[PATCH v1 2/6] RISC-V: Move the hwprobe syscall to its own file

Andrew Jones
2023-10-11T13:56:29Z

As Palmer says, hwprobe is "sort of its own thing now, and it's only
going to get bigger..."

Suggested-by: Palmer Dabbelt <palmer@dabbelt.com>
Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
---
arch/riscv/kernel/Makefile | 1 +
arch/riscv/kernel/sys_hwprobe.c | 276 ++++++++++++++++++++++++++++++++
arch/riscv/kernel/sys_riscv.c | 267 ------------------------------
3 files changed, 277 insertions(+), 267 deletions(-)
create mode 100644 arch/riscv/kernel/sys_hwprobe.c

diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
index 95cf25d48405..db7a43211b30 100644
--- a/arch/riscv/kernel/Makefile
+++ b/arch/riscv/kernel/Makefile
@@ -50,6 +50,7 @@ obj-y += setup.o
obj-y += signal.o
obj-y += syscall_table.o
obj-y += sys_riscv.o
+obj-y += sys_hwprobe.o
obj-y += time.o
obj-y += traps.o
obj-y += riscv_ksyms.o
diff --git a/arch/riscv/kernel/sys_hwprobe.c b/arch/riscv/kernel/sys_hwprobe.c
new file mode 100644
index 000000000000..69ad5f793374
--- /dev/null
+++ b/arch/riscv/kernel/sys_hwprobe.c
@@ -0,0 +1,276 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * The hwprobe interface, for allowing userspace to probe to see which features
+ * are supported by the hardware. See Documentation/riscv/hwprobe.rst for more
+ * details.
+ *
+ * Copyright (C) 2012 Regents of the University of California
+ * Copyright (C) 2014 Darius Rad <darius@bluespec.com>
+ * Copyright (C) 2017 SiFive
+ */
+
+#include <linux/syscalls.h>
+#include <asm/cacheflush.h>
+#include <asm/cpufeature.h>
+#include <asm/hwprobe.h>
+#include <asm/sbi.h>
+#include <asm/switch_to.h>
+#include <asm/uaccess.h>
+#include <asm/unistd.h>
+#include <asm/vector.h>
+#include <vdso/vsyscall.h>
+
+
+static void hwprobe_arch_id(struct riscv_hwprobe *pair,
+ const struct cpumask *cpus)
+{
+ u64 id = -1ULL;
+ bool first = true;
+ int cpu;
+
+ for_each_cpu(cpu, cpus) {
+ u64 cpu_id;
+
+ switch (pair->key) {
+ case RISCV_HWPROBE_KEY_MVENDORID:
+ cpu_id = riscv_cached_mvendorid(cpu);
+ break;
+ case RISCV_HWPROBE_KEY_MIMPID:
+ cpu_id = riscv_cached_mimpid(cpu);
+ break;
+ case RISCV_HWPROBE_KEY_MARCHID:
+ cpu_id = riscv_cached_marchid(cpu);
+ break;
+ }
+
+ if (first) {
+ id = cpu_id;
+ first = false;
+ }
+
+ /*
+ * If there's a mismatch for the given set, return -1 in the
+ * value.
+ */
+ if (id != cpu_id) {
+ id = -1ULL;
+ break;
+ }
+ }
+
+ pair->value = id;
+}
+
+static void hwprobe_isa_ext0(struct riscv_hwprobe *pair,
+ const struct cpumask *cpus)
+{
+ int cpu;
+ u64 missing = 0;
+
+ pair->value = 0;
+ if (has_fpu())
+ pair->value |= RISCV_HWPROBE_IMA_FD;
+
+ if (riscv_isa_extension_available(NULL, c))
+ pair->value |= RISCV_HWPROBE_IMA_C;
+
+ if (has_vector())
+ pair->value |= RISCV_HWPROBE_IMA_V;
+
+ /*
+ * Loop through and record extensions that 1) anyone has, and 2) anyone
+ * doesn't have.
+ */
+ for_each_cpu(cpu, cpus) {
+ struct riscv_isainfo *isainfo = &hart_isa[cpu];
+
+ if (riscv_isa_extension_available(isainfo->isa, ZBA))
+ pair->value |= RISCV_HWPROBE_EXT_ZBA;
+ else
+ missing |= RISCV_HWPROBE_EXT_ZBA;
+
+ if (riscv_isa_extension_available(isainfo->isa, ZBB))
+ pair->value |= RISCV_HWPROBE_EXT_ZBB;
+ else
+ missing |= RISCV_HWPROBE_EXT_ZBB;
+
+ if (riscv_isa_extension_available(isainfo->isa, ZBS))
+ pair->value |= RISCV_HWPROBE_EXT_ZBS;
+ else
+ missing |= RISCV_HWPROBE_EXT_ZBS;
+ }
+
+ /* Now turn off reporting features if any CPU is missing it. */
+ pair->value &= ~missing;
+}
+
+static u64 hwprobe_misaligned(const struct cpumask *cpus)
+{
+ int cpu;
+ u64 perf = -1ULL;
+
+ for_each_cpu(cpu, cpus) {
+ int this_perf = per_cpu(misaligned_access_speed, cpu);
+
+ if (perf == -1ULL)
+ perf = this_perf;
+
+ if (perf != this_perf) {
+ perf = RISCV_HWPROBE_MISALIGNED_UNKNOWN;
+ break;
+ }
+ }
+
+ if (perf == -1ULL)
+ return RISCV_HWPROBE_MISALIGNED_UNKNOWN;
+
+ return perf;
+}
+
+static void hwprobe_one_pair(struct riscv_hwprobe *pair,
+ const struct cpumask *cpus)
+{
+ switch (pair->key) {
+ case RISCV_HWPROBE_KEY_MVENDORID:
+ case RISCV_HWPROBE_KEY_MARCHID:
+ case RISCV_HWPROBE_KEY_MIMPID:
+ hwprobe_arch_id(pair, cpus);
+ break;
+ /*
+ * The kernel already assumes that the base single-letter ISA
+ * extensions are supported on all harts, and only supports the
+ * IMA base, so just cheat a bit here and tell that to
+ * userspace.
+ */
+ case RISCV_HWPROBE_KEY_BASE_BEHAVIOR:
+ pair->value = RISCV_HWPROBE_BASE_BEHAVIOR_IMA;
+ break;
+
+ case RISCV_HWPROBE_KEY_IMA_EXT_0:
+ hwprobe_isa_ext0(pair, cpus);
+ break;
+
+ case RISCV_HWPROBE_KEY_CPUPERF_0:
+ pair->value = hwprobe_misaligned(cpus);
+ break;
+
+ /*
+ * For forward compatibility, unknown keys don't fail the whole
+ * call, but get their element key set to -1 and value set to 0
+ * indicating they're unrecognized.
+ */
+ default:
+ pair->key = -1;
+ pair->value = 0;
+ break;
+ }
+}
+
+static int do_riscv_hwprobe(struct riscv_hwprobe __user *pairs,
+ size_t pair_count, size_t cpusetsize,
+ unsigned long __user *cpus_user,
+ unsigned int flags)
+{
+ size_t out;
+ int ret;
+ cpumask_t cpus;
+
+ /* Check the reserved flags. */
+ if (flags != 0)
+ return -EINVAL;
+
+ /*
+ * The interface supports taking in a CPU mask, and returns values that
+ * are consistent across that mask. Allow userspace to specify NULL and
+ * 0 as a shortcut to all online CPUs.
+ */
+ cpumask_clear(&cpus);
+ if (!cpusetsize && !cpus_user) {
+ cpumask_copy(&cpus, cpu_online_mask);
+ } else {
+ if (cpusetsize > cpumask_size())
+ cpusetsize = cpumask_size();
+
+ ret = copy_from_user(&cpus, cpus_user, cpusetsize);
+ if (ret)
+ return -EFAULT;
+
+ /*
+ * Userspace must provide at least one online CPU, without that
+ * there's no way to define what is supported.
+ */
+ cpumask_and(&cpus, &cpus, cpu_online_mask);
+ if (cpumask_empty(&cpus))
+ return -EINVAL;
+ }
+
+ for (out = 0; out < pair_count; out++, pairs++) {
+ struct riscv_hwprobe pair;
+
+ if (get_user(pair.key, &pairs->key))
+ return -EFAULT;
+
+ pair.value = 0;
+ hwprobe_one_pair(&pair, &cpus);
+ ret = put_user(pair.key, &pairs->key);
+ if (ret == 0)
+ ret = put_user(pair.value, &pairs->value);
+
+ if (ret)
+ return -EFAULT;
+ }
+
+ return 0;
+}
+
+#ifdef CONFIG_MMU
+
+static int __init init_hwprobe_vdso_data(void)
+{
+ struct vdso_data *vd = __arch_get_k_vdso_data();
+ struct arch_vdso_data *avd = &vd->arch_data;
+ u64 id_bitsmash = 0;
+ struct riscv_hwprobe pair;
+ int key;
+
+ /*
+ * Initialize vDSO data with the answers for the "all CPUs" case, to
+ * save a syscall in the common case.
+ */
+ for (key = 0; key <= RISCV_HWPROBE_MAX_KEY; key++) {
+ pair.key = key;
+ hwprobe_one_pair(&pair, cpu_online_mask);
+
+ WARN_ON_ONCE(pair.key < 0);
+
+ avd->all_cpu_hwprobe_values[key] = pair.value;
+ /*
+ * Smash together the vendor, arch, and impl IDs to see if
+ * they're all 0 or any negative.
+ */
+ if (key <= RISCV_HWPROBE_KEY_MIMPID)
+ id_bitsmash |= pair.value;
+ }
+
+ /*
+ * If the arch, vendor, and implementation ID are all the same across
+ * all harts, then assume all CPUs are the same, and allow the vDSO to
+ * answer queries for arbitrary masks. However if all values are 0 (not
+ * populated) or any value returns -1 (varies across CPUs), then the
+ * vDSO should defer to the kernel for exotic cpu masks.
+ */
+ avd->homogeneous_cpus = id_bitsmash != 0 && id_bitsmash != -1;
+ return 0;
+}
+
+arch_initcall_sync(init_hwprobe_vdso_data);
+
+#endif /* CONFIG_MMU */
+
+SYSCALL_DEFINE5(riscv_hwprobe, struct riscv_hwprobe __user *, pairs,
+ size_t, pair_count, size_t, cpusetsize, unsigned long __user *,
+ cpus, unsigned int, flags)
+{
+ return do_riscv_hwprobe(pairs, pair_count, cpusetsize,
+ cpus, flags);
+}
diff --git a/arch/riscv/kernel/sys_riscv.c b/arch/riscv/kernel/sys_riscv.c
index ed3545eb1b2b..f1c1416a9f1e 100644
--- a/arch/riscv/kernel/sys_riscv.c
+++ b/arch/riscv/kernel/sys_riscv.c
@@ -7,15 +7,7 @@

#include <linux/syscalls.h>
#include <asm/cacheflush.h>
-#include <asm/cpufeature.h>
-#include <asm/hwprobe.h>
-#include <asm/sbi.h>
-#include <asm/vector.h>
-#include <asm/switch_to.h>
-#include <asm/uaccess.h>
-#include <asm/unistd.h>
#include <asm-generic/mman-common.h>
-#include <vdso/vsyscall.h>

static long riscv_sys_mmap(unsigned long addr, unsigned long len,
unsigned long prot, unsigned long flags,
@@ -77,265 +69,6 @@ SYSCALL_DEFINE3(riscv_flush_icache, uintptr_t, start, uintptr_t, end,
return 0;
}

-/*
- * The hwprobe interface, for allowing userspace to probe to see which features
- * are supported by the hardware. See Documentation/riscv/hwprobe.rst for more
- * details.
- */
-static void hwprobe_arch_id(struct riscv_hwprobe *pair,
- const struct cpumask *cpus)
-{
- u64 id = -1ULL;
- bool first = true;
- int cpu;
-
- for_each_cpu(cpu, cpus) {
- u64 cpu_id;
-
- switch (pair->key) {
- case RISCV_HWPROBE_KEY_MVENDORID:
- cpu_id = riscv_cached_mvendorid(cpu);
- break;
- case RISCV_HWPROBE_KEY_MIMPID:
- cpu_id = riscv_cached_mimpid(cpu);
- break;
- case RISCV_HWPROBE_KEY_MARCHID:
- cpu_id = riscv_cached_marchid(cpu);
- break;
- }
-
- if (first) {
- id = cpu_id;
- first = false;
- }
-
- /*
- * If there's a mismatch for the given set, return -1 in the
- * value.
- */
- if (id != cpu_id) {
- id = -1ULL;
- break;
- }
- }
-
- pair->value = id;
-}
-
-static void hwprobe_isa_ext0(struct riscv_hwprobe *pair,
- const struct cpumask *cpus)
-{
- int cpu;
- u64 missing = 0;
-
- pair->value = 0;
- if (has_fpu())
- pair->value |= RISCV_HWPROBE_IMA_FD;
-
- if (riscv_isa_extension_available(NULL, c))
- pair->value |= RISCV_HWPROBE_IMA_C;
-
- if (has_vector())
- pair->value |= RISCV_HWPROBE_IMA_V;
-
- /*
- * Loop through and record extensions that 1) anyone has, and 2) anyone
- * doesn't have.
- */
- for_each_cpu(cpu, cpus) {
- struct riscv_isainfo *isainfo = &hart_isa[cpu];
-
- if (riscv_isa_extension_available(isainfo->isa, ZBA))
- pair->value |= RISCV_HWPROBE_EXT_ZBA;
- else
- missing |= RISCV_HWPROBE_EXT_ZBA;
-
- if (riscv_isa_extension_available(isainfo->isa, ZBB))
- pair->value |= RISCV_HWPROBE_EXT_ZBB;
- else
- missing |= RISCV_HWPROBE_EXT_ZBB;
-
- if (riscv_isa_extension_available(isainfo->isa, ZBS))
- pair->value |= RISCV_HWPROBE_EXT_ZBS;
- else
- missing |= RISCV_HWPROBE_EXT_ZBS;
- }
-
- /* Now turn off reporting features if any CPU is missing it. */
- pair->value &= ~missing;
-}
-
-static u64 hwprobe_misaligned(const struct cpumask *cpus)
-{
- int cpu;
- u64 perf = -1ULL;
-
- for_each_cpu(cpu, cpus) {
- int this_perf = per_cpu(misaligned_access_speed, cpu);
-
- if (perf == -1ULL)
- perf = this_perf;
-
- if (perf != this_perf) {
- perf = RISCV_HWPROBE_MISALIGNED_UNKNOWN;
- break;
- }
- }
-
- if (perf == -1ULL)
- return RISCV_HWPROBE_MISALIGNED_UNKNOWN;
-
- return perf;
-}
-
-static void hwprobe_one_pair(struct riscv_hwprobe *pair,
- const struct cpumask *cpus)
-{
- switch (pair->key) {
- case RISCV_HWPROBE_KEY_MVENDORID:
- case RISCV_HWPROBE_KEY_MARCHID:
- case RISCV_HWPROBE_KEY_MIMPID:
- hwprobe_arch_id(pair, cpus);
- break;
- /*
- * The kernel already assumes that the base single-letter ISA
- * extensions are supported on all harts, and only supports the
- * IMA base, so just cheat a bit here and tell that to
- * userspace.
- */
- case RISCV_HWPROBE_KEY_BASE_BEHAVIOR:
- pair->value = RISCV_HWPROBE_BASE_BEHAVIOR_IMA;
- break;
-
- case RISCV_HWPROBE_KEY_IMA_EXT_0:
- hwprobe_isa_ext0(pair, cpus);
- break;
-
- case RISCV_HWPROBE_KEY_CPUPERF_0:
- pair->value = hwprobe_misaligned(cpus);
- break;
-
- /*
- * For forward compatibility, unknown keys don't fail the whole
- * call, but get their element key set to -1 and value set to 0
- * indicating they're unrecognized.
- */
- default:
- pair->key = -1;
- pair->value = 0;
- break;
- }
-}
-
-static int do_riscv_hwprobe(struct riscv_hwprobe __user *pairs,
- size_t pair_count, size_t cpusetsize,
- unsigned long __user *cpus_user,
- unsigned int flags)
-{
- size_t out;
- int ret;
- cpumask_t cpus;
-
- /* Check the reserved flags. */
- if (flags != 0)
- return -EINVAL;
-
- /*
- * The interface supports taking in a CPU mask, and returns values that
- * are consistent across that mask. Allow userspace to specify NULL and
- * 0 as a shortcut to all online CPUs.
- */
- cpumask_clear(&cpus);
- if (!cpusetsize && !cpus_user) {
- cpumask_copy(&cpus, cpu_online_mask);
- } else {
- if (cpusetsize > cpumask_size())
- cpusetsize = cpumask_size();
-
- ret = copy_from_user(&cpus, cpus_user, cpusetsize);
- if (ret)
- return -EFAULT;
-
- /*
- * Userspace must provide at least one online CPU, without that
- * there's no way to define what is supported.
- */
- cpumask_and(&cpus, &cpus, cpu_online_mask);
- if (cpumask_empty(&cpus))
- return -EINVAL;
- }
-
- for (out = 0; out < pair_count; out++, pairs++) {
- struct riscv_hwprobe pair;
-
- if (get_user(pair.key, &pairs->key))
- return -EFAULT;
-
- pair.value = 0;
- hwprobe_one_pair(&pair, &cpus);
- ret = put_user(pair.key, &pairs->key);
- if (ret == 0)
- ret = put_user(pair.value, &pairs->value);
-
- if (ret)
- return -EFAULT;
- }
-
- return 0;
-}
-
-#ifdef CONFIG_MMU
-
-static int __init init_hwprobe_vdso_data(void)
-{
- struct vdso_data *vd = __arch_get_k_vdso_data();
- struct arch_vdso_data *avd = &vd->arch_data;
- u64 id_bitsmash = 0;
- struct riscv_hwprobe pair;
- int key;
-
- /*
- * Initialize vDSO data with the answers for the "all CPUs" case, to
- * save a syscall in the common case.
- */
- for (key = 0; key <= RISCV_HWPROBE_MAX_KEY; key++) {
- pair.key = key;
- hwprobe_one_pair(&pair, cpu_online_mask);
-
- WARN_ON_ONCE(pair.key < 0);
-
- avd->all_cpu_hwprobe_values[key] = pair.value;
- /*
- * Smash together the vendor, arch, and impl IDs to see if
- * they're all 0 or any negative.
- */
- if (key <= RISCV_HWPROBE_KEY_MIMPID)
- id_bitsmash |= pair.value;
- }
-
- /*
- * If the arch, vendor, and implementation ID are all the same across
- * all harts, then assume all CPUs are the same, and allow the vDSO to
- * answer queries for arbitrary masks. However if all values are 0 (not
- * populated) or any value returns -1 (varies across CPUs), then the
- * vDSO should defer to the kernel for exotic cpu masks.
- */
- avd->homogeneous_cpus = id_bitsmash != 0 && id_bitsmash != -1;
- return 0;
-}
-
-arch_initcall_sync(init_hwprobe_vdso_data);
-
-#endif /* CONFIG_MMU */
-
-SYSCALL_DEFINE5(riscv_hwprobe, struct riscv_hwprobe __user *, pairs,
- size_t, pair_count, size_t, cpusetsize, unsigned long __user *,
- cpus, unsigned int, flags)
-{
- return do_riscv_hwprobe(pairs, pair_count, cpusetsize,
- cpus, flags);
-}
-
/* Not defined using SYSCALL_DEFINE0 to avoid error injection */
asmlinkage long __riscv_sys_ni_syscall(const struct pt_regs *__unused)
{
--
2.41.0