[RFC 3/6] RISC-V: deprecate riscv,isa & replace it with per-extension properties
Conor Dooley
conor at kernel.org
Mon May 8 11:16:23 PDT 2023
From: Conor Dooley <conor.dooley at microchip.com>
riscv,isa is a bit of a problem-in-waiting, as we don't have control
over what the extensions mean. Give us the ability to define what the
versions of an extension mean, and provide a compatible-like interface
for a dts to specify which known-version of an extension a hart is
compatible with.
Signed-off-by: Conor Dooley <conor.dooley at microchip.com>
---
arch/riscv/include/asm/hwcap.h | 25 +++++-
arch/riscv/kernel/cpufeature.c | 147 +++++++++++++++++++++++++++------
2 files changed, 146 insertions(+), 26 deletions(-)
diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
index aa61031f7923..f963a7a82ce1 100644
--- a/arch/riscv/include/asm/hwcap.h
+++ b/arch/riscv/include/asm/hwcap.h
@@ -14,15 +14,20 @@
#include <uapi/asm/hwcap.h>
#define RISCV_ISA_EXT_a ('a' - 'a')
+#define RISCV_ISA_EXT_b ('b' - 'a')
#define RISCV_ISA_EXT_c ('c' - 'a')
#define RISCV_ISA_EXT_d ('d' - 'a')
#define RISCV_ISA_EXT_f ('f' - 'a')
#define RISCV_ISA_EXT_h ('h' - 'a')
#define RISCV_ISA_EXT_i ('i' - 'a')
+#define RISCV_ISA_EXT_j ('j' - 'a')
+#define RISCV_ISA_EXT_k ('k' - 'a')
#define RISCV_ISA_EXT_m ('m' - 'a')
+#define RISCV_ISA_EXT_p ('p' - 'a')
+#define RISCV_ISA_EXT_q ('q' - 'a')
#define RISCV_ISA_EXT_s ('s' - 'a')
#define RISCV_ISA_EXT_u ('u' - 'a')
-
+#define RISCV_ISA_EXT_v ('v' - 'a')
/*
* These macros represent the logical IDs of each multi-letter RISC-V ISA
* extension and are used in the ISA bitmap. The logical IDs start from
@@ -61,6 +66,24 @@ struct riscv_isa_ext_data {
unsigned int isa_ext_id;
};
+struct riscv_isa_extension {
+ const u64 key;
+ const char *name;
+ const char *version;
+ const char *prop_name;
+ const bool multi_letter;
+};
+
+#define RISCV_ISA_EXT_CFG(_name, _key, _version, _multi) { \
+ .name = #_name, \
+ .prop_name = "riscv,isa-extension-" #_name, \
+ .key = _key, \
+ .version = _version, \
+ .multi_letter = _multi, \
+}
+
+extern const struct riscv_isa_extension riscv_isa_extensions[];
+
unsigned long riscv_isa_extension_base(const unsigned long *isa_bitmap);
#define riscv_isa_extension_mask(ext) BIT_MASK(RISCV_ISA_EXT_##ext)
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 92f0e7b78eef..1ead76adf60f 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -93,12 +93,39 @@ static bool riscv_isa_extension_check(int id)
return true;
}
-void __init riscv_fill_hwcap(void)
+const struct riscv_isa_extension riscv_isa_extensions[] = {
+ RISCV_ISA_EXT_CFG(i, RISCV_ISA_EXT_i, "v1.0.0", false),
+ RISCV_ISA_EXT_CFG(m, RISCV_ISA_EXT_m, "v1.0.0", false),
+ RISCV_ISA_EXT_CFG(a, RISCV_ISA_EXT_a, "v1.0.0", false),
+ RISCV_ISA_EXT_CFG(f, RISCV_ISA_EXT_f, "v1.0.0", false),
+ RISCV_ISA_EXT_CFG(d, RISCV_ISA_EXT_d, "v1.0.0", false),
+ RISCV_ISA_EXT_CFG(q, RISCV_ISA_EXT_q, "v1.0.0", false),
+ RISCV_ISA_EXT_CFG(c, RISCV_ISA_EXT_c, "v1.0.0", false),
+ RISCV_ISA_EXT_CFG(b, RISCV_ISA_EXT_b, "v1.0.0", false),
+ RISCV_ISA_EXT_CFG(k, RISCV_ISA_EXT_k, "v1.0.0", false),
+ RISCV_ISA_EXT_CFG(j, RISCV_ISA_EXT_j, "v1.0.0", false),
+ RISCV_ISA_EXT_CFG(p, RISCV_ISA_EXT_p, "v1.0.0", false),
+ RISCV_ISA_EXT_CFG(v, RISCV_ISA_EXT_v, "v1.0.0", false),
+ RISCV_ISA_EXT_CFG(h, RISCV_ISA_EXT_h, "v1.0.0", false),
+ RISCV_ISA_EXT_CFG(zicbom, RISCV_ISA_EXT_ZICBOM, "v1.0.0", true),
+ RISCV_ISA_EXT_CFG(zicboz, RISCV_ISA_EXT_ZICBOZ, "v1.0.0", true),
+ RISCV_ISA_EXT_CFG(zicsr, RISCV_ISA_EXT_ZICSR, "v1.0.0", true),
+ RISCV_ISA_EXT_CFG(zifencei, RISCV_ISA_EXT_ZIFENCEI, "v1.0.0", true),
+ RISCV_ISA_EXT_CFG(zihintpause, RISCV_ISA_EXT_ZIHINTPAUSE, "v1.0.0", true),
+ RISCV_ISA_EXT_CFG(zbb, RISCV_ISA_EXT_ZBB, "v1.0.0", true),
+ RISCV_ISA_EXT_CFG(sscofpmf, RISCV_ISA_EXT_SSCOFPMF, "v1.0.0", true),
+ RISCV_ISA_EXT_CFG(sstc, RISCV_ISA_EXT_SSTC, "v1.0.0", true),
+ RISCV_ISA_EXT_CFG(svinval, RISCV_ISA_EXT_SVINVAL, "v1.0.0", true),
+ RISCV_ISA_EXT_CFG(svnapot, RISCV_ISA_EXT_SVNAPOT, "v1.0.0", true),
+ RISCV_ISA_EXT_CFG(svpbmt, RISCV_ISA_EXT_SVPBMT, "v1.0.0", true),
+ RISCV_ISA_EXT_CFG("", RISCV_ISA_EXT_MAX, "", false),
+};
+
+static void __init riscv_fill_hwcap_isa_string(void)
{
struct device_node *node;
const char *isa;
- char print_str[NUM_ALPHA_EXTS + 1];
- int i, j, rc;
+ int rc;
unsigned long isa2hwcap[26] = {0};
unsigned int cpu;
@@ -109,13 +136,12 @@ void __init riscv_fill_hwcap(void)
isa2hwcap['d' - 'a'] = COMPAT_HWCAP_ISA_D;
isa2hwcap['c' - 'a'] = COMPAT_HWCAP_ISA_C;
- elf_hwcap = 0;
-
- bitmap_zero(riscv_isa, RISCV_ISA_EXT_MAX);
+ pr_info("Falling back to reading hwcap from deprecated riscv,isa\n");
for_each_possible_cpu(cpu) {
unsigned long this_hwcap = 0;
DECLARE_BITMAP(this_isa, RISCV_ISA_EXT_MAX);
+ bitmap_zero(this_isa, RISCV_ISA_EXT_MAX);
node = of_cpu_device_node_get(cpu);
if (!node) {
@@ -138,7 +164,6 @@ void __init riscv_fill_hwcap(void)
*/
isa += 4;
- bitmap_zero(this_isa, RISCV_ISA_EXT_MAX);
while (*isa) {
const char *ext = isa++;
const char *ext_end = isa;
@@ -278,26 +303,77 @@ void __init riscv_fill_hwcap(void)
set_bit(nr, this_isa);
}
} else {
- /* sorted alphabetically */
- SET_ISA_EXT_MAP("sscofpmf", RISCV_ISA_EXT_SSCOFPMF);
- SET_ISA_EXT_MAP("sstc", RISCV_ISA_EXT_SSTC);
- SET_ISA_EXT_MAP("svinval", RISCV_ISA_EXT_SVINVAL);
- SET_ISA_EXT_MAP("svnapot", RISCV_ISA_EXT_SVNAPOT);
- SET_ISA_EXT_MAP("svpbmt", RISCV_ISA_EXT_SVPBMT);
- SET_ISA_EXT_MAP("zbb", RISCV_ISA_EXT_ZBB);
- SET_ISA_EXT_MAP("zicbom", RISCV_ISA_EXT_ZICBOM);
- SET_ISA_EXT_MAP("zicboz", RISCV_ISA_EXT_ZICBOZ);
- SET_ISA_EXT_MAP("zihintpause", RISCV_ISA_EXT_ZIHINTPAUSE);
+ for (int i = 0; i < ARRAY_SIZE(riscv_isa_extensions); i++)
+ SET_ISA_EXT_MAP(riscv_isa_extensions[i].name, riscv_isa_extensions[i].key);
}
#undef SET_ISA_EXT_MAP
}
- /*
- * Linux requires Zicsr & Zifencei, so we may as well always
- * set them.
- */
- set_bit(RISCV_ISA_EXT_ZIFENCEI, this_isa);
- set_bit(RISCV_ISA_EXT_ZICSR, this_isa);
+ /*
+ * Linux requires Zicsr & Zifencei, so we may as well always
+ * set them.
+ */
+ set_bit(RISCV_ISA_EXT_ZIFENCEI, this_isa);
+ set_bit(RISCV_ISA_EXT_ZICSR, this_isa);
+
+ /*
+ * All "okay" hart should have same isa. Set HWCAP based on
+ * common capabilities of every "okay" hart, in case they don't
+ * have.
+ */
+ if (elf_hwcap)
+ elf_hwcap &= this_hwcap;
+ else
+ elf_hwcap = this_hwcap;
+
+ if (bitmap_empty(riscv_isa, RISCV_ISA_EXT_MAX))
+ bitmap_copy(riscv_isa, this_isa, RISCV_ISA_EXT_MAX);
+ else
+ bitmap_and(riscv_isa, riscv_isa, this_isa, RISCV_ISA_EXT_MAX);
+ }
+}
+
+static bool __init riscv_fill_hwcap_new(void)
+{
+ struct device_node *node;
+ bool detected;
+ unsigned long isa2hwcap[26] = {0};
+ unsigned int cpu;
+
+ isa2hwcap['i' - 'a'] = COMPAT_HWCAP_ISA_I;
+ isa2hwcap['m' - 'a'] = COMPAT_HWCAP_ISA_M;
+ isa2hwcap['a' - 'a'] = COMPAT_HWCAP_ISA_A;
+ isa2hwcap['f' - 'a'] = COMPAT_HWCAP_ISA_F;
+ isa2hwcap['d' - 'a'] = COMPAT_HWCAP_ISA_D;
+ isa2hwcap['c' - 'a'] = COMPAT_HWCAP_ISA_C;
+
+ for_each_possible_cpu(cpu) {
+ unsigned long this_hwcap = 0;
+ DECLARE_BITMAP(this_isa, RISCV_ISA_EXT_MAX);
+
+ node = of_cpu_device_node_get(cpu);
+ if (!node) {
+ pr_warn("Unable to find cpu node\n");
+ continue;
+ }
+
+ for (int k = 0; k < ARRAY_SIZE(riscv_isa_extensions) - 1; k++) {
+ const char *tmp;
+
+ of_property_read_string(node, riscv_isa_extensions[k].prop_name, &tmp);
+ if (!tmp)
+ continue;
+
+ detected = true;
+
+ if (riscv_isa_extension_check(riscv_isa_extensions[k].key) &&
+ !strcmp(riscv_isa_extensions[k].version, tmp)) {
+ if (!riscv_isa_extensions[k].multi_letter)
+ this_hwcap |= isa2hwcap[riscv_isa_extensions[k].key];
+
+ set_bit(riscv_isa_extensions[k].key, this_isa);
+ }
+ }
/*
* All "okay" hart should have same isa. Set HWCAP based on
@@ -315,8 +391,29 @@ void __init riscv_fill_hwcap(void)
bitmap_and(riscv_isa, riscv_isa, this_isa, RISCV_ISA_EXT_MAX);
}
- /* We don't support systems with F but without D, so mask those out
- * here. */
+ return detected;
+}
+
+void __init riscv_fill_hwcap(void)
+{
+ char print_str[NUM_ALPHA_EXTS + 1];
+ int i, j;
+
+ elf_hwcap = 0;
+
+ bitmap_zero(riscv_isa, RISCV_ISA_EXT_MAX);
+
+ /*
+ * Since old dtbs must continue to work just as well/badly as they ever
+ * did, fall back to the isa string if the new method doesn't work.
+ */
+ if (!riscv_fill_hwcap_new())
+ riscv_fill_hwcap_isa_string();
+
+ /*
+ * We don't support systems with F but without D, so mask those out
+ * here.
+ */
if ((elf_hwcap & COMPAT_HWCAP_ISA_F) && !(elf_hwcap & COMPAT_HWCAP_ISA_D)) {
pr_info("This kernel does not support systems with F but not D\n");
elf_hwcap &= ~COMPAT_HWCAP_ISA_F;
--
2.39.2
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