kern/amd64: Add panic function + MU helpers

This commit introduces a panic function as well as a panic machine
unifier layer for MD specifics that help bring the system to a halt.

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

6 files changed, 210 insertions, 9 deletions

diff --git a/sys/arch/amd64/Makefile b/sys/arch/amd64/Makefile
index 265948a..7c6c6c8 100644
--- a/sys/arch/amd64/Makefile
+++ b/sys/arch/amd64/Makefile
@@ -5,17 +5,23 @@ CC =
 LD =
 SYS_CFLAGS =
 ASMFILES = $(shell find . -name "*.S")
+CFILES = $(shell find . -name "*.c")
 ASMOBJS = $(ASMFILES:.S=.S.o)
+COBJ = $(CFILES:.c=.o)
 MISC_OFILES = $(shell find ../../ -name "*.o")
 
 .PHONY: all
-all: $(ASMOBJS)
+all: $(ASMOBJS) $(COBJ)
 	$(LD) -Tconf/link.ld $(MISC_OFILES) -o ../../rv7
 
 %.S.o: %.S
 	$(PROMPT) " [AS] " $<
 	$(CC) -c -I../../target/inc/ $(SYS_CFLAGS) $< -o $@
 
+%.o: %.c
+	$(PROMPT) " [CC] " $<
+	$(CC) -c -I../../target/inc/ -I../../inc/ $(SYS_CFLAGS) $< -o $@
+
 .PHONY: clean
 clean:
 	rm $(MISC_OFILES)
diff --git a/sys/arch/amd64/cpu/trap.S b/sys/arch/amd64/cpu/trap.S
index 1761358..d3b9887 100644
--- a/sys/arch/amd64/cpu/trap.S
+++ b/sys/arch/amd64/cpu/trap.S
@@ -64,22 +64,17 @@ trapstr_tab:
 
     .text
     .globl trap_dispatch
-    .extern uart_write
+    .extern panic
 trap_dispatch:
     mov 0(%rdi), %rax               /* Vector */
-    push %rax                       /* Save it */
     cmp $TRAPSTR_ENTRIES, %rax      /* Too big? */
     jg .unknown_trap                /* Yeah... */
 
-    lea error_header(%rip), %rdi    /* Load the error header */
-    call uart_puts                  /* Print it */
-
-    pop %rcx                        /* Get the vector number */
+    mov %rax, %rcx                  /* Vector -> RCX */
     lea trapstr_convtab(%rip), %rdi /* Load the base here */
     leaq (%rdi, %rcx, 8), %rdi      /* Scale by the vector */
     mov (%rdi), %rdi                /* Get the error string address */
-
-    call uart_puts
+    call panic
     retq
 .unknown_trap:
     lea error_unknown(%rip), %rdi
diff --git a/sys/arch/amd64/os/os_panic.c b/sys/arch/amd64/os/os_panic.c
new file mode 100644
index 0000000..cd55aac
--- /dev/null
+++ b/sys/arch/amd64/os/os_panic.c
@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2025 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 PURPKERNE
+ * 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; LKERNS 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
+ * PKERNSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/types.h>
+#include <mu/panic.h>
+
+void
+mu_panic_preamble(void)
+{
+    static uint64_t sync = 0;
+
+    asm volatile(
+        "cli\n\t"
+        "mov $1, %%rax\n\t"
+        "1:\n\t"
+        "   pause\n\t"
+        "   xchg %0, %%rax\n\t"
+        "   or %%rax, %%rax\n\t"
+        "   jnz 1b\n"
+        :
+        : "m" (sync)
+        : "memory"
+    );
+}
+
+void
+mu_panic_hcf(void)
+{
+    for (;;) {
+        asm volatile("cli; hlt");
+    }
+}
diff --git a/sys/inc/kern/panic.h b/sys/inc/kern/panic.h
new file mode 100644
index 0000000..59963a3
--- /dev/null
+++ b/sys/inc/kern/panic.h
@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2025 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 PURPKERNE
+ * 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; LKERNS 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
+ * PKERNSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _KE_PANIC_H_
+#define _KE_PANIC_H_ 1
+
+#include <sys/cdefs.h>
+#include <lib/stdarg.h>
+
+/*
+ * Signal to the user that a fatal error has
+ * occured and the system needs to halt
+ */
+__dead void panic(const char *fmt, ...);
+
+#endif  /* !_KE_PANIC_H_ */
diff --git a/sys/inc/mu/panic.h b/sys/inc/mu/panic.h
new file mode 100644
index 0000000..b592fcc
--- /dev/null
+++ b/sys/inc/mu/panic.h
@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) 2025 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 PURPKERNE
+ * 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; LKERNS 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
+ * PKERNSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _MU_PANIC_H_
+#define _MU_PANIC_H_ 1
+
+#include <sys/types.h>
+
+/*
+ * Called as soon as a panic is invoked, prevents other
+ * processors from continuing and disables interrupts
+ */
+void mu_panic_preamble(void);
+
+/*
+ * Used internally by the panic function and implemented
+ * per architecture to bring the system to a halt.
+ */
+void mu_panic_hcf(void);
+
+#endif  /* !_MU_PANIC_H_ */
diff --git a/sys/kern/kern_panic.c b/sys/kern/kern_panic.c
new file mode 100644
index 0000000..d6beccb
--- /dev/null
+++ b/sys/kern/kern_panic.c
@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2025 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 PURPKERNE
+ * 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; LKERNS 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
+ * PKERNSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <kern/panic.h>
+#include <kern/serial.h>
+#include <mu/panic.h>
+#include <lib/string.h>
+#include <lib/stdarg.h>
+#include <lib/stdbool.h>
+
+void
+panic(const char *fmt, ...)
+{
+    static bool lock = false;
+    static char buf[256];
+    static va_list ap;
+
+    mu_panic_preamble();
+    va_start(ap, fmt);
+
+    vsnprintf(buf, sizeof(buf), fmt, ap);
+    serial_write("panic: ", 7);
+    serial_write(buf, strlen(buf));
+
+    mu_panic_hcf();
+    __builtin_unreachable();
+}