Public bug reported:
Valgrind, including version 3.16, mishandles the L field of the sync
instruction.
More details are available at: https://bugs.kde.org/show_bug.cgi?id=422677
A fix is available upstream:
commit fb6f7abcbc92506d302fb18a2c5fc853d2929248
Author: Carl Love <c...@us.ibm.com>
Date: Tue Jun 9 10:42:03 2020 -0500
Power PC Fix extraction of the L field for sync instruction
The L field is currently a two bit[22:21] field in ISA 3.0. The size of the
L field has changed over time.
Currently the ISA 3.0 Valgrind sync instruction support code sets the
flag_L for the instruction L field to a five bit value that includes bits
that are marked reserved the sync instruction. This patch fixes the issue
for ISA 3.0
to only setting flag_L the specified two bits.
Steps to Reproduce:
$ cat test-sync.c
#define __SYNC(l) ".long (0x7c0004AC | ((" #l ") << 21))"
int
main ()
{
asm volatile(__SYNC(4) : : : "memory");
}
$ gcc test-sync.c && valgrind --tool=none ./a.out
==150073== Nulgrind, the minimal Valgrind tool
==150073== Copyright (C) 2002-2017, and GNU GPL'd, by Nicholas Nethercote.
==150073== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info
==150073== Command: ./a.out
==150073==
dis_memsync(ppc)(sync/lwsync,flag_L)
disInstr(ppc): unhandled instruction: 0x7C8004AC
primary 31(0x1F), secondary 1196(0x4AC)
==150073== valgrind: Unrecognised instruction at address 0x180788.
==150073== at 0x180788: main (in /home/tuliom/tmp/a.out)
==150073== Your program just tried to execute an instruction that Valgrind
==150073== did not recognise.
** Affects: valgrind
Importance: Unknown
Status: Unknown
** Affects: valgrind (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1884117
Title:
Valgrind: PPC sync instruction L field should only be 2 bits in ISA
3.0
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