From 6bdd17edca2fa58263db47841e007cee5a01a26c Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Tue, 14 May 2024 11:36:23 -0400
Subject: kernel: machdep: Add machine_panic() + panic beep

machine_panic() handles things like backtracing, beeping the speaker and
halting the processor.

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 sys/arch/amd64/amd64/machdep.c | 34 +++++++++++++++++++++++++++++++++-
 sys/include/sys/machdep.h      |  2 +-
 sys/kern/kern_panic.c          |  3 +--
 3 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/sys/arch/amd64/amd64/machdep.c b/sys/arch/amd64/amd64/machdep.c
index f73d773..4476053 100644
--- a/sys/arch/amd64/amd64/machdep.c
+++ b/sys/arch/amd64/amd64/machdep.c
@@ -31,6 +31,7 @@
 #include <sys/cdefs.h>
 #include <sys/panic.h>
 #include <sys/ksyms.h>
+#include <sys/timer.h>
 #include <machine/trap.h>
 #include <machine/idt.h>
 #include <machine/io.h>
@@ -40,6 +41,7 @@
 #include <machine/lapic.h>
 #include <machine/tss.h>
 #include <machine/spectre.h>
+#include <machine/isa/spkr.h>
 #include <machine/cpu.h>
 #include <machine/uart.h>
 #include <machine/cpuid.h>
@@ -192,7 +194,7 @@ backtrace_addr_to_name(uintptr_t addr, off_t *off)
     return NULL;
 }
 
-void
+static void
 backtrace(void)
 {
     uintptr_t *rbp;
@@ -218,6 +220,36 @@ backtrace(void)
     }
 }
 
+/*
+ * Called last within panic()
+ */
+void
+machine_panic(void)
+{
+    struct timer tmr = {0};
+    bool has_timer = true;
+
+    if (req_timer(TIMER_GP, &tmr) != TMRR_SUCCESS)
+        has_timer = false;
+    if (tmr.msleep == NULL)
+        has_timer = false;
+
+    backtrace();
+
+    /*
+     * If we can use the timer, beep twice to
+     * alert the user.
+     */
+    if (has_timer) {
+        for (int i = 0; i < 2; ++i) {
+            pcspkr_tone(1050, 200);
+            tmr.msleep(100);
+        }
+    }
+
+    processor_halt();
+}
+
 void
 cpu_halt_others(void)
 {
diff --git a/sys/include/sys/machdep.h b/sys/include/sys/machdep.h
index 99ebbac..31385ce 100644
--- a/sys/include/sys/machdep.h
+++ b/sys/include/sys/machdep.h
@@ -45,10 +45,10 @@ void processor_init(void);
 void processor_halt(void);
 void intr_mask(void);
 void intr_unmask(void);
+void machine_panic(void);
 __weak void chips_init(void);
 __weak void pre_init(void);
 __weak void serial_dbgch(char c);
-__weak void backtrace(void);
 __weak void cpu_halt_others(void);
 
 #endif  /* defined(_KERNEL) */
diff --git a/sys/kern/kern_panic.c b/sys/kern/kern_panic.c
index 5b90dc8..aec7be3 100644
--- a/sys/kern/kern_panic.c
+++ b/sys/kern/kern_panic.c
@@ -55,8 +55,7 @@ panic(const char *fmt, ...)
 
     kprintf("panic: ");
     vkprintf(fmt, &ap);
-    __TRY_CALL(backtrace);
 
-    processor_halt();
+    machine_panic();
     __builtin_unreachable();
 }
-- 
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