We can't call kstat_create(9) when bringing up the secondary CPUs as it

uses an rwlock and curproc isn't initialized yet for these CPUs at this
point.  As a result we hit a "locking against myself" panic if there is
any lock contention.

Fix this by adding a new ci_midr member to struct cpu_info which gets
initialized when we identify the CPUs and use that to attach the kstat
stuff.

ok tobhe@, dlg@

diff --git a/sys/arch/arm64/arm64/cpu.c b/sys/arch/arm64/arm64/cpu.c
index ca530c0..70382cc 100644 (file)
--- a/sys/arch/arm64/arm64/cpu.c
+++ b/sys/arch/arm64/arm64/cpu.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: cpu.c,v 1.102 2023/12/26 09:19:15 kettenis Exp $      */
+/*     $OpenBSD: cpu.c,v 1.103 2024/01/15 11:58:45 kettenis Exp $      */
 
 /*
  * Copyright (c) 2016 Dale Rahn <drahn@dalerahn.com>
@@ -275,6 +275,7 @@ cpu_identify(struct cpu_info *ci)
        midr = READ_SPECIALREG(midr_el1);
        impl = CPU_IMPL(midr);
        part = CPU_PART(midr);
+       ci->ci_midr = midr;
 
        for (i = 0; cpu_implementers[i].name; i++) {
                if (impl == cpu_implementers[i].id) {
@@ -947,14 +948,14 @@ cpu_attach(struct device *parent, struct device *dev, void *aux)
                }
 
                cpu_init();
-
-#if NKSTAT > 0
-               cpu_kstat_attach(ci);
-#endif
 #ifdef MULTIPROCESSOR
        }
 #endif
 
+#if NKSTAT > 0
+       cpu_kstat_attach(ci);
+#endif
+
        opp = OF_getpropint(ci->ci_node, "operating-points-v2", 0);
        if (opp)
                cpu_opp_init(ci, opp);
@@ -1204,10 +1205,6 @@ cpu_init_secondary(struct cpu_info *ci)
 
        spllower(IPL_NONE);
 
-#if NKSTAT > 0
-       cpu_kstat_attach(ci);
-#endif
-
        sched_toidle();
 }
 
@@ -1862,25 +1859,22 @@ cpu_kstat_attach(struct cpu_info *ci)
 {
        struct kstat *ks;
        struct cpu_kstats *ck;
-
-       uint64_t midr, impl, part;
+       uint64_t impl, part;
        const char *impl_name = NULL, *part_name = NULL;
        const struct cpu_cores *coreselecter = cpu_cores_none;
-       size_t i;
+       int i;
 
        ks = kstat_create(ci->ci_dev->dv_xname, 0, "mach", 0, KSTAT_T_KV, 0);
        if (ks == NULL) {
                printf("%s: unable to create cpu kstats\n",
                    ci->ci_dev->dv_xname);
-               /* printf? */
                return;
        }
 
        ck = malloc(sizeof(*ck), M_DEVBUF, M_WAITOK);
 
-       midr = READ_SPECIALREG(midr_el1);
-       impl = CPU_IMPL(midr);
-       part = CPU_PART(midr);
+       impl = CPU_IMPL(ci->ci_midr);
+       part = CPU_PART(ci->ci_midr);
 
        for (i = 0; cpu_implementers[i].name; i++) {
                if (impl == cpu_implementers[i].id) {
@@ -1913,7 +1907,7 @@ cpu_kstat_attach(struct cpu_info *ci)
 
        kstat_kv_init(&ck->ck_rev, "rev", KSTAT_KV_T_ISTR);
        snprintf(kstat_kv_istr(&ck->ck_rev), sizeof(kstat_kv_istr(&ck->ck_rev)),
-           "r%llup%llu", CPU_VAR(midr), CPU_REV(midr));
+           "r%llup%llu", CPU_VAR(ci->ci_midr), CPU_REV(ci->ci_midr));
 
        ks->ks_softc = ci;
        ks->ks_data = ck;

diff --git a/sys/arch/arm64/include/cpu.h b/sys/arch/arm64/include/cpu.h
index a457f27..37ae5c4 100644 (file)
--- a/sys/arch/arm64/include/cpu.h
+++ b/sys/arch/arm64/include/cpu.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: cpu.h,v 1.40 2023/12/26 09:19:15 kettenis Exp $ */
+/* $OpenBSD: cpu.h,v 1.41 2024/01/15 11:58:45 kettenis Exp $ */
 /*
  * Copyright (c) 2016 Dale Rahn <drahn@dalerahn.com>
  *
@@ -116,6 +116,7 @@ struct cpu_info {
 
        u_int32_t               ci_cpuid;
        uint64_t                ci_mpidr;
+       uint64_t                ci_midr;
        u_int                   ci_acpi_proc_id;
        int                     ci_node;
        struct cpu_info         *ci_self;