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| author | Lluc Alvarez <lluc.alvarez@bsc.es> | 2012-09-21 04:51:18 -0400 |
|---|---|---|
| committer | Lluc Alvarez <lluc.alvarez@bsc.es> | 2012-09-21 04:51:18 -0400 |
| commit | c8de7654682dd8f5efa920f79d6041f2cac2fbeb (patch) | |
| tree | 4076d89b387c27a66e4403a341dae3cc3c807c0a | |
| parent | 9cd0c5ecc896690d923d443f3d419a05aec79ac1 (diff) | |
| download | gem5-c8de7654682dd8f5efa920f79d6041f2cac2fbeb.tar.xz | |
SE: Ignore FUTEX_PRIVATE_FLAG of sys_futex
This patch ignores the FUTEX_PRIVATE_FLAG of the sys_futex system call
in SE mode.
With this patch, when sys_futex with the options FUTEX_WAIT_PRIVATE or
FUTEX_WAKE_PRIVATE is emulated, the FUTEX_PRIVATE_FLAG is ignored and
so their behaviours are the regular FUTEX_WAIT and FUTEX_WAKE.
Emulating FUTEX_WAIT_PRIVATE and FUTEX_WAKE_PRIVATE as if they were
non-private is safe from a functional point of view. The
FUTEX_PRIVATE_FLAG does not change the semantics of the futex, it's
just a mechanism to improve performance under certain circunstances
that can be ignored in SE mode.
| -rw-r--r-- | src/kern/linux/linux.hh | 1 | ||||
| -rw-r--r-- | src/sim/syscall_emul.hh | 3 |
2 files changed, 3 insertions, 1 deletions
diff --git a/src/kern/linux/linux.hh b/src/kern/linux/linux.hh index 1d52ff323..1fcd80444 100644 --- a/src/kern/linux/linux.hh +++ b/src/kern/linux/linux.hh @@ -225,6 +225,7 @@ class Linux : public OperatingSystem static const unsigned TGT_FUTEX_WAKE = 1; static const unsigned TGT_EAGAIN = 11; static const unsigned TGT_EWOULDBLOCK = TGT_EAGAIN; + static const unsigned TGT_FUTEX_PRIVATE_FLAG = 128; }; // class Linux diff --git a/src/sim/syscall_emul.hh b/src/sim/syscall_emul.hh index aec159838..e98e771d5 100644 --- a/src/sim/syscall_emul.hh +++ b/src/sim/syscall_emul.hh @@ -359,6 +359,7 @@ futexFunc(SyscallDesc *desc, int callnum, LiveProcess *process, DPRINTF(SyscallVerbose, "In sys_futex: Address=%llx, op=%d, val=%d\n", uaddr, op, val); + op &= ~OS::TGT_FUTEX_PRIVATE_FLAG; if (op == OS::TGT_FUTEX_WAIT) { if (timeout != 0) { @@ -410,7 +411,7 @@ futexFunc(SyscallDesc *desc, int callnum, LiveProcess *process, "thread contexts\n", wokenUp); return wokenUp; } else { - warn("sys_futex: op %d is not implemented, just returning..."); + warn("sys_futex: op %d is not implemented, just returning...", op); return 0; } |