um: Add support for CONFIG_STACKTRACE

Add stacktrace support for User Mode Linux

Signed-off-by: Daniel Walter <dwalter@google.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

5 files changed, 142 insertions, 53 deletions

diff --git a/arch/um/Kconfig.common b/arch/um/Kconfig.common
index 6915d28cf118..87bc86821bc9 100644
--- a/arch/um/Kconfig.common
+++ b/arch/um/Kconfig.common
@@ -39,7 +39,8 @@ config LOCKDEP_SUPPORT
 
 config STACKTRACE_SUPPORT
         bool
-        default n
+        default y
+        select STACKTRACE
 
 config GENERIC_CALIBRATE_DELAY
         bool
diff --git a/arch/um/include/asm/stacktrace.h b/arch/um/include/asm/stacktrace.h
new file mode 100644
index 000000000000..9a864328c67f
--- /dev/null
+++ b/arch/um/include/asm/stacktrace.h
@@ -0,0 +1,42 @@
+#ifndef _ASM_UML_STACKTRACE_H
+#define _ASM_UML_STACKTRACE_H
+
+#include <linux/uaccess.h>
+#include <linux/ptrace.h>
+
+struct stack_frame {
+        struct stack_frame *next_frame;
+        unsigned long return_address;
+};
+
+struct stacktrace_ops {
+        void (*address)(void *data, unsigned long address, int reliable);
+};
+
+#ifdef CONFIG_FRAME_POINTER
+static inline unsigned long
+get_frame_pointer(struct task_struct *task, struct pt_regs *segv_regs)
+{
+        if (!task || task == current)
+                return segv_regs ? PT_REGS_BP(segv_regs) : current_bp();
+        return KSTK_EBP(task);
+}
+#else
+static inline unsigned long
+get_frame_pointer(struct task_struct *task, struct pt_regs *segv_regs)
+{
+        return 0;
+}
+#endif
+
+static inline unsigned long
+*get_stack_pointer(struct task_struct *task, struct pt_regs *segv_regs)
+{
+        if (!task || task == current)
+                return segv_regs ? (unsigned long *)PT_REGS_SP(segv_regs) : current_sp();
+        return (unsigned long *)KSTK_ESP(task);
+}
+
+void dump_trace(struct task_struct *tsk, const struct stacktrace_ops *ops, void *data);
+
+#endif /* _ASM_UML_STACKTRACE_H */
diff --git a/arch/um/kernel/Makefile b/arch/um/kernel/Makefile
index d8b78a03855c..2d840a070c8b 100644
--- a/arch/um/kernel/Makefile
+++ b/arch/um/kernel/Makefile
@@ -19,6 +19,7 @@ obj-$(CONFIG_BLK_DEV_INITRD) += initrd.o
 obj-$(CONFIG_GPROF)     += gprof_syms.o
 obj-$(CONFIG_GCOV)      += gmon_syms.o
 obj-$(CONFIG_EARLY_PRINTK) += early_printk.o
+obj-$(CONFIG_STACKTRACE) += 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 000000000000..ebe7bcf62684
--- /dev/null
+++ b/arch/um/kernel/stacktrace.c
@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Copyright (C) 2013 Richard Weinberger <richard@nod.at>
+ * Copyright (C) 2014 Google Inc., Author: Daniel Walter <dwalter@google.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/kallsyms.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/stacktrace.h>
+#include <linux/module.h>
+#include <linux/uaccess.h>
+#include <asm/stacktrace.h>
+
+void dump_trace(struct task_struct *tsk,
+                const struct stacktrace_ops *ops,
+                void *data)
+{
+        int reliable = 0;
+        unsigned long *sp, bp, addr;
+        struct pt_regs *segv_regs = tsk->thread.segv_regs;
+        struct stack_frame *frame;
+
+        bp = get_frame_pointer(tsk, segv_regs);
+        sp = get_stack_pointer(tsk, segv_regs);
+
+        frame = (struct stack_frame *)bp;
+        while (((long) sp & (THREAD_SIZE-1)) != 0) {
+                addr = *sp;
+                if (__kernel_text_address(addr)) {
+                        reliable = 0;
+                        if ((unsigned long) sp == bp + sizeof(long)) {
+                                frame = frame ? frame->next_frame : NULL;
+                                bp = (unsigned long)frame;
+                                reliable = 1;
+                        }
+                        ops->address(data, addr, reliable);
+                }
+                sp++;
+        }
+}
+
+static void save_addr(void *data, unsigned long address, int reliable)
+{
+        struct stack_trace *trace = data;
+
+        if (!reliable)
+                return;
+        if (trace->nr_entries >= trace->max_entries)
+                return;
+
+        trace->entries[trace->nr_entries++] = address;
+}
+
+static const struct stacktrace_ops dump_ops = {
+        .address = save_addr
+};
+
+static void __save_stack_trace(struct task_struct *tsk, struct stack_trace *trace)
+{
+        dump_trace(tsk, &dump_ops, trace);
+        if (trace->nr_entries < trace->max_entries)
+                trace->entries[trace->nr_entries++] = ULONG_MAX;
+}
+
+void save_stack_trace(struct stack_trace *trace)
+{
+        __save_stack_trace(current, trace);
+}
+EXPORT_SYMBOL_GPL(save_stack_trace);
+
+void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
+{
+        __save_stack_trace(tsk, trace);
+}
+EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
diff --git a/arch/um/kernel/sysrq.c b/arch/um/kernel/sysrq.c
index 799d7e413bf5..894c8d303cda 100644
--- a/arch/um/kernel/sysrq.c
+++ b/arch/um/kernel/sysrq.c
@@ -12,57 +12,20 @@
 #include <linux/module.h>
 #include <linux/sched.h>
 #include <asm/sysrq.h>
+#include <asm/stacktrace.h>
 #include <os.h>
 
-struct stack_frame {
-        struct stack_frame *next_frame;
-        unsigned long return_address;
-};
-
-static void do_stack_trace(unsigned long *sp, unsigned long bp)
+static void _print_addr(void *data, unsigned long address, int reliable)
 {
-        int reliable;
-        unsigned long addr;
-        struct stack_frame *frame = (struct stack_frame *)bp;
-
-        printk(KERN_INFO "Call Trace:\n");
-        while (((long) sp & (THREAD_SIZE-1)) != 0) {
-                addr = *sp;
-                if (__kernel_text_address(addr)) {
-                        reliable = 0;
-                        if ((unsigned long) sp == bp + sizeof(long)) {
-                                frame = frame ? frame->next_frame : NULL;
-                                bp = (unsigned long)frame;
-                                reliable = 1;
-                        }
-
-                        printk(KERN_INFO " [<%08lx>]", addr);
-                        printk(KERN_CONT " %s", reliable ? "" : "? ");
-                        print_symbol(KERN_CONT "%s", addr);
-                        printk(KERN_CONT "\n");
-                }
-                sp++;
-        }
-        printk(KERN_INFO "\n");
+        pr_info(" [<%08lx>]", address);
+        pr_cont(" %s", reliable ? "" : "? ");
+        print_symbol("%s", address);
+        pr_cont("\n");
 }
 
-static unsigned long get_frame_pointer(struct task_struct *task,
-                                       struct pt_regs *segv_regs)
-{
-        if (!task || task == current)
-                return segv_regs ? PT_REGS_BP(segv_regs) : current_bp();
-        else
-                return KSTK_EBP(task);
-}
-
-static unsigned long *get_stack_pointer(struct task_struct *task,
-                                        struct pt_regs *segv_regs)
-{
-        if (!task || task == current)
-                return segv_regs ? (unsigned long *)PT_REGS_SP(segv_regs) : current_sp();
-        else
-                return (unsigned long *)KSTK_ESP(task);
-}
+static const struct stacktrace_ops stackops = {
+        .address = _print_addr
+};
 
 void show_stack(struct task_struct *task, unsigned long *stack)
 {
@@ -71,7 +34,7 @@ void show_stack(struct task_struct *task, unsigned long *stack)
         int i;
 
         if (!segv_regs && os_is_signal_stack()) {
-                printk(KERN_ERR "Received SIGSEGV in SIGSEGV handler,"
+                pr_err("Received SIGSEGV in SIGSEGV handler,"
                                 " aborting stack trace!\n");
                 return;
         }
@@ -83,16 +46,18 @@ void show_stack(struct task_struct *task, unsigned long *stack)
         if (!stack)
                 sp = get_stack_pointer(task, segv_regs);
 
-        printk(KERN_INFO "Stack:\n");
+        pr_info("Stack:\n");
         stack = sp;
         for (i = 0; i < 3 * STACKSLOTS_PER_LINE; i++) {
                 if (kstack_end(stack))
                         break;
                 if (i && ((i % STACKSLOTS_PER_LINE) == 0))
-                        printk(KERN_CONT "\n");
-                printk(KERN_CONT " %08lx", *stack++);
+                        pr_cont("\n");
+                pr_cont(" %08lx", *stack++);
         }
-        printk(KERN_CONT "\n");
+        pr_cont("\n");
 
-        do_stack_trace(sp, bp);
+        pr_info("Call Trace:\n");
+        dump_trace(current, &stackops, NULL);
+        pr_info("\n");
 }