[PATCH v5 05/17] riscv: Extend cpufeature.c to detect vendor extensions

Charlie Jenkins
2024-05-03T04:46:55Z

Separate vendor extensions out into one struct per vendor
instead of adding vendor extensions onto riscv_isa_ext.

Add a hidden config RISCV_ISA_VENDOR_EXT to conditionally include this
code.

The xtheadvector vendor extension is added using these changes.

Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
---
arch/riscv/Kconfig | 2 +
arch/riscv/Kconfig.vendor | 19 +++++
arch/riscv/include/asm/cpufeature.h | 18 +++++
arch/riscv/include/asm/vendor_extensions.h | 34 +++++++++
arch/riscv/include/asm/vendor_extensions/thead.h | 16 ++++
arch/riscv/kernel/Makefile | 2 +
arch/riscv/kernel/cpufeature.c | 93 +++++++++++++++++++-----
arch/riscv/kernel/vendor_extensions.c | 18 +++++
arch/riscv/kernel/vendor_extensions/Makefile | 3 +
arch/riscv/kernel/vendor_extensions/thead.c | 18 +++++
10 files changed, 203 insertions(+), 20 deletions(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index be09c8836d56..fec86fba3acd 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -759,6 +759,8 @@ config RISCV_EFFICIENT_UNALIGNED_ACCESS

endchoice

+source "arch/riscv/Kconfig.vendor"
+
endmenu # "Platform type"

menu "Kernel features"
diff --git a/arch/riscv/Kconfig.vendor b/arch/riscv/Kconfig.vendor
new file mode 100644
index 000000000000..85ac30496b0e
--- /dev/null
+++ b/arch/riscv/Kconfig.vendor
@@ -0,0 +1,19 @@
+menu "Vendor extensions"
+
+config RISCV_ISA_VENDOR_EXT
+ bool
+
+menu "T-Head"
+config RISCV_ISA_VENDOR_EXT_THEAD
+ bool "T-Head vendor extension support"
+ select RISCV_ISA_VENDOR_EXT
+ default y
+ help
+ Say N here to disable detection of and support for all T-Head vendor
+ extensions. Without this option enabled, T-Head vendor extensions will
+ not be detected at boot and their presence not reported to userspace.
+
+ If you don't know what to do here, say Y.
+endmenu
+
+endmenu
diff --git a/arch/riscv/include/asm/cpufeature.h b/arch/riscv/include/asm/cpufeature.h
index 0c4f08577015..fedd479ccfd1 100644
--- a/arch/riscv/include/asm/cpufeature.h
+++ b/arch/riscv/include/asm/cpufeature.h
@@ -35,6 +35,24 @@ extern u32 riscv_vlenb_of;

void riscv_user_isa_enable(void);

+#define _RISCV_ISA_EXT_DATA(_name, _id, _subset_exts, _subset_exts_size) { \
+ .name = #_name, \
+ .property = #_name, \
+ .id = _id, \
+ .subset_ext_ids = _subset_exts, \
+ .subset_ext_size = _subset_exts_size \
+}
+
+#define __RISCV_ISA_EXT_DATA(_name, _id) _RISCV_ISA_EXT_DATA(_name, _id, NULL, 0)
+
+/* Used to declare pure "lasso" extension (Zk for instance) */
+#define __RISCV_ISA_EXT_BUNDLE(_name, _bundled_exts) \
+ _RISCV_ISA_EXT_DATA(_name, RISCV_ISA_EXT_INVALID, _bundled_exts, ARRAY_SIZE(_bundled_exts))
+
+/* Used to declare extensions that are a superset of other extensions (Zvbb for instance) */
+#define __RISCV_ISA_EXT_SUPERSET(_name, _id, _sub_exts) \
+ _RISCV_ISA_EXT_DATA(_name, _id, _sub_exts, ARRAY_SIZE(_sub_exts))
+
#if defined(CONFIG_RISCV_MISALIGNED)
bool check_unaligned_access_emulated_all_cpus(void);
void unaligned_emulation_finish(void);
diff --git a/arch/riscv/include/asm/vendor_extensions.h b/arch/riscv/include/asm/vendor_extensions.h
new file mode 100644
index 000000000000..bf4dac66e6e6
--- /dev/null
+++ b/arch/riscv/include/asm/vendor_extensions.h
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2024 Rivos, Inc
+ */
+
+#ifndef _ASM_VENDOR_EXTENSIONS_H
+#define _ASM_VENDOR_EXTENSIONS_H
+
+#include <asm/cpufeature.h>
+
+#include <linux/array_size.h>
+#include <linux/types.h>
+
+/*
+ * The extension keys of each vendor must be strictly less than this value.
+ */
+#define RISCV_ISA_VENDOR_EXT_MAX 32
+
+struct riscv_isavendorinfo {
+ DECLARE_BITMAP(isa, RISCV_ISA_VENDOR_EXT_MAX);
+};
+
+struct riscv_isa_vendor_ext_data_list {
+ const size_t ext_data_count;
+ const struct riscv_isa_ext_data *ext_data;
+ struct riscv_isavendorinfo per_hart_isa_bitmap[NR_CPUS];
+ struct riscv_isavendorinfo all_harts_isa_bitmap;
+};
+
+extern struct riscv_isa_vendor_ext_data_list *riscv_isa_vendor_ext_list[];
+
+extern const size_t riscv_isa_vendor_ext_list_size;
+
+#endif /* _ASM_VENDOR_EXTENSIONS_H */
diff --git a/arch/riscv/include/asm/vendor_extensions/thead.h b/arch/riscv/include/asm/vendor_extensions/thead.h
new file mode 100644
index 000000000000..48421d1553ad
--- /dev/null
+++ b/arch/riscv/include/asm/vendor_extensions/thead.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_RISCV_VENDOR_EXTENSIONS_THEAD_H
+#define _ASM_RISCV_VENDOR_EXTENSIONS_THEAD_H
+
+#include <asm/vendor_extensions.h>
+
+#include <linux/types.h>
+
+/*
+ * Extension keys must be strictly less than RISCV_ISA_VENDOR_EXT_MAX.
+ */
+#define RISCV_ISA_VENDOR_EXT_XTHEADVECTOR 0
+
+extern struct riscv_isa_vendor_ext_data_list riscv_isa_vendor_ext_list_thead;
+
+#endif
diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
index 81d94a8ee10f..53361c50fb46 100644
--- a/arch/riscv/kernel/Makefile
+++ b/arch/riscv/kernel/Makefile
@@ -58,6 +58,8 @@ obj-y += riscv_ksyms.o
obj-y += stacktrace.o
obj-y += cacheinfo.o
obj-y += patch.o
+obj-y += vendor_extensions.o
+obj-y += vendor_extensions/
obj-y += probes/
obj-y += tests/
obj-$(CONFIG_MMU) += vdso.o vdso/
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 12c79db0b0bb..cc9ec393c8f6 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -24,6 +24,7 @@
#include <asm/processor.h>
#include <asm/sbi.h>
#include <asm/vector.h>
+#include <asm/vendor_extensions.h>

#define NUM_ALPHA_EXTS ('z' - 'a' + 1)

@@ -102,24 +103,6 @@ static bool riscv_isa_extension_check(int id)
return true;
}

-#define _RISCV_ISA_EXT_DATA(_name, _id, _subset_exts, _subset_exts_size) { \
- .name = #_name, \
- .property = #_name, \
- .id = _id, \
- .subset_ext_ids = _subset_exts, \
- .subset_ext_size = _subset_exts_size \
-}
-
-#define __RISCV_ISA_EXT_DATA(_name, _id) _RISCV_ISA_EXT_DATA(_name, _id, NULL, 0)
-
-/* Used to declare pure "lasso" extension (Zk for instance) */
-#define __RISCV_ISA_EXT_BUNDLE(_name, _bundled_exts) \
- _RISCV_ISA_EXT_DATA(_name, RISCV_ISA_EXT_INVALID, _bundled_exts, ARRAY_SIZE(_bundled_exts))
-
-/* Used to declare extensions that are a superset of other extensions (Zvbb for instance) */
-#define __RISCV_ISA_EXT_SUPERSET(_name, _id, _sub_exts) \
- _RISCV_ISA_EXT_DATA(_name, _id, _sub_exts, ARRAY_SIZE(_sub_exts))
-
static const unsigned int riscv_zk_bundled_exts[] = {
RISCV_ISA_EXT_ZBKB,
RISCV_ISA_EXT_ZBKC,
@@ -353,6 +336,21 @@ static void __init riscv_parse_isa_string(unsigned long *this_hwcap, struct risc
bool ext_long = false, ext_err = false;

switch (*ext) {
+ case 'x':
+ case 'X':
+ if (acpi_disabled)
+ pr_warn_once("Vendor extensions are ignored in riscv,isa. Use riscv,isa-extensions instead.");
+ /*
+ * To skip an extension, we find its end.
+ * As multi-letter extensions must be split from other multi-letter
+ * extensions with an "_", the end of a multi-letter extension will
+ * either be the null character or the "_" at the start of the next
+ * multi-letter extension.
+ */
+ for (; *isa && *isa != '_'; ++isa)
+ ;
+ ext_err = true;
+ break;
case 's':
/*
* Workaround for invalid single-letter 's' & 'u' (QEMU).
@@ -368,8 +366,6 @@ static void __init riscv_parse_isa_string(unsigned long *this_hwcap, struct risc
}
fallthrough;
case 'S':
- case 'x':
- case 'X':
case 'z':
case 'Z':
/*
@@ -572,6 +568,59 @@ static void __init riscv_fill_hwcap_from_isa_string(unsigned long *isa2hwcap)
acpi_put_table((struct acpi_table_header *)rhct);
}

+static void __init riscv_fill_cpu_vendor_ext(struct device_node *cpu_node, int cpu)
+{
+ if (!IS_ENABLED(CONFIG_RISCV_ISA_VENDOR_EXT))
+ return;
+
+ for (int i = 0; i < riscv_isa_vendor_ext_list_size; i++) {
+ struct riscv_isa_vendor_ext_data_list *ext_list = riscv_isa_vendor_ext_list[i];
+
+ for (int j = 0; j < ext_list->ext_data_count; j++) {
+ const struct riscv_isa_ext_data ext = ext_list->ext_data[j];
+ struct riscv_isavendorinfo *isavendorinfo = &ext_list->per_hart_isa_bitmap[cpu];
+
+ if (of_property_match_string(cpu_node, "riscv,isa-extensions",
+ ext.property) < 0)
+ continue;
+
+ /*
+ * Assume that subset extensions are all members of the
+ * same vendor.
+ */
+ if (ext.subset_ext_size)
+ for (int k = 0; k < ext.subset_ext_size; k++)
+ set_bit(ext.subset_ext_ids[k], isavendorinfo->isa);
+
+ set_bit(ext.id, isavendorinfo->isa);
+ }
+ }
+}
+
+static void __init riscv_fill_vendor_ext_list(int cpu)
+{
+ bool first = true;
+
+ if (!IS_ENABLED(CONFIG_RISCV_ISA_VENDOR_EXT))
+ return;
+
+ for (int i = 0; i < riscv_isa_vendor_ext_list_size; i++) {
+ struct riscv_isa_vendor_ext_data_list *ext_list = riscv_isa_vendor_ext_list[i];
+
+ if (first) {
+ bitmap_copy(ext_list->all_harts_isa_bitmap.isa,
+ ext_list->per_hart_isa_bitmap[cpu].isa,
+ RISCV_ISA_VENDOR_EXT_MAX);
+ first = false;
+ } else {
+ bitmap_and(ext_list->all_harts_isa_bitmap.isa,
+ ext_list->all_harts_isa_bitmap.isa,
+ ext_list->per_hart_isa_bitmap[cpu].isa,
+ RISCV_ISA_VENDOR_EXT_MAX);
+ }
+ }
+}
+
static int __init riscv_fill_hwcap_from_ext_list(unsigned long *isa2hwcap)
{
unsigned int cpu;
@@ -615,6 +664,8 @@ static int __init riscv_fill_hwcap_from_ext_list(unsigned long *isa2hwcap)
}
}

+ riscv_fill_cpu_vendor_ext(cpu_node, cpu);
+
of_node_put(cpu_node);

/*
@@ -630,6 +681,8 @@ static int __init riscv_fill_hwcap_from_ext_list(unsigned long *isa2hwcap)
bitmap_copy(riscv_isa, isainfo->isa, RISCV_ISA_EXT_MAX);
else
bitmap_and(riscv_isa, riscv_isa, isainfo->isa, RISCV_ISA_EXT_MAX);
+
+ riscv_fill_vendor_ext_list(cpu);
}

if (bitmap_empty(riscv_isa, RISCV_ISA_EXT_MAX))
diff --git a/arch/riscv/kernel/vendor_extensions.c b/arch/riscv/kernel/vendor_extensions.c
new file mode 100644
index 000000000000..03ba7949a07f
--- /dev/null
+++ b/arch/riscv/kernel/vendor_extensions.c
@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2024 Rivos, Inc
+ */
+
+#include <asm/vendor_extensions.h>
+#include <asm/vendor_extensions/thead.h>
+
+#include <linux/array_size.h>
+#include <linux/types.h>
+
+struct riscv_isa_vendor_ext_data_list *riscv_isa_vendor_ext_list[] = {
+#ifdef CONFIG_RISCV_ISA_VENDOR_EXT_THEAD
+ &riscv_isa_vendor_ext_list_thead,
+#endif
+};
+
+const size_t riscv_isa_vendor_ext_list_size = ARRAY_SIZE(riscv_isa_vendor_ext_list);
diff --git a/arch/riscv/kernel/vendor_extensions/Makefile b/arch/riscv/kernel/vendor_extensions/Makefile
new file mode 100644
index 000000000000..3383066baaab
--- /dev/null
+++ b/arch/riscv/kernel/vendor_extensions/Makefile
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+obj-$(CONFIG_RISCV_ISA_VENDOR_EXT_THEAD) += thead.o
diff --git a/arch/riscv/kernel/vendor_extensions/thead.c b/arch/riscv/kernel/vendor_extensions/thead.c
new file mode 100644
index 000000000000..0934a2086473
--- /dev/null
+++ b/arch/riscv/kernel/vendor_extensions/thead.c
@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <asm/cpufeature.h>
+#include <asm/vendor_extensions.h>
+#include <asm/vendor_extensions/thead.h>
+
+#include <linux/array_size.h>
+#include <linux/types.h>
+
+/* All T-Head vendor extensions supported in Linux */
+const struct riscv_isa_ext_data riscv_isa_vendor_ext_thead[] = {
+ __RISCV_ISA_EXT_DATA(xtheadvector, RISCV_ISA_VENDOR_EXT_XTHEADVECTOR),
+};
+
+struct riscv_isa_vendor_ext_data_list riscv_isa_vendor_ext_list_thead = {
+ .ext_data_count = ARRAY_SIZE(riscv_isa_vendor_ext_thead),
+ .ext_data = riscv_isa_vendor_ext_thead,
+};

--
2.44.0