kernel/amd64: Add machdep thread init function

Signed-off-by: Ian Moffett <ian@osmora.org>

2 files changed, 110 insertions, 0 deletions

diff --git a/sys/arch/amd64/amd64/proc_machdep.c b/sys/arch/amd64/amd64/proc_machdep.c
new file mode 100644
index 0000000..eb3866a
--- /dev/null
+++ b/sys/arch/amd64/amd64/proc_machdep.c
@@ -0,0 +1,107 @@
+/*
+ * Copyright (c) 2023-2024 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/proc.h>
+#include <sys/types.h>
+#include <sys/param.h>
+#include <sys/errno.h>
+#include <machine/frame.h>
+#include <machine/gdt.h>
+#include <vm/physmem.h>
+#include <vm/vm.h>
+#include <vm/map.h>
+#include <string.h>
+
+/*
+ * MD thread init code
+ *
+ * @p: New process.
+ * @parent: Parent of new process.
+ * @ip: Instruction pointer.
+ */
+int
+md_td_init(struct proc *p, struct proc *parent, uintptr_t ip)
+{
+    uintptr_t stack_base;
+    struct trapframe *tfp, *parent_tfp;
+    struct pcb *pcbp;
+    uint8_t rpl;
+    int error;
+
+    tfp = &p->tf;
+
+    /* Create a new VAS for this thread */
+    pcbp = &p->pcb;
+    if ((error = pmap_new_vas(&pcbp->addrsp)) != 0)
+        return error;
+
+    /*
+     * If parent is NULL, assume kernel space and zero the
+     * trapframe. Otherwise we can just set it up normally.
+     */
+    if (parent == NULL) {
+        rpl = 0;
+        memset(tfp, 0, sizeof(*tfp));
+    } else {
+        parent_tfp = &parent->tf;
+        rpl = parent_tfp->cs & 3;
+        memcpy(tfp, &parent->tf, sizeof(*tfp));
+    }
+
+    /*
+     * RPL being 3 indicates that the parent thread is in
+     * userland. If this is the case, we'd want this new thread
+     * to also be in userland.
+     */
+    tfp->rip = ip;
+    tfp->cs = (rpl == 3) ? (USER_CS | 3) : KERNEL_CS;
+    tfp->ss = (rpl == 3) ? (USER_DS | 3) : KERNEL_DS;
+    tfp->rflags = 0x202;
+
+    /* Try to allocate a new stack */
+    stack_base = vm_alloc_frame(PROC_STACK_PAGES);
+    if (stack_base == 0)
+        return -ENOMEM;
+
+    /*
+     * If RPL is 0 (kernel), adjust the stack base to the
+     * higher half. If we have an RPL of 3 (user) then we'll
+     * need to identity map the stack.
+     */
+    if (rpl == 0) {
+        stack_base += VM_HIGHER_HALF;
+    } else {
+        vm_map(pcbp->addrsp, stack_base, stack_base,
+            PROT_READ | PROT_WRITE | PROT_USER, PROC_STACK_PAGES);
+    }
+
+    p->stack_base = stack_base;
+    tfp->rsp = ALIGN_DOWN((stack_base + PROC_STACK_SIZE) - 1, 16);
+    return 0;
+}
diff --git a/sys/include/sys/proc.h b/sys/include/sys/proc.h
index b74cb00..db41a4b 100644
--- a/sys/include/sys/proc.h
+++ b/sys/include/sys/proc.h
@@ -39,6 +39,8 @@
 #endif  /* _KERNEL */
 
 #if defined(_KERNEL)
+#define PROC_STACK_PAGES 8
+#define PROC_STACK_SIZE  (PROC_STACK_PAGES * DEFAULT_PAGESIZE)
 
 struct proc {
     pid_t pid;
@@ -50,6 +52,7 @@ struct proc {
 };
 
 struct proc *this_td(void);
+int md_td_init(struct proc *p, struct proc *parent, uintptr_t ip);
 
 #endif  /* _KERNEL */
 #endif  /* !_SYS_PROC_H_ */