[PATCH 06/19] riscv: Extend cpufeature.c to detect vendor extensions

Charlie Jenkins
2024-04-12T04:12:46Z

Create a private namespace for each vendor above 0x8000. During the
probing of hardware capabilities, the vendorid of each hart is used to
resolve the vendor extension compatibility.

Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
---
arch/riscv/include/asm/cpufeature.h | 7 ++
arch/riscv/include/asm/hwcap.h | 23 ++++
arch/riscv/kernel/cpufeature.c | 203 ++++++++++++++++++++++++++++++------
3 files changed, 200 insertions(+), 33 deletions(-)

diff --git a/arch/riscv/include/asm/cpufeature.h b/arch/riscv/include/asm/cpufeature.h
index 347805446151..b5f4eedcfa86 100644
--- a/arch/riscv/include/asm/cpufeature.h
+++ b/arch/riscv/include/asm/cpufeature.h
@@ -26,11 +26,18 @@ struct riscv_isainfo {
DECLARE_BITMAP(isa, RISCV_ISA_EXT_MAX);
};

+struct riscv_isavendorinfo {
+ DECLARE_BITMAP(isa, RISCV_ISA_VENDOR_EXT_SIZE);
+};
+
DECLARE_PER_CPU(struct riscv_cpuinfo, riscv_cpuinfo);

/* Per-cpu ISA extensions. */
extern struct riscv_isainfo hart_isa[NR_CPUS];

+/* Per-cpu ISA vendor extensions. */
+extern struct riscv_isainfo hart_isa_vendor[NR_CPUS];
+
void riscv_user_isa_enable(void);

#if defined(CONFIG_RISCV_MISALIGNED)
diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
index e17d0078a651..38157be5becd 100644
--- a/arch/riscv/include/asm/hwcap.h
+++ b/arch/riscv/include/asm/hwcap.h
@@ -87,6 +87,29 @@
#define RISCV_ISA_EXT_MAX 128
#define RISCV_ISA_EXT_INVALID U32_MAX

+/*
+ * These macros represent the logical IDs of each vendor RISC-V ISA extension
+ * and are used in each vendor ISA bitmap. The logical IDs start from
+ * RISCV_ISA_VENDOR_EXT_BASE, which allows the 0-0x7999 range to be
+ * reserved for non-vendor extensions. The maximum, RISCV_ISA_VENDOR_EXT_MAX,
+ * is defined in order to allocate the bitmap and may be increased when
+ * necessary.
+ *
+ * Values are expected to overlap between vendors.
+ *
+ * New extensions should just be added to the bottom of the respective vendor,
+ * rather than added alphabetically, in order to avoid unnecessary shuffling.
+ *
+ */
+#define RISCV_ISA_VENDOR_EXT_BASE 0x8000
+
+/* THead Vendor Extensions */
+#define RISCV_ISA_VENDOR_EXT_XTHEADVECTOR 0x8000
+
+#define RISCV_ISA_VENDOR_EXT_MAX 0x8080
+#define RISCV_ISA_VENDOR_EXT_SIZE (RISCV_ISA_VENDOR_EXT_MAX - RISCV_ISA_VENDOR_EXT_BASE)
+#define RISCV_ISA_VENDOR_EXT_INVALID U32_MAX
+
#ifdef CONFIG_RISCV_M_MODE
#define RISCV_ISA_EXT_SxAIA RISCV_ISA_EXT_SMAIA
#else
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 5eb52d270a9a..f72fbdd0d7f5 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -32,9 +32,15 @@ unsigned long elf_hwcap __read_mostly;
/* Host ISA bitmap */
static DECLARE_BITMAP(riscv_isa, RISCV_ISA_EXT_MAX) __read_mostly;

+/* Host ISA vendor bitmap */
+static DECLARE_BITMAP(riscv_isa_vendor, RISCV_ISA_VENDOR_EXT_SIZE) __read_mostly;
+
/* Per-cpu ISA extensions. */
struct riscv_isainfo hart_isa[NR_CPUS];

+/* Per-cpu ISA vendor extensions. */
+struct riscv_isainfo hart_isa_vendor[NR_CPUS];
+
/**
* riscv_isa_extension_base() - Get base extension word
*
@@ -309,8 +315,15 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {

const size_t riscv_isa_ext_count = ARRAY_SIZE(riscv_isa_ext);

+const struct riscv_isa_ext_data riscv_isa_vendor_ext_thead[] = {
+ __RISCV_ISA_EXT_DATA(xtheadvector, RISCV_ISA_VENDOR_EXT_XTHEADVECTOR),
+};
+
+const size_t riscv_isa_vendor_ext_count_thead = ARRAY_SIZE(riscv_isa_vendor_ext_thead);
+
static void __init match_isa_ext(const struct riscv_isa_ext_data *ext, const char *name,
- const char *name_end, struct riscv_isainfo *isainfo)
+ const char *name_end, struct riscv_isainfo *isainfo,
+ unsigned int id_offset)
{
if ((name_end - name == strlen(ext->name)) &&
!strncasecmp(name, ext->name, name_end - name)) {
@@ -321,7 +334,7 @@ static void __init match_isa_ext(const struct riscv_isa_ext_data *ext, const cha
if (ext->subset_ext_size) {
for (int i = 0; i < ext->subset_ext_size; i++) {
if (riscv_isa_extension_check(ext->subset_ext_ids[i]))
- set_bit(ext->subset_ext_ids[i], isainfo->isa);
+ set_bit(ext->subset_ext_ids[i] - id_offset, isainfo->isa);
}
}

@@ -330,12 +343,34 @@ static void __init match_isa_ext(const struct riscv_isa_ext_data *ext, const cha
* (rejected by riscv_isa_extension_check()).
*/
if (riscv_isa_extension_check(ext->id))
- set_bit(ext->id, isainfo->isa);
+ set_bit(ext->id - id_offset, isainfo->isa);
+ }
+}
+
+static bool __init get_isa_vendor_ext(unsigned long vendorid,
+ const struct riscv_isa_ext_data **isa_vendor_ext,
+ size_t *count)
+{
+ bool found_vendor = true;
+
+ switch (vendorid) {
+ case THEAD_VENDOR_ID:
+ *isa_vendor_ext = riscv_isa_vendor_ext_thead;
+ *count = riscv_isa_vendor_ext_count_thead;
+ break;
+ default:
+ *isa_vendor_ext = NULL;
+ *count = 0;
+ found_vendor = false;
+ break;
}
+
+ return found_vendor;
}

static void __init riscv_parse_isa_string(unsigned long *this_hwcap, struct riscv_isainfo *isainfo,
- unsigned long *isa2hwcap, const char *isa)
+ struct riscv_isainfo *isavendorinfo, unsigned long vendorid,
+ unsigned long *isa2hwcap, const char *isa)
{
/*
* For all possible cpus, we have already validated in
@@ -349,8 +384,30 @@ static void __init riscv_parse_isa_string(unsigned long *this_hwcap, struct risc
const char *ext = isa++;
const char *ext_end = isa;
bool ext_long = false, ext_err = false;
+ struct riscv_isainfo *selected_isainfo = isainfo;
+ const struct riscv_isa_ext_data *selected_riscv_isa_ext = riscv_isa_ext;
+ size_t selected_riscv_isa_ext_count = riscv_isa_ext_count;
+ unsigned int id_offset = 0;

switch (*ext) {
+ case 'x':
+ case 'X':
+ bool found;
+
+ found = get_isa_vendor_ext(vendorid,
+ &selected_riscv_isa_ext,
+ &selected_riscv_isa_ext_count);
+ selected_isainfo = isavendorinfo;
+ id_offset = RISCV_ISA_VENDOR_EXT_BASE;
+ if (!found) {
+ pr_warn("No associated vendor extensions with vendor id: %lx\n",
+ vendorid);
+ for (; *isa && *isa != '_'; ++isa)
+ ;
+ ext_err = true;
+ break;
+ }
+ fallthrough;
case 's':
/*
* Workaround for invalid single-letter 's' & 'u' (QEMU).
@@ -366,8 +423,6 @@ static void __init riscv_parse_isa_string(unsigned long *this_hwcap, struct risc
}
fallthrough;
case 'S':
- case 'x':
- case 'X':
case 'z':
case 'Z':
/*
@@ -476,8 +531,10 @@ static void __init riscv_parse_isa_string(unsigned long *this_hwcap, struct risc
set_bit(nr, isainfo->isa);
}
} else {
- for (int i = 0; i < riscv_isa_ext_count; i++)
- match_isa_ext(&riscv_isa_ext[i], ext, ext_end, isainfo);
+ for (int i = 0; i < selected_riscv_isa_ext_count; i++)
+ match_isa_ext(&selected_riscv_isa_ext[i], ext,
+ ext_end, selected_isainfo,
+ id_offset);
}
}
}
@@ -490,8 +547,8 @@ static void __init riscv_fill_hwcap_from_isa_string(unsigned long *isa2hwcap)
struct acpi_table_header *rhct;
acpi_status status;
unsigned int cpu;
- u64 boot_vendorid;
- u64 boot_archid;
+ u64 boot_vendorid = ULL(-1), vendorid;
+ u64 boot_archid = ULL(-1);

if (!acpi_disabled) {
status = acpi_get_table(ACPI_SIG_RHCT, 0, &rhct);
@@ -499,11 +556,9 @@ static void __init riscv_fill_hwcap_from_isa_string(unsigned long *isa2hwcap)
return;
}

- boot_vendorid = riscv_get_mvendorid();
- boot_archid = riscv_get_marchid();
-
for_each_possible_cpu(cpu) {
struct riscv_isainfo *isainfo = &hart_isa[cpu];
+ struct riscv_isainfo *isavendorinfo = &hart_isa_vendor[cpu];
unsigned long this_hwcap = 0;
u64 this_vendorid;
u64 this_archid;
@@ -523,11 +578,19 @@ static void __init riscv_fill_hwcap_from_isa_string(unsigned long *isa2hwcap)
}
if (of_property_read_u64(node, "riscv,vendorid", &this_vendorid) < 0) {
pr_warn("Unable to find \"riscv,vendorid\" devicetree entry, using boot hart mvendorid instead\n");
+
+ if (boot_vendorid == -1)
+ this_vendorid = riscv_get_mvendorid();
+
this_vendorid = boot_vendorid;
}

if (of_property_read_u64(node, "riscv,archid", &this_archid) < 0) {
pr_warn("Unable to find \"riscv,vendorid\" devicetree entry, using boot hart marchid instead\n");
+
+ if (boot_archid == -1)
+ boot_archid = riscv_get_marchid();
+
this_archid = boot_archid;
}
} else {
@@ -540,7 +603,8 @@ static void __init riscv_fill_hwcap_from_isa_string(unsigned long *isa2hwcap)
this_archid = boot_archid;
}

- riscv_parse_isa_string(&this_hwcap, isainfo, isa2hwcap, isa);
+ riscv_parse_isa_string(&this_hwcap, isainfo, isavendorinfo,
+ this_vendorid, isa2hwcap, isa);

/*
* These ones were as they were part of the base ISA when the
@@ -582,21 +646,77 @@ static void __init riscv_fill_hwcap_from_isa_string(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);
+
+ /*
+ * All harts must have the same vendor to have compatible
+ * vendor extensions.
+ */
+ if (bitmap_empty(riscv_isa_vendor, RISCV_ISA_VENDOR_EXT_SIZE)) {
+ vendorid = this_vendorid;
+ bitmap_copy(riscv_isa_vendor, isavendorinfo->isa,
+ RISCV_ISA_VENDOR_EXT_SIZE);
+ } else if (vendorid != this_vendorid) {
+ vendorid = -1ULL;
+ bitmap_clear(riscv_isa_vendor, 0, RISCV_ISA_VENDOR_EXT_SIZE);
+ } else {
+ bitmap_and(riscv_isa_vendor, riscv_isa_vendor,
+ isavendorinfo->isa,
+ RISCV_ISA_VENDOR_EXT_SIZE);
+ }
}

if (!acpi_disabled && rhct)
acpi_put_table((struct acpi_table_header *)rhct);
}

+static void __init riscv_add_cpu_ext(struct device_node *cpu_node,
+ unsigned long *this_hwcap,
+ unsigned long *isa2hwcap,
+ const struct riscv_isa_ext_data *riscv_isa_ext_data,
+ struct riscv_isainfo *isainfo,
+ unsigned int id_offset,
+ size_t riscv_isa_ext_count)
+{
+ for (int i = 0; i < riscv_isa_ext_count; i++) {
+ const struct riscv_isa_ext_data ext = riscv_isa_ext_data[i];
+
+ if (of_property_match_string(cpu_node, "riscv,isa-extensions",
+ ext.property) < 0)
+ continue;
+
+ if (ext.subset_ext_size) {
+ for (int j = 0; j < ext.subset_ext_size; j++) {
+ if (riscv_isa_extension_check(ext.subset_ext_ids[j]))
+ set_bit(ext.subset_ext_ids[j] - id_offset, isainfo->isa);
+ }
+ }
+
+ if (riscv_isa_extension_check(ext.id)) {
+ set_bit(ext.id - id_offset, isainfo->isa);
+
+ /* Only single letter extensions get set in hwcap */
+ if (strnlen(ext.name, 2) == 1)
+ *this_hwcap |= isa2hwcap[ext.id];
+ }
+ }
+}
+
static int __init riscv_fill_hwcap_from_ext_list(unsigned long *isa2hwcap)
{
unsigned int cpu;
+ u64 boot_vendorid, vendorid;

for_each_possible_cpu(cpu) {
unsigned long this_hwcap = 0;
struct device_node *cpu_node;
struct riscv_isainfo *isainfo = &hart_isa[cpu];

+ struct riscv_isainfo *isavendorinfo = &hart_isa_vendor[cpu];
+ size_t riscv_isa_vendor_ext_count;
+ const struct riscv_isa_ext_data *riscv_isa_vendor_ext;
+ u64 this_vendorid;
+ bool found_vendor;
+
cpu_node = of_cpu_device_node_get(cpu);
if (!cpu_node) {
pr_warn("Unable to find cpu node\n");
@@ -608,28 +728,28 @@ static int __init riscv_fill_hwcap_from_ext_list(unsigned long *isa2hwcap)
continue;
}

- for (int i = 0; i < riscv_isa_ext_count; i++) {
- const struct riscv_isa_ext_data *ext = &riscv_isa_ext[i];
+ riscv_add_cpu_ext(cpu_node, &this_hwcap, isa2hwcap,
+ riscv_isa_ext, isainfo, 0,
+ riscv_isa_ext_count);

- if (of_property_match_string(cpu_node, "riscv,isa-extensions",
- ext->property) < 0)
- continue;
-
- if (ext->subset_ext_size) {
- for (int j = 0; j < ext->subset_ext_size; j++) {
- if (riscv_isa_extension_check(ext->subset_ext_ids[j]))
- set_bit(ext->subset_ext_ids[j], isainfo->isa);
- }
- }
+ if (of_property_read_u64(cpu_node, "riscv,vendorid", &this_vendorid) < 0) {
+ pr_warn("Unable to find \"riscv,vendorid\" devicetree entry, using boot hart mvendorid instead\n");
+ if (boot_vendorid == -1)
+ boot_vendorid = riscv_get_mvendorid();
+ this_vendorid = boot_vendorid;
+ }

- if (riscv_isa_extension_check(ext->id)) {
- set_bit(ext->id, isainfo->isa);
+ found_vendor = get_isa_vendor_ext(this_vendorid,
+ &riscv_isa_vendor_ext,
+ &riscv_isa_vendor_ext_count);

- /* Only single letter extensions get set in hwcap */
- if (strnlen(riscv_isa_ext[i].name, 2) == 1)
- this_hwcap |= isa2hwcap[riscv_isa_ext[i].id];
- }
- }
+ if (found_vendor)
+ riscv_add_cpu_ext(cpu_node, &this_hwcap, isa2hwcap,
+ riscv_isa_vendor_ext, isavendorinfo,
+ RISCV_ISA_VENDOR_EXT_BASE, riscv_isa_vendor_ext_count);
+ else
+ pr_warn("No associated vendor extensions with vendor id: %llx\n",
+ vendorid);

of_node_put(cpu_node);

@@ -646,6 +766,23 @@ 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);
+
+ /*
+ * All harts must have the same vendorid to have compatible
+ * vendor extensions.
+ */
+ if (bitmap_empty(riscv_isa_vendor, RISCV_ISA_VENDOR_EXT_SIZE)) {
+ vendorid = this_vendorid;
+ bitmap_copy(riscv_isa_vendor, isavendorinfo->isa,
+ RISCV_ISA_VENDOR_EXT_SIZE);
+ } else if (vendorid != this_vendorid) {
+ vendorid = -1ULL;
+ bitmap_clear(riscv_isa_vendor, 0,
+ RISCV_ISA_VENDOR_EXT_SIZE);
+ } else {
+ bitmap_and(riscv_isa_vendor, riscv_isa_vendor,
+ isavendorinfo->isa, RISCV_ISA_VENDOR_EXT_SIZE);
+ }
}

if (bitmap_empty(riscv_isa, RISCV_ISA_EXT_MAX))

--
2.44.0