Executing "tbegin." on Power9 results in illegal instruction

[Nicolas Koenig]

Trying to execute the "tbegin." instruction on a power9 cpu results in SIGILL. Attached is the testcase.

$ lsb_release -a
Distributor ID: Ubuntu
Description: Ubuntu 18.04.1 LTS
Release: 18.04
Codename: bionic
$ lscpu
Architecture: ppc64le
Byte Order: Little Endian
--snip--
Model: 2.2 (pvr 004e 1202)
Model name: POWER9, altivec supported
--snip--
$ cat testcase.c

void tbegin(void);

asm(".type tbegin,@function\n"\
"tbegin:\n"\
"\ttbegin.");

int
main(int argc, char **argv) {
        tbegin();
        return 0;
}

$ gcc testcase.c && ./a.out
Illegal instruction (core dumped)
$ gdb ./a.out
--snip--
(gdb) r
--snip--
Program received signal SIGILL, Illegal instruction.
0x000000010000077c in tbegin ()
(gdb) disas
Dump of assembler code for function tbegin:
=> 0x000000010000077c <+0>: tbegin.
End of assembler dump.

[Ubuntu Foundations Team Bug Bot (crichton)]

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