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/* Copyright (C) 2001, 2002 Free Software Foundation, Inc.
Contributed by Jakub Jelinek <jakub@redhat.com>.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
/* Locate the FDE entry for a given address, using PT_GNU_EH_FRAME ELF
segment and dl_iterate_phdr to avoid register/deregister calls at
DSO load/unload. */
#ifdef _LIBC
# include <shlib-compat.h>
#endif
#if !defined _LIBC || SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_2_5)
#include <link.h>
#include <stddef.h>
#define _Unwind_Find_FDE _Unwind_Find_registered_FDE
#include <unwind-dw2-fde.c>
#undef _Unwind_Find_FDE
extern fde * _Unwind_Find_registered_FDE (void *pc,
struct dwarf_eh_bases *bases);
extern fde * _Unwind_Find_FDE (void *, struct dwarf_eh_bases *);
struct unw_eh_callback_data
{
_Unwind_Ptr pc;
void *tbase;
void *dbase;
void *func;
fde *ret;
};
struct unw_eh_frame_hdr
{
unsigned char version;
unsigned char eh_frame_ptr_enc;
unsigned char fde_count_enc;
unsigned char table_enc;
};
/* Like base_of_encoded_value, but take the base from a struct object
instead of an _Unwind_Context. */
static _Unwind_Ptr
base_from_cb_data (unsigned char encoding, struct unw_eh_callback_data *data)
{
if (encoding == DW_EH_PE_omit)
return 0;
switch (encoding & 0x70)
{
case DW_EH_PE_absptr:
case DW_EH_PE_pcrel:
case DW_EH_PE_aligned:
return 0;
case DW_EH_PE_textrel:
return (_Unwind_Ptr) data->tbase;
case DW_EH_PE_datarel:
return (_Unwind_Ptr) data->dbase;
}
abort ();
}
static int
_Unwind_IteratePhdrCallback (struct dl_phdr_info *info, size_t size, void *ptr)
{
struct unw_eh_callback_data *data = (struct unw_eh_callback_data *) ptr;
const ElfW(Phdr) *phdr, *p_eh_frame_hdr, *p_dynamic;
long n, match;
_Unwind_Ptr load_base;
const unsigned char *p;
const struct unw_eh_frame_hdr *hdr;
_Unwind_Ptr eh_frame;
struct object ob;
/* Make sure struct dl_phdr_info is at least as big as we need. */
if (size < offsetof (struct dl_phdr_info, dlpi_phnum)
+ sizeof (info->dlpi_phnum))
return -1;
match = 0;
phdr = info->dlpi_phdr;
load_base = info->dlpi_addr;
p_eh_frame_hdr = NULL;
p_dynamic = NULL;
/* See if PC falls into one of the loaded segments. Find the eh_frame
segment at the same time. */
for (n = info->dlpi_phnum; --n >= 0; phdr++)
{
if (phdr->p_type == PT_LOAD)
{
_Unwind_Ptr vaddr = phdr->p_vaddr + load_base;
if (data->pc >= vaddr && data->pc < vaddr + phdr->p_memsz)
match = 1;
}
else if (phdr->p_type == PT_GNU_EH_FRAME)
p_eh_frame_hdr = phdr;
else if (phdr->p_type == PT_DYNAMIC)
p_dynamic = phdr;
}
if (!match || !p_eh_frame_hdr)
return 0;
/* Read .eh_frame_hdr header. */
hdr = (const struct unw_eh_frame_hdr *)
(p_eh_frame_hdr->p_vaddr + load_base);
if (hdr->version != 1)
return 1;
#ifdef CRT_GET_RFIB_DATA
# ifdef __i386__
data->dbase = NULL;
if (p_dynamic)
{
/* For dynamicly linked executables and shared libraries,
DT_PLTGOT is the gp value for that object. */
ElfW(Dyn) *dyn = (ElfW(Dyn) *)(p_dynamic->p_vaddr + load_base);
for (; dyn->d_tag != DT_NULL ; dyn++)
if (dyn->d_tag == DT_PLTGOT)
{
/* On IA-32, _DYNAMIC is writable and GLIBC has relocated it. */
data->dbase = (void *) dyn->d_un.d_ptr;
break;
}
}
# else
# error What is DW_EH_PE_datarel base on this platform?
# endif
#endif
#ifdef CRT_GET_RFIB_TEXT
# error What is DW_EH_PE_textrel base on this platform?
#endif
p = read_encoded_value_with_base (hdr->eh_frame_ptr_enc,
base_from_cb_data (hdr->eh_frame_ptr_enc,
data),
(const unsigned char *) (hdr + 1),
&eh_frame);
/* We require here specific table encoding to speed things up.
Also, DW_EH_PE_datarel here means using PT_GNU_EH_FRAME start
as base, not the processor specific DW_EH_PE_datarel. */
if (hdr->fde_count_enc != DW_EH_PE_omit
&& hdr->table_enc == (DW_EH_PE_datarel | DW_EH_PE_sdata4))
{
_Unwind_Ptr fde_count;
p = read_encoded_value_with_base (hdr->fde_count_enc,
base_from_cb_data (hdr->fde_count_enc,
data),
p, &fde_count);
/* Shouldn't happen. */
if (fde_count == 0)
return 1;
if ((((_Unwind_Ptr) p) & 3) == 0)
{
struct fde_table {
signed initial_loc __attribute__ ((mode (SI)));
signed fde __attribute__ ((mode (SI)));
};
const struct fde_table *table = (const struct fde_table *) p;
size_t lo, hi, mid;
_Unwind_Ptr data_base = (_Unwind_Ptr) hdr;
fde *f;
unsigned int f_enc, f_enc_size;
_Unwind_Ptr range;
mid = fde_count - 1;
if (data->pc < table[0].initial_loc + data_base)
return 1;
else if (data->pc < table[mid].initial_loc + data_base)
{
lo = 0;
hi = mid;
while (lo < hi)
{
mid = (lo + hi) / 2;
if (data->pc < table[mid].initial_loc + data_base)
hi = mid;
else if (data->pc >= table[mid + 1].initial_loc + data_base)
lo = mid + 1;
else
break;
}
if (lo >= hi)
__gxx_abort ();
}
f = (fde *) (table[mid].fde + data_base);
f_enc = get_fde_encoding (f);
f_enc_size = size_of_encoded_value (f_enc);
read_encoded_value_with_base (f_enc & 0x0f, 0,
&f->pc_begin[f_enc_size], &range);
if (data->pc < table[mid].initial_loc + data_base + range)
data->ret = f;
data->func = (void *) (table[mid].initial_loc + data_base);
return 1;
}
}
/* We have no sorted search table, so need to go the slow way.
As soon as GLIBC will provide API so to notify that a library has been
removed, we could cache this (and thus use search_object). */
ob.pc_begin = NULL;
ob.tbase = data->tbase;
ob.dbase = data->dbase;
ob.u.single = (fde *) eh_frame;
ob.s.i = 0;
ob.s.b.mixed_encoding = 1; /* Need to assume worst case. */
data->ret = linear_search_fdes (&ob, (fde *) eh_frame, (void *) data->pc);
if (data->ret != NULL)
{
unsigned int encoding = get_fde_encoding (data->ret);
read_encoded_value_with_base (encoding,
base_from_cb_data (encoding, data),
data->ret->pc_begin,
(_Unwind_Ptr *)&data->func);
}
return 1;
}
# ifdef _LIBC
# define dl_iterate_phdr __dl_iterate_phdr
# endif
fde *
_Unwind_Find_FDE (void *pc, struct dwarf_eh_bases *bases)
{
struct unw_eh_callback_data data;
fde *ret;
ret = _Unwind_Find_registered_FDE (pc, bases);
if (ret != NULL)
return ret;
data.pc = (_Unwind_Ptr) pc;
data.tbase = NULL;
data.dbase = NULL;
data.func = NULL;
data.ret = NULL;
if (dl_iterate_phdr (_Unwind_IteratePhdrCallback, &data) < 0)
return NULL;
if (data.ret)
{
bases->tbase = data.tbase;
bases->dbase = data.dbase;
bases->func = data.func;
}
return data.ret;
}
#endif
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