Hi there,
On 21/10/2024 11:44, Jean-Michel Hautbois wrote:
In order to use tracing, implement a basic arch_stack_walk() based on
the one in PowerPC.
Tested on a M54418 coldfire.
Well, I said it was tested, but it was only compile tested basically.
AFAICT now, I think it is not working as when I use wakeup_rt as a
tracer, I don't have the stack trace:
# wakeup_rt latency trace v1.1.5 on 6.12.0-10380-gb66f06337b66-dirty
# --------------------------------------------------------------------
# latency: 2000 us, #18/18, CPU#0 | (M:preempt VP:0, KP:0, SP:0 HP:0)
# -----------------
# | task: irq/100-enet-fe-118 (uid:0 nice:0 policy:1 rt_prio:50)
# -----------------
#
# _------=> CPU#
# / _-----=> irqs-off/BH-disabled
# | / _----=> need-resched
# || / _---=> hardirq/softirq
# ||| / _--=> preempt-depth
# |||| / _-=> migrate-disable
# ||||| / delay
# cmd pid |||||| time | caller
# \ / |||||| \ | /
kworker/-11 0dnh5. 0us : 11:120:R + [000] 22:
98:R irq_work/0
kworker/-11 0dnh5. 0us : <stack trace>
kworker/-11 0dnh5. 0us : 0
kworker/-11 0d..3. 0us : __schedule
kworker/-11 0d..3. 0us : 11:120:R ==> [000] 22:
98:R irq_work/0
kworker/-11 0d..3. 0us : <stack trace>
telnetd-229 0Dnh4. 0us : 229:120:R + [000] 118:
49:R irq/100-enet-fe
telnetd-229 0Dnh4. 0us : <stack trace>
telnetd-229 0Dnh4. 0us : 0
telnetd-229 0D..3. 0us : __schedule
telnetd-229 0D..3. 0us : 229:120:R ==> [000] 118:
49:R irq/100-enet-fe
telnetd-229 0D..3. 0us : <stack trace>
telnetd-229 0dn.5. 0us : 229:120:R + [000] 118:
49:R irq/100-enet-fe
telnetd-229 0dn.5. 0us : <stack trace>
telnetd-229 0dn.5. 0us#: 0
telnetd-229 0d..3. 2000us : __schedule
telnetd-229 0d..3. 2000us : 229:120:R ==> [000] 118:
49:R irq/100-enet-fe
telnetd-229 0d..3. 2000us : <stack trace>
Geert, Greg, and maybe other highly skilled m68k people, could you
please help me with this particular function :-) ?
Thanks !
JM
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@xxxxxxxxxx>
---
arch/m68k/Kconfig | 5 ++++
arch/m68k/kernel/Makefile | 1 +
arch/m68k/kernel/stacktrace.c | 70 +++++++++++++++++++++++++++++++++++++++++++
3 files changed, 76 insertions(+)
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;
+ }
+}
