From 6cf8f4234acda1acbff3c948efed5f14046f35c5 Mon Sep 17 00:00:00 2001
From: Max Wash <mbswash@gmail.com>
Date: Sat, 6 May 2023 22:18:34 +0100
Subject: [PATCH] x86_64: print stack trace during panic

---
 arch/x86_64/acpi/smp.cpp                  |  1 +
 arch/x86_64/include/socks/machine/panic.h |  5 +-
 arch/x86_64/panic.c                       | 65 ++++++++++++++++++++++-
 kernel/panic.c                            |  7 +++
 4 files changed, 75 insertions(+), 3 deletions(-)

diff --git a/arch/x86_64/acpi/smp.cpp b/arch/x86_64/acpi/smp.cpp
index da1e634..b753238 100644
--- a/arch/x86_64/acpi/smp.cpp
+++ b/arch/x86_64/acpi/smp.cpp
@@ -21,6 +21,7 @@ extern "C" void ap_trampoline_exit(void)
 	__this_ap_ok = 1;
 
 	ml_cpu_block *this_cpu = (ml_cpu_block *)kmalloc(sizeof *this_cpu, VM_NORMAL);
+	memset(this_cpu, 0x00, sizeof *this_cpu);
 	ml_cpu_block_init(this_cpu);
 	ml_cpu_block_use(this_cpu);
 
diff --git a/arch/x86_64/include/socks/machine/panic.h b/arch/x86_64/include/socks/machine/panic.h
index 6441f3e..4bf1366 100644
--- a/arch/x86_64/include/socks/machine/panic.h
+++ b/arch/x86_64/include/socks/machine/panic.h
@@ -1,9 +1,12 @@
 #ifndef SOCKS_X86_64_PANIC_H_
 #define SOCKS_X86_64_PANIC_H_
 
+#include <stdint.h>
+
 struct cpu_context;
 
 extern void ml_print_cpu_state(struct cpu_context *ctx);
-extern void ml_print_stack_trace(struct cpu_context *ctx);
+extern void ml_print_stack_trace(uintptr_t ip);
+extern void ml_print_stack_trace_irq(struct cpu_context *ctx);
 
 #endif
diff --git a/arch/x86_64/panic.c b/arch/x86_64/panic.c
index d0c7397..e6c4a1c 100644
--- a/arch/x86_64/panic.c
+++ b/arch/x86_64/panic.c
@@ -1,3 +1,5 @@
+#include "socks/machine/panic.h"
+#include "socks/vm.h"
 #include <socks/printk.h>
 #include <socks/libc/stdio.h>
 #include <arch/irq.h>
@@ -19,6 +21,11 @@
 #define R_ID 21
 #define R_MAX 21
 
+struct stack_frame {
+	uintptr_t rbp;
+	uintptr_t rip;
+} __attribute__((packed));
+
 const char *pf_rfl_name(int bit)
 {
 	switch (bit) {
@@ -112,7 +119,61 @@ void ml_print_cpu_state(struct cpu_context *ctx)
 	printk("  cr3 %016llx cr4 %016llx", cr3, cr4);
 }
 
-void ml_print_stack_trace(struct cpu_context *ctx)
+static void print_stack_item(uintptr_t addr)
 {
-
+	if (!addr) {
+		return;
+	}
+	
+	char buf[64];
+	size_t i = 0;
+	
+	i += snprintf(buf, sizeof(buf), "  [<%p>] ", addr);
+	
+	size_t offset = 0;
+	char name[128];
+	int found = -1;
+	
+	if (found == 0 && name[0] != '\0') {
+		i += snprintf(buf + i, sizeof(buf) - i, "%s+0x%lx", name, offset);
+	} else {
+		i += snprintf(buf + i, sizeof(buf) - i, "?");
+	}
+	
+	printk("%s", buf);
+}
+
+static void print_stack_trace(uintptr_t ip, uintptr_t *bp)
+{
+	struct stack_frame *stk = (struct stack_frame *)bp;
+	printk("call trace:");
+	
+	print_stack_item(ip);
+
+	int max_frames = 10, current_frame = 0;
+	while (1) {
+		if (!vm_virt_to_phys(stk) ||
+		    bp == NULL ||
+		    current_frame > max_frames) {
+			break;
+		}
+		
+		uintptr_t addr = stk->rip;
+		print_stack_item(addr);
+		
+		stk = (struct stack_frame *)stk->rbp;
+		current_frame++;
+	}
+}
+
+void ml_print_stack_trace(uintptr_t ip)
+{
+	uintptr_t *bp;
+	asm volatile("mov %%rbp, %0" : "=r" (bp));
+	print_stack_trace(ip, bp);
+}
+
+void ml_print_stack_trace_irq(struct cpu_context *ctx)
+{
+	print_stack_trace(ctx->rip, (uintptr_t *)ctx->rbp);
 }
diff --git a/kernel/panic.c b/kernel/panic.c
index 587bca9..566827b 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -37,6 +37,13 @@ void panic_irq(struct cpu_context *ctx, const char *fmt, ...)
 
 	WRITE_ONCE(has_panicked, 1);
 
+	if (ctx) {
+		ml_print_stack_trace_irq(ctx);
+	} else {
+		uintptr_t ip = (uintptr_t)__builtin_return_address(0);
+		ml_print_stack_trace(ip);
+	}
+
 	printk("---[ end kernel panic: %s", buf);
 	ml_halt_cpu();
 }