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Diffstat (limited to 'gdb/solib-svr4.c')
| -rw-r--r-- | gdb/solib-svr4.c | 1586 |
1 files changed, 1586 insertions, 0 deletions
diff --git a/gdb/solib-svr4.c b/gdb/solib-svr4.c new file mode 100644 index 0000000..13fea47 --- /dev/null +++ b/gdb/solib-svr4.c @@ -0,0 +1,1586 @@ +/* Handle SunOS and SVR4 shared libraries for GDB, the GNU Debugger. + Copyright 1990, 91, 92, 93, 94, 95, 96, 98, 1999, 2000 + Free Software Foundation, Inc. + + This file is part of GDB. + + This program 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 2 of the License, or + (at your option) any later version. + + This program 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. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 59 Temple Place - Suite 330, + Boston, MA 02111-1307, USA. */ + +#define _SYSCALL32 /* for Sparc64 cross Sparc32 */ +#include "defs.h" + + +#include <sys/types.h> +#include <signal.h> +#include "gdb_string.h" +#include <sys/param.h> +#include <fcntl.h> + +#ifndef SVR4_SHARED_LIBS + /* SunOS shared libs need the nlist structure. */ +#include <a.out.h> +#else +#include "elf/external.h" +#endif + +#ifdef HAVE_LINK_H +#include <link.h> +#endif + +#include "symtab.h" +#include "bfd.h" +#include "symfile.h" +#include "objfiles.h" +#include "gdbcore.h" +#include "command.h" +#include "target.h" +#include "frame.h" +#include "gdb_regex.h" +#include "inferior.h" +#include "environ.h" +#include "language.h" +#include "gdbcmd.h" + +#include "solist.h" +#include "solib-svr4.h" + +/* Link map info to include in an allocated so_list entry */ + +struct lm_info + { + /* Pointer to copy of link map from inferior. The type is char * + rather than void *, so that we may use byte offsets to find the + various fields without the need for a cast. */ + char *lm; + }; + +/* On SVR4 systems, a list of symbols in the dynamic linker where + GDB can try to place a breakpoint to monitor shared library + events. + + If none of these symbols are found, or other errors occur, then + SVR4 systems will fall back to using a symbol as the "startup + mapping complete" breakpoint address. */ + +#ifdef SVR4_SHARED_LIBS +static char *solib_break_names[] = +{ + "r_debug_state", + "_r_debug_state", + "_dl_debug_state", + "rtld_db_dlactivity", + NULL +}; +#endif + +#define BKPT_AT_SYMBOL 1 + +#if defined (BKPT_AT_SYMBOL) && defined (SVR4_SHARED_LIBS) +static char *bkpt_names[] = +{ +#ifdef SOLIB_BKPT_NAME + SOLIB_BKPT_NAME, /* Prefer configured name if it exists. */ +#endif + "_start", + "main", + NULL +}; +#endif + +/* Symbols which are used to locate the base of the link map structures. */ + +#ifndef SVR4_SHARED_LIBS +static char *debug_base_symbols[] = +{ + "_DYNAMIC", + "_DYNAMIC__MGC", + NULL +}; +#endif + +static char *main_name_list[] = +{ + "main_$main", + NULL +}; + + +/* Fetch (and possibly build) an appropriate link_map_offsets structure + for native targets using struct definitions from link.h. */ + +struct link_map_offsets * +default_svr4_fetch_link_map_offsets (void) +{ +#ifdef HAVE_LINK_H + static struct link_map_offsets lmo; + static struct link_map_offsets *lmp = 0; +#if defined (HAVE_STRUCT_LINK_MAP32) + static struct link_map_offsets lmo32; + static struct link_map_offsets *lmp32 = 0; +#endif + +#ifndef offsetof +#define offsetof(TYPE, MEMBER) ((unsigned long) &((TYPE *)0)->MEMBER) +#endif +#define fieldsize(TYPE, MEMBER) (sizeof (((TYPE *)0)->MEMBER)) + + if (lmp == 0) + { + lmp = &lmo; + +#ifdef SVR4_SHARED_LIBS + lmo.r_debug_size = sizeof (struct r_debug); + + lmo.r_map_offset = offsetof (struct r_debug, r_map); + lmo.r_map_size = fieldsize (struct r_debug, r_map); + + lmo.link_map_size = sizeof (struct link_map); + + lmo.l_addr_offset = offsetof (struct link_map, l_addr); + lmo.l_addr_size = fieldsize (struct link_map, l_addr); + + lmo.l_next_offset = offsetof (struct link_map, l_next); + lmo.l_next_size = fieldsize (struct link_map, l_next); + + lmo.l_prev_offset = offsetof (struct link_map, l_prev); + lmo.l_prev_size = fieldsize (struct link_map, l_prev); + + lmo.l_name_offset = offsetof (struct link_map, l_name); + lmo.l_name_size = fieldsize (struct link_map, l_name); +#else /* !SVR4_SHARED_LIBS */ + lmo.link_map_size = sizeof (struct link_map); + + lmo.l_addr_offset = offsetof (struct link_map, lm_addr); + lmo.l_addr_size = fieldsize (struct link_map, lm_addr); + + lmo.l_next_offset = offsetof (struct link_map, lm_next); + lmo.l_next_size = fieldsize (struct link_map, lm_next); + + lmo.l_name_offset = offsetof (struct link_map, lm_name); + lmo.l_name_size = fieldsize (struct link_map, lm_name); +#endif /* SVR4_SHARED_LIBS */ + } + +#if defined (HAVE_STRUCT_LINK_MAP32) + if (lmp32 == 0) + { + lmp32 = &lmo32; + + lmo32.r_debug_size = sizeof (struct r_debug32); + + lmo32.r_map_offset = offsetof (struct r_debug32, r_map); + lmo32.r_map_size = fieldsize (struct r_debug32, r_map); + + lmo32.link_map_size = sizeof (struct link_map32); + + lmo32.l_addr_offset = offsetof (struct link_map32, l_addr); + lmo32.l_addr_size = fieldsize (struct link_map32, l_addr); + + lmo32.l_next_offset = offsetof (struct link_map32, l_next); + lmo32.l_next_size = fieldsize (struct link_map32, l_next); + + lmo32.l_prev_offset = offsetof (struct link_map32, l_prev); + lmo32.l_prev_size = fieldsize (struct link_map32, l_prev); + + lmo32.l_name_offset = offsetof (struct link_map32, l_name); + lmo32.l_name_size = fieldsize (struct link_map32, l_name); + } +#endif /* defined (HAVE_STRUCT_LINK_MAP32) */ + +#if defined (HAVE_STRUCT_LINK_MAP32) + if (bfd_get_arch_size (exec_bfd) == 32) + return lmp32; + else +#endif + return lmp; + +#else + + internal_error ("default_svr4_fetch_link_map_offsets called without HAVE_LINK_H defined."); + return 0; + +#endif /* HAVE_LINK_H */ +} + +/* Macro to extract an address from a solib structure. + When GDB is configured for some 32-bit targets (e.g. Solaris 2.7 + sparc), BFD is configured to handle 64-bit targets, so CORE_ADDR is + 64 bits. We have to extract only the significant bits of addresses + to get the right address when accessing the core file BFD. */ + +#define SOLIB_EXTRACT_ADDRESS(MEMBER) \ + extract_address (&(MEMBER), sizeof (MEMBER)) + +/* local data declarations */ + +#ifndef SVR4_SHARED_LIBS + +/* NOTE: converted the macros LM_ADDR, LM_NEXT, LM_NAME and + IGNORE_FIRST_LINK_MAP_ENTRY into functions (see below). + MVS, June 2000 */ + +static struct link_dynamic dynamic_copy; +static struct link_dynamic_2 ld_2_copy; +static struct ld_debug debug_copy; +static CORE_ADDR debug_addr; +static CORE_ADDR flag_addr; + +#endif /* !SVR4_SHARED_LIBS */ + +/* link map access functions */ + +static CORE_ADDR +LM_ADDR (struct so_list *so) +{ + struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); + + return extract_address (so->lm_info->lm + lmo->l_addr_offset, lmo->l_addr_size); +} + +static CORE_ADDR +LM_NEXT (struct so_list *so) +{ + struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); + + return extract_address (so->lm_info->lm + lmo->l_next_offset, lmo->l_next_size); +} + +static CORE_ADDR +LM_NAME (struct so_list *so) +{ + struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); + + return extract_address (so->lm_info->lm + lmo->l_name_offset, lmo->l_name_size); +} + +#ifndef SVR4_SHARED_LIBS + +static int +IGNORE_FIRST_LINK_MAP_ENTRY (struct so_list *so) +{ + return 0; +} + +#else /* SVR4_SHARED_LIBS */ + +static int +IGNORE_FIRST_LINK_MAP_ENTRY (struct so_list *so) +{ + struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); + + return extract_address (so->lm_info->lm + lmo->l_prev_offset, + lmo->l_prev_size) == 0; +} + +#endif /* !SVR4_SHARED_LIBS */ + + +static CORE_ADDR debug_base; /* Base of dynamic linker structures */ +static CORE_ADDR breakpoint_addr; /* Address where end bkpt is set */ + +/* Local function prototypes */ + +static int match_main (char *); + +/* If non-zero, this is a prefix that will be added to the front of the name + shared libraries with an absolute filename for loading. */ +static char *solib_absolute_prefix = NULL; + +/* If non-empty, this is a search path for loading non-absolute shared library + symbol files. This takes precedence over the environment variables PATH + and LD_LIBRARY_PATH. */ +static char *solib_search_path = NULL; + + +#ifndef SVR4_SHARED_LIBS + +/* Allocate the runtime common object file. */ + +static void +allocate_rt_common_objfile (void) +{ + struct objfile *objfile; + struct objfile *last_one; + + objfile = (struct objfile *) xmalloc (sizeof (struct objfile)); + memset (objfile, 0, sizeof (struct objfile)); + objfile->md = NULL; + obstack_specify_allocation (&objfile->psymbol_cache.cache, 0, 0, + xmalloc, free); + obstack_specify_allocation (&objfile->psymbol_obstack, 0, 0, xmalloc, + free); + obstack_specify_allocation (&objfile->symbol_obstack, 0, 0, xmalloc, + free); + obstack_specify_allocation (&objfile->type_obstack, 0, 0, xmalloc, + free); + objfile->name = mstrsave (objfile->md, "rt_common"); + + /* Add this file onto the tail of the linked list of other such files. */ + + objfile->next = NULL; + if (object_files == NULL) + object_files = objfile; + else + { + for (last_one = object_files; + last_one->next; + last_one = last_one->next); + last_one->next = objfile; + } + + rt_common_objfile = objfile; +} + +/* Read all dynamically loaded common symbol definitions from the inferior + and put them into the minimal symbol table for the runtime common + objfile. */ + +static void +solib_add_common_symbols (CORE_ADDR rtc_symp) +{ + struct rtc_symb inferior_rtc_symb; + struct nlist inferior_rtc_nlist; + int len; + char *name; + + /* Remove any runtime common symbols from previous runs. */ + + if (rt_common_objfile != NULL && rt_common_objfile->minimal_symbol_count) + { + obstack_free (&rt_common_objfile->symbol_obstack, 0); + obstack_specify_allocation (&rt_common_objfile->symbol_obstack, 0, 0, + xmalloc, free); + rt_common_objfile->minimal_symbol_count = 0; + rt_common_objfile->msymbols = NULL; + } + + init_minimal_symbol_collection (); + make_cleanup_discard_minimal_symbols (); + + while (rtc_symp) + { + read_memory (rtc_symp, + (char *) &inferior_rtc_symb, + sizeof (inferior_rtc_symb)); + read_memory (SOLIB_EXTRACT_ADDRESS (inferior_rtc_symb.rtc_sp), + (char *) &inferior_rtc_nlist, + sizeof (inferior_rtc_nlist)); + if (inferior_rtc_nlist.n_type == N_COMM) + { + /* FIXME: The length of the symbol name is not available, but in the + current implementation the common symbol is allocated immediately + behind the name of the symbol. */ + len = inferior_rtc_nlist.n_value - inferior_rtc_nlist.n_un.n_strx; + + name = xmalloc (len); + read_memory (SOLIB_EXTRACT_ADDRESS (inferior_rtc_nlist.n_un.n_name), + name, len); + + /* Allocate the runtime common objfile if necessary. */ + if (rt_common_objfile == NULL) + allocate_rt_common_objfile (); + + prim_record_minimal_symbol (name, inferior_rtc_nlist.n_value, + mst_bss, rt_common_objfile); + free (name); + } + rtc_symp = SOLIB_EXTRACT_ADDRESS (inferior_rtc_symb.rtc_next); + } + + /* Install any minimal symbols that have been collected as the current + minimal symbols for the runtime common objfile. */ + + install_minimal_symbols (rt_common_objfile); +} + +#endif /* SVR4_SHARED_LIBS */ + + +#ifdef SVR4_SHARED_LIBS + +static CORE_ADDR bfd_lookup_symbol (bfd *, char *); + +/* + + LOCAL FUNCTION + + bfd_lookup_symbol -- lookup the value for a specific symbol + + SYNOPSIS + + CORE_ADDR bfd_lookup_symbol (bfd *abfd, char *symname) + + DESCRIPTION + + An expensive way to lookup the value of a single symbol for + bfd's that are only temporary anyway. This is used by the + shared library support to find the address of the debugger + interface structures in the shared library. + + Note that 0 is specifically allowed as an error return (no + such symbol). + */ + +static CORE_ADDR +bfd_lookup_symbol (bfd *abfd, char *symname) +{ + unsigned int storage_needed; + asymbol *sym; + asymbol **symbol_table; + unsigned int number_of_symbols; + unsigned int i; + struct cleanup *back_to; + CORE_ADDR symaddr = 0; + + storage_needed = bfd_get_symtab_upper_bound (abfd); + + if (storage_needed > 0) + { + symbol_table = (asymbol **) xmalloc (storage_needed); + back_to = make_cleanup (free, (PTR) symbol_table); + number_of_symbols = bfd_canonicalize_symtab (abfd, symbol_table); + + for (i = 0; i < number_of_symbols; i++) + { + sym = *symbol_table++; + if (STREQ (sym->name, symname)) + { + /* Bfd symbols are section relative. */ + symaddr = sym->value + sym->section->vma; + break; + } + } + do_cleanups (back_to); + } + + if (symaddr) + return symaddr; + + /* On FreeBSD, the dynamic linker is stripped by default. So we'll + have to check the dynamic string table too. */ + + storage_needed = bfd_get_dynamic_symtab_upper_bound (abfd); + + if (storage_needed > 0) + { + symbol_table = (asymbol **) xmalloc (storage_needed); + back_to = make_cleanup (free, (PTR) symbol_table); + number_of_symbols = bfd_canonicalize_dynamic_symtab (abfd, symbol_table); + + for (i = 0; i < number_of_symbols; i++) + { + sym = *symbol_table++; + if (STREQ (sym->name, symname)) + { + /* Bfd symbols are section relative. */ + symaddr = sym->value + sym->section->vma; + break; + } + } + do_cleanups (back_to); + } + + return symaddr; +} + +#ifdef HANDLE_SVR4_EXEC_EMULATORS + +/* + Solaris BCP (the part of Solaris which allows it to run SunOS4 + a.out files) throws in another wrinkle. Solaris does not fill + in the usual a.out link map structures when running BCP programs, + the only way to get at them is via groping around in the dynamic + linker. + The dynamic linker and it's structures are located in the shared + C library, which gets run as the executable's "interpreter" by + the kernel. + + Note that we can assume nothing about the process state at the time + we need to find these structures. We may be stopped on the first + instruction of the interpreter (C shared library), the first + instruction of the executable itself, or somewhere else entirely + (if we attached to the process for example). + */ + +static char *debug_base_symbols[] = +{ + "r_debug", /* Solaris 2.3 */ + "_r_debug", /* Solaris 2.1, 2.2 */ + NULL +}; + +static int look_for_base (int, CORE_ADDR); + +/* + + LOCAL FUNCTION + + look_for_base -- examine file for each mapped address segment + + SYNOPSYS + + static int look_for_base (int fd, CORE_ADDR baseaddr) + + DESCRIPTION + + This function is passed to proc_iterate_over_mappings, which + causes it to get called once for each mapped address space, with + an open file descriptor for the file mapped to that space, and the + base address of that mapped space. + + Our job is to find the debug base symbol in the file that this + fd is open on, if it exists, and if so, initialize the dynamic + linker structure base address debug_base. + + Note that this is a computationally expensive proposition, since + we basically have to open a bfd on every call, so we specifically + avoid opening the exec file. + */ + +static int +look_for_base (int fd, CORE_ADDR baseaddr) +{ + bfd *interp_bfd; + CORE_ADDR address = 0; + char **symbolp; + + /* If the fd is -1, then there is no file that corresponds to this + mapped memory segment, so skip it. Also, if the fd corresponds + to the exec file, skip it as well. */ + + if (fd == -1 + || (exec_bfd != NULL + && fdmatch (fileno ((FILE *) (exec_bfd->iostream)), fd))) + { + return (0); + } + + /* Try to open whatever random file this fd corresponds to. Note that + we have no way currently to find the filename. Don't gripe about + any problems we might have, just fail. */ + + if ((interp_bfd = bfd_fdopenr ("unnamed", gnutarget, fd)) == NULL) + { + return (0); + } + if (!bfd_check_format (interp_bfd, bfd_object)) + { + /* FIXME-leak: on failure, might not free all memory associated with + interp_bfd. */ + bfd_close (interp_bfd); + return (0); + } + + /* Now try to find our debug base symbol in this file, which we at + least know to be a valid ELF executable or shared library. */ + + for (symbolp = debug_base_symbols; *symbolp != NULL; symbolp++) + { + address = bfd_lookup_symbol (interp_bfd, *symbolp); + if (address != 0) + { + break; + } + } + if (address == 0) + { + /* FIXME-leak: on failure, might not free all memory associated with + interp_bfd. */ + bfd_close (interp_bfd); + return (0); + } + + /* Eureka! We found the symbol. But now we may need to relocate it + by the base address. If the symbol's value is less than the base + address of the shared library, then it hasn't yet been relocated + by the dynamic linker, and we have to do it ourself. FIXME: Note + that we make the assumption that the first segment that corresponds + to the shared library has the base address to which the library + was relocated. */ + + if (address < baseaddr) + { + address += baseaddr; + } + debug_base = address; + /* FIXME-leak: on failure, might not free all memory associated with + interp_bfd. */ + bfd_close (interp_bfd); + return (1); +} +#endif /* HANDLE_SVR4_EXEC_EMULATORS */ + +/* + + LOCAL FUNCTION + + elf_locate_base -- locate the base address of dynamic linker structs + for SVR4 elf targets. + + SYNOPSIS + + CORE_ADDR elf_locate_base (void) + + DESCRIPTION + + For SVR4 elf targets the address of the dynamic linker's runtime + structure is contained within the dynamic info section in the + executable file. The dynamic section is also mapped into the + inferior address space. Because the runtime loader fills in the + real address before starting the inferior, we have to read in the + dynamic info section from the inferior address space. + If there are any errors while trying to find the address, we + silently return 0, otherwise the found address is returned. + + */ + +static CORE_ADDR +elf_locate_base (void) +{ + sec_ptr dyninfo_sect; + int dyninfo_sect_size; + CORE_ADDR dyninfo_addr; + char *buf; + char *bufend; + int arch_size; + + /* Find the start address of the .dynamic section. */ + dyninfo_sect = bfd_get_section_by_name (exec_bfd, ".dynamic"); + if (dyninfo_sect == NULL) + return 0; + dyninfo_addr = bfd_section_vma (exec_bfd, dyninfo_sect); + + /* Read in .dynamic section, silently ignore errors. */ + dyninfo_sect_size = bfd_section_size (exec_bfd, dyninfo_sect); + buf = alloca (dyninfo_sect_size); + if (target_read_memory (dyninfo_addr, buf, dyninfo_sect_size)) + return 0; + + /* Find the DT_DEBUG entry in the the .dynamic section. + For mips elf we look for DT_MIPS_RLD_MAP, mips elf apparently has + no DT_DEBUG entries. */ + + arch_size = bfd_get_arch_size (exec_bfd); + if (arch_size == -1) /* failure */ + return 0; + + if (arch_size == 32) + { /* 32-bit elf */ + for (bufend = buf + dyninfo_sect_size; + buf < bufend; + buf += sizeof (Elf32_External_Dyn)) + { + Elf32_External_Dyn *x_dynp = (Elf32_External_Dyn *) buf; + long dyn_tag; + CORE_ADDR dyn_ptr; + + dyn_tag = bfd_h_get_32 (exec_bfd, (bfd_byte *) x_dynp->d_tag); + if (dyn_tag == DT_NULL) + break; + else if (dyn_tag == DT_DEBUG) + { + dyn_ptr = bfd_h_get_32 (exec_bfd, + (bfd_byte *) x_dynp->d_un.d_ptr); + return dyn_ptr; + } +#ifdef DT_MIPS_RLD_MAP + else if (dyn_tag == DT_MIPS_RLD_MAP) + { + char *pbuf; + + pbuf = alloca (TARGET_PTR_BIT / HOST_CHAR_BIT); + /* DT_MIPS_RLD_MAP contains a pointer to the address + of the dynamic link structure. */ + dyn_ptr = bfd_h_get_32 (exec_bfd, + (bfd_byte *) x_dynp->d_un.d_ptr); + if (target_read_memory (dyn_ptr, pbuf, sizeof (pbuf))) + return 0; + return extract_unsigned_integer (pbuf, sizeof (pbuf)); + } +#endif + } + } + else /* 64-bit elf */ + { + for (bufend = buf + dyninfo_sect_size; + buf < bufend; + buf += sizeof (Elf64_External_Dyn)) + { + Elf64_External_Dyn *x_dynp = (Elf64_External_Dyn *) buf; + long dyn_tag; + CORE_ADDR dyn_ptr; + + dyn_tag = bfd_h_get_64 (exec_bfd, (bfd_byte *) x_dynp->d_tag); + if (dyn_tag == DT_NULL) + break; + else if (dyn_tag == DT_DEBUG) + { + dyn_ptr = bfd_h_get_64 (exec_bfd, + (bfd_byte *) x_dynp->d_un.d_ptr); + return dyn_ptr; + } + } + } + + /* DT_DEBUG entry not found. */ + return 0; +} + +#endif /* SVR4_SHARED_LIBS */ + +/* + + LOCAL FUNCTION + + locate_base -- locate the base address of dynamic linker structs + + SYNOPSIS + + CORE_ADDR locate_base (void) + + DESCRIPTION + + For both the SunOS and SVR4 shared library implementations, if the + inferior executable has been linked dynamically, there is a single + address somewhere in the inferior's data space which is the key to + locating all of the dynamic linker's runtime structures. This + address is the value of the debug base symbol. The job of this + function is to find and return that address, or to return 0 if there + is no such address (the executable is statically linked for example). + + For SunOS, the job is almost trivial, since the dynamic linker and + all of it's structures are statically linked to the executable at + link time. Thus the symbol for the address we are looking for has + already been added to the minimal symbol table for the executable's + objfile at the time the symbol file's symbols were read, and all we + have to do is look it up there. Note that we explicitly do NOT want + to find the copies in the shared library. + + The SVR4 version is a bit more complicated because the address + is contained somewhere in the dynamic info section. We have to go + to a lot more work to discover the address of the debug base symbol. + Because of this complexity, we cache the value we find and return that + value on subsequent invocations. Note there is no copy in the + executable symbol tables. + + */ + +static CORE_ADDR +locate_base (void) +{ + +#ifndef SVR4_SHARED_LIBS + + struct minimal_symbol *msymbol; + CORE_ADDR address = 0; + char **symbolp; + + /* For SunOS, we want to limit the search for the debug base symbol to the + executable being debugged, since there is a duplicate named symbol in the + shared library. We don't want the shared library versions. */ + + for (symbolp = debug_base_symbols; *symbolp != NULL; symbolp++) + { + msymbol = lookup_minimal_symbol (*symbolp, NULL, symfile_objfile); + if ((msymbol != NULL) && (SYMBOL_VALUE_ADDRESS (msymbol) != 0)) + { + address = SYMBOL_VALUE_ADDRESS (msymbol); + return (address); + } + } + return (0); + +#else /* SVR4_SHARED_LIBS */ + + /* Check to see if we have a currently valid address, and if so, avoid + doing all this work again and just return the cached address. If + we have no cached address, try to locate it in the dynamic info + section for ELF executables. */ + + if (debug_base == 0) + { + if (exec_bfd != NULL + && bfd_get_flavour (exec_bfd) == bfd_target_elf_flavour) + debug_base = elf_locate_base (); +#ifdef HANDLE_SVR4_EXEC_EMULATORS + /* Try it the hard way for emulated executables. */ + else if (inferior_pid != 0 && target_has_execution) + proc_iterate_over_mappings (look_for_base); +#endif + } + return (debug_base); + +#endif /* !SVR4_SHARED_LIBS */ + +} + +/* + + LOCAL FUNCTION + + first_link_map_member -- locate first member in dynamic linker's map + + SYNOPSIS + + static CORE_ADDR first_link_map_member (void) + + DESCRIPTION + + Find the first element in the inferior's dynamic link map, and + return its address in the inferior. This function doesn't copy the + link map entry itself into our address space; current_sos actually + does the reading. */ + +static CORE_ADDR +first_link_map_member (void) +{ + CORE_ADDR lm = 0; + +#ifndef SVR4_SHARED_LIBS + + read_memory (debug_base, (char *) &dynamic_copy, sizeof (dynamic_copy)); + if (dynamic_copy.ld_version >= 2) + { + /* It is a version that we can deal with, so read in the secondary + structure and find the address of the link map list from it. */ + read_memory (SOLIB_EXTRACT_ADDRESS (dynamic_copy.ld_un.ld_2), + (char *) &ld_2_copy, sizeof (struct link_dynamic_2)); + lm = SOLIB_EXTRACT_ADDRESS (ld_2_copy.ld_loaded); + } + +#else /* SVR4_SHARED_LIBS */ + struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); + char *r_map_buf = xmalloc (lmo->r_map_size); + struct cleanup *cleanups = make_cleanup (free, r_map_buf); + + read_memory (debug_base + lmo->r_map_offset, r_map_buf, lmo->r_map_size); + + lm = extract_address (r_map_buf, lmo->r_map_size); + + /* FIXME: Perhaps we should validate the info somehow, perhaps by + checking r_version for a known version number, or r_state for + RT_CONSISTENT. */ + + do_cleanups (cleanups); + +#endif /* !SVR4_SHARED_LIBS */ + + return (lm); +} + +#ifdef SVR4_SHARED_LIBS +/* + + LOCAL FUNCTION + + open_symbol_file_object + + SYNOPSIS + + void open_symbol_file_object (void *from_tty) + + DESCRIPTION + + If no open symbol file, attempt to locate and open the main symbol + file. On SVR4 systems, this is the first link map entry. If its + name is here, we can open it. Useful when attaching to a process + without first loading its symbol file. + + If FROM_TTYP dereferences to a non-zero integer, allow messages to + be printed. This parameter is a pointer rather than an int because + open_symbol_file_object() is called via catch_errors() and + catch_errors() requires a pointer argument. */ + +static int +open_symbol_file_object (void *from_ttyp) +{ + CORE_ADDR lm, l_name; + char *filename; + int errcode; + int from_tty = *(int *)from_ttyp; + struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); + char *l_name_buf = xmalloc (lmo->l_name_size); + struct cleanup *cleanups = make_cleanup (free, l_name_buf); + + if (symfile_objfile) + if (!query ("Attempt to reload symbols from process? ")) + return 0; + + if ((debug_base = locate_base ()) == 0) + return 0; /* failed somehow... */ + + /* First link map member should be the executable. */ + if ((lm = first_link_map_member ()) == 0) + return 0; /* failed somehow... */ + + /* Read address of name from target memory to GDB. */ + read_memory (lm + lmo->l_name_offset, l_name_buf, lmo->l_name_size); + + /* Convert the address to host format. */ + l_name = extract_address (l_name_buf, lmo->l_name_size); + + /* Free l_name_buf. */ + do_cleanups (cleanups); + + if (l_name == 0) + return 0; /* No filename. */ + + /* Now fetch the filename from target memory. */ + target_read_string (l_name, &filename, SO_NAME_MAX_PATH_SIZE - 1, &errcode); + + if (errcode) + { + warning ("failed to read exec filename from attached file: %s", + safe_strerror (errcode)); + return 0; + } + + make_cleanup (free, filename); + /* Have a pathname: read the symbol file. */ + symbol_file_command (filename, from_tty); + + return 1; +} +#else + +static int +open_symbol_file_object (int *from_ttyp) +{ + return 1; +} + +#endif /* SVR4_SHARED_LIBS */ + + +/* LOCAL FUNCTION + + current_sos -- build a list of currently loaded shared objects + + SYNOPSIS + + struct so_list *current_sos () + + DESCRIPTION + + Build a list of `struct so_list' objects describing the shared + objects currently loaded in the inferior. This list does not + include an entry for the main executable file. + + Note that we only gather information directly available from the + inferior --- we don't examine any of the shared library files + themselves. The declaration of `struct so_list' says which fields + we provide values for. */ + +static struct so_list * +svr4_current_sos (void) +{ + CORE_ADDR lm; + struct so_list *head = 0; + struct so_list **link_ptr = &head; + + /* Make sure we've looked up the inferior's dynamic linker's base + structure. */ + if (! debug_base) + { + debug_base = locate_base (); + + /* If we can't find the dynamic linker's base structure, this + must not be a dynamically linked executable. Hmm. */ + if (! debug_base) + return 0; + } + + /* Walk the inferior's link map list, and build our list of + `struct so_list' nodes. */ + lm = first_link_map_member (); + while (lm) + { + struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS (); + struct so_list *new + = (struct so_list *) xmalloc (sizeof (struct so_list)); + struct cleanup *old_chain = make_cleanup (free, new); + + memset (new, 0, sizeof (*new)); + + new->lm_info = xmalloc (sizeof (struct lm_info)); + make_cleanup (free, new->lm_info); + + new->lm_info->lm = xmalloc (lmo->link_map_size); + make_cleanup (free, new->lm_info->lm); + memset (new->lm_info->lm, 0, lmo->link_map_size); + + read_memory (lm, new->lm_info->lm, lmo->link_map_size); + + lm = LM_NEXT (new); + + /* For SVR4 versions, the first entry in the link map is for the + inferior executable, so we must ignore it. For some versions of + SVR4, it has no name. For others (Solaris 2.3 for example), it + does have a name, so we can no longer use a missing name to + decide when to ignore it. */ + if (IGNORE_FIRST_LINK_MAP_ENTRY (new)) + free_so (new); + else + { + int errcode; + char *buffer; + + /* Extract this shared object's name. */ + target_read_string (LM_NAME (new), &buffer, + SO_NAME_MAX_PATH_SIZE - 1, &errcode); + if (errcode != 0) + { + warning ("current_sos: Can't read pathname for load map: %s\n", + safe_strerror (errcode)); + } + else + { + strncpy (new->so_name, buffer, SO_NAME_MAX_PATH_SIZE - 1); + new->so_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0'; + free (buffer); + strcpy (new->so_original_name, new->so_name); + } + + /* If this entry has no name, or its name matches the name + for the main executable, don't include it in the list. */ + if (! new->so_name[0] + || match_main (new->so_name)) + free_so (new); + else + { + new->next = 0; + *link_ptr = new; + link_ptr = &new->next; + } + } + + discard_cleanups (old_chain); + } + + return head; +} + + +/* On some systems, the only way to recognize the link map entry for + the main executable file is by looking at its name. Return + non-zero iff SONAME matches one of the known main executable names. */ + +static int +match_main (char *soname) +{ + char **mainp; + + for (mainp = main_name_list; *mainp != NULL; mainp++) + { + if (strcmp (soname, *mainp) == 0) + return (1); + } + + return (0); +} + + +#ifdef SVR4_SHARED_LIBS + +/* Return 1 if PC lies in the dynamic symbol resolution code of the + SVR4 run time loader. */ + +static CORE_ADDR interp_text_sect_low; +static CORE_ADDR interp_text_sect_high; +static CORE_ADDR interp_plt_sect_low; +static CORE_ADDR interp_plt_sect_high; + +int +in_svr4_dynsym_resolve_code (CORE_ADDR pc) +{ + return ((pc >= interp_text_sect_low && pc < interp_text_sect_high) + || (pc >= interp_plt_sect_low && pc < interp_plt_sect_high) + || in_plt_section (pc, NULL)); +} +#endif + +/* + + LOCAL FUNCTION + + disable_break -- remove the "mapping changed" breakpoint + + SYNOPSIS + + static int disable_break () + + DESCRIPTION + + Removes the breakpoint that gets hit when the dynamic linker + completes a mapping change. + + */ + +#ifndef SVR4_SHARED_LIBS + +static int +disable_break (void) +{ + int status = 1; + + int in_debugger = 0; + + /* Read the debugger structure from the inferior to retrieve the + address of the breakpoint and the original contents of the + breakpoint address. Remove the breakpoint by writing the original + contents back. */ + + read_memory (debug_addr, (char *) &debug_copy, sizeof (debug_copy)); + + /* Set `in_debugger' to zero now. */ + + write_memory (flag_addr, (char *) &in_debugger, sizeof (in_debugger)); + + breakpoint_addr = SOLIB_EXTRACT_ADDRESS (debug_copy.ldd_bp_addr); + write_memory (breakpoint_addr, (char *) &debug_copy.ldd_bp_inst, + sizeof (debug_copy.ldd_bp_inst)); + + /* For the SVR4 version, we always know the breakpoint address. For the + SunOS version we don't know it until the above code is executed. + Grumble if we are stopped anywhere besides the breakpoint address. */ + + if (stop_pc != breakpoint_addr) + { + warning ("stopped at unknown breakpoint while handling shared libraries"); + } + + return (status); +} + +#endif /* #ifdef SVR4_SHARED_LIBS */ + +/* + + LOCAL FUNCTION + + enable_break -- arrange for dynamic linker to hit breakpoint + + SYNOPSIS + + int enable_break (void) + + DESCRIPTION + + Both the SunOS and the SVR4 dynamic linkers have, as part of their + debugger interface, support for arranging for the inferior to hit + a breakpoint after mapping in the shared libraries. This function + enables that breakpoint. + + For SunOS, there is a special flag location (in_debugger) which we + set to 1. When the dynamic linker sees this flag set, it will set + a breakpoint at a location known only to itself, after saving the + original contents of that place and the breakpoint address itself, + in it's own internal structures. When we resume the inferior, it + will eventually take a SIGTRAP when it runs into the breakpoint. + We handle this (in a different place) by restoring the contents of + the breakpointed location (which is only known after it stops), + chasing around to locate the shared libraries that have been + loaded, then resuming. + + For SVR4, the debugger interface structure contains a member (r_brk) + which is statically initialized at the time the shared library is + built, to the offset of a function (_r_debug_state) which is guaran- + teed to be called once before mapping in a library, and again when + the mapping is complete. At the time we are examining this member, + it contains only the unrelocated offset of the function, so we have + to do our own relocation. Later, when the dynamic linker actually + runs, it relocates r_brk to be the actual address of _r_debug_state(). + + The debugger interface structure also contains an enumeration which + is set to either RT_ADD or RT_DELETE prior to changing the mapping, + depending upon whether or not the library is being mapped or unmapped, + and then set to RT_CONSISTENT after the library is mapped/unmapped. + */ + +static int +enable_break (void) +{ + int success = 0; + +#ifndef SVR4_SHARED_LIBS + + int j; + int in_debugger; + + /* Get link_dynamic structure */ + + j = target_read_memory (debug_base, (char *) &dynamic_copy, + sizeof (dynamic_copy)); + if (j) + { + /* unreadable */ + return (0); + } + + /* Calc address of debugger interface structure */ + + debug_addr = SOLIB_EXTRACT_ADDRESS (dynamic_copy.ldd); + + /* Calc address of `in_debugger' member of debugger interface structure */ + + flag_addr = debug_addr + (CORE_ADDR) ((char *) &debug_copy.ldd_in_debugger - + (char *) &debug_copy); + + /* Write a value of 1 to this member. */ + + in_debugger = 1; + write_memory (flag_addr, (char *) &in_debugger, sizeof (in_debugger)); + success = 1; + +#else /* SVR4_SHARED_LIBS */ + +#ifdef BKPT_AT_SYMBOL + + struct minimal_symbol *msymbol; + char **bkpt_namep; + asection *interp_sect; + + /* First, remove all the solib event breakpoints. Their addresses + may have changed since the last time we ran the program. */ + remove_solib_event_breakpoints (); + +#ifdef SVR4_SHARED_LIBS + interp_text_sect_low = interp_text_sect_high = 0; + interp_plt_sect_low = interp_plt_sect_high = 0; + + /* Find the .interp section; if not found, warn the user and drop + into the old breakpoint at symbol code. */ + interp_sect = bfd_get_section_by_name (exec_bfd, ".interp"); + if (interp_sect) + { + unsigned int interp_sect_size; + char *buf; + CORE_ADDR load_addr; + bfd *tmp_bfd; + CORE_ADDR sym_addr = 0; + + /* Read the contents of the .interp section into a local buffer; + the contents specify the dynamic linker this program uses. */ + interp_sect_size = bfd_section_size (exec_bfd, interp_sect); + buf = alloca (interp_sect_size); + bfd_get_section_contents (exec_bfd, interp_sect, + buf, 0, interp_sect_size); + + /* Now we need to figure out where the dynamic linker was + loaded so that we can load its symbols and place a breakpoint + in the dynamic linker itself. + + This address is stored on the stack. However, I've been unable + to find any magic formula to find it for Solaris (appears to + be trivial on GNU/Linux). Therefore, we have to try an alternate + mechanism to find the dynamic linker's base address. */ + tmp_bfd = bfd_openr (buf, gnutarget); + if (tmp_bfd == NULL) + goto bkpt_at_symbol; + + /* Make sure the dynamic linker's really a useful object. */ + if (!bfd_check_format (tmp_bfd, bfd_object)) + { + warning ("Unable to grok dynamic linker %s as an object file", buf); + bfd_close (tmp_bfd); + goto bkpt_at_symbol; + } + + /* We find the dynamic linker's base address by examining the + current pc (which point at the entry point for the dynamic + linker) and subtracting the offset of the entry point. */ + load_addr = read_pc () - tmp_bfd->start_address; + + /* Record the relocated start and end address of the dynamic linker + text and plt section for in_svr4_dynsym_resolve_code. */ + interp_sect = bfd_get_section_by_name (tmp_bfd, ".text"); + if (interp_sect) + { + interp_text_sect_low = + bfd_section_vma (tmp_bfd, interp_sect) + load_addr; + interp_text_sect_high = + interp_text_sect_low + bfd_section_size (tmp_bfd, interp_sect); + } + interp_sect = bfd_get_section_by_name (tmp_bfd, ".plt"); + if (interp_sect) + { + interp_plt_sect_low = + bfd_section_vma (tmp_bfd, interp_sect) + load_addr; + interp_plt_sect_high = + interp_plt_sect_low + bfd_section_size (tmp_bfd, interp_sect); + } + + /* Now try to set a breakpoint in the dynamic linker. */ + for (bkpt_namep = solib_break_names; *bkpt_namep != NULL; bkpt_namep++) + { + sym_addr = bfd_lookup_symbol (tmp_bfd, *bkpt_namep); + if (sym_addr != 0) + break; + } + + /* We're done with the temporary bfd. */ + bfd_close (tmp_bfd); + + if (sym_addr != 0) + { + create_solib_event_breakpoint (load_addr + sym_addr); + return 1; + } + + /* For whatever reason we couldn't set a breakpoint in the dynamic + linker. Warn and drop into the old code. */ + bkpt_at_symbol: + warning ("Unable to find dynamic linker breakpoint function.\nGDB will be unable to debug shared library initializers\nand track explicitly loaded dynamic code."); + } +#endif + + /* Scan through the list of symbols, trying to look up the symbol and + set a breakpoint there. Terminate loop when we/if we succeed. */ + + breakpoint_addr = 0; + for (bkpt_namep = bkpt_names; *bkpt_namep != NULL; bkpt_namep++) + { + msymbol = lookup_minimal_symbol (*bkpt_namep, NULL, symfile_objfile); + if ((msymbol != NULL) && (SYMBOL_VALUE_ADDRESS (msymbol) != 0)) + { + create_solib_event_breakpoint (SYMBOL_VALUE_ADDRESS (msymbol)); + return 1; + } + } + + /* Nothing good happened. */ + success = 0; + +#endif /* BKPT_AT_SYMBOL */ + +#endif /* !SVR4_SHARED_LIBS */ + + return (success); +} + +/* + + LOCAL FUNCTION + + special_symbol_handling -- additional shared library symbol handling + + SYNOPSIS + + void special_symbol_handling () + + DESCRIPTION + + Once the symbols from a shared object have been loaded in the usual + way, we are called to do any system specific symbol handling that + is needed. + + For SunOS4, this consists of grunging around in the dynamic + linkers structures to find symbol definitions for "common" symbols + and adding them to the minimal symbol table for the runtime common + objfile. + + */ + +static void +svr4_special_symbol_handling (void) +{ +#ifndef SVR4_SHARED_LIBS + int j; + + if (debug_addr == 0) + { + /* Get link_dynamic structure */ + + j = target_read_memory (debug_base, (char *) &dynamic_copy, + sizeof (dynamic_copy)); + if (j) + { + /* unreadable */ + return; + } + + /* Calc address of debugger interface structure */ + /* FIXME, this needs work for cross-debugging of core files + (byteorder, size, alignment, etc). */ + + debug_addr = SOLIB_EXTRACT_ADDRESS (dynamic_copy.ldd); + } + + /* Read the debugger structure from the inferior, just to make sure + we have a current copy. */ + + j = target_read_memory (debug_addr, (char *) &debug_copy, + sizeof (debug_copy)); + if (j) + return; /* unreadable */ + + /* Get common symbol definitions for the loaded object. */ + + if (debug_copy.ldd_cp) + { + solib_add_common_symbols (SOLIB_EXTRACT_ADDRESS (debug_copy.ldd_cp)); + } + +#endif /* !SVR4_SHARED_LIBS */ +} + +/* + + GLOBAL FUNCTION + + svr4_solib_create_inferior_hook -- shared library startup support + + SYNOPSIS + + void svr4_solib_create_inferior_hook() + + DESCRIPTION + + When gdb starts up the inferior, it nurses it along (through the + shell) until it is ready to execute it's first instruction. At this + point, this function gets called via expansion of the macro + SOLIB_CREATE_INFERIOR_HOOK. + + For SunOS executables, this first instruction is typically the + one at "_start", or a similar text label, regardless of whether + the executable is statically or dynamically linked. The runtime + startup code takes care of dynamically linking in any shared + libraries, once gdb allows the inferior to continue. + + For SVR4 executables, this first instruction is either the first + instruction in the dynamic linker (for dynamically linked + executables) or the instruction at "start" for statically linked + executables. For dynamically linked executables, the system + first exec's /lib/libc.so.N, which contains the dynamic linker, + and starts it running. The dynamic linker maps in any needed + shared libraries, maps in the actual user executable, and then + jumps to "start" in the user executable. + + For both SunOS shared libraries, and SVR4 shared libraries, we + can arrange to cooperate with the dynamic linker to discover the + names of shared libraries that are dynamically linked, and the + base addresses to which they are linked. + + This function is responsible for discovering those names and + addresses, and saving sufficient information about them to allow + their symbols to be read at a later time. + + FIXME + + Between enable_break() and disable_break(), this code does not + properly handle hitting breakpoints which the user might have + set in the startup code or in the dynamic linker itself. Proper + handling will probably have to wait until the implementation is + changed to use the "breakpoint handler function" method. + + Also, what if child has exit()ed? Must exit loop somehow. + */ + +void +svr4_solib_create_inferior_hook (void) +{ + /* If we are using the BKPT_AT_SYMBOL code, then we don't need the base + yet. In fact, in the case of a SunOS4 executable being run on + Solaris, we can't get it yet. current_sos will get it when it needs + it. */ +#if !(defined (SVR4_SHARED_LIBS) && defined (BKPT_AT_SYMBOL)) + if ((debug_base = locate_base ()) == 0) + { + /* Can't find the symbol or the executable is statically linked. */ + return; + } +#endif + + if (!enable_break ()) + { + warning ("shared library handler failed to enable breakpoint"); + return; + } + +#if !defined(SVR4_SHARED_LIBS) || defined(_SCO_DS) + /* SCO and SunOS need the loop below, other systems should be using the + special shared library breakpoints and the shared library breakpoint + service routine. + + Now run the target. It will eventually hit the breakpoint, at + which point all of the libraries will have been mapped in and we + can go groveling around in the dynamic linker structures to find + out what we need to know about them. */ + + clear_proceed_status (); + stop_soon_quietly = 1; + stop_signal = TARGET_SIGNAL_0; + do + { + target_resume (-1, 0, stop_signal); + wait_for_inferior (); + } + while (stop_signal != TARGET_SIGNAL_TRAP); + stop_soon_quietly = 0; + +#if !defined(_SCO_DS) + /* We are now either at the "mapping complete" breakpoint (or somewhere + else, a condition we aren't prepared to deal with anyway), so adjust + the PC as necessary after a breakpoint, disable the breakpoint, and + add any shared libraries that were mapped in. */ + + if (DECR_PC_AFTER_BREAK) + { + stop_pc -= DECR_PC_AFTER_BREAK; + write_register (PC_REGNUM, stop_pc); + } + + if (!disable_break ()) + { + warning ("shared library handler failed to disable breakpoint"); + } + + if (auto_solib_add) + solib_add ((char *) 0, 0, (struct target_ops *) 0); +#endif /* ! _SCO_DS */ +#endif +} + +static void +svr4_clear_solib (void) +{ + debug_base = 0; +} + +static void +svr4_free_so (struct so_list *so) +{ + free (so->lm_info->lm); + free (so->lm_info); +} + +static struct target_so_ops svr4_so_ops; + +void +_initialize_svr4_solib (void) +{ + svr4_so_ops.lm_addr = LM_ADDR; + svr4_so_ops.free_so = svr4_free_so; + svr4_so_ops.clear_solib = svr4_clear_solib; + svr4_so_ops.solib_create_inferior_hook = svr4_solib_create_inferior_hook; + svr4_so_ops.special_symbol_handling = svr4_special_symbol_handling; + svr4_so_ops.current_sos = svr4_current_sos; + svr4_so_ops.open_symbol_file_object = open_symbol_file_object; + + /* FIXME: Don't do this here. *_gdbarch_init() should set so_ops. */ + current_target_so_ops = &svr4_so_ops; +} + |