[PATCH 1/2] RISC-V: Add Zicclsm to cpufeature and hwprobe

Jesse Taube
2024-08-09T16:23:35Z

> Zicclsm Misaligned loads and stores to main memory regions with both
> the cacheability and coherence PMAs must be supported.
> Note:
> This introduces a new extension name for this feature.
> This requires misaligned support for all regular load and store
> instructions (including scalar and vector) but not AMOs or other
> specialized forms of memory access. Even though mandated, misaligned
> loads and stores might execute extremely slowly. Standard software
> distributions should assume their existence only for correctness,
> not for performance.

Signed-off-by: Jesse Taube <jesse@rivosinc.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Andy Chiu <andy.chiu@sifive.com>
---
V1 -> V2:
- Add documentation for Zicclsm
- Move Zicclsm to correct location
V2 -> V3:
- No changes
V3 -> V4:
- Add definitions to hwprobe.rst
V4 -> V5:
- No changes
V5 -> V6:
- No changes
V6 -> V7:
- No changes
V7 -> V8:
- Rebase onto 2d1f51d8a4b0 (palmer/for-next)
- Change commit description
---
Documentation/arch/riscv/hwprobe.rst | 5 +++++
arch/riscv/include/asm/hwcap.h | 1 +
arch/riscv/include/uapi/asm/hwprobe.h | 1 +
arch/riscv/kernel/cpufeature.c | 1 +
arch/riscv/kernel/sys_hwprobe.c | 1 +
5 files changed, 9 insertions(+)

diff --git a/Documentation/arch/riscv/hwprobe.rst b/Documentation/arch/riscv/hwprobe.rst
index 3db60a0911df..22c118df520b 100644
--- a/Documentation/arch/riscv/hwprobe.rst
+++ b/Documentation/arch/riscv/hwprobe.rst
@@ -239,6 +239,11 @@ The following keys are defined:
ratified in commit 98918c844281 ("Merge pull request #1217 from
riscv/zawrs") of riscv-isa-manual.

+ * :c:macro:`RISCV_HWPROBE_EXT_ZICCLSM`: The Zicclsm extension is supported as
+ defined in the RISC-V RVA Profiles Specification. Misaligned support for
+ all regular load and store instructions (including scalar and vector) but
+ not AMOs or other specialized forms of memory access.
+
* :c:macro:`RISCV_HWPROBE_KEY_CPUPERF_0`: A bitmask that contains performance
information about the selected set of processors.

diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
index 5a0bd27fd11a..c93d957458f0 100644
--- a/arch/riscv/include/asm/hwcap.h
+++ b/arch/riscv/include/asm/hwcap.h
@@ -92,6 +92,7 @@
#define RISCV_ISA_EXT_ZCF 83
#define RISCV_ISA_EXT_ZCMOP 84
#define RISCV_ISA_EXT_ZAWRS 85
+#define RISCV_ISA_EXT_ZICCLSM 86

#define RISCV_ISA_EXT_XLINUXENVCFG 127

diff --git a/arch/riscv/include/uapi/asm/hwprobe.h b/arch/riscv/include/uapi/asm/hwprobe.h
index b706c8e47b02..a9370968fc9f 100644
--- a/arch/riscv/include/uapi/asm/hwprobe.h
+++ b/arch/riscv/include/uapi/asm/hwprobe.h
@@ -72,6 +72,7 @@ struct riscv_hwprobe {
#define RISCV_HWPROBE_EXT_ZCF (1ULL << 46)
#define RISCV_HWPROBE_EXT_ZCMOP (1ULL << 47)
#define RISCV_HWPROBE_EXT_ZAWRS (1ULL << 48)
+#define RISCV_HWPROBE_EXT_ZICCLSM (1ULL << 49)
#define RISCV_HWPROBE_KEY_CPUPERF_0 5
#define RISCV_HWPROBE_MISALIGNED_UNKNOWN (0 << 0)
#define RISCV_HWPROBE_MISALIGNED_EMULATED (1 << 0)
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 8f20607adb40..2f54d811a9b8 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -314,6 +314,7 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
riscv_ext_zicbom_validate),
__RISCV_ISA_EXT_SUPERSET_VALIDATE(zicboz, RISCV_ISA_EXT_ZICBOZ, riscv_xlinuxenvcfg_exts,
riscv_ext_zicboz_validate),
+ __RISCV_ISA_EXT_DATA(zicclsm, RISCV_ISA_EXT_ZICCLSM),
__RISCV_ISA_EXT_DATA(zicntr, RISCV_ISA_EXT_ZICNTR),
__RISCV_ISA_EXT_DATA(zicond, RISCV_ISA_EXT_ZICOND),
__RISCV_ISA_EXT_DATA(zicsr, RISCV_ISA_EXT_ZICSR),
diff --git a/arch/riscv/kernel/sys_hwprobe.c b/arch/riscv/kernel/sys_hwprobe.c
index 8d1b5c35d2a7..01eea29a56cd 100644
--- a/arch/riscv/kernel/sys_hwprobe.c
+++ b/arch/riscv/kernel/sys_hwprobe.c
@@ -107,6 +107,7 @@ static void hwprobe_isa_ext0(struct riscv_hwprobe *pair,
EXT_KEY(ZCB);
EXT_KEY(ZCMOP);
EXT_KEY(ZICBOZ);
+ EXT_KEY(ZICCLSM);
EXT_KEY(ZICOND);
EXT_KEY(ZIHINTNTL);
EXT_KEY(ZIHINTPAUSE);
--
2.45.2