* solib-aix5.c (map_index_vs_section_name_okay): New function.
(aix5_relocate_main_executable): Don't use file offsets for determining corresponding sections and map file entries. Call map_index_vs_section_name_okay() to do this instead.
This commit is contained in:
Kevin Buettner
parent
1c33f1da00
commit
00c7912d77
@ -1,3 +1,10 @@
|
||||
2001-04-16 Kevin Buettner <kevinb@redhat.com>
|
||||
|
||||
* solib-aix5.c (map_index_vs_section_name_okay): New function.
|
||||
(aix5_relocate_main_executable): Don't use file offsets for
|
||||
determining corresponding sections and map file entries. Call
|
||||
map_index_vs_section_name_okay() to do this instead.
|
||||
|
||||
2001-04-16 Kevin Buettner <kevinb@redhat.com>
|
||||
|
||||
* procfs.c (open_with_retry): New function.
|
||||
|
||||
131
gdb/solib-aix5.c
131
gdb/solib-aix5.c
@ -562,6 +562,133 @@ aix5_special_symbol_handling (void)
|
||||
/* Nothing needed (yet) for AIX5. */
|
||||
}
|
||||
|
||||
/* On AIX5, the /proc/PID/map information is used to determine
|
||||
the relocation offsets needed for relocating the main executable.
|
||||
There is no problem determining which map entries correspond
|
||||
to the main executable, because these will have the MA_MAINEXEC
|
||||
flag set. The tricky part is determining which sections correspond
|
||||
to which map entries. To date, the following approaches have
|
||||
been tried:
|
||||
|
||||
- Use the MA_WRITE attribute of pr_mflags to distinguish the read-only
|
||||
mapping from the read/write mapping. (This assumes that there are
|
||||
only two mappings for the main executable.) All writable sections
|
||||
are associated with the read/write mapping and all non-writable
|
||||
sections are associated with the read-only mapping.
|
||||
|
||||
This approach worked quite well until we came across executables
|
||||
which didn't have a read-only mapping. Both mappings had the
|
||||
same attributes represented in pr_mflags and it was impossible
|
||||
to tell them apart.
|
||||
|
||||
- Use the pr_off field (which represents the offset into the
|
||||
executable) to determine the section-to-mapping relationship.
|
||||
Unfortunately, this approach doesn't work either, because the
|
||||
offset value contained in the mapping is rounded down by some
|
||||
moderately large power-of-2 value (4096 is a typical value).
|
||||
A small (e.g. "Hello World") program will appear to have all
|
||||
of its sections belonging to both mappings.
|
||||
|
||||
Also, the following approach has been considered, but dismissed:
|
||||
|
||||
- The section vma values typically look (something) like
|
||||
0x00000001xxxxxxxx or 0x00000002xxxxxxxx. Furthermore, the
|
||||
0x00000001xxxxxxxx values always belong to one mapping and
|
||||
the 0x00000002xxxxxxxx values always belong to the other.
|
||||
Thus it seems conceivable that GDB could use the bit patterns
|
||||
in the upper portion (for some definition of "upper") in a
|
||||
section's vma to help determine the section-to-mapping
|
||||
relationship.
|
||||
|
||||
This approach was dismissed because there is nothing to prevent
|
||||
the linker from lumping the section vmas together in one large
|
||||
contiguous space and still expecting the dynamic linker to
|
||||
separate them and relocate them independently. Also, different
|
||||
linkers have been observed to use different patterns for the
|
||||
upper portions of the vma addresses and it isn't clear what the
|
||||
mask ought to be for distinguishing these patterns.
|
||||
|
||||
The current (admittedly inelegant) approach uses a lookup
|
||||
table which associates section names with the map index that
|
||||
they're permitted to be in. This is inelegant because we are
|
||||
making the following assumptions:
|
||||
|
||||
1) There will only be two mappings.
|
||||
2) The relevant (i.e. main executable) mappings will always appear
|
||||
in the same order in the map file.
|
||||
3) The sections named in the table will always belong to the
|
||||
indicated mapping.
|
||||
4) The table completely enumerates all possible section names.
|
||||
|
||||
IMO, any of these deficiencies alone will normally be sufficient
|
||||
to disqualify this approach, but I haven't been able to think of
|
||||
a better way to do it.
|
||||
|
||||
map_index_vs_section_name_okay() is a predicate which returns
|
||||
true iff the section name NAME is associated with the map index
|
||||
IDX in its builtin table. Of course, there's no guarantee that
|
||||
this association is actually valid... */
|
||||
|
||||
static int
|
||||
map_index_vs_section_name_okay (int idx, const char *name)
|
||||
{
|
||||
static struct
|
||||
{
|
||||
char *name;
|
||||
int idx;
|
||||
} okay[] =
|
||||
{
|
||||
{ ".interp", 0 },
|
||||
{ ".hash", 0 },
|
||||
{ ".dynsym", 0 },
|
||||
{ ".dynstr", 0 },
|
||||
{ ".rela.text", 0 },
|
||||
{ ".rela.rodata", 0 },
|
||||
{ ".rela.data", 0 },
|
||||
{ ".rela.ctors", 0 },
|
||||
{ ".rela.dtors", 0 },
|
||||
{ ".rela.got", 0 },
|
||||
{ ".rela.sdata", 0 },
|
||||
{ ".rela.IA_64.pltoff", 0 },
|
||||
{ ".rel.data", 0 },
|
||||
{ ".rel.sdata", 0 },
|
||||
{ ".rel.got", 0 },
|
||||
{ ".rel.AIX.pfdesc", 0 },
|
||||
{ ".rel.IA_64.pltoff", 0 },
|
||||
{ ".dynamic", 0 },
|
||||
{ ".init", 0 },
|
||||
{ ".plt", 0 },
|
||||
{ ".text", 0 },
|
||||
{ ".fini", 0 },
|
||||
{ ".rodata", 0 },
|
||||
{ ".IA_64.unwind_info", 0 },
|
||||
{ ".IA_64.unwind", 0 },
|
||||
{ ".AIX.mustrel", 0 },
|
||||
|
||||
{ ".data", 1 },
|
||||
{ ".ctors", 1 },
|
||||
{ ".dtors", 1 },
|
||||
{ ".got", 1 },
|
||||
{ ".dynamic", 1},
|
||||
{ ".sdata", 1 },
|
||||
{ ".IA_64.pltoff", 1 },
|
||||
{ ".sbss", 1 },
|
||||
{ ".bss", 1 },
|
||||
{ ".AIX.pfdesc", 1 }
|
||||
};
|
||||
int i;
|
||||
|
||||
for (i = 0; i < sizeof (okay) / sizeof (okay[0]); i++)
|
||||
{
|
||||
if (strcmp (name, okay[i].name) == 0)
|
||||
return idx == okay[i].idx;
|
||||
}
|
||||
|
||||
warning ("solib-aix5.c: Ignoring section %s when relocating the executable\n",
|
||||
name);
|
||||
return 0;
|
||||
}
|
||||
|
||||
#define SECTMAPMASK (~ (CORE_ADDR) 0x03ffffff)
|
||||
|
||||
static void
|
||||
@ -608,8 +735,8 @@ aix5_relocate_main_executable (void)
|
||||
if (flags & SEC_ALLOC)
|
||||
{
|
||||
file_ptr filepos = sect->the_bfd_section->filepos;
|
||||
if (mapping->offset <= filepos
|
||||
&& filepos <= mapping->offset + mapping->size)
|
||||
if (map_index_vs_section_name_okay (i,
|
||||
bfd_get_section_name (obfd, sect->the_bfd_section)))
|
||||
{
|
||||
int idx = sect->the_bfd_section->index;
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user