x86: Eliminate bp argument from the stack tracing routines

The various stack tracing routines take a 'bp' argument in which the
caller is supposed to provide the base pointer to use, or 0 if doesn't
have one. Since bp is garbage whenever CONFIG_FRAME_POINTER is not
defined, this means all callers in principle should either always pass
0, or be conditional on CONFIG_FRAME_POINTER.

However, there are only really three use cases for stack tracing:

(a) Trace the current task, including IRQ stack if any
(b) Trace the current task, but skip IRQ stack
(c) Trace some other task

In all cases, if CONFIG_FRAME_POINTER is not defined, bp should just
be 0.  If it _is_ defined, then

- in case (a) bp should be gotten directly from the CPU's register, so
  the caller should pass NULL for regs,

- in case (b) the caller should should pass the IRQ registers to
  dump_trace(),

- in case (c) bp should be gotten from the top of the task's stack, so
  the caller should pass NULL for regs.

Hence, the bp argument is not necessary because the combination of
task and regs is sufficient to determine an appropriate value for bp.

This patch introduces a new inline function stack_frame(task, regs)
that computes the desired bp. This function is then called from the
two versions of dump_stack().

Signed-off-by: Soren Sandmann <ssp@redhat.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arjan van de Ven <arjan@infradead.org>,
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>,
LKML-Reference: <m3oc9rop28.fsf@dhcp-100-3-82.bos.redhat.com>>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

diff --git a/arch/x86/include/asm/kdebug.h b/arch/x86/include/asm/kdebug.h
index 5bdfca86581beb3b45c60fd1f8d900a5daa68bf9..f23eb2528464f4a51ad6d14d70db0f7c33d92e0a 100644 (file)
--- a/arch/x86/include/asm/kdebug.h
+++ b/arch/x86/include/asm/kdebug.h
@@ -28,7 +28,7 @@ extern void die(const char *, struct pt_regs *,long);
 extern int __must_check __die(const char *, struct pt_regs *, long);
 extern void show_registers(struct pt_regs *regs);
 extern void show_trace(struct task_struct *t, struct pt_regs *regs,
-                      unsigned long *sp, unsigned long bp);
+                      unsigned long *sp);
 extern void __show_regs(struct pt_regs *regs, int all);
 extern void show_regs(struct pt_regs *regs);
 extern unsigned long oops_begin(void);

diff --git a/arch/x86/include/asm/stacktrace.h b/arch/x86/include/asm/stacktrace.h
index 2b16a2ad23dc6b9647028c0808f8f45b094e74ac..52b5c7ed3608d9fc439c5ca69bf58ca1b8ebef88 100644 (file)
--- a/arch/x86/include/asm/stacktrace.h
+++ b/arch/x86/include/asm/stacktrace.h
@@ -7,6 +7,7 @@
 #define _ASM_X86_STACKTRACE_H
 
 #include <linux/uaccess.h>
+#include <linux/ptrace.h>
 
 extern int kstack_depth_to_print;
 
@@ -46,7 +47,7 @@ struct stacktrace_ops {
 };
 
 void dump_trace(struct task_struct *tsk, struct pt_regs *regs,
-               unsigned long *stack, unsigned long bp,
+               unsigned long *stack,
                const struct stacktrace_ops *ops, void *data);
 
 #ifdef CONFIG_X86_32
@@ -57,13 +58,39 @@ void dump_trace(struct task_struct *tsk, struct pt_regs *regs,
 #define get_bp(bp) asm("movq %%rbp, %0" : "=r" (bp) :)
 #endif
 
+#ifdef CONFIG_FRAME_POINTER
+static inline unsigned long
+stack_frame(struct task_struct *task, struct pt_regs *regs)
+{
+       unsigned long bp;
+
+       if (regs)
+               return regs->bp;
+
+       if (task == current) {
+               /* Grab bp right from our regs */
+               get_bp(bp);
+               return bp;
+       }
+
+       /* bp is the last reg pushed by switch_to */
+       return *(unsigned long *)task->thread.sp;
+}
+#else
+static inline unsigned long
+stack_frame(struct task_struct *task, struct pt_regs *regs)
+{
+       return 0;
+}
+#endif
+
 extern void
 show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
-               unsigned long *stack, unsigned long bp, char *log_lvl);
+                  unsigned long *stack, char *log_lvl);
 
 extern void
 show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
-               unsigned long *sp, unsigned long bp, char *log_lvl);
+                  unsigned long *sp, char *log_lvl);
 
 extern unsigned int code_bytes;
 

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index ed6310183efb4337de7489362b350f81031ca2c8..461a85dcaba46eb7d4453f775c96463952126659 100644 (file)
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -1666,7 +1666,7 @@ perf_callchain_kernel(struct perf_callchain_entry *entry, struct pt_regs *regs)
 
        perf_callchain_store(entry, regs->ip);
 
-       dump_trace(NULL, regs, NULL, regs->bp, &backtrace_ops, entry);
+       dump_trace(NULL, regs, NULL, &backtrace_ops, entry);
 }
 
 #ifdef CONFIG_COMPAT

diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 6e8752c1bd5241fc9e7e63ee088f06c84d0526fb..8474c998cbd40d2f3481f87879f5a42d1f105e52 100644 (file)
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -175,21 +175,21 @@ static const struct stacktrace_ops print_trace_ops = {
 
 void
 show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
-               unsigned long *stack, unsigned long bp, char *log_lvl)
+               unsigned long *stack, char *log_lvl)
 {
        printk("%sCall Trace:\n", log_lvl);
-       dump_trace(task, regs, stack, bp, &print_trace_ops, log_lvl);
+       dump_trace(task, regs, stack, &print_trace_ops, log_lvl);
 }
 
 void show_trace(struct task_struct *task, struct pt_regs *regs,
-               unsigned long *stack, unsigned long bp)
+               unsigned long *stack)
 {
-       show_trace_log_lvl(task, regs, stack, bp, "");
+       show_trace_log_lvl(task, regs, stack, "");
 }
 
 void show_stack(struct task_struct *task, unsigned long *sp)
 {
-       show_stack_log_lvl(task, NULL, sp, 0, "");
+       show_stack_log_lvl(task, NULL, sp, "");
 }
 
 /*
@@ -210,7 +210,7 @@ void dump_stack(void)
                init_utsname()->release,
                (int)strcspn(init_utsname()->version, " "),
                init_utsname()->version);
-       show_trace(NULL, NULL, &stack, bp);
+       show_trace(NULL, NULL, &stack);
 }
 EXPORT_SYMBOL(dump_stack);
 

diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c
index 1bc7f75a5bdaf823999f7b90271808819b6f3ad3..74cc1eda384b8d26437a10fa55e3f64cfcf4545a 100644 (file)
--- a/arch/x86/kernel/dumpstack_32.c
+++ b/arch/x86/kernel/dumpstack_32.c
@@ -17,11 +17,12 @@
 #include <asm/stacktrace.h>
 
 
-void dump_trace(struct task_struct *task, struct pt_regs *regs,
-               unsigned long *stack, unsigned long bp,
+void dump_trace(struct task_struct *task,
+               struct pt_regs *regs, unsigned long *stack,
                const struct stacktrace_ops *ops, void *data)
 {
        int graph = 0;
+       unsigned long bp;
 
        if (!task)
                task = current;
@@ -34,18 +35,7 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs,
                        stack = (unsigned long *)task->thread.sp;
        }
 
-#ifdef CONFIG_FRAME_POINTER
-       if (!bp) {
-               if (task == current) {
-                       /* Grab bp right from our regs */
-                       get_bp(bp);
-               } else {
-                       /* bp is the last reg pushed by switch_to */
-                       bp = *(unsigned long *) task->thread.sp;
-               }
-       }
-#endif
-
+       bp = stack_frame(task, regs);
        for (;;) {
                struct thread_info *context;
 
@@ -65,7 +55,7 @@ EXPORT_SYMBOL(dump_trace);
 
 void
 show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
-                  unsigned long *sp, unsigned long bp, char *log_lvl)
+                  unsigned long *sp, char *log_lvl)
 {
        unsigned long *stack;
        int i;
@@ -87,7 +77,7 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
                touch_nmi_watchdog();
        }
        printk(KERN_CONT "\n");
-       show_trace_log_lvl(task, regs, sp, bp, log_lvl);
+       show_trace_log_lvl(task, regs, sp, log_lvl);
 }
 
 
@@ -112,8 +102,7 @@ void show_registers(struct pt_regs *regs)
                u8 *ip;
 
                printk(KERN_EMERG "Stack:\n");
-               show_stack_log_lvl(NULL, regs, &regs->sp,
-                               0, KERN_EMERG);
+               show_stack_log_lvl(NULL, regs, &regs->sp, KERN_EMERG);
 
                printk(KERN_EMERG "Code: ");
 

diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index 6a340485249a965f29686ac84117458d6cb72be6..64101335de19aad09ec03d75dea8260b28051747 100644 (file)
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -139,8 +139,8 @@ fixup_bp_irq_link(unsigned long bp, unsigned long *stack,
  * severe exception (double fault, nmi, stack fault, debug, mce) hardware stack
  */
 
-void dump_trace(struct task_struct *task, struct pt_regs *regs,
-               unsigned long *stack, unsigned long bp,
+void dump_trace(struct task_struct *task,
+               struct pt_regs *regs, unsigned long *stack,
                const struct stacktrace_ops *ops, void *data)
 {
        const unsigned cpu = get_cpu();
@@ -149,6 +149,7 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs,
        unsigned used = 0;
        struct thread_info *tinfo;
        int graph = 0;
+       unsigned long bp;
 
        if (!task)
                task = current;
@@ -160,18 +161,7 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs,
                        stack = (unsigned long *)task->thread.sp;
        }
 
-#ifdef CONFIG_FRAME_POINTER
-       if (!bp) {
-               if (task == current) {
-                       /* Grab bp right from our regs */
-                       get_bp(bp);
-               } else {
-                       /* bp is the last reg pushed by switch_to */
-                       bp = *(unsigned long *) task->thread.sp;
-               }
-       }
-#endif
-
+       bp = stack_frame(task, regs);
        /*
         * Print function call entries in all stacks, starting at the
         * current stack address. If the stacks consist of nested
@@ -235,7 +225,7 @@ EXPORT_SYMBOL(dump_trace);
 
 void
 show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
-                  unsigned long *sp, unsigned long bp, char *log_lvl)
+                  unsigned long *sp, char *log_lvl)
 {
        unsigned long *irq_stack_end;
        unsigned long *irq_stack;
@@ -279,7 +269,7 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
        preempt_enable();
 
        printk(KERN_CONT "\n");
-       show_trace_log_lvl(task, regs, sp, bp, log_lvl);
+       show_trace_log_lvl(task, regs, sp, log_lvl);
 }
 
 void show_registers(struct pt_regs *regs)
@@ -308,7 +298,7 @@ void show_registers(struct pt_regs *regs)
 
                printk(KERN_EMERG "Stack:\n");
                show_stack_log_lvl(NULL, regs, (unsigned long *)sp,
-                               regs->bp, KERN_EMERG);
+                                  KERN_EMERG);
 
                printk(KERN_EMERG "Code: ");
 

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 57d1868a86aadc060bc2260b34139809a98ffab5..96ed1aac543a39b773117c7411641a40450bc6c9 100644 (file)
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -91,8 +91,7 @@ void exit_thread(void)
 void show_regs(struct pt_regs *regs)
 {
        show_registers(regs);
-       show_trace(NULL, regs, (unsigned long *)kernel_stack_pointer(regs),
-                  regs->bp);
+       show_trace(NULL, regs, (unsigned long *)kernel_stack_pointer(regs));
 }
 
 void show_regs_common(void)

diff --git a/arch/x86/kernel/stacktrace.c b/arch/x86/kernel/stacktrace.c
index b53c525368a75cf07489b0327de138bfab5b16d5..938c8e10a19abeae0e2c814e182a0920ff0328f9 100644 (file)
--- a/arch/x86/kernel/stacktrace.c
+++ b/arch/x86/kernel/stacktrace.c
@@ -73,22 +73,22 @@ static const struct stacktrace_ops save_stack_ops_nosched = {
  */
 void save_stack_trace(struct stack_trace *trace)
 {
-       dump_trace(current, NULL, NULL, 0, &save_stack_ops, trace);
+       dump_trace(current, NULL, NULL, &save_stack_ops, trace);
        if (trace->nr_entries < trace->max_entries)
                trace->entries[trace->nr_entries++] = ULONG_MAX;
 }
 EXPORT_SYMBOL_GPL(save_stack_trace);
 
-void save_stack_trace_bp(struct stack_trace *trace, unsigned long bp)
+void save_stack_trace_regs(struct stack_trace *trace, struct pt_regs *regs)
 {
-       dump_trace(current, NULL, NULL, bp, &save_stack_ops, trace);
+       dump_trace(current, regs, NULL, &save_stack_ops, trace);
        if (trace->nr_entries < trace->max_entries)
                trace->entries[trace->nr_entries++] = ULONG_MAX;
 }
 
 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
 {
-       dump_trace(tsk, NULL, NULL, 0, &save_stack_ops_nosched, trace);
+       dump_trace(tsk, NULL, NULL, &save_stack_ops_nosched, trace);
        if (trace->nr_entries < trace->max_entries)
                trace->entries[trace->nr_entries++] = ULONG_MAX;
 }

diff --git a/arch/x86/mm/kmemcheck/error.c b/arch/x86/mm/kmemcheck/error.c
index af3b6c8a436f7b7ec49a2366738a28faa58cdfc5..704a37cedddb59404a3c1fc773e44853b2089939 100644 (file)
--- a/arch/x86/mm/kmemcheck/error.c
+++ b/arch/x86/mm/kmemcheck/error.c
@@ -185,7 +185,7 @@ void kmemcheck_error_save(enum kmemcheck_shadow state,
        e->trace.entries = e->trace_entries;
        e->trace.max_entries = ARRAY_SIZE(e->trace_entries);
        e->trace.skip = 0;
-       save_stack_trace_bp(&e->trace, regs->bp);
+       save_stack_trace_regs(&e->trace, regs);
 
        /* Round address down to nearest 16 bytes */
        shadow_copy = kmemcheck_shadow_lookup(address

diff --git a/arch/x86/oprofile/backtrace.c b/arch/x86/oprofile/backtrace.c
index 2d49d4e19a3619c0be2c7d17a892b8aea582048f..72cbec14d783867cb5f5fa8547eb6fcee2fe28b9 100644 (file)
--- a/arch/x86/oprofile/backtrace.c
+++ b/arch/x86/oprofile/backtrace.c
@@ -126,7 +126,7 @@ x86_backtrace(struct pt_regs * const regs, unsigned int depth)
        if (!user_mode_vm(regs)) {
                unsigned long stack = kernel_stack_pointer(regs);
                if (depth)
-                       dump_trace(NULL, regs, (unsigned long *)stack, 0,
+                       dump_trace(NULL, regs, (unsigned long *)stack,
                                   &backtrace_ops, &depth);
                return;
        }

diff --git a/include/linux/stacktrace.h b/include/linux/stacktrace.h
index 51efbef38fb0e204cfddb61b56619d52cefab623..25310f1d7f3773c540e51e7103a4edfa98db7a33 100644 (file)
--- a/include/linux/stacktrace.h
+++ b/include/linux/stacktrace.h
@@ -2,6 +2,7 @@
 #define __LINUX_STACKTRACE_H
 
 struct task_struct;
+struct pt_regs;
 
 #ifdef CONFIG_STACKTRACE
 struct task_struct;
@@ -13,7 +14,8 @@ struct stack_trace {
 };
 
 extern void save_stack_trace(struct stack_trace *trace);
-extern void save_stack_trace_bp(struct stack_trace *trace, unsigned long bp);
+extern void save_stack_trace_regs(struct stack_trace *trace,
+                                 struct pt_regs *regs);
 extern void save_stack_trace_tsk(struct task_struct *tsk,
                                struct stack_trace *trace);