Re: GDB TLS testing [actually running some tests finally: a success with -pthread used]
John Baldwin <[email protected]>
| Newsgroups | gmane.os.freebsd.devel.ppc |
|---|---|
| Message-ID | <[email protected]> |
On 1/23/19 12:19 AM, Mark Millard wrote: > > > On 2019-Jan-22, at 22:53, Mark Millard <[email protected]> wrote: > > > >> On 2019-Jan-22, at 19:19, Mark Millard <marklmi at yahoo.com> wrote: >> >> >> >>> On 2019-Jan-22, at 18:32, Mark Millard <marklm at yahoo.com> wrote: >>> >>> >>> >>>> On 2019-Jan-22, at 17:06, Mark Millard <marklmi at yahoo.com> wrote: >>>> >>>> >>>> >>>> . . . >>>> So I'm trying: >>>> >>>> # git clean -f >>>> # rm */config.cache */*/config.cache >>>> # env CPATH=/usr/local/include ./configure >>>> . . . >>>> # env CPATH=/usr/local/include gmake >>>> . . . >>>> >>>> in order to try to add paths after the command line -I paths. >>>> >>>> . . . This looks like it built. I've not used the build yet. >>>> >>> >>> Looking at a *.core did not go well for my context: >>> >>> # cc -g -O2 tls_gdb_test.c >>> tls_gdb_test.c:16:2: warning: indirection of non-volatile null pointer will be deleted, not trap [-Wnull-dereference] >>> *(char *)NULL = 1; >>> ^~~~~~~~~~~~~ >>> tls_gdb_test.c:16:2: note: consider using __builtin_trap() or qualifying pointer with 'volatile' >>> 1 warning generated. For me, builtin_trap didn't DTRT on ppc before, but that was probably using gcc rather than clang (and possibly using gcc4.2). >>> . . . >> >> >> So far all tried-combinations of using gcc versions for build >> the test program and/or building the gdb used do not work for >> "p id" and "p &id" in doing the test. clang is not essential >> to the behavior observed. > > Using "-g -O2 -pthread" to build the test program via system > clang or gcc8 (for example) did lead to the likes of: > > (gdb) run > Starting program: /root/c_tests/a.out > main: PID 15350 > id = 15350 (0x810055020) > > ^C > Program received signal SIGINT, Interrupt. > main (ac=<optimized out>, av=<optimized out>) at tls_gdb_test.c:16 > 16 *(char *)NULL = 1; > (gdb) bt > #0 main (ac=<optimized out>, av=<optimized out>) at tls_gdb_test.c:16 > (gdb) info threads > Id Target Id Frame > * 1 LWP 100324 of process 15350 main (ac=<optimized out>, av=<optimized out>) at tls_gdb_test.c:16 > (gdb) p id > $1 = 15350 > (gdb) p &id > $2 = (int *) 0x810055020 > > So it appears one branch of: > > static void > fbsd_fetch_rtld_offsets (struct gdbarch *gdbarch, struct fbsd_pspace_data *data) > { > TRY > { > /* Fetch offsets from debug symbols in rtld. */ > data->off_linkmap = parse_and_eval_long ("&((Obj_Entry *)0)->linkmap"); > data->off_tlsindex = parse_and_eval_long ("&((Obj_Entry *)0)->tlsindex"); > data->rtld_offsets_valid = true; > return; > } > CATCH (e, RETURN_MASK_ERROR) > { > data->off_linkmap = -1; > } > END_CATCH > > TRY > { > /* Fetch offsets from global variables in libthr. Note that > this does not work for single-threaded processes that are not > linked against libthr. */ > data->off_linkmap = fbsd_read_integer_by_name(gdbarch, > "_thread_off_linkmap"); > data->off_tlsindex = fbsd_read_integer_by_name(gdbarch, > "_thread_off_tlsindex"); > data->rtld_offsets_valid = true; > return; > } > CATCH (e, RETURN_MASK_ERROR) > { > data->off_linkmap = -1; > } > END_CATCH > } > > is working when -pthread is used. Yes. The second one only works for programs linked against -lthr. Otherwise you need to have built your system with debug symbols (which is the default), and gdb needs to be able to access /usr/lib/debug/libexec/ld-elf.so.1.debug to determine the offsets of the two fields in Obj_Entry (this is what the first TRY clause does). -- John Baldwin _______________________________________________ [email protected] mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-ppc To unsubscribe, send any mail to "[email protected]"