[PATCH 19/23] Add ARM AArch64 signal trampoline argument setup for bsd-user

[Ajeet Singh <itachis6234@gmail.com>]

From: Stacey Son <sson@FreeBSD.org>

function to set up signal handler arguments it populates
register values in `CPUARMState` based on the provided
signal, signal frame, signal action, and frame address

Signed-off-by: Stacey Son <sson@FreeBSD.org>
Signed-off-by: Ajeet Singh <itachis@FreeBSD.org>
---
 bsd-user/aarch64/signal.c | 53 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)
 create mode 100644 bsd-user/aarch64/signal.c

diff --git a/bsd-user/aarch64/signal.c b/bsd-user/aarch64/signal.c
new file mode 100644
index 0000000000..98861f9ab3
--- /dev/null
+++ b/bsd-user/aarch64/signal.c
@@ -0,0 +1,53 @@
+/*
+ * ARM AArch64 specific signal definitions for bsd-user
+ *
+ * Copyright (c) 2015 Stacey D. Son <sson at FreeBSD>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ */
+#include "qemu/osdep.h"
+
+#include "qemu.h"
+
+/*
+ * Compare to sendsig() in sys/arm64/arm64/machdep.c
+ * Assumes that target stack frame memory is locked.
+ */
+abi_long set_sigtramp_args(CPUARMState *regs, int sig,
+                           struct target_sigframe *frame,
+                           abi_ulong frame_addr,
+                           struct target_sigaction *ka)
+{
+    /*
+     * Arguments to signal handler:
+     *  x0 = signal number
+     *  x1 = siginfo pointer
+     *  x2 = ucontext pointer
+     *  pc/elr = signal handler pointer
+     *  sp = sigframe struct pointer
+     *  lr = sigtramp at base of user stack
+     */
+
+    regs->xregs[0] = sig;
+    regs->xregs[1] = frame_addr +
+        offsetof(struct target_sigframe, sf_si);
+    regs->xregs[2] = frame_addr +
+        offsetof(struct target_sigframe, sf_uc);
+
+    regs->pc = ka->_sa_handler;
+    regs->xregs[TARGET_REG_SP] = frame_addr;
+    regs->xregs[TARGET_REG_LR] = TARGET_PS_STRINGS - TARGET_SZSIGCODE;
+
+    return 0;
+}
-- 
2.34.1