From fb4002d54b25ab70d46649a76bf536c67cb92bf4 Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Fri, 16 May 2025 20:07:43 -0400
Subject: kernel: Add cpu_halt_others() and harden panic()

Ensure interrupts are disabled at the start of panic()
to prevent any interrupts from further degrading the
state of the system. Also adds a newline before "panic: "
to clean up the logs.

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 sys/arch/aarch64/aarch64/machdep.c |  7 +++++++
 sys/arch/amd64/amd64/machdep.c     | 15 +++++++++++++++
 sys/include/arch/aarch64/cpu.h     |  2 ++
 sys/include/arch/amd64/cpu.h       |  1 +
 sys/kern/kern_panic.c              |  8 +++++++-
 5 files changed, 32 insertions(+), 1 deletion(-)

(limited to 'sys')

diff --git a/sys/arch/aarch64/aarch64/machdep.c b/sys/arch/aarch64/aarch64/machdep.c
index a29ad7e..7c21e62 100644
--- a/sys/arch/aarch64/aarch64/machdep.c
+++ b/sys/arch/aarch64/aarch64/machdep.c
@@ -41,6 +41,13 @@ cpu_startup(struct cpu_info *ci)
     return;
 }
 
+void
+cpu_halt_others(void)
+{
+    /* TODO: STUB */
+    return;
+}
+
 void
 serial_init(void)
 {
diff --git a/sys/arch/amd64/amd64/machdep.c b/sys/arch/amd64/amd64/machdep.c
index 07d6cdd..4a885fa 100644
--- a/sys/arch/amd64/amd64/machdep.c
+++ b/sys/arch/amd64/amd64/machdep.c
@@ -174,6 +174,21 @@ cpu_halt_all(void)
     for (;;);
 }
 
+/*
+ * Same as cpu_halt_all() but for all other
+ * cores but ourselves.
+ */
+void
+cpu_halt_others(void)
+{
+    if (rdmsr(IA32_GS_BASE) == 0) {
+        __ASMV("cli; hlt");
+    }
+
+    /* Send IPI to all cores */
+    lapic_send_ipi(0, IPI_SHORTHAND_OTHERS, halt_vector);
+}
+
 void
 serial_init(void)
 {
diff --git a/sys/include/arch/aarch64/cpu.h b/sys/include/arch/aarch64/cpu.h
index a6ccdec..2f62d95 100644
--- a/sys/include/arch/aarch64/cpu.h
+++ b/sys/include/arch/aarch64/cpu.h
@@ -40,6 +40,8 @@ struct cpu_info {
 };
 
 void cpu_startup(struct cpu_info *ci);
+void cpu_halt_others(void);
+
 void mp_bootstrap_aps(struct cpu_info *ci);
 struct cpu_info *this_cpu(void);
 
diff --git a/sys/include/arch/amd64/cpu.h b/sys/include/arch/amd64/cpu.h
index ce42416..dd753b7 100644
--- a/sys/include/arch/amd64/cpu.h
+++ b/sys/include/arch/amd64/cpu.h
@@ -49,6 +49,7 @@ struct cpu_info {
 };
 
 __dead void cpu_halt_all(void);
+void cpu_halt_others(void);
 void cpu_startup(struct cpu_info *ci);
 
 struct cpu_info *this_cpu(void);
diff --git a/sys/kern/kern_panic.c b/sys/kern/kern_panic.c
index 950ea8f..7660fff 100644
--- a/sys/kern/kern_panic.c
+++ b/sys/kern/kern_panic.c
@@ -31,6 +31,8 @@
 #include <sys/spinlock.h>
 #include <sys/syslog.h>
 #include <sys/reboot.h>
+#include <machine/cdefs.h>
+#include <machine/cpu.h>
 
 /*
  * Burn and sizzle - the core logic that really ends
@@ -69,8 +71,12 @@ panic(const char *fmt, ...)
 {
     va_list ap;
 
+    /* Shut everything else up */
+    md_intoff();
+    cpu_halt_others();
+
     va_start(ap, fmt);
-    kprintf(OMIT_TIMESTAMP "panic: ");
+    kprintf(OMIT_TIMESTAMP "\npanic: ");
     vkprintf(fmt, &ap);
     bas(true, REBOOT_HALT);
 
-- 
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