Author: bdragon
Date: Wed Sep 23 01:33:54 2020
New Revision: 366046
URL: https://svnweb.freebsd.org/changeset/base/366046
Log:
[PowerPC64LE] Implement endian-independent dword atomic PTE lock.
It's much easier to implement this in an endian-independent way when we
don't also have to worry about masking half of the dword off.
Given that this code ran on a machine that ran a poudriere bulk with no
kernel oddities, I am relatively certain it is correctly implemented. ;)
This should be a minor performance boost on BE as well.
Sponsored by: Tag1 Consulting, Inc.
Modified:
head/sys/powerpc/aim/moea64_native.c
Modified: head/sys/powerpc/aim/moea64_native.c
==============================================================================
--- head/sys/powerpc/aim/moea64_native.c Wed Sep 23 01:29:33 2020
(r366045)
+++ head/sys/powerpc/aim/moea64_native.c Wed Sep 23 01:33:54 2020
(r366046)
@@ -633,15 +633,46 @@ static int
atomic_pte_lock(volatile struct lpte *pte, uint64_t bitmask, uint64_t *oldhi)
{
int ret;
+#ifdef __powerpc64__
+ uint64_t temp;
+#else
uint32_t oldhihalf;
+#endif
/*
* Note: in principle, if just the locked bit were set here, we
* could avoid needing the eviction lock. However, eviction occurs
* so rarely that it isn't worth bothering about in practice.
*/
-
+#ifdef __powerpc64__
+ /*
+ * Note: Success of this sequence has the side effect of invalidating
+ * the PTE, as we are setting it to LPTE_LOCKED and discarding the
+ * other bits, including LPTE_V.
+ */
__asm __volatile (
+ "1:\tldarx %1, 0, %3\n\t" /* load old value */
+ "and. %0,%1,%4\n\t" /* check if any bits set */
+ "bne 2f\n\t" /* exit if any set */
+ "stdcx. %5, 0, %3\n\t" /* attempt to store */
+ "bne- 1b\n\t" /* spin if failed */
+ "li %0, 1\n\t" /* success - retval = 1 */
+ "b 3f\n\t" /* we've succeeded */
+ "2:\n\t"
+ "stdcx. %1, 0, %3\n\t" /* clear reservation (74xx) */
+ "li %0, 0\n\t" /* failure - retval = 0 */
+ "3:\n\t"
+ : "=&r" (ret), "=&r"(temp), "=m" (pte->pte_hi)
+ : "r" ((volatile char *)&pte->pte_hi),
+ "r" (htobe64(bitmask)), "r" (htobe64(LPTE_LOCKED)),
+ "m" (pte->pte_hi)
+ : "cr0", "cr1", "cr2", "memory");
+ *oldhi = be64toh(temp);
+#else
+ /*
+ * This code is used on bridge mode only.
+ */
+ __asm __volatile (
"1:\tlwarx %1, 0, %3\n\t" /* load old value */
"and. %0,%1,%4\n\t" /* check if any bits set */
"bne 2f\n\t" /* exit if any set */
@@ -660,6 +691,7 @@ atomic_pte_lock(volatile struct lpte *pte, uint64_t bi
: "cr0", "cr1", "cr2", "memory");
*oldhi = (pte->pte_hi & 0xffffffff00000000ULL) | oldhihalf;
+#endif
return (ret);
}
_______________________________________________
svn-src-all@freebsd.org mailing list
https://lists.freebsd.org/mailman/listinfo/svn-src-all
To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
