Date: Wed, 23 Jan 2019 00:19:54 -0800 From: Mark Millard <marklmi@yahoo.com> To: John Baldwin <jhb@freebsd.org> Cc: "freebsd-ppc@freebsd.org" <freebsd-ppc@FreeBSD.org> Subject: Re: GDB TLS testing [actually running some tests finally: a success with -pthread used] Message-ID: <52E66D9B-C332-4565-B8E7-F54F6454B062@yahoo.com> In-Reply-To: <B07EC3F9-6C08-4B5D-89D0-4048AF305A2D@yahoo.com> References: <b0f5b62f-54fb-309f-a578-7b4d9e340a55@FreeBSD.org> <19343397-859C-4629-A4A5-B0DCDE25957B@yahoo.com> <AB56B3D1-1762-4115-B7B4-91D4B997F1C4@yahoo.com> <eff896f3-e385-9a12-5132-3884e69689ca@FreeBSD.org> <D0B83B01-5428-42F0-B785-221826AF7EC4@yahoo.com> <a1da2471-535d-1497-ddf3-93aa0d29df59@FreeBSD.org> <5AA68ED2-2615-438B-A6AE-406CBD8E49F7@yahoo.com> <20027C29-0093-4001-A135-23783F8B87F3@yahoo.com> <4048D2A4-7E14-481C-9B5D-00567BCF4463@yahoo.com> <2AAC9738-73BD-475A-888A-252EE853A5C6@yahoo.com> <493AC0BE-3EC6-42B7-B027-FFB6454761B5@yahoo.com> <B07EC3F9-6C08-4B5D-89D0-4048AF305A2D@yahoo.com>
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On 2019-Jan-22, at 22:53, Mark Millard <marklmi@yahoo.com> wrote: > On 2019-Jan-22, at 19:19, Mark Millard <marklmi at yahoo.com> wrote: >=20 >=20 >=20 >> On 2019-Jan-22, at 18:32, Mark Millard <marklm at yahoo.com> wrote: >>=20 >>=20 >>=20 >>> On 2019-Jan-22, at 17:06, Mark Millard <marklmi at yahoo.com> wrote: >>>=20 >>>=20 >>>=20 >>> . . . >>> So I'm trying: >>>=20 >>> # git clean -f >>> # rm */config.cache */*/config.cache >>> # env CPATH=3D/usr/local/include ./configure >>> . . . >>> # env CPATH=3D/usr/local/include gmake >>> . . . >>>=20 >>> in order to try to add paths after the command line -I paths. >>>=20 >>> . . . This looks like it built. I've not used the build yet. >>>=20 >>=20 >> Looking at a *.core did not go well for my context: >>=20 >> # cc -g -O2 tls_gdb_test.c=20 >> tls_gdb_test.c:16:2: warning: indirection of non-volatile null = pointer will be deleted, not trap [-Wnull-dereference] >> *(char *)NULL =3D 1; >> ^~~~~~~~~~~~~ >> tls_gdb_test.c:16:2: note: consider using __builtin_trap() or = qualifying pointer with 'volatile' >> 1 warning generated. >> . . . >=20 >=20 > 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=20 Starting program: /root/c_tests/a.out=20 main: PID 15350 id =3D 15350 (0x810055020) ^C Program received signal SIGINT, Interrupt. main (ac=3D<optimized out>, av=3D<optimized out>) at tls_gdb_test.c:16 16 *(char *)NULL =3D 1; (gdb) bt #0 main (ac=3D<optimized out>, av=3D<optimized out>) at = tls_gdb_test.c:16 (gdb) info threads Id Target Id Frame=20 * 1 LWP 100324 of process 15350 main (ac=3D<optimized out>, = av=3D<optimized out>) at tls_gdb_test.c:16 (gdb) p id $1 =3D 15350 (gdb) p &id $2 =3D (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 =3D parse_and_eval_long ("&((Obj_Entry = *)0)->linkmap"); data->off_tlsindex =3D parse_and_eval_long ("&((Obj_Entry = *)0)->tlsindex"); data->rtld_offsets_valid =3D true; return; } CATCH (e, RETURN_MASK_ERROR) { data->off_linkmap =3D -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 =3D fbsd_read_integer_by_name(gdbarch, = "_thread_off_linkmap"); data->off_tlsindex =3D fbsd_read_integer_by_name(gdbarch, = "_thread_off_tlsindex"); data->rtld_offsets_valid =3D true; return; } CATCH (e, RETURN_MASK_ERROR) { data->off_linkmap =3D -1; } END_CATCH } is working when -pthread is used. =3D=3D=3D Mark Millard marklmi at yahoo.com ( dsl-only.net went away in early 2018-Mar)
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