[RFC,2/2] arch: m68k: Add STACKTRACE support

Commit Message

Jean-Michel Hautbois Oct. 21, 2024, 9:44 a.m. UTC

In order to use tracing, implement a basic arch_stack_walk() based on
the one in PowerPC.
Tested on a M54418 coldfire.

Signed-off-by: Jean-Michel Hautbois <[e-mail]>
---
 arch/m68k/Kconfig             |  5 ++++
 arch/m68k/kernel/Makefile     |  1 +
 arch/m68k/kernel/stacktrace.c | 70 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 76 insertions(+)

Patch

diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index ab3375475721fa63418c40d4ba6ac76679ebc77d..7142f9759181a90269ae1ba9e682d331ee2ddbf6 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -40,6 +40,7 @@  config M68K
 	select UACCESS_MEMCPY if !MMU
 	select ZONE_DMA
 	select TRACE_IRQFLAGS_SUPPORT
+	select ARCH_STACKWALK
 
 config CPU_BIG_ENDIAN
 	def_bool y
@@ -107,6 +108,10 @@  config BOOTINFO_PROC
 	  Say Y to export the bootinfo used to boot the kernel in a
 	  "bootinfo" file in procfs.  This is useful with kexec.
 
+config STACKTRACE_SUPPORT
+	bool
+	default y
+
 menu "Platform setup"
 
 source "arch/m68k/Kconfig.cpu"
diff --git a/arch/m68k/kernel/Makefile b/arch/m68k/kernel/Makefile
index f335bf3268a108a45bab079fbf0a1c8ead9beb71..4efe92af0b711b19cb1d5129f74e67a739e289b1 100644
--- a/arch/m68k/kernel/Makefile
+++ b/arch/m68k/kernel/Makefile
@@ -31,3 +31,4 @@  obj-$(CONFIG_UBOOT)		+= uboot.o
 
 obj-$(CONFIG_EARLY_PRINTK)	+= early_printk.o
 
+obj-y	+= stacktrace.o
diff --git a/arch/m68k/kernel/stacktrace.c b/arch/m68k/kernel/stacktrace.c
new file mode 100644
index 0000000000000000000000000000000000000000..06c7459373bd25b3bb3540cfe2a909259c1db3ce
--- /dev/null
+++ b/arch/m68k/kernel/stacktrace.c
@@ -0,0 +1,70 @@ 
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Stack trace utility functions etc.
+ *
+ * Copyright 2024 Jean-Michel Hautbois, Yoseli SAS.
+ */
+
+#include <asm/current.h>
+#include <asm/ptrace.h>
+#include <linux/sched.h>
+#include <linux/sched/task_stack.h>
+#include <linux/stacktrace.h>
+
+static inline unsigned long current_stack_frame(void)
+{
+	unsigned long sp;
+
+	asm volatile("movl %%sp, %0" : "=r"(sp));
+	return sp;
+}
+
+static inline int validate_sp(unsigned long sp, struct task_struct *task)
+{
+	unsigned long stack_start, stack_end;
+
+	if (task == current)
+		stack_start = (unsigned long)task_stack_page(task);
+	else
+		stack_start = (unsigned long)task->thread.esp0;
+
+	stack_end = stack_start + THREAD_SIZE;
+
+	if (sp < stack_start || sp >= stack_end)
+		return 0;
+
+	return 1;
+}
+
+void __no_sanitize_address arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
+					   struct task_struct *task, struct pt_regs *regs)
+{
+	unsigned long sp;
+
+	if (regs && !consume_entry(cookie, regs->pc))
+		return;
+
+	if (regs)
+		sp = (unsigned long) regs;
+	else if (task == current)
+		sp = current_stack_frame();
+	else
+		sp = task->thread.ksp;
+
+	for (;;) {
+		unsigned long *stack = (unsigned long *) sp;
+		unsigned long newsp, ip;
+
+		if (!validate_sp(sp, task))
+			return;
+
+		newsp = stack[0];
+		ip = stack[1];
+
+		if (!consume_entry(cookie, ip))
+			return;
+
+		sp = newsp;
+	}
+}