kernel: signals: Add initial signal implementation

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

2 files changed, 106 insertions, 0 deletions

diff --git a/sys/kern/kern_sched.c b/sys/kern/kern_sched.c
index afaf6a8..877c55d 100644
--- a/sys/kern/kern_sched.c
+++ b/sys/kern/kern_sched.c
@@ -38,6 +38,7 @@
 #include <sys/panic.h>
 #include <sys/machdep.h>
 #include <sys/filedesc.h>
+#include <sys/signal.h>
 #include <fs/initramfs.h>
 #include <vm/dynalloc.h>
 #include <vm/physseg.h>
@@ -353,6 +354,10 @@ sched_context_switch(struct trapframe *tf)
     struct sched_state *state = &ci->sched_state;
     struct proc *td, *next_td;
 
+    if (state->td != NULL) {
+        signal_handle(state->td);
+    }
+
     /*
      * If we have no threads, we should not
      * preempt at all.
diff --git a/sys/kern/kern_signal.c b/sys/kern/kern_signal.c
new file mode 100644
index 0000000..96c02a5
--- /dev/null
+++ b/sys/kern/kern_signal.c
@@ -0,0 +1,101 @@
+/*
+ * 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/sched.h>
+#include <sys/cdefs.h>
+#include <sys/syslog.h>
+#include <sys/signal.h>
+#include <dev/vcons/vcons.h>
+#include <string.h>
+
+__MODULE_NAME("kern_signal");
+__KERNEL_META("$Hyra$: kern_signal.c, Ian Marco Moffett, "
+              "Signal handling code");
+
+static void
+signal_log(const char *s)
+{
+    vcons_putstr(&g_syslog_screen, s, strlen(s));
+}
+
+/*
+ * Handle any signals within the current thread
+ *
+ * TODO: Add sigaction support, default action
+ *       for all currently is killing the process.
+ */
+void
+signal_handle(struct proc *curtd)
+{
+    int signo = curtd->signal;
+
+    spinlock_acquire(&curtd->lock);
+    if (signo == 0) {
+        return;
+    }
+
+    curtd->signal = 0;
+    switch (signo) {
+    case SIGFPE:
+        signal_log("Arithmetic error\n");
+        break;
+    case SIGSEGV:
+        signal_log("Segmentation fault\n");
+        break;
+    case SIGKILL:
+        signal_log("Killed\n");
+        break;
+    }
+
+    spinlock_release(&curtd->lock);
+    sched_exit();
+}
+
+/*
+ * Raise a signal for a process
+ *
+ * @to: Can be NULL to mean the current process
+ * @signal: Signal to send
+ *
+ * TODO: Add more functionality.
+ */
+void
+signal_raise(struct proc *to, int signal)
+{
+    if (to == NULL) {
+        to = this_td();
+    }
+
+    to->signal = signal;
+    if (to == this_td()) {
+        /* Current process, just preempt */
+        sched_context_switch(to->tf);
+    }
+}