[PULL 21/40] bsd-user/host/x86_64/host-signal.h: Implement host_signal_*

[Warner Losh]

Implement host_signal_pc, host_signal_set_pc and host_signal_write for
x86_64.

Signed-off-by: Kyle Evans <kevans@freebsd.org>
Signed-off-by: Warner Losh <imp@bsdimp.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
---
 bsd-user/host/x86_64/host-signal.h | 37 ++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)
 create mode 100644 bsd-user/host/x86_64/host-signal.h

diff --git a/bsd-user/host/x86_64/host-signal.h 
b/bsd-user/host/x86_64/host-signal.h
new file mode 100644
index 00000000000..47ca19f8814
--- /dev/null
+++ b/bsd-user/host/x86_64/host-signal.h
@@ -0,0 +1,37 @@
+/*
+ * host-signal.h: signal info dependent on the host architecture
+ *
+ * Copyright (c) 2021 Warner Losh
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#ifndef X86_64_HOST_SIGNAL_H
+#define X86_64_HOST_SIGNAL_H
+
+#include <sys/ucontext.h>
+#include <machine/trap.h>
+#include <vm/pmap.h>
+#include <machine/pmap.h>
+
+static inline uintptr_t host_signal_pc(ucontext_t *uc)
+{
+    return uc->uc_mcontext.mc_rip;
+}
+
+static inline void host_signal_set_pc(ucontext_t *uc, uintptr_t pc)
+{
+    uc->uc_mcontext.mc_rip = pc;
+}
+
+static inline bool host_signal_write(siginfo_t *info, ucontext_t *uc)
+{
+    /*
+     * Look in sys/amd64/amd64/trap.c. NOTE: mc_err == tr_err due to type
+     * punning between a trapframe and mcontext on FreeBSD/amd64.
+     */
+    return uc->uc_mcontext.mc_trapno == T_PAGEFLT &&
+        uc->uc_mcontext.mc_err & PGEX_W;
+}
+
+#endif
-- 
2.33.1