Hello all, I'm writing a Valgrind tool that makes use of function wrapping. From what I understand, wrappers need to run on the simulated CPU. I wrote a simple example which imitates the way Memcheck uses mc_replace_strmem.c to generate a preloaded .so that contains my own wrappers. A simplified version of my code is attached; I've been having some problems with it.
After compiling and running the tool (using the 3.12.0 codebase on Linux), the instrumented programs crash in odd ways: $ inst/bin/valgrind --tool=simplewrap ls ==1201== SimpleWrap, do only basic function wrapping ==1201== basic example for mailing list ==1201== Using Valgrind-3.12.0 and LibVEX; rerun with -h for copyright info ==1201== Command: ls ==1201== --1201-- VG_USERREQ__CLIENT_CALL1: func=0x0 --1201-- VG_USERREQ__CLIENT_CALL1: func=0x0 --1201-- VG_USERREQ__CLIENT_CALL1: func=0x0 --1201-- VG_USERREQ__CLIENT_CALL1: func=0x0 --1201-- VG_USERREQ__CLIENT_CALL1: func=0x0 --1201-- VG_USERREQ__CLIENT_CALL1: func=0x0 --1201-- VG_USERREQ__CLIENT_CALL1: func=0x0 ls: memory exhausted ==1201== $ ./vg-in-place --tool=wrapsimple gcc --help ==1215== SimpleWrap, do only basic function wrapping ==1215== basic example for mailing list ==1215== Using Valgrind-3.12.0 and LibVEX; rerun with -h for copyright info ==1215== Command: gcc --help ==1215== --1215-- VG_USERREQ__CLIENT_CALL1: func=0x0 --1215-- VG_USERREQ__CLIENT_CALL1: func=0x0 terminate called without an active exception ==1215== ==1215== Process terminating with default action of signal 6 (SIGABRT) ==1215== at 0x516F91F: raise (raise.c:58) ==1215== by 0x5171519: abort (abort.c:89) ==1215== by 0x47347C: ??? (in /usr/bin/gcc) ==1215== by 0x472F05: ??? (in /usr/bin/gcc) ==1215== by 0x472F50: ??? (in /usr/bin/gcc) ==1215== by 0x471C51: ??? (in /usr/bin/gcc) ==1215== by 0x4717A7: ??? (in /usr/bin/gcc) ==1215== by 0x4657B6: ??? (in /usr/bin/gcc) ==1215== by 0x441FED: ??? (in /usr/bin/gcc) ==1215== by 0x481AAC: ??? (in /usr/bin/gcc) ==1215== by 0x515A38F: (below main) (libc-start.c:245) ==1215== Aborted (core dumped) These crashes also happen if I comment out the wrapper function and compile the tool with an 'empty' sw_wrap.c, so the cause appears to relate to something I'm (not) doing with the build system to set up the preloaded .so, rather than the way the wrapper itself is written. Does anyone have a suggestion for how to properly add function wrappers to a Valgrind tool? All the best, Serguei Makarov
Makefile.am
Description: Binary data
#include "pub_tool_basics.h"
#include "pub_tool_tooliface.h"
static void sw_post_clo_init(void)
{
}
static
IRSB* sw_instrument ( VgCallbackClosure* closure,
IRSB* bb,
const VexGuestLayout* layout,
const VexGuestExtents* vge,
const VexArchInfo* archinfo_host,
IRType gWordTy, IRType hWordTy )
{
return bb;
}
static void sw_fini(Int exitcode)
{
}
static void sw_pre_clo_init(void)
{
VG_(details_name) ("SimpleWrap");
VG_(details_version) (NULL);
VG_(details_description) ("do only basic function wrapping");
VG_(details_copyright_author)(
"basic example for mailing list");
VG_(details_bug_reports_to) (VG_BUGS_TO);
VG_(details_avg_translation_sizeB) ( 275 );
VG_(basic_tool_funcs) (sw_post_clo_init,
sw_instrument,
sw_fini);
/* No needs, no core events to track */
}
VG_DETERMINE_INTERFACE_VERSION(sw_pre_clo_init)
#include "pub_tool_basics.h"
// #include "pub_tool_poolalloc.h"
#include "pub_tool_hashtable.h"
#include "pub_tool_redir.h"
#include "pub_tool_tooliface.h"
#include "pub_tool_clreq.h"
static UWord count = 0;
#if 1
// #if 0
// Let's wrap malloc just for the sake of argument:
void *VG_WRAP_FUNCTION_ZU(VG_Z_LIBC_SONAME, malloc) (SSizeT size)
{
OrigFn fn; VALGRIND_GET_ORIG_FN(fn);
UWord result;
CALL_FN_W_W(result, fn, size);
count++;
return result;
}
#endif
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