816 lines
20 KiB
C
816 lines
20 KiB
C
/* Subroutines needed for unwinding stack frames for exception handling. */
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/* Compile this one with gcc. */
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/* Copyright (C) 1997 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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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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/* As a special exception, if you link this library with other files,
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some of which are compiled with GCC, to produce an executable,
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this library does not by itself cause the resulting executable
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to be covered by the GNU General Public License.
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This exception does not however invalidate any other reasons why
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the executable file might be covered by the GNU General Public License. */
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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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/* We disable this when inhibit_libc, so that gcc can still be built without
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needing header files first. */
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/* ??? This is not a good solution, since prototypes may be required in
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some cases for correct code. See also libgcc2.c. */
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#ifndef inhibit_libc
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/* fixproto guarantees these system headers exist. */
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#include <stdlib.h>
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#include <unistd.h>
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#endif
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#include "defaults.h"
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#ifdef DWARF2_UNWIND_INFO
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#include "gansidecl.h"
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#include "dwarf2.h"
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#include <stddef.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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/* 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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/* 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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/* Sorting an array of FDEs by address.
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(Ideally we would have the linker sort the FDEs so we don't have to do
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it at run time. But the linkers are not yet prepared for this.) */
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/* This is a special mix of insertion sort and heap sort, optimized for
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the data sets that actually occur. They look like
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101 102 103 127 128 105 108 110 190 111 115 119 125 160 126 129 130.
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I.e. a linearly increasing sequence (coming from functions in the text
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section), with additionally a few unordered elements (coming from functions
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in gnu_linkonce sections) whose values are higher than the values in the
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surrounding linear sequence (but not necessarily higher than the values
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at the end of the linear sequence!).
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The worst-case total run time is O(N) + O(n log (n)), where N is the
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total number of FDEs and n is the number of erratic ones. */
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typedef struct fde_vector
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{
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fde **array;
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size_t count;
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} fde_vector;
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typedef struct fde_accumulator
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{
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fde_vector linear;
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fde_vector erratic;
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} fde_accumulator;
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static inline void
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start_fde_sort (fde_accumulator *accu, size_t count)
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{
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accu->linear.array = (fde **) malloc (sizeof (fde *) * count);
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accu->erratic.array = (fde **) malloc (sizeof (fde *) * count);
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accu->linear.count = 0;
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accu->erratic.count = 0;
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}
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static inline void
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fde_insert (fde_accumulator *accu, fde *this_fde)
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{
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accu->linear.array[accu->linear.count++] = this_fde;
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}
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/* Split LINEAR into a linear sequence with low values and an erratic
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sequence with high values, put the linear one (of longest possible
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length) into LINEAR and the erratic one into ERRATIC. This is O(N). */
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static inline void
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fde_split (fde_vector *linear, fde_vector *erratic)
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{
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size_t count = linear->count;
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size_t linear_max = (size_t) -1;
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size_t previous_max[count];
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size_t i, j;
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for (i = 0; i < count; i++)
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{
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for (j = linear_max;
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j != (size_t) -1
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&& fde_compare (linear->array[i], linear->array[j]) < 0;
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j = previous_max[j])
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{
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erratic->array[erratic->count++] = linear->array[j];
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linear->array[j] = (fde *) NULL;
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}
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previous_max[i] = j;
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linear_max = i;
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}
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for (i = 0, j = 0; i < count; i++)
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if (linear->array[i] != (fde *) NULL)
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linear->array[j++] = linear->array[i];
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linear->count = j;
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}
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/* This is O(n log(n)). BSD/OS defines heapsort in stdlib.h, so we must
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use a name that does not conflict. */
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static inline void
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frame_heapsort (fde_vector *erratic)
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{
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/* For a description of this algorithm, see:
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Samuel P. Harbison, Guy L. Steele Jr.: C, a reference manual, 2nd ed.,
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p. 60-61. */
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fde ** a = erratic->array;
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/* A portion of the array is called a "heap" if for all i>=0:
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If i and 2i+1 are valid indices, then a[i] >= a[2i+1].
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If i and 2i+2 are valid indices, then a[i] >= a[2i+2]. */
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#define SWAP(x,y) do { fde * tmp = x; x = y; y = tmp; } while (0)
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size_t n = erratic->count;
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size_t m = n;
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size_t i;
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while (m > 0)
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{
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/* Invariant: a[m..n-1] is a heap. */
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m--;
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for (i = m; 2*i+1 < n; )
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{
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if (2*i+2 < n
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&& fde_compare (a[2*i+2], a[2*i+1]) > 0
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&& fde_compare (a[2*i+2], a[i]) > 0)
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{
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SWAP (a[i], a[2*i+2]);
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i = 2*i+2;
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}
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else if (fde_compare (a[2*i+1], a[i]) > 0)
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{
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SWAP (a[i], a[2*i+1]);
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i = 2*i+1;
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}
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else
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break;
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}
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}
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while (n > 1)
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{
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/* Invariant: a[0..n-1] is a heap. */
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n--;
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SWAP (a[0], a[n]);
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for (i = 0; 2*i+1 < n; )
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{
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if (2*i+2 < n
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&& fde_compare (a[2*i+2], a[2*i+1]) > 0
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&& fde_compare (a[2*i+2], a[i]) > 0)
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{
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SWAP (a[i], a[2*i+2]);
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i = 2*i+2;
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}
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else if (fde_compare (a[2*i+1], a[i]) > 0)
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{
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SWAP (a[i], a[2*i+1]);
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i = 2*i+1;
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}
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else
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break;
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}
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}
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#undef SWAP
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}
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/* Merge V1 and V2, both sorted, and put the result into V1. */
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static void
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fde_merge (fde_vector *v1, const fde_vector *v2)
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{
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size_t i1, i2;
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fde * fde2;
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i2 = v2->count;
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if (i2 > 0)
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{
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i1 = v1->count;
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do {
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i2--;
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fde2 = v2->array[i2];
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while (i1 > 0 && fde_compare (v1->array[i1-1], fde2) > 0)
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{
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v1->array[i1+i2] = v1->array[i1-1];
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i1--;
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}
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v1->array[i1+i2] = fde2;
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} while (i2 > 0);
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v1->count += v2->count;
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}
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}
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static fde **
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end_fde_sort (fde_accumulator *accu, size_t count)
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{
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if (accu->linear.count != count)
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abort ();
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fde_split (&accu->linear, &accu->erratic);
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if (accu->linear.count + accu->erratic.count != count)
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abort ();
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frame_heapsort (&accu->erratic);
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fde_merge (&accu->linear, &accu->erratic);
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free (accu->erratic.array);
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return accu->linear.array;
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}
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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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/* 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. */
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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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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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start_fde_sort (&accu, count);
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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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ob->fde_array = end_fde_sort (&accu, count);
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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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__gthread_mutex_lock (&object_mutex);
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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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__gthread_mutex_unlock (&object_mutex);
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if (ob == 0)
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return 0;
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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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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);
|
||
p = decode_sleb128 (p, &c->data_align);
|
||
c->ra_regno = *(unsigned char *)p++;
|
||
|
||
/* If the augmentation starts with 'z', we now see the length of the
|
||
augmentation fields. */
|
||
if (c->augmentation[0] == 'z')
|
||
{
|
||
p = decode_uleb128 (p, &i);
|
||
p += i;
|
||
}
|
||
|
||
return p;
|
||
}
|
||
|
||
/* 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);
|
||
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);
|
||
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_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;
|
||
|
||
default:
|
||
abort ();
|
||
}
|
||
return p;
|
||
}
|
||
|
||
/* Called from crtbegin.o to register the unwind info for an object. */
|
||
|
||
void
|
||
__register_frame_info (void *begin, struct object *ob)
|
||
{
|
||
ob->fde_begin = begin;
|
||
|
||
ob->pc_begin = ob->pc_end = 0;
|
||
ob->fde_array = 0;
|
||
ob->count = 0;
|
||
|
||
__gthread_mutex_lock (&object_mutex);
|
||
|
||
ob->next = objects;
|
||
objects = ob;
|
||
|
||
__gthread_mutex_unlock (&object_mutex);
|
||
}
|
||
|
||
void
|
||
__register_frame (void *begin)
|
||
{
|
||
struct object *ob = (struct object *) malloc (sizeof (struct object));
|
||
__register_frame_info (begin, ob);
|
||
}
|
||
|
||
/* Similar, but BEGIN is actually a pointer to a table of unwind entries
|
||
for different translation units. Called from the file generated by
|
||
collect2. */
|
||
|
||
void
|
||
__register_frame_info_table (void *begin, struct object *ob)
|
||
{
|
||
ob->fde_begin = begin;
|
||
ob->fde_array = begin;
|
||
|
||
ob->pc_begin = ob->pc_end = 0;
|
||
ob->count = 0;
|
||
|
||
__gthread_mutex_lock (&object_mutex);
|
||
|
||
ob->next = objects;
|
||
objects = ob;
|
||
|
||
__gthread_mutex_unlock (&object_mutex);
|
||
}
|
||
|
||
void
|
||
__register_frame_table (void *begin)
|
||
{
|
||
struct object *ob = (struct object *) malloc (sizeof (struct object));
|
||
__register_frame_info_table (begin, ob);
|
||
}
|
||
|
||
/* Called from crtbegin.o to deregister the unwind info for an object. */
|
||
|
||
void *
|
||
__deregister_frame_info (void *begin)
|
||
{
|
||
struct object **p;
|
||
|
||
__gthread_mutex_lock (&object_mutex);
|
||
|
||
p = &objects;
|
||
while (*p)
|
||
{
|
||
if ((*p)->fde_begin == begin)
|
||
{
|
||
struct object *ob = *p;
|
||
*p = (*p)->next;
|
||
|
||
/* If we've run init_frame for this object, free the FDE array. */
|
||
if (ob->pc_begin)
|
||
free (ob->fde_array);
|
||
|
||
__gthread_mutex_unlock (&object_mutex);
|
||
return (void *) ob;
|
||
}
|
||
p = &((*p)->next);
|
||
}
|
||
|
||
__gthread_mutex_unlock (&object_mutex);
|
||
abort ();
|
||
}
|
||
|
||
void
|
||
__deregister_frame (void *begin)
|
||
{
|
||
free (__deregister_frame_info (begin));
|
||
}
|
||
|
||
/* 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 */
|