1 files changed, 243 insertions, 32 deletions

diff --git a/sys/kern/kern_sched.c b/sys/kern/kern_sched.c
index f61c592..7b3776d 100644
--- a/sys/kern/kern_sched.c
+++ b/sys/kern/kern_sched.c
@@ -34,10 +34,36 @@
 #include <sys/timer.h>
 #include <sys/cdefs.h>
 #include <sys/spinlock.h>
+#include <sys/loader.h>
+#include <sys/panic.h>
+#include <sys/machdep.h>
+#include <sys/filedesc.h>
+#include <fs/initramfs.h>
 #include <vm/dynalloc.h>
+#include <vm/physseg.h>
+#include <vm/pmap.h>
+#include <vm/map.h>
+#include <vm/vm.h>
 #include <assert.h>
 #include <string.h>
 
+#define STACK_PAGES 8
+#define STACK_SIZE (STACK_PAGES*vm_get_page_size())
+
+/*
+ * The PHYS_TO_VIRT/VIRT_TO_PHYS macros convert
+ * addresses to lower and higher half addresses.
+ * Userspace addresses are on the lower half,
+ * therefore, we can just wrap over these to
+ * keep things simple.
+ *
+ * XXX: TODO: This won't work when not identity mapping
+ *            lowerhalf addresses. Once that is updated,
+ *            get rid of this.
+ */
+#define USER_TO_KERN(user) PHYS_TO_VIRT(user)
+#define KERN_TO_USER(kern) VIRT_TO_PHYS(kern)
+
 /*
  * Thread ready queue - all threads ready to be
  * scheduled should be added to this queue.
@@ -51,9 +77,6 @@ static size_t nthread = 0;
  */
 static struct spinlock tdq_lock = {0};
 
-/* In sys/<machine>/<machine>/switch.S */
-void __sched_switch_to(struct trapframe *tf);
-
 static inline void
 sched_oneshot(void)
 {
@@ -97,13 +120,11 @@ sched_dequeue_td(void)
 
     spinlock_acquire(&tdq_lock);
 
-    if (TAILQ_EMPTY(&td_queue)) {
-        goto done;
+    if (!TAILQ_EMPTY(&td_queue)) {
+        td = TAILQ_FIRST(&td_queue);
+        TAILQ_REMOVE(&td_queue, td, link);
     }
 
-    td = TAILQ_FIRST(&td_queue);
-    TAILQ_REMOVE(&td_queue, td, link);
-done:
     spinlock_release(&tdq_lock);
     return td;
 }
@@ -121,12 +142,101 @@ sched_enter(void)
     }
 }
 
+static uintptr_t
+sched_init_stack(void *stack_top, char *argvp[], char *envp[], struct auxval auxv)
+{
+    uintptr_t *sp = stack_top;
+    void *env_ptr = NULL, *argv_ptr = NULL;
+    size_t argc, envc, len;
+
+    /* Copy argument and environment strings */
+    for (envc = 0; envp[envc] != NULL; ++envc) {
+        len = strlen(envp[envc]);
+        sp -= len - 1;
+        memcpy(sp, envp[envc], len);
+    }
+
+    __assert(envc >= 1);
+    env_ptr = sp;
+
+    for (argc = 0; argvp[argc] != NULL; ++argc) {
+        len = strlen(argvp[argc]);
+        sp -= len - 1;
+        memcpy(sp, argvp[argc], len);
+    }
+
+    __assert(argc >= 1);
+    argv_ptr = sp;
+
+    /* Ensure the stack is aligned */
+    sp = (void *)__ALIGN_DOWN((uintptr_t)sp, 16);
+    if (((argc + envc + 1) & 1) != 0)
+        --sp;
+
+    AUXVAL(sp, AT_NULL, 0x0);
+    AUXVAL(sp, AT_SECURE, 0x0);
+    AUXVAL(sp, AT_ENTRY, auxv.at_entry);
+    AUXVAL(sp, AT_PHDR, auxv.at_phdr);
+    AUXVAL(sp, AT_PHNUM, auxv.at_phnum);
+    STACK_PUSH(sp, 0);
+
+    /* Push environment string pointers */
+    for (int i = 0; i < envc; ++i) {
+        len = strlen(env_ptr);
+        sp -= len;
+
+        *sp = (uintptr_t)KERN_TO_USER((uintptr_t)env_ptr);
+        env_ptr = (char *)env_ptr + len;
+    }
+
+    /* Push argument string pointers */
+    STACK_PUSH(sp, 0);
+    for (int i = 0; i < argc; ++i) {
+        len = strlen(argv_ptr);
+        sp -= len;
+
+        *sp = (uintptr_t)KERN_TO_USER((uintptr_t)argv_ptr);
+        argv_ptr = (char *)argv_ptr + len;
+    }
+
+    STACK_PUSH(sp, argc);
+
+    return (uintptr_t)sp;
+}
+
+static uintptr_t
+sched_create_stack(struct vas vas, bool user, char *argvp[],
+                   char *envp[], struct auxval auxv, struct proc *td)
+{
+    int status;
+    uintptr_t stack;
+    const vm_prot_t USER_STACK_PROT = PROT_WRITE | PROT_USER;
+
+    if (!user) {
+        stack = (uintptr_t)dynalloc(STACK_SIZE);
+        td->stack_base = (uintptr_t)stack;
+        return sched_init_stack((void *)(stack + STACK_SIZE), argvp, envp, auxv);
+    }
+
+    stack = vm_alloc_pageframe(STACK_PAGES);
+    td->stack_base = stack;
+    status = vm_map_create(vas, stack, stack, USER_STACK_PROT, STACK_SIZE);
+
+    if (status != 0) {
+        return 0;
+    }
+
+    memset(USER_TO_KERN(stack), 0, STACK_SIZE);
+    stack = sched_init_stack((void *)USER_TO_KERN(stack + STACK_SIZE), argvp, envp, auxv);
+    return stack;
+}
+
 static struct proc *
-sched_create_td(uintptr_t rip)
+sched_create_td(uintptr_t rip, char *argvp[], char *envp[], struct auxval auxv,
+                struct vas vas, bool is_user)
 {
-    const size_t STACK_SIZE = 0x100000; /* 1 MiB */
     struct proc *td;
-    void *stack;
+    uintptr_t stack;
     struct trapframe *tf;
 
     tf = dynalloc(sizeof(struct trapframe));
@@ -134,32 +244,103 @@ sched_create_td(uintptr_t rip)
         return NULL;
     }
 
-    stack = dynalloc(STACK_SIZE);
-    if (stack == NULL) {
+    td = dynalloc(sizeof(struct proc));
+    if (td == NULL) {
+        /* TODO: Free stack */
         dynfree(tf);
         return NULL;
     }
 
-    td = dynalloc(sizeof(struct proc));
-    if (td == NULL) {
+    stack = sched_create_stack(vas, is_user, argvp, envp, auxv, td);
+    if (stack == 0) {
         dynfree(tf);
-        dynfree(stack);
+        dynfree(td);
         return NULL;
     }
 
     memset(tf, 0, sizeof(struct trapframe));
-    memset(stack, 0, STACK_SIZE);
+    memset(td, 0, sizeof(struct proc));
 
     /* Setup process itself */
     td->pid = 0;        /* Don't assign PID until enqueued */
     td->cpu = NULL;     /* Not yet assigned a core */
     td->tf = tf;
+    td->addrsp = vas;
+    td->is_user = is_user;
+    processor_init_pcb(td);
+
+    /* Allocate standard file descriptors */
+    __assert(fd_alloc(td) != NULL);       /* STDIN */
+    __assert(fd_alloc(td) != NULL);       /* STDOUT */
+    __assert(fd_alloc(td) != NULL);       /* STDERR */
 
     /* Setup trapframe */
-    init_frame(tf, rip, (uintptr_t)stack + STACK_SIZE - 1);
+    if (!is_user) {
+        init_frame(tf, rip, (uintptr_t)stack);
+    } else {
+        init_frame_user(tf, rip, KERN_TO_USER(stack));
+    }
     return td;
 }
 
+static void
+sched_destroy_td(struct proc *td)
+{
+    processor_free_pcb(td);
+
+    /*
+     * User stacks are allocated with vm_alloc_pageframe(),
+     * while kernel stacks are allocated with dynalloc().
+     * We want to check if we are a user program or kernel
+     * program to perform the proper deallocation method.
+     */
+    if (td->is_user) {
+        vm_free_pageframe(td->stack_base, STACK_PAGES);
+    } else {
+        dynfree((void *)td->stack_base);
+    }
+
+    /* Close all of the file descriptors */
+    for (size_t i = 0; i < PROC_MAX_FDS; ++i) {
+        fd_close_fdnum(td, i);
+    }
+
+    pmap_free_vas(vm_get_ctx(), td->addrsp);
+    dynfree(td);
+}
+
+void
+sched_exit(void)
+{
+    struct proc *td;
+    struct vas kvas = vm_get_kvas();
+
+    intr_mask();
+
+    td = this_td();
+
+    /* Switch back to the kernel address space and destroy ourself */
+    pmap_switch_vas(vm_get_ctx(), kvas);
+    sched_destroy_td(td);
+
+    intr_unmask();
+    sched_enter();
+}
+
+/*
+ * Get the current running thread.
+ */
+struct proc *
+this_td(void)
+{
+    struct sched_state *state;
+    struct cpu_info *ci;
+
+    ci = this_cpu();
+    state = &ci->sched_state;
+    return state->td;
+}
+
 /*
  * Thread context switch routine
  */
@@ -174,43 +355,73 @@ sched_context_switch(struct trapframe *tf)
      * If we have no threads, we should not
      * preempt at all.
      */
-    if (nthread == 0) {
-        goto done;
-    } else if ((next_td = sched_dequeue_td()) == NULL) {
-        /* Empty */
-        goto done;
+    if (nthread == 0 || (next_td = sched_dequeue_td()) == NULL) {
+        sched_oneshot();
+        return;
     }
 
+    /*
+     * If we have a thread currently running and we are switching
+     * to another, we shall save our current register state
+     * by copying the trapframe.
+     */
     if (state->td != NULL) {
-        /* Save our trapframe */
         td = state->td;
         memcpy(td->tf, tf, sizeof(struct trapframe));
     }
 
-    /* Copy to stack */
+    /* Copy over the next thread's register state to us */
     memcpy(tf, next_td->tf, sizeof(struct trapframe));
 
     td = state->td;
     state->td = next_td;
 
+    /* Re-enqueue the previous thread if it exists */
     if (td != NULL) {
         sched_enqueue_td(td);
     }
-done:
+
+    /* Do architecture specific context switch logic */
+    processor_switch_to(td, next_td);
+
+    /* Done, switch out our vas and oneshot */
+    pmap_switch_vas(vm_get_ctx(), next_td->addrsp);
     sched_oneshot();
 }
 
 void
 sched_init(void)
 {
+    struct proc *init;
+    struct auxval auxv = {0}, ld_auxv = {0};
+    struct vas vas = pmap_create_vas(vm_get_ctx());
+    const char *init_bin, *ld_bin;
+
+    char *ld_path;
+    char *argv[] = {"/usr/sbin/init", NULL};
+    char *envp[] = {"", NULL};
+
     TAILQ_INIT(&td_queue);
 
-    /*
-     * TODO: Create init with sched_create_td()
-     *       and enqueue with sched_enqueue_td()
-     */
-    (void)sched_create_td;
-    (void)sched_enqueue_td;
+    if ((init_bin = initramfs_open("/usr/sbin/init")) == NULL) {
+        panic("Could not open /usr/boot/init\n");
+    }
+    if (loader_load(vas, init_bin, &auxv, 0, &ld_path) != 0) {
+        panic("Could not load init\n");
+    }
+    if ((ld_bin = initramfs_open(ld_path)) == NULL) {
+        panic("Could not open %s\n", ld_path);
+    }
+    if (loader_load(vas, ld_bin, &ld_auxv, 0x00, NULL) != 0) {
+        panic("Could not load %s\n", ld_path);
+    }
+
+    init = sched_create_td((uintptr_t)ld_auxv.at_entry, argv, envp, ld_auxv, vas, true);
+    if (init == NULL) {
+        panic("Failed to create thread for init\n");
+    }
+
+    sched_enqueue_td(init);
 }
 
 /*