From f5aace8300a7b611c1111452a7cf27ce4c9982f5 Mon Sep 17 00:00:00 2001 From: Steve Reinhardt Date: Fri, 18 Jul 2014 22:05:51 -0700 Subject: [PATCH] syscall emulation: fix DPRINTF arg ordering bug When we switched getSyscallArg() from explicit arg indices to the implicit method, some DPRINTF arguments were left as calls to getSyscallArg(), even though C/C++ doesn't guarantee anything about the order of invocation of these calls. As a result, the args could be printed out in arbitrary orders. Interestingly, this bug has been around since 2009: http://repo.gem5.org/gem5/rev/4842482e1bd1 --- src/sim/syscall_emul.cc | 31 +++++++++++++++++-------------- 1 file changed, 17 insertions(+), 14 deletions(-) diff --git a/src/sim/syscall_emul.cc b/src/sim/syscall_emul.cc index 61ba32955..ff22aea54 100644 --- a/src/sim/syscall_emul.cc +++ b/src/sim/syscall_emul.cc @@ -55,16 +55,19 @@ using namespace TheISA; void SyscallDesc::doSyscall(int callnum, LiveProcess *process, ThreadContext *tc) { -#if TRACING_ON - int index = 0; -#endif - DPRINTFR(SyscallVerbose, - "%d: %s: syscall %s called w/arguments %d,%d,%d,%d\n", - curTick(), tc->getCpuPtr()->name(), name, - process->getSyscallArg(tc, index), - process->getSyscallArg(tc, index), - process->getSyscallArg(tc, index), - process->getSyscallArg(tc, index)); + if (DTRACE(SyscallVerbose)) { + int index = 0; + IntReg arg[4]; + + // we can't just put the calls to getSyscallArg() in the + // DPRINTF arg list, because C++ doesn't guarantee their order + for (int i = 0; i < 4; ++i) + arg[i] = process->getSyscallArg(tc, index); + + DPRINTFNR("%d: %s: syscall %s called w/arguments %d,%d,%d,%d\n", + curTick(), tc->getCpuPtr()->name(), name, + arg[0], arg[1], arg[2], arg[3]); + } SyscallReturn retval = (*funcPtr)(this, callnum, process, tc); @@ -91,8 +94,8 @@ ignoreFunc(SyscallDesc *desc, int callnum, LiveProcess *process, ThreadContext *tc) { int index = 0; - warn("ignoring syscall %s(%d, %d, ...)", desc->name, - process->getSyscallArg(tc, index), process->getSyscallArg(tc, index)); + warn("ignoring syscall %s(%d, ...)", desc->name, + process->getSyscallArg(tc, index)); return 0; } @@ -103,8 +106,8 @@ ignoreWarnOnceFunc(SyscallDesc *desc, int callnum, LiveProcess *process, ThreadContext *tc) { int index = 0; - warn_once("ignoring syscall %s(%d, %d, ...)", desc->name, - process->getSyscallArg(tc, index), process->getSyscallArg(tc, index)); + warn_once("ignoring syscall %s(%d, ...)", desc->name, + process->getSyscallArg(tc, index)); return 0; } -- 2.30.2