[PATCH v3 09/17] bsd-user: Add RISC-V thread setup and initialization support

[Ajeet Singh]

From: Mark Corbin <mark@dibsco.co.uk>

Implemented functions for setting up and initializing threads in the
RISC-V architecture.
The 'target_thread_set_upcall' function sets up the stack pointer,
program counter, and function argument for new threads.
The 'target_thread_init' function initializes thread registers based on
the provided image information.

Signed-off-by: Mark Corbin <mark@dibsco.co.uk>
Signed-off-by: Ajeet Singh <itachis@FreeBSD.org>
Co-authored-by: Jessica Clarke <jrtc27@jrtc27.com>
Co-authored-by: Kyle Evans <kevans@FreeBSD.org>
---
 bsd-user/riscv/target_arch_thread.h | 47 +++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)
 create mode 100644 bsd-user/riscv/target_arch_thread.h

diff --git a/bsd-user/riscv/target_arch_thread.h 
b/bsd-user/riscv/target_arch_thread.h
new file mode 100644
index 0000000000..db0f9eb52c
--- /dev/null
+++ b/bsd-user/riscv/target_arch_thread.h
@@ -0,0 +1,47 @@
+/*
+ *  RISC-V thread support
+ *
+ *  Copyright (c) 2019 Mark Corbin
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program 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 General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef TARGET_ARCH_THREAD_H
+#define TARGET_ARCH_THREAD_H
+
+/* Compare with cpu_set_upcall() in riscv/riscv/vm_machdep.c */
+static inline void target_thread_set_upcall(CPURISCVState *regs,
+    abi_ulong entry, abi_ulong arg, abi_ulong stack_base,
+    abi_ulong stack_size)
+{
+    abi_ulong sp;
+
+    sp = ROUND_DOWN(stack_base + stack_size,16);
+
+    regs->gpr[xSP] = sp;
+    regs->pc = entry;
+    regs->gpr[xA0] = arg;
+}
+
+/* Compare with exec_setregs() in riscv/riscv/machdep.c */
+static inline void target_thread_init(struct target_pt_regs *regs,
+    struct image_info *infop)
+{
+    regs->sepc = infop->entry;
+    regs->regs[xRA] = infop->entry;
+    regs->regs[xA0] = infop->start_stack;               
+    regs->regs[xSP] = ROUND_DOWN(infop->start_stack,16);
+}
+
+#endif /* TARGET_ARCH_THREAD_H */
-- 
2.34.1