[PATCH v4 03/11] riscv: add ISA parsing for Zca, Zcf, Zcd and Zcb

Clément Léger
2024-04-29T15:06:35Z

The Zc* standard extension for code reduction introduces new extensions.
This patch adds support for Zca, Zcf, Zcd and Zcb. Zce, Zcmt and Zcmp
are left out of this patch since they are targeting microcontrollers/
embedded CPUs instead of application processors.

Signed-off-by: Clément Léger <cleger@rivosinc.com>
---
arch/riscv/include/asm/hwcap.h | 4 +++
arch/riscv/kernel/cpufeature.c | 47 +++++++++++++++++++++++++++++++++-
2 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
index 543e3ea2da0e..b7551bad341b 100644
--- a/arch/riscv/include/asm/hwcap.h
+++ b/arch/riscv/include/asm/hwcap.h
@@ -82,6 +82,10 @@
#define RISCV_ISA_EXT_ZACAS 73
#define RISCV_ISA_EXT_XANDESPMU 74
#define RISCV_ISA_EXT_ZIMOP 75
+#define RISCV_ISA_EXT_ZCA 76
+#define RISCV_ISA_EXT_ZCB 77
+#define RISCV_ISA_EXT_ZCD 78
+#define RISCV_ISA_EXT_ZCF 79

#define RISCV_ISA_EXT_XLINUXENVCFG 127

diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index cb2ffa6c8c33..c74bdb9c0a9f 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -103,6 +103,29 @@ static int riscv_ext_zicboz_validate(const struct riscv_isa_ext_data *data,
return 0;
}

+static int riscv_ext_zca_depends(const struct riscv_isa_ext_data *data,
+ const unsigned long *isa_bitmap)
+{
+ return __riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_ZCA) ? 0 : -EPROBE_DEFER;
+}
+static int riscv_ext_zcd_validate(const struct riscv_isa_ext_data *data,
+ const unsigned long *isa_bitmap)
+{
+ return __riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_ZCA) &&
+ __riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_d) ? 0 : -EPROBE_DEFER;
+}
+
+static int riscv_ext_zcf_validate(const struct riscv_isa_ext_data *data,
+ const unsigned long *isa_bitmap)
+{
+#ifdef CONFIG_64BIT
+ return -EINVAL;
+#else
+ return __riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_ZCA) &&
+ __riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_f) ? 0 : -EPROBE_DEFER;
+#endif
+}
+
#define _RISCV_ISA_EXT_DATA(_name, _id, _subset_exts, _subset_exts_size, _validate) { \
.name = #_name, \
.property = #_name, \
@@ -114,6 +137,9 @@ static int riscv_ext_zicboz_validate(const struct riscv_isa_ext_data *data,

#define __RISCV_ISA_EXT_DATA(_name, _id) _RISCV_ISA_EXT_DATA(_name, _id, NULL, 0, NULL)

+#define __RISCV_ISA_EXT_DATA_VALIDATE(_name, _id, _validate) \
+ _RISCV_ISA_EXT_DATA(_name, _id, NULL, 0, _validate)
+
/* Used to declare pure "lasso" extension (Zk for instance) */
#define __RISCV_ISA_EXT_BUNDLE(_name, _bundled_exts) \
_RISCV_ISA_EXT_DATA(_name, RISCV_ISA_EXT_INVALID, _bundled_exts, \
@@ -205,6 +231,21 @@ static const unsigned int riscv_xlinuxenvcfg_exts[] = {
RISCV_ISA_EXT_XLINUXENVCFG
};

+/*
+ * Zc* spec states that:
+ * - C always implies Zca
+ * - C+F implies Zcf (RV32 only)
+ * - C+D implies Zcd
+ *
+ * These extensions will be enabled and then validated depending on the
+ * availability of F/D RV32.
+ */
+static const unsigned int riscv_c_exts[] = {
+ RISCV_ISA_EXT_ZCA,
+ RISCV_ISA_EXT_ZCF,
+ RISCV_ISA_EXT_ZCD,
+};
+
/*
* The canonical order of ISA extension names in the ISA string is defined in
* chapter 27 of the unprivileged specification.
@@ -251,7 +292,7 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
__RISCV_ISA_EXT_DATA(f, RISCV_ISA_EXT_f),
__RISCV_ISA_EXT_DATA(d, RISCV_ISA_EXT_d),
__RISCV_ISA_EXT_DATA(q, RISCV_ISA_EXT_q),
- __RISCV_ISA_EXT_DATA(c, RISCV_ISA_EXT_c),
+ __RISCV_ISA_EXT_SUPERSET(c, RISCV_ISA_EXT_c, riscv_c_exts),
__RISCV_ISA_EXT_DATA(v, RISCV_ISA_EXT_v),
__RISCV_ISA_EXT_DATA(h, RISCV_ISA_EXT_h),
__RISCV_ISA_EXT_SUPERSET_VALIDATE(zicbom, RISCV_ISA_EXT_ZICBOM, riscv_xlinuxenvcfg_exts,
@@ -270,6 +311,10 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
__RISCV_ISA_EXT_DATA(zfa, RISCV_ISA_EXT_ZFA),
__RISCV_ISA_EXT_DATA(zfh, RISCV_ISA_EXT_ZFH),
__RISCV_ISA_EXT_DATA(zfhmin, RISCV_ISA_EXT_ZFHMIN),
+ __RISCV_ISA_EXT_DATA(zca, RISCV_ISA_EXT_ZCA),
+ __RISCV_ISA_EXT_DATA_VALIDATE(zcb, RISCV_ISA_EXT_ZCB, riscv_ext_zca_depends),
+ __RISCV_ISA_EXT_DATA_VALIDATE(zcd, RISCV_ISA_EXT_ZCD, riscv_ext_zcd_validate),
+ __RISCV_ISA_EXT_DATA_VALIDATE(zcf, RISCV_ISA_EXT_ZCF, riscv_ext_zcf_validate),
__RISCV_ISA_EXT_DATA(zba, RISCV_ISA_EXT_ZBA),
__RISCV_ISA_EXT_DATA(zbb, RISCV_ISA_EXT_ZBB),
__RISCV_ISA_EXT_DATA(zbc, RISCV_ISA_EXT_ZBC),
--
2.43.0