riscv: hwprobe: export missing Zbc ISA extension

While Zba and Zbb were exported through hwprobe, Zbc was not. Export it.
Signed-off-by: Clément Léger <cleger@rivosinc.com>
Link: https://lore.kernel.org/r/20231114141256.126749-3-cleger@rivosinc.comSigned-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Documentation/arch/riscv/hwprobe.rst

@@ -80,6 +80,9 @@ The following keys are defined:
   * :c:macro:`RISCV_HWPROBE_EXT_ZICBOZ`: The Zicboz extension is supported, as
        ratified in commit 3dd606f ("Create cmobase-v1.0.pdf") of riscv-CMOs.
 
+  * :c:macro:`RISCV_HWPROBE_EXT_ZBC` The Zbc extension is supported, as defined
+       in version 1.0 of the Bit-Manipulation ISA extensions.
+
 * :c:macro:`RISCV_HWPROBE_KEY_CPUPERF_0`: A bitmask that contains performance
   information about the selected set of processors.
 

arch/riscv/include/uapi/asm/hwprobe.h

@@ -30,6 +30,7 @@ struct riscv_hwprobe {
 #define		RISCV_HWPROBE_EXT_ZBB		(1 << 4)
 #define		RISCV_HWPROBE_EXT_ZBS		(1 << 5)
 #define		RISCV_HWPROBE_EXT_ZICBOZ	(1 << 6)
+#define		RISCV_HWPROBE_EXT_ZBC		(1 << 7)
 #define RISCV_HWPROBE_KEY_CPUPERF_0	5
 #define		RISCV_HWPROBE_MISALIGNED_UNKNOWN	(0 << 0)
 #define		RISCV_HWPROBE_MISALIGNED_EMULATED	(1 << 0)

arch/riscv/kernel/sys_riscv.c

@@ -162,6 +162,7 @@ static void hwprobe_isa_ext0(struct riscv_hwprobe *pair,
 		EXT_KEY(ZBB);
 		EXT_KEY(ZBS);
 		EXT_KEY(ZICBOZ);
+		EXT_KEY(ZBC);
 #undef EXT_KEY
 	}