UML: Enable CONFIG_STACKTRACE_SUPPORT
Adds a simple stacktrace function, only tested/enabled on X86
Signed-off-by: Paul Menage <men...@google.com>
---
arch/um/Kconfig.common | 2 +
arch/um/kernel/Makefile | 1 +
arch/um/kernel/stacktrace.c | 68 +++++++++++++++++++++++++++++++++++++++++++
arch/um/kernel/sysrq.c | 20 +++++++++++++
4 files changed, 90 insertions(+), 1 deletions(-)
create mode 100644 arch/um/kernel/stacktrace.c
diff --git a/arch/um/Kconfig.common b/arch/um/Kconfig.common
index 8a54ae4..b757c36 100644
--- a/arch/um/Kconfig.common
+++ b/arch/um/Kconfig.common
@@ -44,7 +44,7 @@ config LOCKDEP_SUPPORT
config STACKTRACE_SUPPORT
bool
- default n
+ default UML_X86
config GENERIC_CALIBRATE_DELAY
bool
diff --git a/arch/um/kernel/Makefile b/arch/um/kernel/Makefile
index 388ec0a..b1867a0 100644
--- a/arch/um/kernel/Makefile
+++ b/arch/um/kernel/Makefile
@@ -14,6 +14,7 @@ obj-y = config.o exec.o exitcode.o init_task.o irq.o ksyms.o
mem.o \
obj-$(CONFIG_BLK_DEV_INITRD) += initrd.o
obj-$(CONFIG_GPROF) += gprof_syms.o
obj-$(CONFIG_GCOV) += gmon_syms.o
+obj-$(CONFIG_STACKTRACE_SUPPORT) += stacktrace.o
USER_OBJS := config.o
diff --git a/arch/um/kernel/stacktrace.c b/arch/um/kernel/stacktrace.c
new file mode 100644
index 0000000..a0d6a60
--- /dev/null
+++ b/arch/um/kernel/stacktrace.c
@@ -0,0 +1,68 @@
+/*
+ * Simple stacktrace function. Only tested on x86, but can probably
+ * be adapted to other architectures with minimal work. (E.g. checking
+ * stack direction)
+ */
+#include "linux/stddef.h"
+#include <linux/stacktrace.h>
+#include <linux/kallsyms.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+
+static void save_stack_address(unsigned long addr, struct stack_trace *trace)
+{
+ if (!__kernel_text_address(addr))
+ return;
+
+ if (trace->skip) {
+ trace->skip--;
+ return;
+ }
+
+ trace->entries[trace->nr_entries++] = addr;
+}
+
+#define THREAD_MASK (THREAD_SIZE-1)
+
+#ifdef CONFIG_FRAME_POINTER
+
+struct stack_frame {
+ struct stack_frame *next_frame;
+ unsigned long return_address;
+};
+
+void save_stack_trace(struct stack_trace *trace)
+{
+ unsigned long addr;
+ struct stack_frame *frame, *end;
+ frame = __builtin_frame_address(0);
+ end = (struct stack_frame *)
+ ((((unsigned long)frame) + THREAD_MASK) & ~THREAD_MASK);
+ while (trace->nr_entries < trace->max_entries) {
+ addr = frame->return_address;
+ save_stack_address(addr, trace);
+ if (frame->next_frame <= frame || frame->next_frame > end)
+ break;
+ frame = frame->next_frame;
+ }
+ if (trace->nr_entries < trace->max_entries)
+ trace->entries[trace->nr_entries++] = ULONG_MAX;
+}
+#else
+
+void save_stack_trace(struct stack_trace *trace)
+{
+ unsigned long addr;
+ unsigned long *stack = (unsigned long *)&stack;
+ while (trace->nr_entries < trace->max_entries) {
+ addr = *stack;
+ save_stack_address(addr, trace);
+ stack++;
+ if (!(stack & THREAD_MASK))
+ break;
+ }
+ if (trace->nr_entries < trace->max_entries)
+ trace->entries[trace->nr_entries++] = ULONG_MAX;
+}
+#endif
diff --git a/arch/um/kernel/sysrq.c b/arch/um/kernel/sysrq.c
index 56d43d0..42b832c 100644
--- a/arch/um/kernel/sysrq.c
+++ b/arch/um/kernel/sysrq.c
@@ -11,6 +11,25 @@
/* Catch non-i386 SUBARCH's. */
#if !defined(CONFIG_UML_X86) || defined(CONFIG_64BIT)
+#ifdef CONFIG_STACKTRACE
+void show_trace(struct task_struct *task, unsigned long * stack)
+{
+ struct stack_trace trace;
+ unsigned long entries[64];
+
+ if (!stack) {
+ stack = (unsigned long *) &stack;
+ WARN_ON(1);
+ }
+
+ trace.nr_entries = 0;
+ trace.max_entries = ARRAY_SIZE(entries);
+ trace.entries = entries;
+ trace.skip = 0;
+ save_stack_trace(&trace);
+ print_stack_trace(&trace, 0);
+}
+#else
void show_trace(struct task_struct *task, unsigned long * stack)
{
unsigned long addr;
@@ -33,6 +52,7 @@ void show_trace(struct task_struct *task, unsigned long *
stack)
}
printk(KERN_INFO "\n");
}
+#endif /& CONFIG_STACKTRACE */
#endif
/*
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