Remove existing non-working support for self-modifying code, and instead
add a simple compromise, in which the client can notify valgrind
that certain code address ranges are invalid and should be retranslated.
This is done using the VALGRIND_DISCARD_TRANSLATIONS macro in valgrind.h.
At the same time take the opportunity to close the potentially fatal
loophole that translations for executable segments were not being
discarded when those segments were munmapped. They are now.
Documentation updated.
git-svn-id: svn://svn.valgrind.org/valgrind/trunk@274 a5019735-40e9-0310-863c-91ae7b9d1cf9
diff --git a/coregrind/vg_symtab2.c b/coregrind/vg_symtab2.c
index c781751..eb3b394 100644
--- a/coregrind/vg_symtab2.c
+++ b/coregrind/vg_symtab2.c
@@ -36,13 +36,16 @@
/* Majorly rewritten Sun 3 Feb 02 to enable loading symbols from
dlopen()ed libraries, which is something that KDE3 does a lot.
- Still kludgey, though less than before:
- * we don't check whether we should throw away some symbol tables
- when munmap() happens
+ Stabs reader greatly improved by Nick Nethercode, Apr 02.
- * symbol table reading code for ELF binaries is a shambles.
- Use GHC's fptools/ghc/rts/Linker.c as the basis for something better.
+ 16 May 02: when notified about munmap, return a Bool indicating
+ whether or not the area being munmapped had executable permissions.
+ This is then used to determine whether or not
+ VG_(invalid_translations) should be called for that area. In order
+ that this work even if --instrument=no, in this case we still keep
+ track of the mapped executable segments, but do not load any debug
+ info or symbols.
*/
/*------------------------------------------------------------*/
@@ -1181,9 +1184,11 @@
= si->start==VG_ASSUMED_EXE_BASE ? 0 : si->start;
/* And actually fill it up. */
- vg_read_lib_symbols ( si );
- canonicaliseSymtab ( si );
- canonicaliseLoctab ( si );
+ if (VG_(clo_instrument) || VG_(clo_cachesim)) {
+ vg_read_lib_symbols ( si );
+ canonicaliseSymtab ( si );
+ canonicaliseLoctab ( si );
+ }
}
@@ -1197,9 +1202,6 @@
which happen to correspond to the munmap()d area. */
void VG_(read_symbols) ( void )
{
- if (! VG_(clo_instrument) && ! VG_(clo_cachesim))
- return;
-
VG_(read_procselfmaps) ( read_symtab_callback );
/* Do a sanity check on the symbol tables: ensure that the address
@@ -1222,7 +1224,6 @@
/* the main assertion */
overlap = (lo <= lo2 && lo2 <= hi)
|| (lo <= hi2 && hi2 <= hi);
- //vg_assert(!overlap);
if (overlap) {
VG_(printf)("\n\nOVERLAPPING SEGMENTS\n" );
ppSegInfo ( si );
@@ -1240,15 +1241,16 @@
to a segment for a .so, and if so discard the relevant SegInfo.
This might not be a very clever idea from the point of view of
accuracy of error messages, but we need to do it in order to
- maintain the no-overlapping invariant.
+ maintain the no-overlapping invariant.
+
+ 16 May 02: Returns a Bool indicating whether or not the discarded
+ range falls inside a known executable segment. See comment at top
+ of file for why.
*/
-void VG_(symtab_notify_munmap) ( Addr start, UInt length )
+Bool VG_(symtab_notify_munmap) ( Addr start, UInt length )
{
SegInfo *prev, *curr;
- if (! VG_(clo_instrument))
- return;
-
prev = NULL;
curr = segInfo;
while (True) {
@@ -1257,7 +1259,8 @@
prev = curr;
curr = curr->next;
}
- if (curr == NULL) return;
+ if (curr == NULL)
+ return False;
VG_(message)(Vg_UserMsg,
"discard syms in %s due to munmap()",
@@ -1272,6 +1275,7 @@
}
freeSegInfo(curr);
+ return True;
}