From 18c07d23da5a48525b2955aa269b8bb108c19300 Mon Sep 17 00:00:00 2001
From: Guo Ren <guoren@linux.alibaba.com>
Date: Wed, 13 May 2020 15:15:25 +0800
Subject: csky: Fixup calltrace panic
The implementation of show_stack will panic with wrong fp:
addr = *fp++;
because the fp isn't checked properly.
The current implementations of show_stack, wchan and stack_trace
haven't been designed properly, so just deprecate them.
This patch is a reference to riscv's way, all codes are modified from
arm's. The patch is passed with:
- cat /proc/<pid>/stack
- cat /proc/<pid>/wchan
- echo c > /proc/sysrq-trigger
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
---
arch/csky/kernel/Makefile | 2 +-
arch/csky/kernel/dumpstack.c | 49 ------------
arch/csky/kernel/process.c | 31 --------
arch/csky/kernel/stacktrace.c | 176 +++++++++++++++++++++++++++++++++---------
4 files changed, 140 insertions(+), 118 deletions(-)
delete mode 100644 arch/csky/kernel/dumpstack.c
(limited to 'arch/csky/kernel')
diff --git a/arch/csky/kernel/Makefile b/arch/csky/kernel/Makefile
index fd6d9dc8b7f3..37f37c0e934a 100644
--- a/arch/csky/kernel/Makefile
+++ b/arch/csky/kernel/Makefile
@@ -3,7 +3,7 @@ extra-y := head.o vmlinux.lds
obj-y += entry.o atomic.o signal.o traps.o irq.o time.o vdso.o
obj-y += power.o syscall.o syscall_table.o setup.o
-obj-y += process.o cpu-probe.o ptrace.o dumpstack.o
+obj-y += process.o cpu-probe.o ptrace.o stacktrace.o
obj-y += probes/
obj-$(CONFIG_MODULES) += module.o
diff --git a/arch/csky/kernel/dumpstack.c b/arch/csky/kernel/dumpstack.c
deleted file mode 100644
index d67f9777cfd9..000000000000
--- a/arch/csky/kernel/dumpstack.c
+++ /dev/null
@@ -1,49 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
-
-#include <linux/ptrace.h>
-
-int kstack_depth_to_print = 48;
-
-void show_trace(unsigned long *stack)
-{
- unsigned long *stack_end;
- unsigned long *stack_start;
- unsigned long *fp;
- unsigned long addr;
-
- addr = (unsigned long) stack & THREAD_MASK;
- stack_start = (unsigned long *) addr;
- stack_end = (unsigned long *) (addr + THREAD_SIZE);
-
- fp = stack;
- pr_info("\nCall Trace:");
-
- while (fp > stack_start && fp < stack_end) {
-#ifdef CONFIG_STACKTRACE
- addr = fp[1];
- fp = (unsigned long *) fp[0];
-#else
- addr = *fp++;
-#endif
- if (__kernel_text_address(addr))
- pr_cont("\n[<%08lx>] %pS", addr, (void *)addr);
- }
- pr_cont("\n");
-}
-
-void show_stack(struct task_struct *task, unsigned long *stack)
-{
- if (!stack) {
- if (task)
- stack = (unsigned long *)thread_saved_fp(task);
- else
-#ifdef CONFIG_STACKTRACE
- asm volatile("mov %0, r8\n":"=r"(stack)::"memory");
-#else
- stack = (unsigned long *)&stack;
-#endif
- }
-
- show_trace(stack);
-}
diff --git a/arch/csky/kernel/process.c b/arch/csky/kernel/process.c
index f7b231ca269a..4ad6db56c3cd 100644
--- a/arch/csky/kernel/process.c
+++ b/arch/csky/kernel/process.c
@@ -98,37 +98,6 @@ int dump_task_regs(struct task_struct *tsk, elf_gregset_t *pr_regs)
return 1;
}
-unsigned long get_wchan(struct task_struct *p)
-{
- unsigned long lr;
- unsigned long *fp, *stack_start, *stack_end;
- int count = 0;
-
- if (!p || p == current || p->state == TASK_RUNNING)
- return 0;
-
- 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 (fp < stack_start || fp > stack_end)
- return 0;
-#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);
-
#ifndef CONFIG_CPU_PM_NONE
void arch_cpu_idle(void)
{
diff --git a/arch/csky/kernel/stacktrace.c b/arch/csky/kernel/stacktrace.c
index fec777a643f1..92809e1da723 100644
--- a/arch/csky/kernel/stacktrace.c
+++ b/arch/csky/kernel/stacktrace.c
@@ -1,57 +1,159 @@
// 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>
+#include <linux/ptrace.h>
-void save_stack_trace(struct stack_trace *trace)
+#ifdef CONFIG_FRAME_POINTER
+
+struct stackframe {
+ unsigned long fp;
+ unsigned long ra;
+};
+
+void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
+ bool (*fn)(unsigned long, void *), void *arg)
{
- save_stack_trace_tsk(current, trace);
+ unsigned long fp, sp, pc;
+
+ if (regs) {
+ fp = frame_pointer(regs);
+ sp = user_stack_pointer(regs);
+ pc = instruction_pointer(regs);
+ } else if (task == NULL || task == current) {
+ const register unsigned long current_sp __asm__ ("sp");
+ const register unsigned long current_fp __asm__ ("r8");
+ fp = current_fp;
+ sp = current_sp;
+ pc = (unsigned long)walk_stackframe;
+ } else {
+ /* task blocked in __switch_to */
+ fp = thread_saved_fp(task);
+ sp = thread_saved_sp(task);
+ pc = thread_saved_lr(task);
+ }
+
+ for (;;) {
+ unsigned long low, high;
+ struct stackframe *frame;
+
+ if (unlikely(!__kernel_text_address(pc) || fn(pc, arg)))
+ break;
+
+ /* Validate frame pointer */
+ low = sp;
+ high = ALIGN(sp, THREAD_SIZE);
+ if (unlikely(fp < low || fp > high || fp & 0x3))
+ break;
+ /* Unwind stack frame */
+ frame = (struct stackframe *)fp;
+ sp = fp;
+ fp = frame->fp;
+ pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
+ (unsigned long *)(fp - 8));
+ }
}
-EXPORT_SYMBOL_GPL(save_stack_trace);
-void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
+#else /* !CONFIG_FRAME_POINTER */
+
+static void notrace walk_stackframe(struct task_struct *task,
+ struct pt_regs *regs, bool (*fn)(unsigned long, void *), void *arg)
{
- unsigned long *fp, *stack_start, *stack_end;
- unsigned long addr;
- int skip = trace->skip;
- int savesched;
- int graph_idx = 0;
+ unsigned long sp, pc;
+ unsigned long *ksp;
- if (tsk == current) {
- asm volatile("mov %0, r8\n":"=r"(fp));
- savesched = 1;
+ if (regs) {
+ sp = user_stack_pointer(regs);
+ pc = instruction_pointer(regs);
+ } else if (task == NULL || task == current) {
+ const register unsigned long current_sp __asm__ ("sp");
+ sp = current_sp;
+ pc = (unsigned long)walk_stackframe;
} else {
- fp = (unsigned long *)thread_saved_fp(tsk);
- savesched = 0;
+ /* task blocked in __switch_to */
+ sp = thread_saved_sp(task);
+ pc = thread_saved_lr(task);
}
- 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;
+ if (unlikely(sp & 0x3))
+ return;
- fpp = fp[0];
- lpp = fp[1];
- if (!__kernel_text_address(lpp))
+ ksp = (unsigned long *)sp;
+ while (!kstack_end(ksp)) {
+ if (__kernel_text_address(pc) && unlikely(fn(pc, arg)))
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;
+ pc = (*ksp++) - 0x4;
}
}
+#endif /* CONFIG_FRAME_POINTER */
+
+static bool print_trace_address(unsigned long pc, void *arg)
+{
+ print_ip_sym(pc);
+ return false;
+}
+
+void show_stack(struct task_struct *task, unsigned long *sp)
+{
+ pr_cont("Call Trace:\n");
+ walk_stackframe(task, NULL, print_trace_address, NULL);
+}
+
+static bool save_wchan(unsigned long pc, void *arg)
+{
+ if (!in_sched_functions(pc)) {
+ unsigned long *p = arg;
+ *p = pc;
+ return true;
+ }
+ return false;
+}
+
+unsigned long get_wchan(struct task_struct *task)
+{
+ unsigned long pc = 0;
+
+ if (likely(task && task != current && task->state != TASK_RUNNING))
+ walk_stackframe(task, NULL, save_wchan, &pc);
+ return pc;
+}
+
+#ifdef CONFIG_STACKTRACE
+static bool __save_trace(unsigned long pc, void *arg, bool nosched)
+{
+ struct stack_trace *trace = arg;
+
+ if (unlikely(nosched && in_sched_functions(pc)))
+ return false;
+ if (unlikely(trace->skip > 0)) {
+ trace->skip--;
+ return false;
+ }
+
+ trace->entries[trace->nr_entries++] = pc;
+ return (trace->nr_entries >= trace->max_entries);
+}
+
+static bool save_trace(unsigned long pc, void *arg)
+{
+ return __save_trace(pc, arg, false);
+}
+
+/*
+ * Save stack-backtrace addresses into a stack_trace buffer.
+ */
+void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
+{
+ walk_stackframe(tsk, NULL, save_trace, trace);
+}
EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
+
+void save_stack_trace(struct stack_trace *trace)
+{
+ save_stack_trace_tsk(NULL, trace);
+}
+EXPORT_SYMBOL_GPL(save_stack_trace);
+
+#endif /* CONFIG_STACKTRACE */
--
cgit