https://bugs.kde.org/show_bug.cgi?id=411189
Bug ID: 411189
Summary: Valgrind does not support POWER9 "DARN" RNG
instructions
Product: valgrind
Version: 3.15 SVN
Platform: Other
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: general
Assignee: jsew...@acm.org
Reporter: ll...@randombit.net
Target Milestone: ---
SUMMARY
Valgrind does not currently support the POWER9 DARN RNG instructions. These are
similar to x86 RDRAND/RDSEED.
STEPS TO REPRODUCE
$ cat min_darn.c
#include <stdint.h>
#include <stdio.h>
int main()
{
uint64_t darn = __builtin_darn();
printf("%016llX\n", darn);
return 0;
}
$ powerpc64le-unknown-linux-gnu-gcc -mcpu=power9 -O min_darn.c -o min_darn
$ ./min_darn
51302492414386A8 # this will differ each time the program is run
$ valgrind ./min_darn
OBSERVED RESULT
==129755== Memcheck, a memory error detector
==129755== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==129755== Using Valgrind-3.15.0 and LibVEX; rerun with -h for copyright info
==129755== Command: ./min_darn
==129755==
disInstr(ppc): unhandled instruction: 0x7C8105E6
primary 31(0x1F), secondary 1510(0x5E6)
==129755== valgrind: Unrecognised instruction at address 0x100005d0.
==129755== at 0x100005D0: main (in /home/lloyd/min_darn)
==129755== Your program just tried to execute an instruction that Valgrind
==129755== did not recognise. There are two possible reasons for this.
==129755== 1. Your program has a bug and erroneously jumped to a non-code
==129755== location. If you are running Memcheck and you just saw a
==129755== warning about a bad jump, it's probably your program's fault.
==129755== 2. The instruction is legitimate but Valgrind doesn't handle it,
==129755== i.e. it's Valgrind's fault. If you think this is the case or
==129755== you are not sure, please let us know and we'll try to fix it.
==129755== Either way, Valgrind will now raise a SIGILL signal which will
==129755== probably kill your program.
==129755==
==129755== Process terminating with default action of signal 4 (SIGILL)
==129755== Illegal opcode at address 0x100005D0
==129755== at 0x100005D0: main (in /home/lloyd/min_darn)
==129755==
==129755== HEAP SUMMARY:
==129755== in use at exit: 0 bytes in 0 blocks
==129755== total heap usage: 0 allocs, 0 frees, 0 bytes allocated
==129755==
==129755== All heap blocks were freed -- no leaks are possible
==129755==
==129755== For lists of detected and suppressed errors, rerun with: -s
==129755== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
Illegal instruction
EXPECTED RESULT
It should run ;)
SOFTWARE/OS VERSIONS
Valgrind 3.15.0 release
GCC 9.2.0 release
POWER9 running CentOS 7, kernel 4.14.0
ADDITIONAL INFORMATION
A POWER9 machine is available on the GCC compile farm (gcc135).
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