Module Name: src
Committed By: riastradh
Date: Sun Feb 13 13:42:12 UTC 2022
Modified Files:
src/sys/arch/or1k/include: lock.h
Log Message:
or1k: __cpu_simple_lock membar audit.
To generate a diff of this commit:
cvs rdiff -u -r1.2 -r1.3 src/sys/arch/or1k/include/lock.h
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/arch/or1k/include/lock.h
diff -u src/sys/arch/or1k/include/lock.h:1.2 src/sys/arch/or1k/include/lock.h:1.3
--- src/sys/arch/or1k/include/lock.h:1.2 Sun Sep 17 00:01:08 2017
+++ src/sys/arch/or1k/include/lock.h Sun Feb 13 13:42:12 2022
@@ -1,4 +1,4 @@
-/* $NetBSD: lock.h,v 1.2 2017/09/17 00:01:08 christos Exp $ */
+/* $NetBSD: lock.h,v 1.3 2022/02/13 13:42:12 riastradh Exp $ */
/*-
* Copyright (c) 2014 The NetBSD Foundation, Inc.
@@ -86,7 +86,16 @@ __cpu_simple_lock(__cpu_simple_lock_t *_
}
#else
int tmp;
- __asm(
+ /*
+ * No explicit memory barrier needed around ll/sc:
+ *
+ * `In implementations that use a weakly-ordered memory model,
+ * l.swa nad l.lwa will serve as synchronization points,
+ * similar to lsync.'
+ *
+ * https://openrisc.io/or1k.html#__RefHeading__341344_552419154
+ */
+ __asm volatile(
"1:"
"\t" "l.lwa %[tmp],0(%[ptr])"
"\n\t" "l.sfeqi\t%[tmp],%[unlocked]"
@@ -99,7 +108,8 @@ __cpu_simple_lock(__cpu_simple_lock_t *_
: [tmp] "=&r" (tmp)
: [newval] "r" (__SIMPLELOCK_LOCKED),
[ptr] "r" (__ptr),
- [unlocked] "n" (__SIMPLELOCK_UNLOCKED));
+ [unlocked] "n" (__SIMPLELOCK_UNLOCKED)
+ : "cc", "memory");
#endif
}
@@ -110,7 +120,8 @@ __cpu_simple_lock_try(__cpu_simple_lock_
return !__atomic_test_and_set(__ptr, __ATOMIC_ACQUIRE);
#else
int oldval;
- __asm(
+ /* No explicit memory barrier needed, as in __cpu_simple_lock. */
+ __asm volatile(
"1:"
"\t" "l.lwa %[oldval],0(%[ptr])"
"\n\t" "l.swa 0(%[ptr]),%[newval]"
@@ -118,7 +129,8 @@ __cpu_simple_lock_try(__cpu_simple_lock_
"\n\t" "l.nop"
: [oldval] "=&r" (oldval)
: [newval] "r" (__SIMPLELOCK_LOCKED),
- [ptr] "r" (__ptr));
+ [ptr] "r" (__ptr)
+ : "cc", "memory");
return oldval == __SIMPLELOCK_UNLOCKED;
#endif
}
@@ -129,6 +141,7 @@ __cpu_simple_unlock(__cpu_simple_lock_t
#if 0
__atomic_clear(__ptr, __ATOMIC_RELEASE);
#else
+ __asm volatile("l.msync" ::: "");
*__ptr = __SIMPLELOCK_UNLOCKED;
#endif
}
