Author: avg
Date: Mon Oct 7 12:53:27 2019
New Revision: 353270
URL: https://svnweb.freebsd.org/changeset/base/353270
Log:
fix up r353168, add atomic_swap_64 to i386 version of opensolaris_atomic.S
The compatibility code for the atomic operations in ZFS code is a bit
messy. In some cases the native definitions are directly made
available, in some cases there are emulated operations in
opensolaris_atomic.c and in yet other cases there are atomic operations
implemented in assembly that were obtained from OpenSolaris / illumos.
This commit adds atomic_swap_64 for use with i386 userland.
The code is copied from illumos.
I am not sure why FreeBSD does not provide that operation natively.
Maybe because we try (or pretend) to support processors that did not
have the necessary instructions.
While here I also added atomic_load_64 for the same reasons.
This is original code based on iilumos atomic_swap_64 and FreeBSD
atomic_load_acq_64_i586.
Pointyhat to: avg
MFC after: 1 week
Modified:
head/sys/cddl/contrib/opensolaris/common/atomic/i386/opensolaris_atomic.S
Modified:
head/sys/cddl/contrib/opensolaris/common/atomic/i386/opensolaris_atomic.S
==============================================================================
--- head/sys/cddl/contrib/opensolaris/common/atomic/i386/opensolaris_atomic.S
Mon Oct 7 12:51:36 2019 (r353269)
+++ head/sys/cddl/contrib/opensolaris/common/atomic/i386/opensolaris_atomic.S
Mon Oct 7 12:53:27 2019 (r353270)
@@ -126,6 +126,34 @@
ret
SET_SIZE(atomic_cas_64)
+ ENTRY(atomic_swap_64)
+ pushl %esi
+ pushl %ebx
+ movl 12(%esp), %esi
+ movl 16(%esp), %ebx
+ movl 20(%esp), %ecx
+ movl (%esi), %eax
+ movl 4(%esi), %edx // %edx:%eax = old value
+1:
+ lock
+ cmpxchg8b (%esi)
+ jne 1b
+ popl %ebx
+ popl %esi
+ ret
+ SET_SIZE(atomic_swap_64)
+
+ ENTRY(atomic_load_64)
+ pushl %esi
+ movl 8(%esp), %esi
+ movl %ebx, %eax // make old and new values equal, so that
+ movl %ecx, %edx // destination is never changed
+ lock
+ cmpxchg8b (%esi)
+ popl %esi
+ ret
+ SET_SIZE(atomic_load_64)
+
ENTRY(membar_producer)
lock
xorl $0, (%esp)
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