From 48a5e34fcd07852b4a68825ce8e37feb6f6d04d7 Mon Sep 17 00:00:00 2001
From: Mole Shang <135e2@135e2.dev>
Date: Sun, 11 Feb 2024 14:41:35 +0800
Subject: lab traps: finish
---
kernel/printf.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
(limited to 'kernel/printf.c')
diff --git a/kernel/printf.c b/kernel/printf.c
index 1a50203..509c1c5 100644
--- a/kernel/printf.c
+++ b/kernel/printf.c
@@ -122,6 +122,8 @@ panic(char *s)
printf("panic: ");
printf(s);
printf("\n");
+ backtrace();
+
panicked = 1; // freeze uart output from other CPUs
for(;;)
;
@@ -133,3 +135,18 @@ printfinit(void)
initlock(&pr.lock, "pr");
pr.locking = 1;
}
+
+void
+backtrace(void)
+{
+ uint64 fp = r_fp();
+ printf("backtrace:\n");
+ uint64 stackpg = PGROUNDDOWN(fp);
+ // Whereever fp points to should always live in the stack page
+ while(PGROUNDDOWN(fp) == stackpg){
+ // print the return addr (stored in fp-8)
+ printf("%p\n", *(uint64 *)(fp-8));
+ // load previous (upper stack) fp
+ fp = *(uint64 *)(fp-16);
+ }
+}
--
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