riscv: Add ISA extension parsing for pointer masking

The RISC-V Pointer Masking specification defines three extensions:
Smmpm, Smnpm, and Ssnpm. Add support for parsing each of them. The
specific extension which provides pointer masking support to userspace
(Supm) depends on the kernel's privilege mode, so provide a macro to
abstract this selection.

Smmpm implies the existence of the mseccfg CSR. As it is the only user
of this CSR so far, there is no need for an Xlinuxmseccfg extension.

Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
Link: https://lore.kernel.org/r/20241016202814.4061541-3-samuel.holland@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
index 46d9de5..8608883 100644 (file)
--- a/arch/riscv/include/asm/hwcap.h
+++ b/arch/riscv/include/asm/hwcap.h
@@ -93,6 +93,9 @@
 #define RISCV_ISA_EXT_ZCMOP            84
 #define RISCV_ISA_EXT_ZAWRS            85
 #define RISCV_ISA_EXT_SVVPTC           86
+#define RISCV_ISA_EXT_SMMPM            87
+#define RISCV_ISA_EXT_SMNPM            88
+#define RISCV_ISA_EXT_SSNPM            89
 
 #define RISCV_ISA_EXT_XLINUXENVCFG     127
 
@@ -101,8 +104,10 @@
 
 #ifdef CONFIG_RISCV_M_MODE
 #define RISCV_ISA_EXT_SxAIA            RISCV_ISA_EXT_SMAIA
+#define RISCV_ISA_EXT_SUPM             RISCV_ISA_EXT_SMNPM
 #else
 #define RISCV_ISA_EXT_SxAIA            RISCV_ISA_EXT_SSAIA
+#define RISCV_ISA_EXT_SUPM             RISCV_ISA_EXT_SSNPM
 #endif
 
 #endif /* _ASM_RISCV_HWCAP_H */

diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index b3a057c..94596bc 100644 (file)
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -377,9 +377,12 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
        __RISCV_ISA_EXT_BUNDLE(zvksg, riscv_zvksg_bundled_exts),
        __RISCV_ISA_EXT_DATA(zvkt, RISCV_ISA_EXT_ZVKT),
        __RISCV_ISA_EXT_DATA(smaia, RISCV_ISA_EXT_SMAIA),
+       __RISCV_ISA_EXT_DATA(smmpm, RISCV_ISA_EXT_SMMPM),
+       __RISCV_ISA_EXT_SUPERSET(smnpm, RISCV_ISA_EXT_SMNPM, riscv_xlinuxenvcfg_exts),
        __RISCV_ISA_EXT_DATA(smstateen, RISCV_ISA_EXT_SMSTATEEN),
        __RISCV_ISA_EXT_DATA(ssaia, RISCV_ISA_EXT_SSAIA),
        __RISCV_ISA_EXT_DATA(sscofpmf, RISCV_ISA_EXT_SSCOFPMF),
+       __RISCV_ISA_EXT_SUPERSET(ssnpm, RISCV_ISA_EXT_SSNPM, riscv_xlinuxenvcfg_exts),
        __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),