| /* Copyright (C) 2001-2018 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, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| /* 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; |
| const ElfW(Phdr) *p_dynamic __attribute__ ((unused)); |
| 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); |
| _Unwind_Ptr func; |
| read_encoded_value_with_base (encoding, |
| base_from_cb_data (encoding, data), |
| data->ret->pc_begin, &func); |
| data->func = (void *) 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 |