The Linux kernel parses the ISA extensions from "riscv,isa" DT
property. It used to parse only the single letter base extensions
until now. A generic ISA extension parsing framework was proposed[1]
recently that can parse multi-letter ISA extensions as well.
Generate the extended ISA string by appending the available ISA extensions
to the "riscv,isa" string if it is enabled so that kernel can process it.
[1] https://lkml.org/lkml/2022/2/15/263
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Suggested-by: Heiko Stubner <heiko@sntech.de>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
---
Changes from v5->v6:
1. Improved commit message.
2. Fixed a typo for Zfh.
Changes from v4->v5:
1. Fixed the order of Zxx extensions.
2. Added a comment clearly describing the rules of extension order.
Changes from v3->v4:
1. Fixed the order of the extension names.
2. Added all the available ISA extensions in Qemu.
Changes from v2->v3:
1. Used g_strconcat to replace snprintf & a max isa string length as
suggested by Anup.
2. I have not included the Tested-by Tag from Heiko because the
implementation changed from v2 to v3.
Changes from v1->v2:
1. Improved the code redability by using arrays instead of individual check
---
target/riscv/cpu.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 60 insertions(+)
diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index ddda4906ffb7..937ccdda997b 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -34,6 +34,11 @@
/* RISC-V CPU definitions */
+struct isa_ext_data {
+ const char *name;
+ bool enabled;
Nit: Should be 4 spaces indent.
Regards,
Frank Chang
+};
+
static const char riscv_exts[26] = "IEMAFDQCLBJTPVNSUHKORWXYZG";
const char * const riscv_int_regnames[] = {
@@ -898,6 +903,60 @@ static void riscv_cpu_class_init(ObjectClass *c, void *data)
device_class_set_props(dc, riscv_cpu_properties);
}
+#define ISA_EDATA_ENTRY(name, prop) {#name, cpu->cfg.prop}
+
+static void riscv_isa_string_ext(RISCVCPU *cpu, char **isa_str, int max_str_len)
+{
+ char *old = *isa_str;
+ char *new = *isa_str;
+ int i;
+
+ /**
+ * Here are the ordering rules of extension naming defined by RISC-V
+ * specification :
+ * 1. All extensions should be separated from from other multi-letter
+ * extensions by an underscore.
+ * 2. The first letter following the 'Z' conventionally indicates the most
+ * closely related alphabetical extension category, IMAFDQLCBKJTPVH.
+ * If multiple 'Z' extensions are named, they should be ordered first
+ * by category, then alphabetically within a category.
+ * 3. Standard supervisor-level extensions (starts with 'S') should be
+ * listed after standard unprivileged extensions. If multiple
+ * supervisor-level extensions are listed, they should be ordered
+ * alphabetically.
+ * 4. Non-standard extensions (starts with 'X') must be listed after all
+ * standard extensions. They must be separated from other multi-letter
+ * extensions by an underscore.
+ */
+ struct isa_ext_data isa_edata_arr[] = {
+ ISA_EDATA_ENTRY(zfh, ext_zfh),
+ ISA_EDATA_ENTRY(zfhmin, ext_zfhmin),
+ ISA_EDATA_ENTRY(zfinx, ext_zfinx),
+ ISA_EDATA_ENTRY(zdinx, ext_zdinx),
+ ISA_EDATA_ENTRY(zba, ext_zba),
+ ISA_EDATA_ENTRY(zbb, ext_zbb),
+ ISA_EDATA_ENTRY(zbc, ext_zbc),
+ ISA_EDATA_ENTRY(zbs, ext_zbs),
+ ISA_EDATA_ENTRY(zve32f, ext_zve32f),
+ ISA_EDATA_ENTRY(zve64f, ext_zve64f),
+ ISA_EDATA_ENTRY(zhinx, ext_zhinx),
+ ISA_EDATA_ENTRY(zhinxmin, ext_zhinxmin),
+ ISA_EDATA_ENTRY(svinval, ext_svinval),
+ ISA_EDATA_ENTRY(svnapot, ext_svnapot),
+ ISA_EDATA_ENTRY(svpbmt, ext_svpbmt),
+ };
+
+ for (i = 0; i < ARRAY_SIZE(isa_edata_arr); i++) {
+ if (isa_edata_arr[i].enabled) {
+ new = g_strconcat(old, "_", isa_edata_arr[i].name, NULL);
+ g_free(old);
+ old = new;
+ }
+ }
+
+ *isa_str = new;
+}
+
char *riscv_isa_string(RISCVCPU *cpu)
{
int i;
@@ -910,6 +969,7 @@ char *riscv_isa_string(RISCVCPU *cpu)
}
}
*p = '\0';
+ riscv_isa_string_ext(cpu, &isa_str, maxlen);
return isa_str;
}
--
2.25.1