;
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}
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}
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else
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{
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/* Long slow labourious linear search, cos we've no memory. */
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fde *f;
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if (ob->fde_array)
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{
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fde **p = ob->fde_array;
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do
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{
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f = search_fdes (*p, pc);
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if (f)
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break;
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p++;
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}
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while (*p);
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}
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else
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f = search_fdes (ob->fde_begin, pc);
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__gthread_mutex_unlock (&object_mutex);
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return f;
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}
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return 0;
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}
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static inline struct dwarf_cie *
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get_cie (fde *f)
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{
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return ((void *)&f->CIE_delta) - f->CIE_delta;
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}
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/* Extract any interesting information from the CIE for the translation
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unit F belongs to. */
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static void *
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extract_cie_info (fde *f, struct cie_info *c)
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{
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void *p;
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int i;
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c->augmentation = get_cie (f)->augmentation;
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if (strcmp (c->augmentation, "") != 0
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&& strcmp (c->augmentation, "eh") != 0
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&& c->augmentation[0] != 'z')
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return 0;
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p = c->augmentation + strlen (c->augmentation) + 1;
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if (strcmp (c->augmentation, "eh") == 0)
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{
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c->eh_ptr = read_pointer (p);
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p += sizeof (void *);
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}
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else
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c->eh_ptr = 0;
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p = decode_uleb128 (p, &c->code_align);
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p = decode_sleb128 (p, &c->data_align);
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c->ra_regno = *(unsigned char *)p++;
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/* If the augmentation starts with 'z', we now see the length of the
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augmentation fields. */
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if (c->augmentation[0] == 'z')
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{
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p = decode_uleb128 (p, &i);
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p += i;
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}
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return p;
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}
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/* Decode a DW_OP stack operation. */
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static void *
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decode_stack_op (unsigned char *buf, struct frame_state *state)
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{
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enum dwarf_location_atom op;
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int offset;
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op = *buf++;
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switch (op)
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{
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case DW_OP_reg0:
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case DW_OP_reg1:
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case DW_OP_reg2:
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case DW_OP_reg3:
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case DW_OP_reg4:
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case DW_OP_reg5:
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case DW_OP_reg6:
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case DW_OP_reg7:
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case DW_OP_reg8:
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case DW_OP_reg9:
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case DW_OP_reg10:
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case DW_OP_reg11:
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case DW_OP_reg12:
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case DW_OP_reg13:
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case DW_OP_reg14:
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case DW_OP_reg15:
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case DW_OP_reg16:
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case DW_OP_reg17:
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case DW_OP_reg18:
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case DW_OP_reg19:
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case DW_OP_reg20:
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case DW_OP_reg21:
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case DW_OP_reg22:
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case DW_OP_reg23:
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case DW_OP_reg24:
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case DW_OP_reg25:
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case DW_OP_reg26:
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case DW_OP_reg27:
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case DW_OP_reg28:
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case DW_OP_reg29:
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case DW_OP_reg30:
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case DW_OP_reg31:
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state->cfa_reg = op - DW_OP_reg0;
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break;
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case DW_OP_regx:
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buf = decode_sleb128 (buf, &offset);
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state->cfa_reg = offset;
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break;
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case DW_OP_breg0:
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case DW_OP_breg1:
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case DW_OP_breg2:
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case DW_OP_breg3:
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case DW_OP_breg4:
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case DW_OP_breg5:
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case DW_OP_breg6:
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case DW_OP_breg7:
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case DW_OP_breg8:
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case DW_OP_breg9:
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case DW_OP_breg10:
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case DW_OP_breg11:
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case DW_OP_breg12:
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case DW_OP_breg13:
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case DW_OP_breg14:
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case DW_OP_breg15:
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case DW_OP_breg16:
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case DW_OP_breg17:
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case DW_OP_breg18:
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case DW_OP_breg19:
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case DW_OP_breg20:
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case DW_OP_breg21:
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case DW_OP_breg22:
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case DW_OP_breg23:
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case DW_OP_breg24:
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case DW_OP_breg25:
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case DW_OP_breg26:
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case DW_OP_breg27:
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case DW_OP_breg28:
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case DW_OP_breg29:
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case DW_OP_breg30:
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case DW_OP_breg31:
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||
state->cfa_reg = op - DW_OP_breg0;
|
||
buf = decode_sleb128 (buf, &offset);
|
||
state->base_offset = offset;
|
||
break;
|
||
case DW_OP_bregx:
|
||
buf = decode_sleb128 (buf, &offset);
|
||
state->cfa_reg = offset;
|
||
buf = decode_sleb128 (buf, &offset);
|
||
state->base_offset = offset;
|
||
break;
|
||
case DW_OP_deref:
|
||
state->indirect = 1;
|
||
break;
|
||
case DW_OP_plus_uconst:
|
||
buf = decode_uleb128 (buf, &offset);
|
||
state->cfa_offset = offset;
|
||
break;
|
||
default:
|
||
abort ();
|
||
}
|
||
return buf;
|
||
}
|
||
/* Decode one instruction's worth of DWARF 2 call frame information.
|
||
Used by __frame_state_for. Takes pointers P to the instruction to
|
||
decode, STATE to the current register unwind information, INFO to the
|
||
current CIE information, and PC to the current PC value. Returns a
|
||
pointer to the next instruction. */
|
||
|
||
static void *
|
||
execute_cfa_insn (void *p, struct frame_state_internal *state,
|
||
struct cie_info *info, void **pc)
|
||
{
|
||
unsigned insn = *(unsigned char *)p++;
|
||
unsigned reg;
|
||
int offset;
|
||
|
||
if (insn & DW_CFA_advance_loc)
|
||
*pc += ((insn & 0x3f) * info->code_align);
|
||
else if (insn & DW_CFA_offset)
|
||
{
|
||
reg = (insn & 0x3f);
|
||
p = decode_uleb128 (p, &offset);
|
||
if (reg == state->s.cfa_reg)
|
||
/* Don't record anything about this register; it's only used to
|
||
reload SP in the epilogue. We don't want to copy in SP
|
||
values for outer frames; we handle restoring SP specially. */;
|
||
else
|
||
{
|
||
offset *= info->data_align;
|
||
state->s.saved[reg] = REG_SAVED_OFFSET;
|
||
state->s.reg_or_offset[reg] = offset;
|
||
}
|
||
}
|
||
else if (insn & DW_CFA_restore)
|
||
{
|
||
reg = (insn & 0x3f);
|
||
state->s.saved[reg] = REG_UNSAVED;
|
||
}
|
||
else switch (insn)
|
||
{
|
||
case DW_CFA_set_loc:
|
||
*pc = read_pointer (p);
|
||
p += sizeof (void *);
|
||
break;
|
||
case DW_CFA_advance_loc1:
|
||
*pc += read_1byte (p);
|
||
p += 1;
|
||
break;
|
||
case DW_CFA_advance_loc2:
|
||
*pc += read_2byte (p);
|
||
p += 2;
|
||
break;
|
||
case DW_CFA_advance_loc4:
|
||
*pc += read_4byte (p);
|
||
p += 4;
|
||
break;
|
||
|
||
case DW_CFA_offset_extended:
|
||
p = decode_uleb128 (p, ®);
|
||
p = decode_uleb128 (p, &offset);
|
||
if (reg == state->s.cfa_reg)
|
||
/* Don't record anything; see above. */;
|
||
else
|
||
{
|
||
offset *= info->data_align;
|
||
state->s.saved[reg] = REG_SAVED_OFFSET;
|
||
state->s.reg_or_offset[reg] = offset;
|
||
}
|
||
break;
|
||
case DW_CFA_restore_extended:
|
||
p = decode_uleb128 (p, ®);
|
||
state->s.saved[reg] = REG_UNSAVED;
|
||
break;
|
||
|
||
case DW_CFA_undefined:
|
||
case DW_CFA_same_value:
|
||
case DW_CFA_nop:
|
||
break;
|
||
|
||
case DW_CFA_register:
|
||
{
|
||
unsigned reg2;
|
||
p = decode_uleb128 (p, ®);
|
||
p = decode_uleb128 (p, ®2);
|
||
state->s.saved[reg] = REG_SAVED_REG;
|
||
state->s.reg_or_offset[reg] = reg2;
|
||
}
|
||
break;
|
||
|
||
case DW_CFA_def_cfa:
|
||
p = decode_uleb128 (p, ®);
|
||
p = decode_uleb128 (p, &offset);
|
||
state->s.cfa_reg = reg;
|
||
state->s.cfa_offset = offset;
|
||
break;
|
||
case DW_CFA_def_cfa_register:
|
||
p = decode_uleb128 (p, ®);
|
||
state->s.cfa_reg = reg;
|
||
break;
|
||
case DW_CFA_def_cfa_offset:
|
||
p = decode_uleb128 (p, &offset);
|
||
state->s.cfa_offset = offset;
|
||
break;
|
||
case DW_CFA_def_cfa_expression:
|
||
{
|
||
void *end;
|
||
state->s.cfa_reg = 0;
|
||
state->s.cfa_offset = 0;
|
||
state->s.base_offset = 0;
|
||
state->s.indirect = 0;
|
||
|
||
p = decode_uleb128 (p, &offset);
|
||
end = p + offset;
|
||
while (p < end)
|
||
p = decode_stack_op (p, &(state->s));
|
||
break;
|
||
}
|
||
|
||
case DW_CFA_remember_state:
|
||
{
|
||
struct frame_state_internal *save =
|
||
(struct frame_state_internal *)
|
||
malloc (sizeof (struct frame_state_internal));
|
||
memcpy (save, state, sizeof (struct frame_state_internal));
|
||
state->saved_state = save;
|
||
}
|
||
break;
|
||
case DW_CFA_restore_state:
|
||
{
|
||
struct frame_state_internal *save = state->saved_state;
|
||
memcpy (state, save, sizeof (struct frame_state_internal));
|
||
free (save);
|
||
}
|
||
break;
|
||
|
||
/* FIXME: Hardcoded for SPARC register window configuration. */
|
||
case DW_CFA_GNU_window_save:
|
||
for (reg = 16; reg < 32; ++reg)
|
||
{
|
||
state->s.saved[reg] = REG_SAVED_OFFSET;
|
||
state->s.reg_or_offset[reg] = (reg - 16) * sizeof (void *);
|
||
}
|
||
break;
|
||
|
||
case DW_CFA_GNU_args_size:
|
||
p = decode_uleb128 (p, &offset);
|
||
state->s.args_size = offset;
|
||
break;
|
||
|
||
case DW_CFA_GNU_negative_offset_extended:
|
||
p = decode_uleb128 (p, ®);
|
||
p = decode_uleb128 (p, &offset);
|
||
offset *= info->data_align;
|
||
state->s.saved[reg] = REG_SAVED_OFFSET;
|
||
state->s.reg_or_offset[reg] = -offset;
|
||
break;
|
||
|
||
default:
|
||
abort ();
|
||
}
|
||
return p;
|
||
}
|
||
|
||
/* Called from __throw to find the registers to restore for a given
|
||
PC_TARGET. The caller should allocate a local variable of `struct
|
||
frame_state' (declared in frame.h) and pass its address to STATE_IN. */
|
||
|
||
struct frame_state *
|
||
__frame_state_for (void *pc_target, struct frame_state *state_in)
|
||
{
|
||
fde *f;
|
||
void *insn, *end, *pc;
|
||
struct cie_info info;
|
||
struct frame_state_internal state;
|
||
|
||
f = find_fde (pc_target);
|
||
if (f == 0)
|
||
return 0;
|
||
|
||
insn = extract_cie_info (f, &info);
|
||
if (insn == 0)
|
||
return 0;
|
||
|
||
memset (&state, 0, sizeof (state));
|
||
state.s.retaddr_column = info.ra_regno;
|
||
state.s.eh_ptr = info.eh_ptr;
|
||
|
||
/* First decode all the insns in the CIE. */
|
||
end = next_fde ((fde*) get_cie (f));
|
||
while (insn < end)
|
||
insn = execute_cfa_insn (insn, &state, &info, 0);
|
||
|
||
insn = ((fde *)f) + 1;
|
||
|
||
if (info.augmentation[0] == 'z')
|
||
{
|
||
int i;
|
||
insn = decode_uleb128 (insn, &i);
|
||
insn += i;
|
||
}
|
||
|
||
/* Then the insns in the FDE up to our target PC. */
|
||
end = next_fde (f);
|
||
pc = f->pc_begin;
|
||
while (insn < end && pc <= pc_target)
|
||
insn = execute_cfa_insn (insn, &state, &info, &pc);
|
||
|
||
memcpy (state_in, &state.s, sizeof (state.s));
|
||
return state_in;
|
||
}
|
||
#endif /* DWARF2_UNWIND_INFO */
|