sys/linux: add syz_pkey_set syscalls

The syscall sets PKRU register which is part of protection keys (pkey).

1 files changed, 24 insertions, 0 deletions

diff --git a/executor/common_linux.h b/executor/common_linux.h
index e53a908ab..a2736624a 100644
--- a/executor/common_linux.h
+++ b/executor/common_linux.h
@@ -5547,3 +5547,27 @@ static long syz_clone3(volatile long a0, volatile long a1)
 }
 
 #endif
+
+#if SYZ_EXECUTOR || __NR_syz_pkey_set
+// syz_pkey_set(key pkey, val flags[pkey_flags])
+static long syz_pkey_set(volatile long pkey, volatile long val)
+{
+#if GOARCH_amd64 || GOARCH_386
+	uint32 eax = 0;
+	uint32 ecx = 0;
+	asm volatile("rdpkru"
+		     : "=a"(eax)
+		     : "c"(ecx)
+		     : "edx");
+	// PKRU register contains 2 bits per key.
+	// Max number of keys is 16.
+	// Clear old bits for the key:
+	eax &= ~(3 << ((pkey % 16) * 2));
+	// Set new bits for the key:
+	eax |= (val & 3) << ((pkey % 16) * 2);
+	uint32 edx = 0;
+	asm volatile("wrpkru" ::"a"(eax), "c"(ecx), "d"(edx));
+#endif
+	return 0;
+}
+#endif