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Re: pie support
Daniel Jacobowitz <drow@false.org> writes:
> I imagine someone (with an FSF copyright assignment) would have to
> take Elena's patches, merge them to the trunk version of GDB, test
> them, and submit them to be included. The last time I checked PIE
> support had been disabled in Ubuntu because the patches no longer
> worked.
The attached patch works for me, but is not very well tested and might
need some cleanup.
Andreas.
--
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
PGP key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5
"And now for something completely different."
--- gdb/Makefile.in
+++ gdb/Makefile.in
@@ -2559,7 +2559,7 @@ objfiles.o: objfiles.c $(defs_h) $(bfd_h
$(objfiles_h) $(gdb_stabs_h) $(target_h) $(bcache_h) $(mdebugread_h) \
$(gdb_assert_h) $(gdb_stat_h) $(gdb_obstack_h) $(gdb_string_h) \
$(hashtab_h) $(breakpoint_h) $(block_h) $(dictionary_h) $(source_h) \
- $(parser_defs_h) $(expression_h) $(addrmap_h)
+ $(parser_defs_h) $(expression_h) $(addrmap_h) $(auxv_h) $(elf_common_h)
observer.o: observer.c $(defs_h) $(observer_h) $(command_h) $(gdbcmd_h) \
$(observer_inc)
obsd-tdep.o: obsd-tdep.c $(defs_h) $(frame_h) $(symtab_h) $(obsd_tdep_h)
@@ -2758,7 +2758,7 @@ solib-sunos.o: solib-sunos.c $(defs_h) $
$(bcache_h) $(regcache_h)
solib-svr4.o: solib-svr4.c $(defs_h) $(elf_external_h) $(elf_common_h) \
$(elf_mips_h) $(symtab_h) $(bfd_h) $(symfile_h) $(objfiles_h) \
- $(gdbcore_h) $(target_h) $(inferior_h) $(gdb_assert_h) \
+ $(gdbcore_h) $(target_h) $(inferior_h) $(command_h) $(gdb_assert_h) \
$(solist_h) $(solib_h) $(solib_svr4_h) $(bfd_target_h) $(elf_bfd_h) \
$(exec_h) $(auxv_h)
solib-target.o: solib-target.c $(defs_h) $(objfiles_h) $(solist_h) \
--- gdb/breakpoint.c
+++ gdb/breakpoint.c
@@ -3892,6 +3892,7 @@ describe_other_breakpoints (CORE_ADDR pc
printf_filtered (" (thread %d)", b->thread);
printf_filtered ("%s%s ",
((b->enable_state == bp_disabled ||
+ b->enable_state == bp_startup_disabled ||
b->enable_state == bp_call_disabled)
? " (disabled)"
: b->enable_state == bp_permanent
@@ -4544,6 +4545,60 @@ disable_breakpoints_in_unloaded_shlib (s
}
}
+void
+disable_breakpoints_at_startup (int silent)
+{
+ struct breakpoint *b;
+ int disabled_startup_breaks = 0;
+
+ if (bfd_get_start_address (exec_bfd) != entry_point_address ())
+ {
+ ALL_BREAKPOINTS (b)
+ {
+ if ((b->type == bp_breakpoint
+ || b->type == bp_hardware_breakpoint)
+ && b->enable_state == bp_enabled
+ && !b->loc->duplicate)
+ {
+ b->enable_state = bp_startup_disabled;
+ if (!silent)
+ {
+ if (!disabled_startup_breaks)
+ {
+ target_terminal_ours_for_output ();
+ warning ("Temporarily disabling breakpoints:");
+ }
+ disabled_startup_breaks = 1;
+ warning ("breakpoint #%d addr 0x%s",
+ b->number, paddr_nz (b->loc->address));
+ }
+ }
+ }
+ }
+}
+
+/* Try to reenable any breakpoints after startup. */
+void
+re_enable_breakpoints_at_startup (void)
+{
+ struct breakpoint *b;
+
+ if (bfd_get_start_address (exec_bfd) != entry_point_address ())
+ {
+ ALL_BREAKPOINTS (b)
+ if (b->enable_state == bp_startup_disabled)
+ {
+ gdb_byte buf[1];
+
+ /* Do not reenable the breakpoint if the shared library
+ is still not mapped in. */
+ if (target_read_memory (b->loc->address, buf, 1) == 0)
+ b->enable_state = bp_enabled;
+ }
+ }
+}
+
+
static void
create_fork_vfork_event_catchpoint (int tempflag, char *cond_string,
enum bptype bp_kind)
@@ -6908,6 +6963,7 @@ delete_breakpoint (struct breakpoint *bp
&& loc2->section == loc->section
&& !loc->duplicate
&& loc2->owner->enable_state != bp_disabled
+ && loc2->owner->enable_state != bp_startup_disabled
&& loc2->enabled
&& !loc2->shlib_disabled
&& loc2->owner->enable_state != bp_call_disabled)
@@ -7230,6 +7286,7 @@ breakpoint_re_set_one (void *bint)
if (not_found
&& (b->condition_not_parsed
|| (b->loc && b->loc->shlib_disabled)
+ || b->enable_state == bp_startup_disabled
|| b->enable_state == bp_disabled))
not_found_and_ok = 1;
--- gdb/breakpoint.h
+++ gdb/breakpoint.h
@@ -144,6 +144,7 @@ enum enable_state
automatically enabled and reset when the call
"lands" (either completes, or stops at another
eventpoint). */
+ bp_startup_disabled,
bp_permanent /* There is a breakpoint instruction hard-wired into
the target's code. Don't try to write another
breakpoint instruction on top of it, or restore
@@ -818,6 +819,10 @@ extern void remove_thread_event_breakpoi
extern void disable_breakpoints_in_shlibs (void);
+extern void disable_breakpoints_at_startup (int silent);
+
+extern void re_enable_breakpoints_at_startup (void);
+
/* This function returns TRUE if ep is a catchpoint. */
extern int ep_is_catchpoint (struct breakpoint *);
--- gdb/dwarf2read.c
+++ gdb/dwarf2read.c
@@ -1222,7 +1222,7 @@ dwarf2_build_psymtabs (struct objfile *o
else
dwarf2_per_objfile->loc_buffer = NULL;
- if (mainline
+ if (mainline == 1
|| (objfile->global_psymbols.size == 0
&& objfile->static_psymbols.size == 0))
{
--- gdb/elfread.c
+++ gdb/elfread.c
@@ -644,7 +644,7 @@ elf_symfile_read (struct objfile *objfil
/* If we are reinitializing, or if we have never loaded syms yet,
set table to empty. MAINLINE is cleared so that *_read_psymtab
functions do not all also re-initialize the psymbol table. */
- if (mainline)
+ if (mainline == 1)
{
init_psymbol_list (objfile, 0);
mainline = 0;
--- gdb/infrun.c
+++ gdb/infrun.c
@@ -2267,6 +2267,11 @@ process_event_stop_test:
#endif
target_terminal_inferior ();
+ /* For PIE executables, we dont really know where the
+ breakpoints are going to be until we start up the
+ inferior. */
+ re_enable_breakpoints_at_startup ();
+
/* If requested, stop when the dynamic linker notifies
gdb of events. This allows the user to get control
and place breakpoints in initializer routines for
--- gdb/objfiles.c
+++ gdb/objfiles.c
@@ -48,6 +48,8 @@
#include "dictionary.h"
#include "source.h"
#include "addrmap.h"
+#include "auxv.h"
+#include "elf/common.h"
/* Prototypes for local functions */
@@ -260,7 +262,16 @@ init_entry_point_info (struct objfile *o
CORE_ADDR
entry_point_address (void)
{
- return symfile_objfile ? symfile_objfile->ei.entry_point : 0;
+ int ret;
+ CORE_ADDR entry_addr;
+
+ /* Find the address of the entry point of the program from the
+ auxv vector. */
+ ret = target_auxv_search (¤t_target, AT_ENTRY, &entry_addr);
+ if (ret > 0)
+ return entry_addr;
+ else
+ return symfile_objfile ? symfile_objfile->ei.entry_point : 0;
}
/* Create the terminating entry of OBJFILE's minimal symbol table.
--- gdb/solib-svr4.c
+++ gdb/solib-svr4.c
@@ -31,6 +31,7 @@
#include "gdbcore.h"
#include "target.h"
#include "inferior.h"
+#include "command.h"
#include "gdb_assert.h"
@@ -246,8 +247,6 @@ static char *debug_loader_name;
/* Local function prototypes */
-static int match_main (char *);
-
static CORE_ADDR bfd_lookup_symbol (bfd *, char *);
/*
@@ -353,6 +352,8 @@ scan_dyntag (int dyntag, bfd *abfd, CORE
Elf32_External_Dyn *x_dynp_32;
Elf64_External_Dyn *x_dynp_64;
struct bfd_section *sect;
+ CORE_ADDR relocated_dyn_addr, entry_addr;
+ int ret;
if (abfd == NULL)
return 0;
@@ -360,11 +361,20 @@ scan_dyntag (int dyntag, bfd *abfd, CORE
if (arch_size == -1)
return 0;
+ /* Find the address of the entry point of the program from the
+ auxv vector. */
+ ret = target_auxv_search (¤t_target, AT_ENTRY, &entry_addr);
+ if (ret <= 0)
+ /* No auxv info, maybe an older kernel. Fake our way through. */
+ entry_addr = bfd_get_start_address (exec_bfd);
+
/* Find the start address of the .dynamic section. */
sect = bfd_get_section_by_name (abfd, ".dynamic");
if (sect == NULL)
return 0;
dyn_addr = bfd_section_vma (abfd, sect);
+ relocated_dyn_addr
+ = dyn_addr + entry_addr - bfd_get_start_address (exec_bfd);
/* Read in .dynamic from the BFD. We will get the actual value
from memory later. */
@@ -404,7 +414,7 @@ scan_dyntag (int dyntag, bfd *abfd, CORE
gdb_byte ptr_buf[8];
CORE_ADDR ptr_addr;
- ptr_addr = dyn_addr + (buf - bufstart) + arch_size / 8;
+ ptr_addr = relocated_dyn_addr + (buf - bufstart) + arch_size / 8;
if (target_read_memory (ptr_addr, ptr_buf, arch_size / 8) == 0)
dyn_ptr = extract_typed_address (ptr_buf,
builtin_type_void_data_ptr);
@@ -740,9 +750,55 @@ svr4_current_sos (void)
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) && ldsomap == 0)
- free_so (new);
+ {
+ /* It is the first link map entry, i.e. it is the main
+ executable. */
+ if (bfd_get_start_address (exec_bfd) == entry_point_address ())
+ {
+ /* Non-pie case, main executable has not been relocated. */
+ free_so (new);
+ }
+ else
+ {
+ /* Pie case, main executable has been relocated. */
+ struct so_list *gdb_solib;
+
+ strncpy (new->so_name, exec_bfd->filename,
+ SO_NAME_MAX_PATH_SIZE - 1);
+ new->so_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0';
+ strcpy (new->so_original_name, new->so_name);
+ new->main_relocated = 0;
+
+ for (gdb_solib = master_so_list ();
+ gdb_solib != NULL;
+ gdb_solib = gdb_solib->next)
+ if (strcmp (gdb_solib->so_name, new->so_name) == 0
+ && gdb_solib->main_relocated)
+ break;
+
+ if (gdb_solib == NULL)
+ {
+ add_to_target_sections (0 /*from_tty*/, ¤t_target, new);
+ new->main_p = 1;
+ }
+
+ /* We need this in the list of shared libs we return because
+ solib_add_stub will loop through it and add the symbol
+ file. */
+ new->next = 0;
+ *link_ptr = new;
+ link_ptr = &new->next;
+ }
+ }
else
{
+ /* This is not the first link map entry, i.e. is not the main
+ executable. Note however that it could be the DSO supplied on
+ certain systems (i.e. Linux 2.6) containing information about
+ the vsyscall page. We must ignore such entry. This entry is
+ nameless (just like the one for the main executable,
+ sigh). */
+
int errcode;
char *buffer;
@@ -760,10 +816,8 @@ svr4_current_sos (void)
}
xfree (buffer);
- /* 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))
+ /* If this entry has no name, don't include it in the list. */
+ if (! new->so_name[0])
free_so (new);
else
{
@@ -862,24 +916,6 @@ svr4_fetch_objfile_link_map (struct objf
return 0;
}
-/* 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);
-}
-
/* Return 1 if PC lies in the dynamic symbol resolution code of the
SVR4 run time loader. */
static CORE_ADDR interp_text_sect_low;
@@ -1369,6 +1405,8 @@ svr4_solib_create_inferior_hook (void)
while (stop_signal != TARGET_SIGNAL_TRAP);
stop_soon = NO_STOP_QUIETLY;
#endif /* defined(_SCO_DS) */
+
+ disable_breakpoints_at_startup (1);
}
static void
--- gdb/solib.c
+++ gdb/solib.c
@@ -411,15 +411,37 @@ symbol_add_stub (void *arg)
/* Have we already loaded this shared object? */
ALL_OBJFILES (so->objfile)
{
- if (strcmp (so->objfile->name, so->so_name) == 0)
+ /* Found an already loaded shared library. */
+ if (strcmp (so->objfile->name, so->so_name) == 0
+ && !so->main_p)
return 1;
+ /* Found an already loaded main executable. This could happen in
+ two circumstances.
+ First case: the main file has already been read in as the first
+ thing that gdb does at startup, and the file hasn't been
+ relocated properly yet. Therefore we need to read it in with the
+ proper section info.
+ Second case: it has been read in with the correct relocation, and
+ therefore we need to skip it. */
+ if (strcmp (so->objfile->name, so->so_name) == 0
+ && so->main_p
+ && so->main_relocated)
+ return 1;
}
sap = build_section_addr_info_from_section_table (so->sections,
so->sections_end);
- so->objfile = symbol_file_add (so->so_name, so->from_tty,
- sap, 0, OBJF_SHARED);
+ if (so->main_p)
+ {
+ so->objfile = symbol_file_add (so->so_name, /*so->from_tty*/ 0,
+ sap, 1, 0);
+ so->main_relocated = 1;
+ }
+ else
+ so->objfile = symbol_file_add (so->so_name, so->from_tty,
+ sap, 0, OBJF_SHARED);
+
free_section_addr_info (sap);
return (1);
@@ -599,28 +621,7 @@ update_solib_list (int from_tty, struct
/* Fill in the rest of each of the `struct so_list' nodes. */
for (i = inferior; i; i = i->next)
{
- i->from_tty = from_tty;
-
- /* Fill in the rest of the `struct so_list' node. */
- catch_errors (solib_map_sections, i,
- "Error while mapping shared library sections:\n",
- RETURN_MASK_ALL);
-
- /* If requested, add the shared object's sections to the TARGET's
- section table. Do this immediately after mapping the object so
- that later nodes in the list can query this object, as is needed
- in solib-osf.c. */
- if (target)
- {
- int count = (i->sections_end - i->sections);
- if (count > 0)
- {
- int space = target_resize_to_sections (target, count);
- memcpy (target->to_sections + space,
- i->sections,
- count * sizeof (i->sections[0]));
- }
- }
+ add_to_target_sections (from_tty, target, i);
/* Notify any observer that the shared object has been
loaded now that we've added it to GDB's tables. */
@@ -716,6 +717,39 @@ solib_add (char *pattern, int from_tty,
}
}
+void
+add_to_target_sections (int from_tty, struct target_ops *target,
+ struct so_list *solib)
+{
+ /* If this is set, then the sections have been already added to the
+ target list. */
+ if (solib->main_p)
+ return;
+
+ solib->from_tty = from_tty;
+
+ /* Fill in the rest of the `struct so_list' node. */
+ catch_errors (solib_map_sections, solib,
+ "Error while mapping shared library sections:\n",
+ RETURN_MASK_ALL);
+
+ /* If requested, add the shared object's sections to the TARGET's
+ section table. Do this immediately after mapping the object so
+ that later nodes in the list can query this object, as is needed
+ in solib-osf.c. */
+ if (target)
+ {
+ int count = solib->sections_end - solib->sections;
+ if (count > 0)
+ {
+ int space = target_resize_to_sections (target, count);
+ memcpy (target->to_sections + space,
+ solib->sections,
+ count * sizeof (solib->sections[0]));
+ }
+ }
+}
+
/*
--- gdb/solist.h
+++ gdb/solist.h
@@ -61,6 +61,8 @@ struct so_list
bfd *abfd;
char symbols_loaded; /* flag: symbols read in yet? */
char from_tty; /* flag: print msgs? */
+ char main_p; /* flag: is this the main executable? */
+ char main_relocated; /* flag: has it been relocated yet? */
struct objfile *objfile; /* objfile for loaded lib */
struct section_table *sections;
struct section_table *sections_end;
@@ -130,6 +132,10 @@ struct so_list *master_so_list (void);
/* Find solib binary file and open it. */
extern int solib_open (char *in_pathname, char **found_pathname);
+/* Add the list of sections in so_list to the target to_sections. */
+extern void add_to_target_sections (int, struct target_ops *,
+ struct so_list *);
+
/* FIXME: gdbarch needs to control this variable */
extern struct target_so_ops *current_target_so_ops;
--- gdb/symfile-mem.c
+++ gdb/symfile-mem.c
@@ -108,7 +108,7 @@ symbol_file_add_from_memory (struct bfd
}
objf = symbol_file_add_from_bfd (nbfd, from_tty,
- sai, 0, OBJF_SHARED);
+ sai, 2, OBJF_SHARED);
/* This might change our ideas about frames already looked at. */
reinit_frame_cache ();
--- gdb/symfile.c
+++ gdb/symfile.c
@@ -779,7 +779,7 @@ syms_from_objfile (struct objfile *objfi
/* Now either addrs or offsets is non-zero. */
- if (mainline)
+ if (mainline == 1)
{
/* We will modify the main symbol table, make sure that all its users
will be cleaned up if an error occurs during symbol reading. */
@@ -807,7 +807,7 @@ syms_from_objfile (struct objfile *objfi
We no longer warn if the lowest section is not a text segment (as
happens for the PA64 port. */
- if (!mainline && addrs && addrs->other[0].name)
+ if (addrs && addrs->other[0].name)
{
asection *lower_sect;
asection *sect;
@@ -976,14 +976,14 @@ new_symfile_objfile (struct objfile *obj
/* If this is the main symbol file we have to clean up all users of the
old main symbol file. Otherwise it is sufficient to fixup all the
breakpoints that may have been redefined by this symbol file. */
- if (mainline)
+ if (mainline == 1)
{
/* OK, make it the "real" symbol file. */
symfile_objfile = objfile;
clear_symtab_users ();
}
- else
+ else if (mainline == 0)
{
breakpoint_re_set ();
}
@@ -1029,7 +1029,7 @@ symbol_file_add_with_addrs_or_offsets (b
interactively wiping out any existing symbols. */
if ((have_full_symbols () || have_partial_symbols ())
- && mainline
+ && mainline == 1
&& from_tty
&& !query ("Load new symbol table from \"%s\"? ", name))
error (_("Not confirmed."));
@@ -1213,6 +1213,11 @@ symbol_file_clear (int from_tty)
symfile_objfile->name)
: !query (_("Discard symbol table? "))))
error (_("Not confirmed."));
+
+#ifdef CLEAR_SOLIB
+ CLEAR_SOLIB ();
+#endif
+
free_all_objfiles ();
/* solib descriptors may have handles to objfiles. Since their
@@ -2467,6 +2472,8 @@ reread_symbols (void)
/* Discard cleanups as symbol reading was successful. */
discard_cleanups (old_cleanups);
+ init_entry_point_info (objfile);
+
/* If the mtime has changed between the time we set new_modtime
and now, we *want* this to be out of date, so don't call stat
again now. */