| /* Copyright (C) 2001-2023 Free Software Foundation, Inc. |
| Contributed by Jakub Jelinek <jakub@redhat.com>. |
| |
| This file is part of GCC. |
| |
| GCC is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 3, or (at your option) |
| any later version. |
| |
| GCC 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 General Public License for more details. |
| |
| Under Section 7 of GPL version 3, you are granted additional |
| permissions described in the GCC Runtime Library Exception, version |
| 3.1, as published by the Free Software Foundation. |
| |
| You should have received a copy of the GNU General Public License and |
| a copy of the GCC Runtime Library Exception along with this program; |
| see the files COPYING3 and COPYING.RUNTIME respectively. 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. */ |
| |
| #ifndef _GNU_SOURCE |
| #define _GNU_SOURCE 1 |
| #endif |
| |
| #include "tconfig.h" |
| #include "tsystem.h" |
| #if !defined(inhibit_libc) && !defined(__OpenBSD__) |
| #include <elf.h> /* Get DT_CONFIG. */ |
| #endif |
| #include "coretypes.h" |
| #include "tm.h" |
| #include "libgcc_tm.h" |
| #include "dwarf2.h" |
| #include "unwind.h" |
| #define NO_BASE_OF_ENCODED_VALUE |
| #include "unwind-pe.h" |
| #include "unwind-dw2-fde.h" |
| #include "unwind-compat.h" |
| #include "gthr.h" |
| |
| #if !defined(inhibit_libc) && defined(HAVE_LD_EH_FRAME_HDR) \ |
| && (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 2) \ |
| || (__GLIBC__ == 2 && __GLIBC_MINOR__ == 2 && defined(DT_CONFIG))) |
| # define USE_PT_GNU_EH_FRAME |
| #endif |
| |
| #if !defined(inhibit_libc) && defined(HAVE_LD_EH_FRAME_HDR) \ |
| && defined(__BIONIC__) |
| # define USE_PT_GNU_EH_FRAME |
| #endif |
| |
| #if !defined(inhibit_libc) && defined(HAVE_LD_EH_FRAME_HDR) \ |
| && defined(TARGET_DL_ITERATE_PHDR) \ |
| && defined(__linux__) |
| # define USE_PT_GNU_EH_FRAME |
| #endif |
| |
| #if !defined(inhibit_libc) && defined(HAVE_LD_EH_FRAME_HDR) \ |
| && defined(TARGET_DL_ITERATE_PHDR) \ |
| && (defined(__DragonFly__) || defined(__FreeBSD__)) |
| # define ElfW __ElfN |
| # define USE_PT_GNU_EH_FRAME |
| #endif |
| |
| #if !defined(inhibit_libc) && defined(HAVE_LD_EH_FRAME_HDR) \ |
| && defined(TARGET_DL_ITERATE_PHDR) \ |
| && (defined(__OpenBSD__) || defined(__NetBSD__)) |
| # define ElfW(type) Elf_##type |
| # define USE_PT_GNU_EH_FRAME |
| #endif |
| |
| #if !defined(inhibit_libc) && defined(HAVE_LD_EH_FRAME_HDR) \ |
| && defined(TARGET_DL_ITERATE_PHDR) \ |
| && defined(__sun__) && defined(__svr4__) |
| # define USE_PT_GNU_EH_FRAME |
| #endif |
| |
| #if defined(USE_PT_GNU_EH_FRAME) |
| |
| #include <link.h> |
| |
| #ifndef __RELOC_POINTER |
| # define __RELOC_POINTER(ptr, base) ((ptr) + (base)) |
| #endif |
| |
| static const fde * _Unwind_Find_registered_FDE (void *pc, struct dwarf_eh_bases *bases); |
| |
| #define _Unwind_Find_FDE _Unwind_Find_registered_FDE |
| #include "unwind-dw2-fde.c" |
| #undef _Unwind_Find_FDE |
| |
| #ifndef PT_GNU_EH_FRAME |
| #define PT_GNU_EH_FRAME (PT_LOOS + 0x474e550) |
| #endif |
| |
| #ifdef CRT_GET_RFIB_DATA |
| #define NEED_DBASE_MEMBER 1 |
| #else |
| #define NEED_DBASE_MEMBER 0 |
| #endif |
| |
| struct unw_eh_callback_data |
| { |
| _Unwind_Ptr pc; |
| #if NEED_DBASE_MEMBER |
| void *dbase; |
| #endif |
| const struct unw_eh_frame_hdr *hdr; |
| int check_cache; |
| }; |
| |
| /* Returns DATA->dbase if available, else NULL. */ |
| static inline _Unwind_Ptr |
| unw_eh_callback_data_dbase (const struct unw_eh_callback_data *data |
| __attribute__ ((unused))) |
| { |
| #if NEED_DBASE_MEMBER |
| return (_Unwind_Ptr) data->dbase; |
| #else |
| return 0; |
| #endif |
| } |
| |
| struct unw_eh_frame_hdr |
| { |
| unsigned char version; |
| unsigned char eh_frame_ptr_enc; |
| unsigned char fde_count_enc; |
| unsigned char table_enc; |
| }; |
| |
| #define FRAME_HDR_CACHE_SIZE 8 |
| |
| static struct frame_hdr_cache_element |
| { |
| _Unwind_Ptr pc_low; |
| _Unwind_Ptr pc_high; |
| #if defined __FRV_FDPIC__ || defined __BFIN_FDPIC__ |
| struct elf32_fdpic_loadaddr load_base; |
| #else |
| _Unwind_Ptr load_base; |
| #endif |
| const ElfW(Phdr) *p_eh_frame_hdr; |
| const ElfW(Phdr) *p_dynamic; |
| struct frame_hdr_cache_element *link; |
| } frame_hdr_cache[FRAME_HDR_CACHE_SIZE]; |
| |
| static struct frame_hdr_cache_element *frame_hdr_cache_head; |
| |
| /* Like base_of_encoded_value, but take the base from a struct |
| unw_eh_callback_data instead of an _Unwind_Context. */ |
| |
| static inline _Unwind_Ptr |
| base_from_cb_data (unsigned char encoding __attribute__ ((unused)), |
| _Unwind_Ptr dbase __attribute__ ((unused))) |
| { |
| #if NEED_DBASE_MEMBER |
| 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 0; |
| case DW_EH_PE_datarel: |
| return dbase; |
| default: |
| gcc_unreachable (); |
| } |
| #else /* !NEED_DBASE_MEMBER */ |
| return 0; |
| #endif |
| } |
| |
| 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; |
| #if defined __FRV_FDPIC__ || defined __BFIN_FDPIC__ |
| struct elf32_fdpic_loadaddr load_base; |
| #else |
| _Unwind_Ptr load_base; |
| #endif |
| _Unwind_Ptr pc_low = 0, pc_high = 0; |
| |
| struct ext_dl_phdr_info |
| { |
| ElfW(Addr) dlpi_addr; |
| const char *dlpi_name; |
| const ElfW(Phdr) *dlpi_phdr; |
| ElfW(Half) dlpi_phnum; |
| unsigned long long int dlpi_adds; |
| unsigned long long int dlpi_subs; |
| }; |
| |
| match = 0; |
| phdr = info->dlpi_phdr; |
| load_base = info->dlpi_addr; |
| p_eh_frame_hdr = NULL; |
| p_dynamic = NULL; |
| |
| struct frame_hdr_cache_element *prev_cache_entry = NULL, |
| *last_cache_entry = NULL; |
| |
| if (data->check_cache && size >= sizeof (struct ext_dl_phdr_info)) |
| { |
| static unsigned long long adds = -1ULL, subs; |
| struct ext_dl_phdr_info *einfo = (struct ext_dl_phdr_info *) info; |
| |
| /* We use a least recently used cache replacement policy. Also, |
| the most recently used cache entries are placed at the head |
| of the search chain. */ |
| |
| if (einfo->dlpi_adds == adds && einfo->dlpi_subs == subs) |
| { |
| /* Find data->pc in shared library cache. |
| Set load_base, p_eh_frame_hdr and p_dynamic |
| plus match from the cache and goto |
| "Read .eh_frame_hdr header." below. */ |
| |
| struct frame_hdr_cache_element *cache_entry; |
| |
| for (cache_entry = frame_hdr_cache_head; |
| cache_entry; |
| cache_entry = cache_entry->link) |
| { |
| if (data->pc >= cache_entry->pc_low |
| && data->pc < cache_entry->pc_high) |
| { |
| load_base = cache_entry->load_base; |
| p_eh_frame_hdr = cache_entry->p_eh_frame_hdr; |
| p_dynamic = cache_entry->p_dynamic; |
| |
| /* And move the entry we're using to the head. */ |
| if (cache_entry != frame_hdr_cache_head) |
| { |
| prev_cache_entry->link = cache_entry->link; |
| cache_entry->link = frame_hdr_cache_head; |
| frame_hdr_cache_head = cache_entry; |
| } |
| goto found; |
| } |
| |
| last_cache_entry = cache_entry; |
| /* Exit early if we found an unused entry. */ |
| if ((cache_entry->pc_low | cache_entry->pc_high) == 0) |
| break; |
| if (cache_entry->link != NULL) |
| prev_cache_entry = cache_entry; |
| } |
| } |
| else |
| { |
| adds = einfo->dlpi_adds; |
| subs = einfo->dlpi_subs; |
| /* Initialize the cache. Create a chain of cache entries, |
| with the final one terminated by a NULL link. */ |
| int i; |
| for (i = 0; i < FRAME_HDR_CACHE_SIZE; i++) |
| { |
| frame_hdr_cache[i].pc_low = 0; |
| frame_hdr_cache[i].pc_high = 0; |
| frame_hdr_cache[i].link = &frame_hdr_cache[i+1]; |
| } |
| frame_hdr_cache[i-1].link = NULL; |
| frame_hdr_cache_head = &frame_hdr_cache[0]; |
| data->check_cache = 0; |
| } |
| } |
| |
| /* 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; |
| |
| /* 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 = (_Unwind_Ptr) |
| __RELOC_POINTER (phdr->p_vaddr, load_base); |
| if (data->pc >= vaddr && data->pc < vaddr + phdr->p_memsz) |
| { |
| match = 1; |
| pc_low = vaddr; |
| pc_high = vaddr + phdr->p_memsz; |
| } |
| } |
| else if (phdr->p_type == PT_GNU_EH_FRAME) |
| p_eh_frame_hdr = phdr; |
| #ifdef PT_SUNW_UNWIND |
| /* Sun ld emits PT_SUNW_UNWIND .eh_frame_hdr sections instead of |
| PT_SUNW_EH_FRAME/PT_GNU_EH_FRAME, so accept them as well. */ |
| else if (phdr->p_type == PT_SUNW_UNWIND) |
| p_eh_frame_hdr = phdr; |
| #endif |
| else if (phdr->p_type == PT_DYNAMIC) |
| p_dynamic = phdr; |
| } |
| |
| if (!match) |
| return 0; |
| |
| if (size >= sizeof (struct ext_dl_phdr_info)) |
| { |
| /* Move the cache entry we're about to overwrite to the head of |
| the list. If either last_cache_entry or prev_cache_entry are |
| NULL, that cache entry is already at the head. */ |
| if (last_cache_entry != NULL && prev_cache_entry != NULL) |
| { |
| prev_cache_entry->link = last_cache_entry->link; |
| last_cache_entry->link = frame_hdr_cache_head; |
| frame_hdr_cache_head = last_cache_entry; |
| } |
| |
| frame_hdr_cache_head->load_base = load_base; |
| frame_hdr_cache_head->p_eh_frame_hdr = p_eh_frame_hdr; |
| frame_hdr_cache_head->p_dynamic = p_dynamic; |
| frame_hdr_cache_head->pc_low = pc_low; |
| frame_hdr_cache_head->pc_high = pc_high; |
| } |
| |
| found: |
| |
| if (!p_eh_frame_hdr) |
| return 0; |
| |
| /* Read .eh_frame_hdr header. */ |
| data->hdr = (const struct unw_eh_frame_hdr *) |
| __RELOC_POINTER (p_eh_frame_hdr->p_vaddr, load_base); |
| |
| #ifdef CRT_GET_RFIB_DATA |
| # if defined __i386__ || defined __nios2__ |
| data->dbase = NULL; |
| if (p_dynamic) |
| { |
| /* For dynamically linked executables and shared libraries, |
| DT_PLTGOT is the gp value for that object. */ |
| ElfW(Dyn) *dyn = (ElfW(Dyn) *) |
| __RELOC_POINTER (p_dynamic->p_vaddr, load_base); |
| for (; dyn->d_tag != DT_NULL ; dyn++) |
| if (dyn->d_tag == DT_PLTGOT) |
| { |
| data->dbase = (void *) dyn->d_un.d_ptr; |
| #if defined __linux__ |
| /* On IA-32 Linux, _DYNAMIC is writable and GLIBC has |
| relocated it. */ |
| #elif defined __sun__ && defined __svr4__ |
| /* On Solaris 2/x86, we need to do this ourselves. */ |
| data->dbase += load_base; |
| #endif |
| break; |
| } |
| } |
| # elif (defined __FRV_FDPIC__ || defined __BFIN_FDPIC__) && defined __linux__ |
| data->dbase = load_base.got_value; |
| # else |
| # error What is DW_EH_PE_datarel base on this platform? |
| # endif |
| #endif |
| |
| return 1; |
| } |
| |
| /* Find the FDE for the program counter PC, in a previously located |
| PT_GNU_EH_FRAME data region. *BASES is updated if an FDE to return is |
| found. */ |
| |
| static const fde * |
| find_fde_tail (_Unwind_Ptr pc, |
| const struct unw_eh_frame_hdr *hdr, |
| _Unwind_Ptr dbase, |
| struct dwarf_eh_bases *bases) |
| { |
| const unsigned char *p = (const unsigned char *) (hdr + 1); |
| _Unwind_Ptr eh_frame; |
| struct object ob; |
| |
| if (hdr->version != 1) |
| return NULL; |
| |
| if (__builtin_expect (hdr->eh_frame_ptr_enc == (DW_EH_PE_sdata4 |
| | DW_EH_PE_pcrel), 1)) |
| { |
| /* Specialized version of read_encoded_value_with_base, based on what |
| BFD ld generates. */ |
| signed value __attribute__ ((mode (SI))); |
| memcpy (&value, p, sizeof (value)); |
| eh_frame = p + value; |
| p += sizeof (value); |
| } |
| else |
| p = read_encoded_value_with_base (hdr->eh_frame_ptr_enc, |
| base_from_cb_data (hdr->eh_frame_ptr_enc, |
| dbase), |
| p, &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; |
| |
| if (__builtin_expect (hdr->fde_count_enc == DW_EH_PE_udata4, 1)) |
| { |
| /* Specialized version of read_encoded_value_with_base, based on |
| what BFD ld generates. */ |
| unsigned value __attribute__ ((mode (SI))); |
| memcpy (&value, p, sizeof (value)); |
| p += sizeof (value); |
| fde_count = value; |
| } |
| else |
| p = read_encoded_value_with_base (hdr->fde_count_enc, |
| base_from_cb_data (hdr->fde_count_enc, |
| dbase), |
| p, &fde_count); |
| /* Shouldn't happen. */ |
| if (fde_count == 0) |
| return NULL; |
| 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 (pc < table[0].initial_loc + data_base) |
| return NULL; |
| else if (pc < table[mid].initial_loc + data_base) |
| { |
| lo = 0; |
| hi = mid; |
| |
| while (lo < hi) |
| { |
| mid = (lo + hi) / 2; |
| if (pc < table[mid].initial_loc + data_base) |
| hi = mid; |
| else if (pc >= table[mid + 1].initial_loc + data_base) |
| lo = mid + 1; |
| else |
| break; |
| } |
| |
| gcc_assert (lo < hi); |
| } |
| |
| f = (fde *) (table[mid].fde + data_base); |
| f_enc = get_fde_encoding (f); |
| f_enc_size = size_of_encoded_value (f_enc); |
| |
| /* BFD ld uses DW_EH_PE_sdata4 | DW_EH_PE_pcrel on non-FDPIC targets, |
| so optimize for that. |
| |
| This optimization is not valid for FDPIC targets. f_enc & 0x0f as |
| passed to read_encoded_value_with_base masks away the base flags, |
| but they are implicit for FDPIC. */ |
| #ifndef __FDPIC__ |
| if (__builtin_expect (f_enc == (DW_EH_PE_sdata4 | DW_EH_PE_pcrel), |
| 1)) |
| { |
| signed value __attribute__ ((mode (SI))); |
| memcpy (&value, &f->pc_begin[f_enc_size], sizeof (value)); |
| range = value; |
| } |
| else |
| #endif |
| read_encoded_value_with_base (f_enc & 0x0f, 0, |
| &f->pc_begin[f_enc_size], &range); |
| _Unwind_Ptr func = table[mid].initial_loc + data_base; |
| if (pc < table[mid].initial_loc + data_base + range) |
| { |
| bases->tbase = NULL; |
| bases->dbase = (void *) dbase; |
| bases->func = (void *) func; |
| return f; |
| } |
| else |
| return NULL; |
| } |
| } |
| |
| /* 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 = NULL; |
| ob.dbase = (void *) dbase; |
| ob.u.single = (fde *) eh_frame; |
| ob.s.i = 0; |
| ob.s.b.mixed_encoding = 1; /* Need to assume worst case. */ |
| const fde *entry = linear_search_fdes (&ob, (fde *) eh_frame, (void *) pc); |
| if (entry != NULL) |
| { |
| _Unwind_Ptr func; |
| unsigned int encoding = get_fde_encoding (entry); |
| |
| read_encoded_value_with_base (encoding, |
| base_from_cb_data (encoding, dbase), |
| entry->pc_begin, &func); |
| bases->tbase = NULL; |
| bases->dbase = (void *) dbase; |
| bases->func = (void *) func; |
| } |
| return entry; |
| } |
| |
| const fde * |
| _Unwind_Find_FDE (void *pc, struct dwarf_eh_bases *bases) |
| { |
| struct unw_eh_callback_data data; |
| const fde *ret; |
| |
| ret = _Unwind_Find_registered_FDE (pc, bases); |
| if (ret != NULL) |
| return ret; |
| |
| /* Use DLFO_STRUCT_HAS_EH_DBASE as a proxy for the existence of a glibc-style |
| _dl_find_object function. */ |
| #ifdef DLFO_STRUCT_HAS_EH_DBASE |
| { |
| struct dl_find_object dlfo; |
| if (_dl_find_object (pc, &dlfo) == 0 && dlfo.dlfo_eh_frame != NULL) |
| return find_fde_tail ((_Unwind_Ptr) pc, dlfo.dlfo_eh_frame, |
| # if DLFO_STRUCT_HAS_EH_DBASE |
| (_Unwind_Ptr) dlfo.dlfo_eh_dbase, |
| # else |
| 0, |
| # endif |
| bases); |
| else |
| return NULL; |
| } |
| #endif /* DLFO_STRUCT_HAS_EH_DBASE */ |
| |
| data.pc = (_Unwind_Ptr) pc; |
| #if NEED_DBASE_MEMBER |
| data.dbase = NULL; |
| #endif |
| data.check_cache = 1; |
| |
| if (dl_iterate_phdr (_Unwind_IteratePhdrCallback, &data) <= 0) |
| return NULL; |
| |
| _Unwind_Ptr dbase = unw_eh_callback_data_dbase (&data); |
| return find_fde_tail ((_Unwind_Ptr) pc, data.hdr, dbase, bases); |
| } |
| |
| #else |
| /* Prevent multiple include of header files. */ |
| #define _Unwind_Find_FDE _Unwind_Find_FDE |
| #include "unwind-dw2-fde.c" |
| #endif |
| |
| #if defined (USE_GAS_SYMVER) && defined (SHARED) && defined (USE_LIBUNWIND_EXCEPTIONS) |
| alias (_Unwind_Find_FDE); |
| #endif |