Module Name: src
Committed By: riastradh
Date: Sat Feb 12 17:09:07 UTC 2022
Modified Files:
src/sys/arch/hppa/hppa: ipifuncs.c
Log Message:
hppa: Membar audit in ipifuncs.c.
To generate a diff of this commit:
cvs rdiff -u -r1.5 -r1.6 src/sys/arch/hppa/hppa/ipifuncs.c
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/hppa/hppa/ipifuncs.c
diff -u src/sys/arch/hppa/hppa/ipifuncs.c:1.5 src/sys/arch/hppa/hppa/ipifuncs.c:1.6
--- src/sys/arch/hppa/hppa/ipifuncs.c:1.5 Mon Apr 15 20:45:08 2019
+++ src/sys/arch/hppa/hppa/ipifuncs.c Sat Feb 12 17:09:07 2022
@@ -1,4 +1,4 @@
-/* $NetBSD: ipifuncs.c,v 1.5 2019/04/15 20:45:08 skrll Exp $ */
+/* $NetBSD: ipifuncs.c,v 1.6 2022/02/12 17:09:07 riastradh Exp $ */
/* $OpenBSD: ipi.c,v 1.4 2011/01/14 13:20:06 jsing Exp $ */
/*
@@ -83,6 +83,7 @@ hppa_ipi_intr(void *arg)
/* Handle an IPI. */
ipi_pending = atomic_swap_ulong(&ci->ci_ipi, 0);
+ membar_enter(); /* matches membar_exit in xc_send_ipi, cpu_ipi */
KASSERT(ipi_pending);
@@ -108,10 +109,22 @@ hppa_ipi_send(struct cpu_info *ci, u_lon
atomic_or_ulong(&ci->ci_ipi, (1L << ipi));
- /* Send an IPI to the specified CPU by triggering EIR{1} (irq 30). */
+ /*
+ * Send an IPI to the specified CPU by triggering EIR{1} (irq 30).
+ *
+ * The `load-acquire operation' matching this store-release is
+ * somewhere inside the silicon or firmware -- the point is
+ * that the store to ci->ci_ipi above must happen before
+ * writing to EIR{1}; there is conceptually some magic inside
+ * the silicon or firmware on the target CPU that effectively
+ * does
+ *
+ * if (atomic_load_acquire(&cpu->io_eir)) {
+ * enter_interrupt_vector();
+ * }
+ */
cpu = (struct iomod *)(ci->ci_hpa);
- cpu->io_eir = 1;
- membar_sync();
+ atomic_store_release(&cpu->io_eir, 1);
return 0;
}
@@ -156,6 +169,7 @@ xc_send_ipi(struct cpu_info *ci)
KASSERT(kpreempt_disabled());
KASSERT(curcpu() != ci);
+ membar_exit(); /* matches membar_enter in hppa_ipi_intr */
if (ci) {
/* Unicast: remote CPU. */
hppa_ipi_send(ci, HPPA_IPI_XCALL);
@@ -171,6 +185,7 @@ cpu_ipi(struct cpu_info *ci)
KASSERT(kpreempt_disabled());
KASSERT(curcpu() != ci);
+ membar_exit(); /* matches membar_enter in hppa_ipi_intr */
if (ci) {
/* Unicast: remote CPU. */
hppa_ipi_send(ci, HPPA_IPI_GENERIC);
