[PULL 19/38] util/cpuinfo-riscv: Detect Zbkb

RISCV_HWPROBE_EXT_ZBKB was introduced in linux 6.10
with the rest of the hwprobe api.

Reviewed-by: Alistair Francis <[email protected]>
Reviewed-by: Philippe Mathieu-Daudé <[email protected]>
Signed-off-by: Richard Henderson <[email protected]>
---
 host/include/riscv64/host/cpuinfo.h |  1 +
 util/cpuinfo-riscv.c                | 17 +++++++++++++++--
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/host/include/riscv64/host/cpuinfo.h b/host/include/riscv64/host/cpuinfo.h
index b2b53dbf62..1f047051a3 100644
--- a/host/include/riscv64/host/cpuinfo.h
+++ b/host/include/riscv64/host/cpuinfo.h
@@ -12,6 +12,7 @@
 #define CPUINFO_ZBS             (1u << 3)
 #define CPUINFO_ZICOND          (1u << 4)
 #define CPUINFO_ZVE64X          (1u << 5)
+#define CPUINFO_ZBKB            (1u << 6)
 
 /* Initialized with a constructor. */
 extern unsigned cpuinfo;
diff --git a/util/cpuinfo-riscv.c b/util/cpuinfo-riscv.c
index 0291b7218a..8c48b1ea91 100644
--- a/util/cpuinfo-riscv.c
+++ b/util/cpuinfo-riscv.c
@@ -36,7 +36,7 @@ static void sigill_handler(int signo, siginfo_t *si, void *data)
 /* Called both as constructor and (possibly) via other constructors. */
 unsigned __attribute__((constructor)) cpuinfo_init(void)
 {
-    unsigned left = CPUINFO_ZBA | CPUINFO_ZBB | CPUINFO_ZBS
+    unsigned left = CPUINFO_ZBA | CPUINFO_ZBB | CPUINFO_ZBS | CPUINFO_ZBKB
                   | CPUINFO_ZICOND | CPUINFO_ZVE64X;
     unsigned info = cpuinfo;
 
@@ -60,6 +60,9 @@ unsigned __attribute__((constructor)) cpuinfo_init(void)
 #if defined(__riscv_arch_test) && \
     (defined(__riscv_vector) || defined(__riscv_zve64x))
     info |= CPUINFO_ZVE64X;
+#endif
+#if defined(__riscv_arch_test) && defined(__riscv_zbkb)
+    info |= CPUINFO_ZBKB;
 #endif
     left &= ~info;
 
@@ -76,7 +79,8 @@ unsigned __attribute__((constructor)) cpuinfo_init(void)
             info |= pair.value & RISCV_HWPROBE_EXT_ZBA ? CPUINFO_ZBA : 0;
             info |= pair.value & RISCV_HWPROBE_EXT_ZBB ? CPUINFO_ZBB : 0;
             info |= pair.value & RISCV_HWPROBE_EXT_ZBS ? CPUINFO_ZBS : 0;
-            left &= ~(CPUINFO_ZBA | CPUINFO_ZBB | CPUINFO_ZBS);
+            info |= pair.value & RISCV_HWPROBE_EXT_ZBKB ? CPUINFO_ZBKB : 0;
+            left &= ~(CPUINFO_ZBA | CPUINFO_ZBB | CPUINFO_ZBS | CPUINFO_ZBKB);
 #ifdef RISCV_HWPROBE_EXT_ZICOND
             info |= pair.value & RISCV_HWPROBE_EXT_ZICOND ? CPUINFO_ZICOND : 0;
             left &= ~CPUINFO_ZICOND;
@@ -131,6 +135,15 @@ unsigned __attribute__((constructor)) cpuinfo_init(void)
             left &= ~CPUINFO_ZBS;
         }
 
+        if (left & CPUINFO_ZBKB) {
+            /* Probe for Zbkb: brev8 zero,zero. */
+            got_sigill = 0;
+            asm volatile(".insn i 0x13, 5, zero, zero, 0x687"
+                         : : : "memory");
+            info |= got_sigill ? 0 : CPUINFO_ZBKB;
+            left &= ~CPUINFO_ZBKB;
+        }
+
         if (left & CPUINFO_ZICOND) {
             /* Probe for Zicond: czero.eqz zero,zero,zero. */
             got_sigill = 0;
-- 
2.43.0