[PATCH v5 07/17] riscv: Introduce vendor variants of extension helpers

Charlie Jenkins
2024-05-03T04:46:59Z

Vendor extensions are maintained in per-vendor structs (separate from
standard extensions which live in riscv_isa). Create vendor variants for
the existing extension helpers to interface with the riscv_isa_vendor
bitmaps.

Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
---
arch/riscv/errata/sifive/errata.c | 3 +
arch/riscv/errata/thead/errata.c | 3 +
arch/riscv/include/asm/vendor_extensions.h | 97 ++++++++++++++++++++++++++++++
arch/riscv/kernel/cpufeature.c | 32 +++++++---
arch/riscv/kernel/vendor_extensions.c | 40 ++++++++++++
5 files changed, 167 insertions(+), 8 deletions(-)

diff --git a/arch/riscv/errata/sifive/errata.c b/arch/riscv/errata/sifive/errata.c
index 3d9a32d791f7..b68b023115c2 100644
--- a/arch/riscv/errata/sifive/errata.c
+++ b/arch/riscv/errata/sifive/errata.c
@@ -12,6 +12,7 @@
#include <asm/alternative.h>
#include <asm/vendorid_list.h>
#include <asm/errata_list.h>
+#include <asm/vendor_extensions.h>

struct errata_info_t {
char name[32];
@@ -91,6 +92,8 @@ void sifive_errata_patch_func(struct alt_entry *begin, struct alt_entry *end,
u32 cpu_apply_errata = 0;
u32 tmp;

+ BUILD_BUG_ON(ERRATA_SIFIVE_NUMBER >= RISCV_VENDOR_EXT_ALTERNATIVES_BASE);
+
if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
return;

diff --git a/arch/riscv/errata/thead/errata.c b/arch/riscv/errata/thead/errata.c
index b1c410bbc1ae..6d5d7f8eebbc 100644
--- a/arch/riscv/errata/thead/errata.c
+++ b/arch/riscv/errata/thead/errata.c
@@ -18,6 +18,7 @@
#include <asm/io.h>
#include <asm/patch.h>
#include <asm/vendorid_list.h>
+#include <asm/vendor_extensions.h>

static bool errata_probe_pbmt(unsigned int stage,
unsigned long arch_id, unsigned long impid)
@@ -160,6 +161,8 @@ void thead_errata_patch_func(struct alt_entry *begin, struct alt_entry *end,
u32 tmp;
void *oldptr, *altptr;

+ BUILD_BUG_ON(ERRATA_THEAD_NUMBER >= RISCV_VENDOR_EXT_ALTERNATIVES_BASE);
+
for (alt = begin; alt < end; alt++) {
if (alt->vendor_id != THEAD_VENDOR_ID)
continue;
diff --git a/arch/riscv/include/asm/vendor_extensions.h b/arch/riscv/include/asm/vendor_extensions.h
index bf4dac66e6e6..a6959836f895 100644
--- a/arch/riscv/include/asm/vendor_extensions.h
+++ b/arch/riscv/include/asm/vendor_extensions.h
@@ -31,4 +31,101 @@ extern struct riscv_isa_vendor_ext_data_list *riscv_isa_vendor_ext_list[];

extern const size_t riscv_isa_vendor_ext_list_size;

+/*
+ * The alternatives need some way of distinguishing between vendor extensions
+ * and errata. Incrementing all of the vendor extension keys so they are at
+ * least 0x8000 accomplishes that.
+ */
+#define RISCV_VENDOR_EXT_ALTERNATIVES_BASE 0x8000
+
+#define VENDOR_EXT_ALL_CPUS -1
+
+bool __riscv_isa_vendor_extension_available(int cpu, unsigned long vendor, unsigned int bit);
+#define riscv_cpu_isa_vendor_extension_available(cpu, vendor, ext) \
+ __riscv_isa_vendor_extension_available(cpu, vendor, RISCV_ISA_VENDOR_EXT_##ext)
+#define riscv_isa_vendor_extension_available(vendor, ext) \
+ __riscv_isa_vendor_extension_available(VENDOR_EXT_ALL_CPUS, vendor, \
+ RISCV_ISA_VENDOR_EXT_##ext)
+
+static __always_inline bool __riscv_has_extension_likely(const unsigned long vendor,
+ const unsigned long ext)
+{
+ asm goto(ALTERNATIVE("j %l[l_no]", "nop", %[vendor], %[ext], 1)
+ :
+ : [vendor] "i" (vendor), [ext] "i" (ext)
+ :
+ : l_no);
+
+ return true;
+l_no:
+ return false;
+}
+
+static __always_inline bool __riscv_has_extension_unlikely(const unsigned long vendor,
+ const unsigned long ext)
+{
+ asm goto(ALTERNATIVE("nop", "j %l[l_yes]", %[vendor], %[ext], 1)
+ :
+ : [vendor] "i" (vendor), [ext] "i" (ext)
+ :
+ : l_yes);
+
+ return false;
+l_yes:
+ return true;
+}
+
+static __always_inline bool riscv_has_vendor_extension_likely(const unsigned long vendor,
+ const unsigned long ext)
+{
+ if (!IS_ENABLED(CONFIG_RISCV_ISA_VENDOR_EXT))
+ return false;
+
+ if (IS_ENABLED(CONFIG_RISCV_ALTERNATIVE))
+ return __riscv_has_extension_likely(vendor,
+ ext + RISCV_VENDOR_EXT_ALTERNATIVES_BASE);
+
+ return __riscv_isa_vendor_extension_available(VENDOR_EXT_ALL_CPUS, vendor, ext);
+}
+
+static __always_inline bool riscv_has_vendor_extension_unlikely(const unsigned long vendor,
+ const unsigned long ext)
+{
+ if (!IS_ENABLED(CONFIG_RISCV_ISA_VENDOR_EXT))
+ return false;
+
+ if (IS_ENABLED(CONFIG_RISCV_ALTERNATIVE))
+ return __riscv_has_extension_unlikely(vendor,
+ ext + RISCV_VENDOR_EXT_ALTERNATIVES_BASE);
+
+ return __riscv_isa_vendor_extension_available(VENDOR_EXT_ALL_CPUS, vendor, ext);
+}
+
+static __always_inline bool riscv_cpu_has_vendor_extension_likely(const unsigned long vendor,
+ int cpu, const unsigned long ext)
+{
+ if (!IS_ENABLED(CONFIG_RISCV_ISA_VENDOR_EXT))
+ return false;
+
+ if (IS_ENABLED(CONFIG_RISCV_ALTERNATIVE) &&
+ __riscv_has_extension_likely(vendor, ext + RISCV_VENDOR_EXT_ALTERNATIVES_BASE))
+ return true;
+
+ return __riscv_isa_vendor_extension_available(cpu, vendor, ext);
+}
+
+static __always_inline bool riscv_cpu_has_vendor_extension_unlikely(const unsigned long vendor,
+ int cpu,
+ const unsigned long ext)
+{
+ if (!IS_ENABLED(CONFIG_RISCV_ISA_VENDOR_EXT))
+ return false;
+
+ if (IS_ENABLED(CONFIG_RISCV_ALTERNATIVE) &&
+ __riscv_has_extension_unlikely(vendor, ext + RISCV_VENDOR_EXT_ALTERNATIVES_BASE))
+ return true;
+
+ return __riscv_isa_vendor_extension_available(cpu, vendor, ext);
+}
+
#endif /* _ASM_VENDOR_EXTENSIONS_H */
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index cc9ec393c8f6..b1f35564a1e0 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -860,25 +860,41 @@ void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin,
{
struct alt_entry *alt;
void *oldptr, *altptr;
- u16 id, value;
+ u16 id, value, vendor;

if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
return;

for (alt = begin; alt < end; alt++) {
- if (alt->vendor_id != 0)
- continue;
-
id = PATCH_ID_CPUFEATURE_ID(alt->patch_id);
+ vendor = PATCH_ID_CPUFEATURE_ID(alt->vendor_id);

- if (id >= RISCV_ISA_EXT_MAX) {
+ /*
+ * Any alternative with a patch_id that is less than
+ * RISCV_ISA_EXT_MAX is interpreted as a standard extension.
+ *
+ * Any alternative with patch_id that is greater than or equal
+ * to RISCV_VENDOR_EXT_ALTERNATIVES_BASE is interpreted as a
+ * vendor extension.
+ */
+ if (id < RISCV_ISA_EXT_MAX) {
+ /*
+ * This patch should be treated as errata so skip
+ * processing here.
+ */
+ if (alt->vendor_id != 0)
+ continue;
+
+ if (!__riscv_isa_extension_available(NULL, id))
+ continue;
+ } else if (id >= RISCV_VENDOR_EXT_ALTERNATIVES_BASE) {
+ if (!__riscv_isa_vendor_extension_available(VENDOR_EXT_ALL_CPUS, vendor, id))
+ continue;
+ } else {
WARN(1, "This extension id:%d is not in ISA extension list", id);
continue;
}

- if (!__riscv_isa_extension_available(NULL, id))
- continue;
-
value = PATCH_ID_CPUFEATURE_VALUE(alt->patch_id);
if (!riscv_cpufeature_patch_check(id, value))
continue;
diff --git a/arch/riscv/kernel/vendor_extensions.c b/arch/riscv/kernel/vendor_extensions.c
index 03ba7949a07f..e4ef574b7d08 100644
--- a/arch/riscv/kernel/vendor_extensions.c
+++ b/arch/riscv/kernel/vendor_extensions.c
@@ -3,6 +3,7 @@
* Copyright 2024 Rivos, Inc
*/

+#include <asm/vendorid_list.h>
#include <asm/vendor_extensions.h>
#include <asm/vendor_extensions/thead.h>

@@ -16,3 +17,42 @@ struct riscv_isa_vendor_ext_data_list *riscv_isa_vendor_ext_list[] = {
};

const size_t riscv_isa_vendor_ext_list_size = ARRAY_SIZE(riscv_isa_vendor_ext_list);
+
+/**
+ * __riscv_isa_vendor_extension_available() - Check whether given vendor
+ * extension is available or not.
+ *
+ * @cpu: check if extension is available on this cpu
+ * @vendor: vendor that the extension is a member of
+ * @bit: bit position of the desired extension
+ * Return: true or false
+ *
+ * NOTE: When cpu is -1, will check if extension is available on all cpus
+ */
+bool __riscv_isa_vendor_extension_available(int cpu, unsigned long vendor, unsigned int bit)
+{
+ unsigned long *bmap;
+ struct riscv_isainfo *cpu_bmap;
+ size_t bmap_size;
+
+ switch (vendor) {
+#ifdef CONFIG_RISCV_ISA_VENDOR_EXT_THEAD
+ case THEAD_VENDOR_ID:
+ bmap = riscv_isa_vendor_ext_list_thead.vendor_bitmap;
+ cpu_bmap = riscv_isa_vendor_ext_list_thead.per_hart_vendor_bitmap;
+ bmap_size = riscv_isa_vendor_ext_list_thead.bitmap_size;
+ break;
+#endif
+ default:
+ return false;
+ }
+
+ if (cpu != -1)
+ bmap = cpu_bmap[cpu].isa;
+
+ if (bit >= bmap_size)
+ return false;
+
+ return test_bit(bit, bmap) ? true : false;
+}
+EXPORT_SYMBOL_GPL(__riscv_isa_vendor_extension_available);

--
2.44.0