Implement stacktraces as a great debugging aid. On aarch64 this is cheap
enough to be enabled unconditionally. Unwinding code is taken from the
Kernel.
Signed-off-by: Sascha Hauer <s.ha...@pengutronix.de>
---
arch/arm/cpu/interrupts_64.c | 4 +-
arch/arm/include/asm/barebox.h | 4 +-
arch/arm/include/asm/stacktrace.h | 2 +
arch/arm/lib64/Makefile | 1 +
arch/arm/lib64/stacktrace.c | 86 +++++++++++++++++++++++++++++++++++++++
5 files changed, 95 insertions(+), 2 deletions(-)
create mode 100644 arch/arm/lib64/stacktrace.c
diff --git a/arch/arm/cpu/interrupts_64.c b/arch/arm/cpu/interrupts_64.c
index ffdb87af94..9ed6ed9761 100644
--- a/arch/arm/cpu/interrupts_64.c
+++ b/arch/arm/cpu/interrupts_64.c
@@ -44,7 +44,9 @@ static void __noreturn do_exception(struct pt_regs *pt_regs)
{
show_regs(pt_regs);
- panic("");
+ unwind_backtrace(pt_regs);
+
+ panic("panic: unhandled exception");
}
/**
diff --git a/arch/arm/include/asm/barebox.h b/arch/arm/include/asm/barebox.h
index 5a6622235b..4e89466593 100644
--- a/arch/arm/include/asm/barebox.h
+++ b/arch/arm/include/asm/barebox.h
@@ -2,9 +2,11 @@
#define _BAREBOX_H_ 1
#ifdef CONFIG_ARM_UNWIND
-#ifndef CONFIG_CPU_V8
#define ARCH_HAS_STACK_DUMP
#endif
+
+#ifdef CONFIG_CPU_V8
+#define ARCH_HAS_STACK_DUMP
#endif
#ifdef CONFIG_ARM_EXCEPTIONS
diff --git a/arch/arm/include/asm/stacktrace.h
b/arch/arm/include/asm/stacktrace.h
index 10f70e1675..602e79ced4 100644
--- a/arch/arm/include/asm/stacktrace.h
+++ b/arch/arm/include/asm/stacktrace.h
@@ -4,7 +4,9 @@
struct stackframe {
unsigned long fp;
unsigned long sp;
+#ifdef CONFIG_CPU_32
unsigned long lr;
+#endif
unsigned long pc;
};
diff --git a/arch/arm/lib64/Makefile b/arch/arm/lib64/Makefile
index 679ca556e5..77647128a5 100644
--- a/arch/arm/lib64/Makefile
+++ b/arch/arm/lib64/Makefile
@@ -1,3 +1,4 @@
+obj-y += stacktrace.o
obj-$(CONFIG_ARM_LINUX) += armlinux.o
obj-y += div0.o
obj-$(CONFIG_ARM_OPTIMZED_STRING_FUNCTIONS) += memcpy.o
diff --git a/arch/arm/lib64/stacktrace.c b/arch/arm/lib64/stacktrace.c
new file mode 100644
index 0000000000..b8352c1454
--- /dev/null
+++ b/arch/arm/lib64/stacktrace.c
@@ -0,0 +1,86 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; version 2.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+
+#include <common.h>
+#include <asm/stacktrace.h>
+
+#define THREAD_SIZE 16384
+
+/*
+ * AArch64 PCS assigns the frame pointer to x29.
+ *
+ * A simple function prologue looks like this:
+ * sub sp, sp, #0x10
+ * stp x29, x30, [sp]
+ * mov x29, sp
+ *
+ * A simple function epilogue looks like this:
+ * mov sp, x29
+ * ldp x29, x30, [sp]
+ * add sp, sp, #0x10
+ */
+int unwind_frame(struct stackframe *frame)
+{
+ unsigned long high, low;
+ unsigned long fp = frame->fp;
+
+ low = frame->sp;
+ high = ALIGN(low, THREAD_SIZE);
+
+ if (fp < low || fp > high - 0x18 || fp & 0xf)
+ return -EINVAL;
+
+ frame->sp = fp + 0x10;
+ frame->fp = *(unsigned long *)(fp);
+ frame->pc = *(unsigned long *)(fp + 8);
+
+ return 0;
+}
+
+void dump_backtrace_entry(unsigned long where, unsigned long from)
+{
+#ifdef CONFIG_KALLSYMS
+ printf("[<%08lx>] (%pS) from [<%08lx>] (%pS)\n", where, (void *)where,
from, (void *)from);
+#else
+ printf("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
+#endif
+}
+
+void unwind_backtrace(struct pt_regs *regs)
+{
+ struct stackframe frame = {};
+ register unsigned long current_sp asm ("sp");
+
+ if (regs) {
+ frame.fp = regs->regs[29];
+ frame.pc = regs->elr;
+ } else {
+ frame.fp = (unsigned long)__builtin_frame_address(0);
+ frame.sp = current_sp;
+ frame.pc = (unsigned long)unwind_backtrace;
+ }
+
+ printf("Call trace:\n");
+ while (1) {
+ unsigned long where = frame.pc;
+ int ret;
+
+ ret = unwind_frame(&frame);
+ if (ret < 0)
+ break;
+ dump_backtrace_entry(where, frame.pc);
+ }
+}
+
+void dump_stack(void)
+{
+ unwind_backtrace(NULL);
+}
--
2.16.1
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