Merge patch series "riscv, mm: detect svnapot cpu support at runtime"

[platform/kernel/linux-starfive.git] / arch / riscv / kernel / cpu.c

diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
index 1b9a5a6..7d0271c 100644 (file)
--- a/arch/riscv/kernel/cpu.c
+++ b/arch/riscv/kernel/cpu.c
@@ -144,30 +144,55 @@ arch_initcall(riscv_cpuinfo_init);
                .uprop = #UPROP,                                \
                .isa_ext_id = EXTID,                            \
        }
+
 /*
- * 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
+ * The canonical order of ISA extension names in the ISA string is defined in
+ * chapter 27 of the unprivileged specification.
+ *
+ * Ordinarily, for in-kernel data structures, this order is unimportant but
+ * isa_ext_arr defines the order of the ISA string in /proc/cpuinfo.
+ *
+ * The specification uses vague wording, such as should, when it comes to
+ * ordering, so for our purposes the following rules apply:
+ *
+ * 1. All multi-letter extensions must be separated from other extensions by an
+ *    underscore.
+ *
+ * 2. Additional standard extensions (starting with 'Z') must be sorted after
+ *    single-letter extensions and before any higher-privileged extensions.
+
+ * 3. 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
+ *    If multiple 'Z' extensions are named, they must be ordered first by
+ *    category, then alphabetically within a category.
+ *
+ * 3. Standard supervisor-level extensions (starting with 'S') must be listed
+ *    after standard unprivileged extensions.  If multiple supervisor-level
+ *    extensions are listed, they must be ordered alphabetically.
+ *
+ * 4. Standard machine-level extensions (starting with 'Zxm') must be listed
+ *    after any lower-privileged, standard extensions.  If multiple
+ *    machine-level extensions are listed, they must 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.
+ *
+ * 5. Non-standard extensions (starting with 'X') must be listed after all
+ *    standard extensions. If multiple non-standard extensions are listed, they
+ *    must be ordered alphabetically.
+ *
+ * An example string following the order is:
+ *    rv64imadc_zifoo_zigoo_zafoo_sbar_scar_zxmbaz_xqux_xrux
+ *
+ * New entries to this struct should follow the ordering rules described above.
  */
 static struct riscv_isa_ext_data isa_ext_arr[] = {
+       __RISCV_ISA_EXT_DATA(zicbom, RISCV_ISA_EXT_ZICBOM),
+       __RISCV_ISA_EXT_DATA(zihintpause, RISCV_ISA_EXT_ZIHINTPAUSE),
+       __RISCV_ISA_EXT_DATA(zbb, RISCV_ISA_EXT_ZBB),
        __RISCV_ISA_EXT_DATA(sscofpmf, RISCV_ISA_EXT_SSCOFPMF),
        __RISCV_ISA_EXT_DATA(sstc, RISCV_ISA_EXT_SSTC),
        __RISCV_ISA_EXT_DATA(svinval, RISCV_ISA_EXT_SVINVAL),
+       __RISCV_ISA_EXT_DATA(svnapot, RISCV_ISA_EXT_SVNAPOT),
        __RISCV_ISA_EXT_DATA(svpbmt, RISCV_ISA_EXT_SVPBMT),
-       __RISCV_ISA_EXT_DATA(zicbom, RISCV_ISA_EXT_ZICBOM),
-       __RISCV_ISA_EXT_DATA(zihintpause, RISCV_ISA_EXT_ZIHINTPAUSE),
        __RISCV_ISA_EXT_DATA("", RISCV_ISA_EXT_MAX),
 };