441 lines
12 KiB
C
441 lines
12 KiB
C
/* Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
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Contributed by Jakub Jelinek <jakub@redhat.com>.
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This file is part of GCC.
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GCC 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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GCC 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 GCC; see the file COPYING. If not, write to
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the Free Software Foundation, 51 Franklin Street, Fifth Floor,
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Boston, MA 02110-1301, 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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/* Locate the FDE entry for a given address, using PT_GNU_EH_FRAME ELF
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segment and dl_iterate_phdr to avoid register/deregister calls at
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DSO load/unload. */
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#ifndef _GNU_SOURCE
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#define _GNU_SOURCE 1
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#endif
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#include "tconfig.h"
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#include "tsystem.h"
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#ifndef inhibit_libc
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#include <link.h>
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#endif
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#include "coretypes.h"
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#include "tm.h"
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#include "dwarf2.h"
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#include "unwind.h"
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#define NO_BASE_OF_ENCODED_VALUE
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#include "unwind-pe.h"
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#include "unwind-dw2-fde.h"
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#include "unwind-compat.h"
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#include "gthr.h"
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#if !defined(inhibit_libc) && defined(HAVE_LD_EH_FRAME_HDR) \
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&& (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 2) \
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|| (__GLIBC__ == 2 && __GLIBC_MINOR__ == 2 && defined(DT_CONFIG)))
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#ifndef __RELOC_POINTER
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# define __RELOC_POINTER(ptr, base) ((ptr) + (base))
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#endif
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static const fde * _Unwind_Find_registered_FDE (void *pc, struct dwarf_eh_bases *bases);
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#define _Unwind_Find_FDE _Unwind_Find_registered_FDE
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#include "unwind-dw2-fde.c"
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#undef _Unwind_Find_FDE
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#ifndef PT_GNU_EH_FRAME
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#define PT_GNU_EH_FRAME (PT_LOOS + 0x474e550)
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#endif
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struct unw_eh_callback_data
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{
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_Unwind_Ptr pc;
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void *tbase;
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void *dbase;
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void *func;
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const fde *ret;
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int check_cache;
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};
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struct unw_eh_frame_hdr
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{
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unsigned char version;
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unsigned char eh_frame_ptr_enc;
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unsigned char fde_count_enc;
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unsigned char table_enc;
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};
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#define FRAME_HDR_CACHE_SIZE 8
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static struct frame_hdr_cache_element
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{
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_Unwind_Ptr pc_low;
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_Unwind_Ptr pc_high;
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_Unwind_Ptr load_base;
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const ElfW(Phdr) *p_eh_frame_hdr;
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const ElfW(Phdr) *p_dynamic;
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struct frame_hdr_cache_element *link;
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} frame_hdr_cache[FRAME_HDR_CACHE_SIZE];
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static struct frame_hdr_cache_element *frame_hdr_cache_head;
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/* Like base_of_encoded_value, but take the base from a struct
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unw_eh_callback_data instead of an _Unwind_Context. */
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static _Unwind_Ptr
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base_from_cb_data (unsigned char encoding, struct unw_eh_callback_data *data)
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{
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if (encoding == DW_EH_PE_omit)
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return 0;
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switch (encoding & 0x70)
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{
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case DW_EH_PE_absptr:
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case DW_EH_PE_pcrel:
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case DW_EH_PE_aligned:
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return 0;
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case DW_EH_PE_textrel:
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return (_Unwind_Ptr) data->tbase;
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case DW_EH_PE_datarel:
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return (_Unwind_Ptr) data->dbase;
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default:
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gcc_unreachable ();
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}
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}
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static int
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_Unwind_IteratePhdrCallback (struct dl_phdr_info *info, size_t size, void *ptr)
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{
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struct unw_eh_callback_data *data = (struct unw_eh_callback_data *) ptr;
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const ElfW(Phdr) *phdr, *p_eh_frame_hdr, *p_dynamic;
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long n, match;
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#ifdef __FRV_FDPIC__
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struct elf32_fdpic_loadaddr load_base;
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#else
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_Unwind_Ptr load_base;
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#endif
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const unsigned char *p;
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const struct unw_eh_frame_hdr *hdr;
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_Unwind_Ptr eh_frame;
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struct object ob;
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struct ext_dl_phdr_info
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{
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ElfW(Addr) dlpi_addr;
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const char *dlpi_name;
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const ElfW(Phdr) *dlpi_phdr;
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ElfW(Half) dlpi_phnum;
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unsigned long long int dlpi_adds;
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unsigned long long int dlpi_subs;
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};
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match = 0;
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phdr = info->dlpi_phdr;
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load_base = info->dlpi_addr;
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p_eh_frame_hdr = NULL;
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p_dynamic = NULL;
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struct frame_hdr_cache_element *prev_cache_entry = NULL,
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*last_cache_entry = NULL;
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if (data->check_cache && size >= sizeof (struct ext_dl_phdr_info))
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{
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static unsigned long long adds = -1ULL, subs;
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struct ext_dl_phdr_info *einfo = (struct ext_dl_phdr_info *) info;
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/* We use a least recently used cache replacement policy. Also,
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the most recently used cache entries are placed at the head
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of the search chain. */
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if (einfo->dlpi_adds == adds && einfo->dlpi_subs == subs)
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{
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/* Find data->pc in shared library cache.
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Set load_base, p_eh_frame_hdr and p_dynamic
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plus match from the cache and goto
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"Read .eh_frame_hdr header." below. */
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struct frame_hdr_cache_element *cache_entry;
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for (cache_entry = frame_hdr_cache_head;
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cache_entry;
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cache_entry = cache_entry->link)
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{
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if (data->pc >= cache_entry->pc_low
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&& data->pc < cache_entry->pc_high)
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{
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load_base = cache_entry->load_base;
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p_eh_frame_hdr = cache_entry->p_eh_frame_hdr;
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p_dynamic = cache_entry->p_dynamic;
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/* And move the entry we're using to the head. */
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if (cache_entry != frame_hdr_cache_head)
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{
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prev_cache_entry->link = cache_entry->link;
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cache_entry->link = frame_hdr_cache_head;
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frame_hdr_cache_head = cache_entry;
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}
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goto found;
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}
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last_cache_entry = cache_entry;
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/* Exit early if we found an unused entry. */
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if ((cache_entry->pc_low | cache_entry->pc_high) == 0)
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break;
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if (cache_entry->link != NULL)
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prev_cache_entry = cache_entry;
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}
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}
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else
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{
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adds = einfo->dlpi_adds;
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subs = einfo->dlpi_subs;
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/* Initialize the cache. Create a chain of cache entries,
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with the final one terminated by a NULL link. */
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int i;
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for (i = 0; i < FRAME_HDR_CACHE_SIZE; i++)
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{
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frame_hdr_cache[i].pc_low = 0;
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frame_hdr_cache[i].pc_high = 0;
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frame_hdr_cache[i].link = &frame_hdr_cache[i+1];
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}
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frame_hdr_cache[i-1].link = NULL;
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frame_hdr_cache_head = &frame_hdr_cache[0];
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data->check_cache = 0;
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}
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}
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/* Make sure struct dl_phdr_info is at least as big as we need. */
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if (size < offsetof (struct dl_phdr_info, dlpi_phnum)
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+ sizeof (info->dlpi_phnum))
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return -1;
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_Unwind_Ptr pc_low = 0, pc_high = 0;
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/* See if PC falls into one of the loaded segments. Find the eh_frame
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segment at the same time. */
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for (n = info->dlpi_phnum; --n >= 0; phdr++)
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{
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if (phdr->p_type == PT_LOAD)
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{
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_Unwind_Ptr vaddr = (_Unwind_Ptr)
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__RELOC_POINTER (phdr->p_vaddr, load_base);
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if (data->pc >= vaddr && data->pc < vaddr + phdr->p_memsz)
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{
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match = 1;
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pc_low = vaddr;
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pc_high = vaddr + phdr->p_memsz;
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}
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}
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else if (phdr->p_type == PT_GNU_EH_FRAME)
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p_eh_frame_hdr = phdr;
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else if (phdr->p_type == PT_DYNAMIC)
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p_dynamic = phdr;
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}
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if (!match)
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return 0;
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if (size >= sizeof (struct ext_dl_phdr_info))
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{
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/* Move the cache entry we're about to overwrite to the head of
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the list. If either last_cache_entry or prev_cache_entry are
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NULL, that cache entry is already at the head. */
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if (last_cache_entry != NULL && prev_cache_entry != NULL)
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{
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prev_cache_entry->link = last_cache_entry->link;
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last_cache_entry->link = frame_hdr_cache_head;
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frame_hdr_cache_head = last_cache_entry;
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}
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frame_hdr_cache_head->load_base = load_base;
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frame_hdr_cache_head->p_eh_frame_hdr = p_eh_frame_hdr;
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frame_hdr_cache_head->p_dynamic = p_dynamic;
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frame_hdr_cache_head->pc_low = pc_low;
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frame_hdr_cache_head->pc_high = pc_high;
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}
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found:
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if (!p_eh_frame_hdr)
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return 0;
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/* Read .eh_frame_hdr header. */
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hdr = (const struct unw_eh_frame_hdr *)
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__RELOC_POINTER (p_eh_frame_hdr->p_vaddr, load_base);
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if (hdr->version != 1)
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return 1;
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#ifdef CRT_GET_RFIB_DATA
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# ifdef __i386__
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data->dbase = NULL;
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if (p_dynamic)
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{
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/* For dynamically linked executables and shared libraries,
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DT_PLTGOT is the gp value for that object. */
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ElfW(Dyn) *dyn = (ElfW(Dyn) *)
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__RELOC_POINTER (p_dynamic->p_vaddr, load_base);
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for (; dyn->d_tag != DT_NULL ; dyn++)
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if (dyn->d_tag == DT_PLTGOT)
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{
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/* On IA-32, _DYNAMIC is writable and GLIBC has relocated it. */
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data->dbase = (void *) dyn->d_un.d_ptr;
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break;
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}
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}
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# elif defined __FRV_FDPIC__ && defined __linux__
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data->dbase = load_base.got_value;
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# else
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# error What is DW_EH_PE_datarel base on this platform?
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# endif
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#endif
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p = read_encoded_value_with_base (hdr->eh_frame_ptr_enc,
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base_from_cb_data (hdr->eh_frame_ptr_enc,
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data),
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(const unsigned char *) (hdr + 1),
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&eh_frame);
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/* We require here specific table encoding to speed things up.
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Also, DW_EH_PE_datarel here means using PT_GNU_EH_FRAME start
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as base, not the processor specific DW_EH_PE_datarel. */
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if (hdr->fde_count_enc != DW_EH_PE_omit
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&& hdr->table_enc == (DW_EH_PE_datarel | DW_EH_PE_sdata4))
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{
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_Unwind_Ptr fde_count;
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p = read_encoded_value_with_base (hdr->fde_count_enc,
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base_from_cb_data (hdr->fde_count_enc,
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data),
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p, &fde_count);
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/* Shouldn't happen. */
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if (fde_count == 0)
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return 1;
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if ((((_Unwind_Ptr) p) & 3) == 0)
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{
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struct fde_table {
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signed initial_loc __attribute__ ((mode (SI)));
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signed fde __attribute__ ((mode (SI)));
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};
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const struct fde_table *table = (const struct fde_table *) p;
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size_t lo, hi, mid;
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_Unwind_Ptr data_base = (_Unwind_Ptr) hdr;
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fde *f;
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unsigned int f_enc, f_enc_size;
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_Unwind_Ptr range;
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mid = fde_count - 1;
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if (data->pc < table[0].initial_loc + data_base)
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return 1;
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else if (data->pc < table[mid].initial_loc + data_base)
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{
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lo = 0;
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hi = mid;
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while (lo < hi)
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{
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mid = (lo + hi) / 2;
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if (data->pc < table[mid].initial_loc + data_base)
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hi = mid;
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else if (data->pc >= table[mid + 1].initial_loc + data_base)
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lo = mid + 1;
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else
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break;
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}
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gcc_assert (lo < hi);
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}
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f = (fde *) (table[mid].fde + data_base);
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f_enc = get_fde_encoding (f);
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f_enc_size = size_of_encoded_value (f_enc);
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read_encoded_value_with_base (f_enc & 0x0f, 0,
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&f->pc_begin[f_enc_size], &range);
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if (data->pc < table[mid].initial_loc + data_base + range)
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data->ret = f;
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data->func = (void *) (table[mid].initial_loc + data_base);
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return 1;
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}
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}
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/* We have no sorted search table, so need to go the slow way.
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As soon as GLIBC will provide API so to notify that a library has been
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removed, we could cache this (and thus use search_object). */
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ob.pc_begin = NULL;
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ob.tbase = data->tbase;
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ob.dbase = data->dbase;
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ob.u.single = (fde *) eh_frame;
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ob.s.i = 0;
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ob.s.b.mixed_encoding = 1; /* Need to assume worst case. */
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data->ret = linear_search_fdes (&ob, (fde *) eh_frame, (void *) data->pc);
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if (data->ret != NULL)
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{
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_Unwind_Ptr func;
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unsigned int encoding = get_fde_encoding (data->ret);
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read_encoded_value_with_base (encoding,
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base_from_cb_data (encoding, data),
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data->ret->pc_begin, &func);
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data->func = (void *) func;
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}
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return 1;
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}
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const fde *
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_Unwind_Find_FDE (void *pc, struct dwarf_eh_bases *bases)
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{
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struct unw_eh_callback_data data;
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const fde *ret;
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ret = _Unwind_Find_registered_FDE (pc, bases);
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if (ret != NULL)
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return ret;
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data.pc = (_Unwind_Ptr) pc;
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data.tbase = NULL;
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data.dbase = NULL;
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data.func = NULL;
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data.ret = NULL;
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data.check_cache = 1;
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if (dl_iterate_phdr (_Unwind_IteratePhdrCallback, &data) < 0)
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return NULL;
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if (data.ret)
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{
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bases->tbase = data.tbase;
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bases->dbase = data.dbase;
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bases->func = data.func;
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}
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return data.ret;
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}
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#else
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/* Prevent multiple include of header files. */
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#define _Unwind_Find_FDE _Unwind_Find_FDE
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#include "unwind-dw2-fde.c"
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#endif
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#if defined (USE_GAS_SYMVER) && defined (SHARED) && defined (USE_LIBUNWIND_EXCEPTIONS)
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alias (_Unwind_Find_FDE);
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#endif
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