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 <a...@brainfault.org> Reviewed-by: Alistair Francis <alistair.fran...@wdc.com> Reviewed-by: Frank Chang <frank.ch...@sifive.com> Reviewed-by: Bin Meng <bmeng...@gmail.com> Tested-by: Bin Meng <bmeng...@gmail.com> Suggested-by: Heiko Stubner <he...@sntech.de> Signed-off-by: Atish Patra <ati...@rivosinc.com> --- Changes from v6->v7: 1. Fixed indentation and typo. 2. Added Reviewed-by tags. 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 198274fb34e5..86e48ff54dd1 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; +}; + static const char riscv_exts[26] = "IEMAFDQCLBJTPVNSUHKORWXYZG"; const char * const riscv_int_regnames[] = { @@ -920,6 +925,60 @@ 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 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(zhinx, ext_zhinx), + ISA_EDATA_ENTRY(zhinxmin, ext_zhinxmin), + 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(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; @@ -932,6 +991,7 @@ char *riscv_isa_string(RISCVCPU *cpu) } } *p = '\0'; + riscv_isa_string_ext(cpu, &isa_str, maxlen); return isa_str; } -- 2.25.1
