linux-user: Add code for PR_GET/SET_UNALIGN

This requires extra work for each target, but adds the
common syscall code, and the necessary flag in CPUState.

Reviewed-by: Warner Losh <imp@bsdimp.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20211227150127.2659293-4-richard.henderson@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

2 files changed, 38 insertions, 2 deletions

diff --git a/linux-user/generic/target_prctl_unalign.h b/linux-user/generic/target_prctl_unalign.h
new file mode 100644
index 0000000000..bc3b83af2a
--- /dev/null
+++ b/linux-user/generic/target_prctl_unalign.h
@@ -0,0 +1,27 @@
+/*
+ * Generic prctl unalign functions for linux-user
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+#ifndef GENERIC_TARGET_PRCTL_UNALIGN_H
+#define GENERIC_TARGET_PRCTL_UNALIGN_H
+
+static abi_long do_prctl_get_unalign(CPUArchState *env, target_long arg2)
+{
+    CPUState *cs = env_cpu(env);
+    uint32_t res = PR_UNALIGN_NOPRINT;
+    if (cs->prctl_unalign_sigbus) {
+        res |= PR_UNALIGN_SIGBUS;
+    }
+    return put_user_u32(res, arg2);
+}
+#define do_prctl_get_unalign do_prctl_get_unalign
+
+static abi_long do_prctl_set_unalign(CPUArchState *env, target_long arg2)
+{
+    env_cpu(env)->prctl_unalign_sigbus = arg2 & PR_UNALIGN_SIGBUS;
+    return 0;
+}
+#define do_prctl_set_unalign do_prctl_set_unalign
+
+#endif /* GENERIC_TARGET_PRCTL_UNALIGN_H */
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index d868ef2910..b5112891b0 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -6378,6 +6378,12 @@ static abi_long do_prctl_inval1(CPUArchState *env, abi_long arg2)
 #ifndef do_prctl_get_tagged_addr_ctrl
 #define do_prctl_get_tagged_addr_ctrl do_prctl_inval0
 #endif
+#ifndef do_prctl_get_unalign
+#define do_prctl_get_unalign do_prctl_inval1
+#endif
+#ifndef do_prctl_set_unalign
+#define do_prctl_set_unalign do_prctl_inval1
+#endif
 
 static abi_long do_prctl(CPUArchState *env, abi_long option, abi_long arg2,
                          abi_long arg3, abi_long arg4, abi_long arg5)
@@ -6441,6 +6447,11 @@ static abi_long do_prctl(CPUArchState *env, abi_long option, abi_long arg2,
         }
         return do_prctl_get_tagged_addr_ctrl(env);
 
+    case PR_GET_UNALIGN:
+        return do_prctl_get_unalign(env, arg2);
+    case PR_SET_UNALIGN:
+        return do_prctl_set_unalign(env, arg2);
+
     case PR_GET_DUMPABLE:
     case PR_SET_DUMPABLE:
     case PR_GET_KEEPCAPS:
@@ -6483,8 +6494,6 @@ static abi_long do_prctl(CPUArchState *env, abi_long option, abi_long arg2,
     case PR_SET_THP_DISABLE:
     case PR_GET_TSC:
     case PR_SET_TSC:
-    case PR_GET_UNALIGN:
-    case PR_SET_UNALIGN:
         /* Disable to prevent the target disabling stuff we need. */
         return -TARGET_EINVAL;