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| author | Moyang Wang <mw828@cornell.edu> | 2018-04-02 16:23:13 -0400 |
|---|---|---|
| committer | Tuan Ta <qtt2@cornell.edu> | 2019-02-08 15:25:30 +0000 |
| commit | 165a7dab558c8118622a387683521bea1ebf2e6c (patch) | |
| tree | e3d36c6e12abf4807306f6e4c0d2201f13287568 /src/kern | |
| parent | 758b62cfb2ede5fa2187e4cab899691505179d43 (diff) | |
| download | gem5-165a7dab558c8118622a387683521bea1ebf2e6c.tar.xz | |
kern,sim: implement FUTEX_WAKE_OP
This patch implements FUTEX_WAKE_OP operation in the futex syscall.
Below is its description:
int futex(int *uaddr, int futex_op, int val,
const struct timespec *timeout,
int *uaddr2, int val3);
This operation was added to support some user-space use cases where more
than one futex must be handled at the same time. The most notable
example is the implementation of pthread_cond_signal(3), which requires
operations on two futexes, the one used to implement the mutex and the
one used in the implementation of the wait queue associated with the
condition variable. FUTEX_WAKE_OP allows such cases to be implemented
without leading to high rates of contention and context switching.
Reference: http://man7.org/linux/man-pages/man2/futex.2.html
Change-Id: I215f3c2a7bdc6374e5dfe06ee721c76933a10f2d
Reviewed-on: https://gem5-review.googlesource.com/c/9630
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Brandon Potter <Brandon.Potter@amd.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
Diffstat (limited to 'src/kern')
| -rw-r--r-- | src/kern/linux/linux.hh | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/src/kern/linux/linux.hh b/src/kern/linux/linux.hh index 4ed39028b..93253012a 100644 --- a/src/kern/linux/linux.hh +++ b/src/kern/linux/linux.hh @@ -243,12 +243,28 @@ class Linux : public OperatingSystem static const unsigned TGT_FUTEX_WAKE = 1; static const unsigned TGT_FUTEX_REQUEUE = 3; static const unsigned TGT_FUTEX_CMP_REQUEUE = 4; + static const unsigned TGT_FUTEX_WAKE_OP = 5; static const unsigned TGT_FUTEX_WAIT_BITSET = 9; static const unsigned TGT_FUTEX_WAKE_BITSET = 10; static const unsigned TGT_EAGAIN = 11; static const unsigned TGT_EWOULDBLOCK = TGT_EAGAIN; static const unsigned TGT_FUTEX_PRIVATE_FLAG = 128; static const unsigned TGT_FUTEX_CLOCK_REALTIME_FLAG = 256; + // op field of futex_wake_op operation + static const unsigned TGT_FUTEX_OP_SET = 0; // uaddr2 = oparg; + static const unsigned TGT_FUTEX_OP_ADD = 1; // uaddr2 += oparg; + static const unsigned TGT_FUTEX_OP_OR = 2; // uaddr2 |= oparg; + static const unsigned TGT_FUTEX_OP_ANDN = 3; // uaddr2 &= ~oparg; + static const unsigned TGT_FUTEX_OP_XOR = 4; // uaddr2 ^= oparg; + // Use (1 << oparg) as operand + static const unsigned TGT_FUTEX_OP_ARG_SHIFT = 8; + // cmp field of futex_wake_op operation + static const unsigned TGT_FUTEX_OP_CMP_EQ = 0; + static const unsigned TGT_FUTEX_OP_CMP_NE = 1; + static const unsigned TGT_FUTEX_OP_CMP_LT = 2; + static const unsigned TGT_FUTEX_OP_CMP_LE = 3; + static const unsigned TGT_FUTEX_OP_CMP_GT = 4; + static const unsigned TGT_FUTEX_OP_CMP_GE = 5; // for *at syscalls static const int TGT_AT_FDCWD = -100; |