https://bugs.kde.org/show_bug.cgi?id=374596
--- Comment #8 from bugzi...@dcopp.net --- (In reply to Tom Hughes from comment #7) > I'm not saying it isn't a bug, just explaining what I think is causing it. > > What I do know is it's not likely to be easy to fix, but it probably needs > Julian to comment in more detail about whether it might be fixable and > whether there is any way to word around it. > > I would guess that putting the RDTSCP in a separate function from the check > might work, so long as the compiler doesn't optimise them back together... In the second attachment rdtscp2.cpp, the instruction is relegated to a separate function rdtcsp(), with inlining disabled. Execution proceeds through the negative flow path (the output "RDTCSP not supported" proves this), meaning we never call that function. But we still get the SIGILL from valgrind: RDTSCP not supported 3:28pm mrec-build2.812 ~/dev% ~/bin/valgrind ./a.out ==14720== Memcheck, a memory error detector ==14720== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al. ==14720== Using Valgrind-3.12.0 and LibVEX; rerun with -h for copyright info ==14720== Command: ./a.out ==14720== vex amd64->IR: unhandled instruction bytes: 0xF 0x1 0xF9 0xC9 0xC3 0x55 0x48 0x89 0xE5 0x48 vex amd64->IR: REX=0 REX.W=0 REX.R=0 REX.X=0 REX.B=0 vex amd64->IR: VEX=0 VEX.L=0 VEX.nVVVV=0x0 ESC=0F vex amd64->IR: PFX.66=0 PFX.F2=0 PFX.F3=0 ==14720== valgrind: Unrecognised instruction at address 0x400818. ==14720== at 0x400818: rdtscp() (in /home/joev/dev/a.out) ==14720== by 0x400848: main (in /home/joev/dev/a.out) ==14720== Your program just tried to execute an instruction that Valgrind ==14720== did not recognise. There are two possible reasons for this. ==14720== 1. Your program has a bug and erroneously jumped to a non-code ==14720== location. If you are running Memcheck and you just saw a ==14720== warning about a bad jump, it's probably your program's fault. ==14720== 2. The instruction is legitimate but Valgrind doesn't handle it, ==14720== i.e. it's Valgrind's fault. If you think this is the case or ==14720== you are not sure, please let us know and we'll try to fix it. ==14720== Either way, Valgrind will now raise a SIGILL signal which will ==14720== probably kill your program. ==14720== ==14720== Process terminating with default action of signal 4 (SIGILL) ==14720== Illegal opcode at address 0x400818 ==14720== at 0x400818: rdtscp() (in /home/joev/dev/a.out) ==14720== by 0x400848: main (in /home/joev/dev/a.out) ==14720== ==14720== HEAP SUMMARY: ==14720== in use at exit: 0 bytes in 0 blocks ==14720== total heap usage: 0 allocs, 0 frees, 0 bytes allocated ==14720== ==14720== All heap blocks were freed -- no leaks are possible ==14720== ==14720== For counts of detected and suppressed errors, rerun with: -v ==14720== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 4 from 4) Illegal instruction -- You are receiving this mail because: You are watching all bug changes.
