linux-kernel - [PATCH v2 08/10] riscv: hwprobe: Export the Supm ISA extension

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Date: Tue, 25 Jun 2024 14:09:19 -0700
From: Samuel Holland <samuel.holland@...ive.com>
To: Palmer Dabbelt <palmer@...belt.com>,
	linux-riscv@...ts.infradead.org
Cc: devicetree@...r.kernel.org,
	Catalin Marinas <catalin.marinas@....com>,
	linux-kernel@...r.kernel.org,
	Anup Patel <anup@...infault.org>,
	Conor Dooley <conor@...nel.org>,
	kasan-dev@...glegroups.com,
	Atish Patra <atishp@...shpatra.org>,
	Evgenii Stepanov <eugenis@...gle.com>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
	Rob Herring <robh+dt@...nel.org>,
	"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
	Samuel Holland <samuel.holland@...ive.com>
Subject: [PATCH v2 08/10] riscv: hwprobe: Export the Supm ISA extension

Supm is a virtual ISA extension defined in the RISC-V Pointer Masking
specification, which indicates that pointer masking is available in
U-mode. It can be provided by either Smnpm or Ssnpm, depending on which
mode the kernel runs in. Userspace should not care about this
distinction, so export Supm instead of either underlying extension.

Hide the extension if the kernel was compiled without support for
pointer masking.

Signed-off-by: Samuel Holland <samuel.holland@...ive.com>
---

Changes in v2:
 - New patch for v2

 Documentation/arch/riscv/hwprobe.rst  | 3 +++
 arch/riscv/include/uapi/asm/hwprobe.h | 1 +
 arch/riscv/kernel/sys_hwprobe.c       | 3 +++
 3 files changed, 7 insertions(+)

diff --git a/Documentation/arch/riscv/hwprobe.rst b/Documentation/arch/riscv/hwprobe.rst
index fc015b452ebf..75fbefa0af26 100644
--- a/Documentation/arch/riscv/hwprobe.rst
+++ b/Documentation/arch/riscv/hwprobe.rst
@@ -207,6 +207,9 @@ The following keys are defined:
   * :c:macro:`RISCV_HWPROBE_EXT_ZVE64D`: The Vector sub-extension Zve64d is
     supported, as defined by version 1.0 of the RISC-V Vector extension manual.
 
+  * :c:macro:`RISCV_HWPROBE_EXT_SUPM`: The Supm extension is supported as
+       defined in version 1.0.0-rc2 of the RISC-V Pointer Masking manual.
+
 * :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/uapi/asm/hwprobe.h b/arch/riscv/include/uapi/asm/hwprobe.h
index 7b95fadbea2a..abb7725fd71b 100644
--- a/arch/riscv/include/uapi/asm/hwprobe.h
+++ b/arch/riscv/include/uapi/asm/hwprobe.h
@@ -65,6 +65,7 @@ struct riscv_hwprobe {
 #define		RISCV_HWPROBE_EXT_ZVE64X	(1ULL << 39)
 #define		RISCV_HWPROBE_EXT_ZVE64F	(1ULL << 40)
 #define		RISCV_HWPROBE_EXT_ZVE64D	(1ULL << 41)
+#define		RISCV_HWPROBE_EXT_SUPM		(1ULL << 42)
 #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/sys_hwprobe.c b/arch/riscv/kernel/sys_hwprobe.c
index 83fcc939df67..b4f4b6d93c00 100644
--- a/arch/riscv/kernel/sys_hwprobe.c
+++ b/arch/riscv/kernel/sys_hwprobe.c
@@ -142,6 +142,9 @@ static void hwprobe_isa_ext0(struct riscv_hwprobe *pair,
 			EXT_KEY(ZFHMIN);
 			EXT_KEY(ZFA);
 		}
+
+		if (IS_ENABLED(CONFIG_RISCV_ISA_POINTER_MASKING))
+			EXT_KEY(SUPM);
 #undef EXT_KEY
 	}
 
-- 
2.44.1