Merge patch series "RISC-V: hwprobe: Misaligned scalar perf fix and rename"

Evan Green <evan@rivosinc.com> says:

The CPUPERF0 hwprobe key was documented and identified in code as
a bitmask value, but its contents were an enum. This produced
incorrect behavior in conjunction with the WHICH_CPUS hwprobe flag.
The first patch in this series fixes the bitmask/enum problem by
creating a new hwprobe key that returns the same data, but is
properly described as a value instead of a bitmask. The second patch
renames the value definitions in preparation for adding vector misaligned
access info. As of this version, the old defines are kept in place to
maintain source compatibility with older userspace programs.

* b4-shazam-merge:
  RISC-V: hwprobe: Add SCALAR to misaligned perf defines
  RISC-V: hwprobe: Add MISALIGNED_PERF key

Link: https://lore.kernel.org/r/20240809214444.3257596-1-evan@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

1 files changed, 22 insertions, 14 deletions

diff --git a/Documentation/arch/riscv/hwprobe.rst b/Documentation/arch/riscv/hwprobe.rst
index 3db60a0911df..85b709257918 100644
--- a/Documentation/arch/riscv/hwprobe.rst
+++ b/Documentation/arch/riscv/hwprobe.rst
@@ -239,25 +239,33 @@ The following keys are defined:
        ratified in commit 98918c844281 ("Merge pull request #1217 from
        riscv/zawrs") of riscv-isa-manual.
 
-* :c:macro:`RISCV_HWPROBE_KEY_CPUPERF_0`: A bitmask that contains performance
-  information about the selected set of processors.
+* :c:macro:`RISCV_HWPROBE_KEY_CPUPERF_0`: Deprecated.  Returns similar values to
+     :c:macro:`RISCV_HWPROBE_KEY_MISALIGNED_SCALAR_PERF`, but the key was
+     mistakenly classified as a bitmask rather than a value.
 
-  * :c:macro:`RISCV_HWPROBE_MISALIGNED_UNKNOWN`: The performance of misaligned
-    accesses is unknown.
+* :c:macro:`RISCV_HWPROBE_KEY_MISALIGNED_SCALAR_PERF`: An enum value describing
+  the performance of misaligned scalar native word accesses on the selected set
+  of processors.
 
-  * :c:macro:`RISCV_HWPROBE_MISALIGNED_EMULATED`: Misaligned accesses are
-    emulated via software, either in or below the kernel.  These accesses are
-    always extremely slow.
+  * :c:macro:`RISCV_HWPROBE_MISALIGNED_SCALAR_UNKNOWN`: The performance of
+    misaligned scalar accesses is unknown.
 
-  * :c:macro:`RISCV_HWPROBE_MISALIGNED_SLOW`: Misaligned accesses are slower
-    than equivalent byte accesses.  Misaligned accesses may be supported
-    directly in hardware, or trapped and emulated by software.
+  * :c:macro:`RISCV_HWPROBE_MISALIGNED_SCALAR_EMULATED`: Misaligned scalar
+    accesses are emulated via software, either in or below the kernel.  These
+    accesses are always extremely slow.
 
-  * :c:macro:`RISCV_HWPROBE_MISALIGNED_FAST`: Misaligned accesses are faster
-    than equivalent byte accesses.
+  * :c:macro:`RISCV_HWPROBE_MISALIGNED_SCALAR_SLOW`: Misaligned scalar native
+    word sized accesses are slower than the equivalent quantity of byte
+    accesses. Misaligned accesses may be supported directly in hardware, or
+    trapped and emulated by software.
 
-  * :c:macro:`RISCV_HWPROBE_MISALIGNED_UNSUPPORTED`: Misaligned accesses are
-    not supported at all and will generate a misaligned address fault.
+  * :c:macro:`RISCV_HWPROBE_MISALIGNED_SCALAR_FAST`: Misaligned scalar native
+    word sized accesses are faster than the equivalent quantity of byte
+    accesses.
+
+  * :c:macro:`RISCV_HWPROBE_MISALIGNED_SCALAR_UNSUPPORTED`: Misaligned scalar
+    accesses are not supported at all and will generate a misaligned address
+    fault.
 
 * :c:macro:`RISCV_HWPROBE_KEY_ZICBOZ_BLOCK_SIZE`: An unsigned int which
   represents the size of the Zicboz block in bytes.