[Bug 1884117] Re: Valgrind: PPC sync instruction L field should only be 2 bits in ISA 3.0

[Tulio Magno Quites Machado Filho]

** Bug watch added: KDE Bug Tracking System #422677
   https://bugs.kde.org/show_bug.cgi?id=422677

** Also affects: valgrind via
   https://bugs.kde.org/show_bug.cgi?id=422677
   Importance: Unknown
       Status: Unknown

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Title:
   Valgrind: PPC sync instruction L field should only be 2 bits in ISA
  3.0

Status in Valgrind:
  Unknown
Status in valgrind package in Ubuntu:
  New

Bug description:
  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 <cel at 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.

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