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Subject[PATCH 08/14] csky: stacktrace supported.
Date
From: Guo Ren <ren_guo@c-sky.com>

The gcc option "-mbacktrace" will push fp(r8),lr into stack and we could
unwind the stack with:
fp = *fp
lr = (unsigned int *)fp[1]

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
---
arch/csky/Kconfig | 3 ++
arch/csky/Makefile | 4 +++
arch/csky/include/asm/thread_info.h | 4 +++
arch/csky/kernel/Makefile | 1 +
arch/csky/kernel/process.c | 29 +++++++++++--------
arch/csky/kernel/stacktrace.c | 57 +++++++++++++++++++++++++++++++++++++
6 files changed, 86 insertions(+), 12 deletions(-)
create mode 100644 arch/csky/kernel/stacktrace.c

diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig
index 8bdbe92..65804d1 100644
--- a/arch/csky/Kconfig
+++ b/arch/csky/Kconfig
@@ -94,6 +94,9 @@ config MMU
config RWSEM_GENERIC_SPINLOCK
def_bool y

+config STACKTRACE_SUPPORT
+ def_bool y
+
config TIME_LOW_RES
def_bool y

diff --git a/arch/csky/Makefile b/arch/csky/Makefile
index c639fc1..3607a6e 100644
--- a/arch/csky/Makefile
+++ b/arch/csky/Makefile
@@ -47,6 +47,10 @@ ifeq ($(CSKYABI),abiv2)
KBUILD_CFLAGS += -mno-stack-size
endif

+ifdef CONFIG_STACKTRACE
+KBUILD_CFLAGS += -mbacktrace
+endif
+
abidirs := $(patsubst %,arch/csky/%/,$(CSKYABI))
KBUILD_CFLAGS += $(patsubst %,-I$(srctree)/%inc,$(abidirs))

diff --git a/arch/csky/include/asm/thread_info.h b/arch/csky/include/asm/thread_info.h
index a2c69a7..0e9d035 100644
--- a/arch/csky/include/asm/thread_info.h
+++ b/arch/csky/include/asm/thread_info.h
@@ -10,6 +10,7 @@
#include <asm/types.h>
#include <asm/page.h>
#include <asm/processor.h>
+#include <abi/switch_context.h>

struct thread_info {
struct task_struct *task;
@@ -36,6 +37,9 @@ struct thread_info {

#define THREAD_SIZE_ORDER (THREAD_SHIFT - PAGE_SHIFT)

+#define thread_saved_fp(tsk) \
+ ((unsigned long)(((struct switch_stack *)(tsk->thread.ksp))->r8))
+
static inline struct thread_info *current_thread_info(void)
{
unsigned long sp;
diff --git a/arch/csky/kernel/Makefile b/arch/csky/kernel/Makefile
index 4422de7..ba5ca48 100644
--- a/arch/csky/kernel/Makefile
+++ b/arch/csky/kernel/Makefile
@@ -6,3 +6,4 @@ obj-y += process.o cpu-probe.o ptrace.o dumpstack.o

obj-$(CONFIG_MODULES) += module.o
obj-$(CONFIG_SMP) += smp.o
+obj-$(CONFIG_STACKTRACE) += stacktrace.o
diff --git a/arch/csky/kernel/process.c b/arch/csky/kernel/process.c
index 8ed2002..e555740 100644
--- a/arch/csky/kernel/process.c
+++ b/arch/csky/kernel/process.c
@@ -93,26 +93,31 @@ int dump_task_regs(struct task_struct *tsk, elf_gregset_t *pr_regs)

unsigned long get_wchan(struct task_struct *p)
{
- unsigned long esp, pc;
- unsigned long stack_page;
+ unsigned long lr;
+ unsigned long *fp, *stack_start, *stack_end;
int count = 0;

if (!p || p == current || p->state == TASK_RUNNING)
return 0;

- stack_page = (unsigned long)p;
- esp = p->thread.esp0;
+ stack_start = (unsigned long *)end_of_stack(p);
+ stack_end = (unsigned long *)(task_stack_page(p) + THREAD_SIZE);
+
+ fp = (unsigned long *) thread_saved_fp(p);
do {
- if (esp < stack_page+sizeof(struct task_struct) ||
- esp >= 8184+stack_page)
+ if (fp < stack_start || fp > stack_end)
return 0;
- /*FIXME: There's may be error here!*/
- pc = ((unsigned long *)esp)[1];
- /* FIXME: This depends on the order of these functions. */
- if (!in_sched_functions(pc))
- return pc;
- esp = *(unsigned long *) esp;
+#ifdef CONFIG_STACKTRACE
+ lr = fp[1];
+ fp = (unsigned long *)fp[0];
+#else
+ lr = *fp++;
+#endif
+ if (!in_sched_functions(lr) &&
+ __kernel_text_address(lr))
+ return lr;
} while (count++ < 16);
+
return 0;
}
EXPORT_SYMBOL(get_wchan);
diff --git a/arch/csky/kernel/stacktrace.c b/arch/csky/kernel/stacktrace.c
new file mode 100644
index 0000000..fec777a
--- /dev/null
+++ b/arch/csky/kernel/stacktrace.c
@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd. */
+
+#include <linux/sched/debug.h>
+#include <linux/sched/task_stack.h>
+#include <linux/stacktrace.h>
+#include <linux/ftrace.h>
+
+void save_stack_trace(struct stack_trace *trace)
+{
+ save_stack_trace_tsk(current, trace);
+}
+EXPORT_SYMBOL_GPL(save_stack_trace);
+
+void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
+{
+ unsigned long *fp, *stack_start, *stack_end;
+ unsigned long addr;
+ int skip = trace->skip;
+ int savesched;
+ int graph_idx = 0;
+
+ if (tsk == current) {
+ asm volatile("mov %0, r8\n":"=r"(fp));
+ savesched = 1;
+ } else {
+ fp = (unsigned long *)thread_saved_fp(tsk);
+ savesched = 0;
+ }
+
+ addr = (unsigned long) fp & THREAD_MASK;
+ stack_start = (unsigned long *) addr;
+ stack_end = (unsigned long *) (addr + THREAD_SIZE);
+
+ while (fp > stack_start && fp < stack_end) {
+ unsigned long lpp, fpp;
+
+ fpp = fp[0];
+ lpp = fp[1];
+ if (!__kernel_text_address(lpp))
+ break;
+ else
+ lpp = ftrace_graph_ret_addr(tsk, &graph_idx, lpp, NULL);
+
+ if (savesched || !in_sched_functions(lpp)) {
+ if (skip) {
+ skip--;
+ } else {
+ trace->entries[trace->nr_entries++] = lpp;
+ if (trace->nr_entries >= trace->max_entries)
+ break;
+ }
+ }
+ fp = (unsigned long *)fpp;
+ }
+}
+EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
--
2.7.4
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