git: ac4fa5838bb3 - main - arm64: Add a new CPU feature framework
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Date: Fri, 24 Jan 2025 12:11:49 UTC
The branch main has been updated by andrew:
URL: https://cgit.FreeBSD.org/src/commit/?id=ac4fa5838bb33f0c3ba05fce02d41164bd84a560
commit ac4fa5838bb33f0c3ba05fce02d41164bd84a560
Author: Andrew Turner <andrew@FreeBSD.org>
AuthorDate: 2025-01-24 11:42:29 +0000
Commit: Andrew Turner <andrew@FreeBSD.org>
CommitDate: 2025-01-24 12:09:28 +0000
arm64: Add a new CPU feature framework
This will be used to enable features that are discoverable on boot. It
has support to check if a feature needs to be enabled, and if there is
any errata associated with the feature that mean it shouldn't be
enabled. It can also be used to enable errata workarounds that aren't
associated with a specific feature, e.g. where we need to trap access
to a register in userspace to emulate it.
As some features need to be enabled early, while others can wait there
are two options for when to enable a feature:
* CPU_FEAT_EARLY_BOOT: The feature will be enabled early in the boot.
On the boot CPU this is in initarm, while on secondary CPUs this
is before signalling the CPU has started.
* CPU_FEAT_AFTER_DEV: The feature will be enabled after devices have
attached but before interrupts are enabled.
There are also two scopes for where to enable the feature:
* CPU_FEAT_PER_CPU: The feature will be checked and enabled on all
CPU cores.
* CPU_FEAT_SYSTEM: The feature will only be checked and enabled on a
single core.
It is expected the former will be used for most features, while the
latter is for features that set a global variable to be checked.
Sponsored by: Arm Ltd
Differential Revision: https://reviews.freebsd.org/D47812
---
sys/arm64/arm64/cpu_feat.c | 119 +++++++++++++++++++++++++++++++++++++++++++
sys/arm64/arm64/machdep.c | 4 ++
sys/arm64/arm64/mp_machdep.c | 5 ++
sys/arm64/include/cpu_feat.h | 88 ++++++++++++++++++++++++++++++++
sys/conf/files.arm64 | 1 +
5 files changed, 217 insertions(+)
diff --git a/sys/arm64/arm64/cpu_feat.c b/sys/arm64/arm64/cpu_feat.c
new file mode 100644
index 000000000000..cc262394913d
--- /dev/null
+++ b/sys/arm64/arm64/cpu_feat.c
@@ -0,0 +1,119 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2024 Arm Ltd
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/kernel.h>
+
+#include <machine/cpu.h>
+#include <machine/cpu_feat.h>
+
+/* TODO: Make this a list if we ever grow a callback other than smccc_errata */
+static cpu_feat_errata_check_fn cpu_feat_check_cb = NULL;
+
+void
+enable_cpu_feat(uint32_t stage)
+{
+ struct cpu_feat **featp, *feat;
+ uint32_t midr;
+ u_int errata_count, *errata_list;
+ cpu_feat_errata errata_status;
+
+ MPASS((stage & ~CPU_FEAT_STAGE_MASK) == 0);
+
+ midr = get_midr();
+ SET_FOREACH(featp, cpu_feat_set) {
+ feat = *featp;
+
+ /* Run the enablement code at the correct stage of boot */
+ if ((feat->feat_flags & CPU_FEAT_STAGE_MASK) != stage)
+ continue;
+
+ /* If the feature is system wide run on a single CPU */
+ if ((feat->feat_flags & CPU_FEAT_SCOPE_MASK)==CPU_FEAT_SYSTEM &&
+ PCPU_GET(cpuid) != 0)
+ continue;
+
+ if (feat->feat_check != NULL && !feat->feat_check(feat, midr))
+ continue;
+
+ /*
+ * Check if the feature has any errata that may need a
+ * workaround applied (or it is to install the workaround for
+ * known errata.
+ */
+ errata_status = ERRATA_NONE;
+ errata_list = NULL;
+ errata_count = 0;
+ if (feat->feat_has_errata != NULL) {
+ if (feat->feat_has_errata(feat, midr, &errata_list,
+ &errata_count)) {
+ /* Assume we are affected */
+ errata_status = ERRATA_AFFECTED;
+ }
+ }
+
+ if (errata_status == ERRATA_AFFECTED &&
+ cpu_feat_check_cb != NULL) {
+ for (int i = 0; i < errata_count; i++) {
+ cpu_feat_errata new_status;
+
+ /* Check if affected by this erratum */
+ new_status = cpu_feat_check_cb(feat,
+ errata_list[i]);
+ if (new_status != ERRATA_UNKNOWN) {
+ errata_status = new_status;
+ errata_list = &errata_list[i];
+ errata_count = 1;
+ break;
+ }
+ }
+ }
+
+ /* Shouldn't be possible */
+ MPASS(errata_status != ERRATA_UNKNOWN);
+
+ feat->feat_enable(feat, errata_status, errata_list,
+ errata_count);
+ }
+}
+
+static void
+enable_cpu_feat_after_dev(void *dummy __unused)
+{
+ MPASS(PCPU_GET(cpuid) == 0);
+ enable_cpu_feat(CPU_FEAT_AFTER_DEV);
+}
+SYSINIT(enable_cpu_feat_after_dev, SI_SUB_CONFIGURE, SI_ORDER_MIDDLE,
+ enable_cpu_feat_after_dev, NULL);
+
+void
+cpu_feat_register_errata_check(cpu_feat_errata_check_fn cb)
+{
+ MPASS(cpu_feat_check_cb == NULL);
+ cpu_feat_check_cb = cb;
+}
diff --git a/sys/arm64/arm64/machdep.c b/sys/arm64/arm64/machdep.c
index 03f041851c8f..db223e011c67 100644
--- a/sys/arm64/arm64/machdep.c
+++ b/sys/arm64/arm64/machdep.c
@@ -77,6 +77,7 @@
#include <machine/armreg.h>
#include <machine/cpu.h>
+#include <machine/cpu_feat.h>
#include <machine/debug_monitor.h>
#include <machine/hypervisor.h>
#include <machine/kdb.h>
@@ -999,6 +1000,9 @@ initarm(struct arm64_bootparams *abp)
panic("Invalid bus configuration: %s",
kern_getenv("kern.cfg.order"));
+ /* Detect early CPU feature support */
+ enable_cpu_feat(CPU_FEAT_EARLY_BOOT);
+
/*
* Check if pointer authentication is available on this system, and
* if so enable its use. This needs to be called before init_proc0
diff --git a/sys/arm64/arm64/mp_machdep.c b/sys/arm64/arm64/mp_machdep.c
index 636f26fba939..fe04e39edecc 100644
--- a/sys/arm64/arm64/mp_machdep.c
+++ b/sys/arm64/arm64/mp_machdep.c
@@ -56,6 +56,7 @@
#include <machine/machdep.h>
#include <machine/cpu.h>
+#include <machine/cpu_feat.h>
#include <machine/debug_monitor.h>
#include <machine/intr.h>
#include <machine/smp.h>
@@ -224,6 +225,9 @@ init_secondary(uint64_t cpu)
/* Ensure the stores in identify_cpu have completed */
atomic_thread_fence_acq_rel();
+ /* Detect early CPU feature support */
+ enable_cpu_feat(CPU_FEAT_EARLY_BOOT);
+
/* Signal the BSP and spin until it has released all APs. */
atomic_add_int(&aps_started, 1);
while (!atomic_load_int(&aps_ready))
@@ -241,6 +245,7 @@ init_secondary(uint64_t cpu)
pcpup->pc_curpmap = pmap0;
install_cpu_errata();
+ enable_cpu_feat(CPU_FEAT_AFTER_DEV);
intr_pic_init_secondary();
diff --git a/sys/arm64/include/cpu_feat.h b/sys/arm64/include/cpu_feat.h
new file mode 100644
index 000000000000..9fe6a9dd95d9
--- /dev/null
+++ b/sys/arm64/include/cpu_feat.h
@@ -0,0 +1,88 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2024 Arm Ltd
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef _MACHINE_CPU_FEAT_H_
+#define _MACHINE_CPU_FEAT_H_
+
+#include <sys/linker_set.h>
+
+typedef enum {
+ ERRATA_UNKNOWN, /* Unknown erratum */
+ ERRATA_NONE, /* No errata for this feature on this system. */
+ ERRATA_AFFECTED, /* There is errata on this system. */
+ ERRATA_FW_MITIGAION, /* There is errata, and a firmware */
+ /* mitigation. The mitigation may need a */
+ /* kernel component. */
+} cpu_feat_errata;
+
+#define CPU_FEAT_STAGE_MASK 0x00000001
+#define CPU_FEAT_EARLY_BOOT 0x00000000
+#define CPU_FEAT_AFTER_DEV 0x00000001
+
+#define CPU_FEAT_SCOPE_MASK 0x00000010
+#define CPU_FEAT_PER_CPU 0x00000000
+#define CPU_FEAT_SYSTEM 0x00000010
+
+struct cpu_feat;
+
+typedef bool (cpu_feat_check)(const struct cpu_feat *, u_int);
+typedef bool (cpu_feat_has_errata)(const struct cpu_feat *, u_int,
+ u_int **, u_int *);
+typedef void (cpu_feat_enable)(const struct cpu_feat *, cpu_feat_errata,
+ u_int *, u_int);
+
+struct cpu_feat {
+ const char *feat_name;
+ cpu_feat_check *feat_check;
+ cpu_feat_has_errata *feat_has_errata;
+ cpu_feat_enable *feat_enable;
+ uint32_t feat_flags;
+};
+SET_DECLARE(cpu_feat_set, struct cpu_feat);
+
+/*
+ * Allow drivers to mark an erratum as worked around, e.g. the Errata
+ * Management ABI may know the workaround isn't needed on a given system.
+ */
+typedef cpu_feat_errata (*cpu_feat_errata_check_fn)(const struct cpu_feat *,
+ u_int);
+void cpu_feat_register_errata_check(cpu_feat_errata_check_fn);
+
+void enable_cpu_feat(uint32_t);
+
+/* Check if an erratum is in the list of errata */
+static inline bool
+cpu_feat_has_erratum(u_int *errata_list, u_int errata_count, u_int erratum)
+{
+ for (u_int i = 0; i < errata_count; i++)
+ if (errata_list[0] == erratum)
+ return (true);
+
+ return (false);
+}
+
+#endif /* _MACHINE_CPU_FEAT_H_ */
diff --git a/sys/conf/files.arm64 b/sys/conf/files.arm64
index ed251b7ae0d7..c095bae42996 100644
--- a/sys/conf/files.arm64
+++ b/sys/conf/files.arm64
@@ -32,6 +32,7 @@ arm64/arm64/busdma_machdep.c standard
arm64/arm64/clock.c standard
arm64/arm64/copyinout.S standard
arm64/arm64/cpu_errata.c standard
+arm64/arm64/cpu_feat.c standard
arm64/arm64/cpufunc_asm.S standard
arm64/arm64/db_disasm.c optional ddb
arm64/arm64/db_interface.c optional ddb