s390/dumpstack: merge all four stack tracers

We have four different stack tracers of which three had bugs. So it's
time to merge them to a single stack tracer which allows to specify a
call back function which will be called for each step.

This patch changes behavior a bit:

- the "nosched" and "in_sched_functions" check within
  save_stack_trace_tsk did work only for the last stack frame within a
  context. Now it considers the check for each stack frame like it
  should.

- both the oprofile variant and the perf_events variant did save a
  return address twice if a zero back chain was detected, which
  indicates an interrupt frame. The new dump_trace function will call
  the oprofile and perf_events backends with the psw address that is
  contained within the corresponding pt_regs structure instead.

- the original show_trace and save_context_stack functions did already
  use the psw address of the pt_regs structure if a zero back chain
  was detected. However now we ignore the psw address if it is a user
  space address. After all we trace the kernel stack and not the user
  space stack. This way we also get rid of the garbage user space
  address in case of warnings and / or panic call traces.

So this should make life easier since now there is only one stack
tracer left which we can break.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h
index 073e18bc167637927aa8f594313e0bdb1bd944f4..d6fd22ea270db0e5446a41aaabc3d9ce1445e350 100644 (file)
--- a/arch/s390/include/asm/processor.h
+++ b/arch/s390/include/asm/processor.h
@@ -184,6 +184,10 @@ struct task_struct;
 struct mm_struct;
 struct seq_file;
 
+typedef int (*dump_trace_func_t)(void *data, unsigned long address);
+void dump_trace(dump_trace_func_t func, void *data,
+               struct task_struct *task, unsigned long sp);
+
 void show_cacheinfo(struct seq_file *m);
 
 /* Free all resources held by a thread. */

diff --git a/arch/s390/kernel/dumpstack.c b/arch/s390/kernel/dumpstack.c
index e1c786d239897ec24a7579f20183aab3647c54f3..2150b0139a0b5dd05b568c8a443ac5b7fa5b89a8 100644 (file)
--- a/arch/s390/kernel/dumpstack.c
+++ b/arch/s390/kernel/dumpstack.c
@@ -19,28 +19,28 @@
 #include <asm/ipl.h>
 
 /*
- * For show_trace we have tree different stack to consider:
+ * For dump_trace we have tree different stack to consider:
  *   - the panic stack which is used if the kernel stack has overflown
  *   - the asynchronous interrupt stack (cpu related)
  *   - the synchronous kernel stack (process related)
- * The stack trace can start at any of the three stack and can potentially
+ * The stack trace can start at any of the three stacks and can potentially
  * touch all of them. The order is: panic stack, async stack, sync stack.
  */
 static unsigned long
-__show_trace(unsigned long sp, unsigned long low, unsigned long high)
+__dump_trace(dump_trace_func_t func, void *data, unsigned long sp,
+            unsigned long low, unsigned long high)
 {
        struct stack_frame *sf;
        struct pt_regs *regs;
-       unsigned long addr;
 
        while (1) {
                if (sp < low || sp > high - sizeof(*sf))
                        return sp;
                sf = (struct stack_frame *) sp;
-               addr = sf->gprs[8];
-               printk("([<%016lx>] %pSR)\n", addr, (void *)addr);
                /* Follow the backchain. */
                while (1) {
+                       if (func(data, sf->gprs[8]))
+                               return sp;
                        low = sp;
                        sp = sf->back_chain;
                        if (!sp)
@@ -48,45 +48,58 @@ __show_trace(unsigned long sp, unsigned long low, unsigned long high)
                        if (sp <= low || sp > high - sizeof(*sf))
                                return sp;
                        sf = (struct stack_frame *) sp;
-                       addr = sf->gprs[8];
-                       printk(" [<%016lx>] %pSR\n", addr, (void *)addr);
                }
                /* Zero backchain detected, check for interrupt frame. */
                sp = (unsigned long) (sf + 1);
                if (sp <= low || sp > high - sizeof(*regs))
                        return sp;
                regs = (struct pt_regs *) sp;
-               addr = regs->psw.addr;
-               printk(" [<%016lx>] %pSR\n", addr, (void *)addr);
+               if (!user_mode(regs)) {
+                       if (func(data, regs->psw.addr))
+                               return sp;
+               }
                low = sp;
                sp = regs->gprs[15];
        }
 }
 
-static void show_trace(struct task_struct *task, unsigned long *stack)
+void dump_trace(dump_trace_func_t func, void *data, struct task_struct *task,
+               unsigned long sp)
 {
-       const unsigned long frame_size =
-               STACK_FRAME_OVERHEAD + sizeof(struct pt_regs);
-       unsigned long sp;
+       unsigned long frame_size;
 
-       sp = (unsigned long) stack;
-       if (!sp)
-               sp = task ? task->thread.ksp : current_stack_pointer();
-       printk("Call Trace:\n");
+       frame_size = STACK_FRAME_OVERHEAD + sizeof(struct pt_regs);
 #ifdef CONFIG_CHECK_STACK
-       sp = __show_trace(sp,
+       sp = __dump_trace(func, data, sp,
                          S390_lowcore.panic_stack + frame_size - 4096,
                          S390_lowcore.panic_stack + frame_size);
 #endif
-       sp = __show_trace(sp,
+       sp = __dump_trace(func, data, sp,
                          S390_lowcore.async_stack + frame_size - ASYNC_SIZE,
                          S390_lowcore.async_stack + frame_size);
        if (task)
-               __show_trace(sp, (unsigned long) task_stack_page(task),
-                            (unsigned long) task_stack_page(task) + THREAD_SIZE);
+               __dump_trace(func, data, sp,
+                            (unsigned long)task_stack_page(task),
+                            (unsigned long)task_stack_page(task) + THREAD_SIZE);
        else
-               __show_trace(sp, S390_lowcore.thread_info,
+               __dump_trace(func, data, sp,
+                            S390_lowcore.thread_info,
                             S390_lowcore.thread_info + THREAD_SIZE);
+}
+EXPORT_SYMBOL_GPL(dump_trace);
+
+static int show_address(void *data, unsigned long address)
+{
+       printk("([<%016lx>] %pSR)\n", address, (void *)address);
+       return 0;
+}
+
+static void show_trace(struct task_struct *task, unsigned long sp)
+{
+       if (!sp)
+               sp = task ? task->thread.ksp : current_stack_pointer();
+       printk("Call Trace:\n");
+       dump_trace(show_address, NULL, task, sp);
        if (!task)
                task = current;
        debug_show_held_locks(task);
@@ -112,7 +125,7 @@ void show_stack(struct task_struct *task, unsigned long *sp)
                printk("%016lx ", *stack++);
        }
        printk("\n");
-       show_trace(task, sp);
+       show_trace(task, (unsigned long)sp);
 }
 
 static void show_last_breaking_event(struct pt_regs *regs)
@@ -152,7 +165,7 @@ void show_regs(struct pt_regs *regs)
        show_registers(regs);
        /* Show stack backtrace if pt_regs is from kernel mode */
        if (!user_mode(regs))
-               show_trace(NULL, (unsigned long *) regs->gprs[15]);
+               show_trace(NULL, regs->gprs[15]);
        show_last_breaking_event(regs);
 }
 

diff --git a/arch/s390/kernel/perf_event.c b/arch/s390/kernel/perf_event.c
index 0943b11a2f6e22c088dc13d3b8a0de9b4e6ef92c..a1b708643a2ca89684a9eb7b9f66dedcd8c3ce99 100644 (file)
--- a/arch/s390/kernel/perf_event.c
+++ b/arch/s390/kernel/perf_event.c
@@ -222,64 +222,20 @@ static int __init service_level_perf_register(void)
 }
 arch_initcall(service_level_perf_register);
 
-/* See also arch/s390/kernel/traps.c */
-static unsigned long __store_trace(struct perf_callchain_entry *entry,
-                                  unsigned long sp,
-                                  unsigned long low, unsigned long high)
+static int __perf_callchain_kernel(void *data, unsigned long address)
 {
-       struct stack_frame *sf;
-       struct pt_regs *regs;
-
-       while (1) {
-               if (sp < low || sp > high - sizeof(*sf))
-                       return sp;
-               sf = (struct stack_frame *) sp;
-               perf_callchain_store(entry, sf->gprs[8]);
-               /* Follow the backchain. */
-               while (1) {
-                       low = sp;
-                       sp = sf->back_chain;
-                       if (!sp)
-                               break;
-                       if (sp <= low || sp > high - sizeof(*sf))
-                               return sp;
-                       sf = (struct stack_frame *) sp;
-                       perf_callchain_store(entry, sf->gprs[8]);
-               }
-               /* Zero backchain detected, check for interrupt frame. */
-               sp = (unsigned long) (sf + 1);
-               if (sp <= low || sp > high - sizeof(*regs))
-                       return sp;
-               regs = (struct pt_regs *) sp;
-               perf_callchain_store(entry, sf->gprs[8]);
-               low = sp;
-               sp = regs->gprs[15];
-       }
+       struct perf_callchain_entry *entry = data;
+
+       perf_callchain_store(entry, address);
+       return 0;
 }
 
 void perf_callchain_kernel(struct perf_callchain_entry *entry,
                           struct pt_regs *regs)
 {
-       unsigned long head, frame_size;
-       struct stack_frame *head_sf;
-
        if (user_mode(regs))
                return;
-
-       frame_size = STACK_FRAME_OVERHEAD + sizeof(struct pt_regs);
-       head = regs->gprs[15];
-       head_sf = (struct stack_frame *) head;
-
-       if (!head_sf || !head_sf->back_chain)
-               return;
-
-       head = head_sf->back_chain;
-       head = __store_trace(entry, head,
-                            S390_lowcore.async_stack + frame_size - ASYNC_SIZE,
-                            S390_lowcore.async_stack + frame_size);
-
-       __store_trace(entry, head, S390_lowcore.thread_info,
-                     S390_lowcore.thread_info + THREAD_SIZE);
+       dump_trace(__perf_callchain_kernel, entry, NULL, regs->gprs[15]);
 }
 
 /* Perf defintions for PMU event attributes in sysfs */

diff --git a/arch/s390/kernel/stacktrace.c b/arch/s390/kernel/stacktrace.c
index 7dd8360b1c39b9b806dc912b0415e64b859619c6..44f84b23d4e5996f1ddc594ae3985d762e80aa36 100644 (file)
--- a/arch/s390/kernel/stacktrace.c
+++ b/arch/s390/kernel/stacktrace.c
@@ -10,69 +10,31 @@
 #include <linux/kallsyms.h>
 #include <linux/module.h>
 
-static unsigned long save_context_stack(struct stack_trace *trace,
-                                       unsigned long sp,
-                                       unsigned long low,
-                                       unsigned long high,
-                                       int nosched)
+static int __save_address(void *data, unsigned long address, int nosched)
 {
-       struct stack_frame *sf;
-       struct pt_regs *regs;
-       unsigned long addr;
+       struct stack_trace *trace = data;
 
-       while(1) {
-               if (sp < low || sp > high)
-                       return sp;
-               sf = (struct stack_frame *)sp;
-               while(1) {
-                       addr = sf->gprs[8];
-                       if (!trace->skip)
-                               trace->entries[trace->nr_entries++] = addr;
-                       else
-                               trace->skip--;
-                       if (trace->nr_entries >= trace->max_entries)
-                               return sp;
-                       low = sp;
-                       sp = sf->back_chain;
-                       if (!sp)
-                               break;
-                       if (sp <= low || sp > high - sizeof(*sf))
-                               return sp;
-                       sf = (struct stack_frame *)sp;
-               }
-               /* Zero backchain detected, check for interrupt frame. */
-               sp = (unsigned long)(sf + 1);
-               if (sp <= low || sp > high - sizeof(*regs))
-                       return sp;
-               regs = (struct pt_regs *)sp;
-               addr = regs->psw.addr;
-               if (!nosched || !in_sched_functions(addr)) {
-                       if (!trace->skip)
-                               trace->entries[trace->nr_entries++] = addr;
-                       else
-                               trace->skip--;
-               }
-               if (trace->nr_entries >= trace->max_entries)
-                       return sp;
-               low = sp;
-               sp = regs->gprs[15];
+       if (nosched && in_sched_functions(address))
+               return 0;
+       if (trace->skip > 0) {
+               trace->skip--;
+               return 0;
        }
+       if (trace->nr_entries < trace->max_entries) {
+               trace->entries[trace->nr_entries++] = address;
+               return 0;
+       }
+       return 1;
 }
 
-static void __save_stack_trace(struct stack_trace *trace, unsigned long sp)
+static int save_address(void *data, unsigned long address)
 {
-       unsigned long new_sp, frame_size;
+       return __save_address(data, address, 0);
+}
 
-       frame_size = STACK_FRAME_OVERHEAD + sizeof(struct pt_regs);
-       new_sp = save_context_stack(trace, sp,
-                       S390_lowcore.panic_stack + frame_size - PAGE_SIZE,
-                       S390_lowcore.panic_stack + frame_size, 0);
-       new_sp = save_context_stack(trace, new_sp,
-                       S390_lowcore.async_stack + frame_size - ASYNC_SIZE,
-                       S390_lowcore.async_stack + frame_size, 0);
-       save_context_stack(trace, new_sp,
-                          S390_lowcore.thread_info,
-                          S390_lowcore.thread_info + THREAD_SIZE, 0);
+static int save_address_nosched(void *data, unsigned long address)
+{
+       return __save_address(data, address, 1);
 }
 
 void save_stack_trace(struct stack_trace *trace)
@@ -80,7 +42,7 @@ void save_stack_trace(struct stack_trace *trace)
        unsigned long sp;
 
        sp = current_stack_pointer();
-       __save_stack_trace(trace, sp);
+       dump_trace(save_address, trace, NULL, sp);
        if (trace->nr_entries < trace->max_entries)
                trace->entries[trace->nr_entries++] = ULONG_MAX;
 }
@@ -88,14 +50,12 @@ EXPORT_SYMBOL_GPL(save_stack_trace);
 
 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
 {
-       unsigned long sp, low, high;
+       unsigned long sp;
 
        sp = tsk->thread.ksp;
        if (tsk == current)
                sp = current_stack_pointer();
-       low = (unsigned long) task_stack_page(tsk);
-       high = (unsigned long) task_pt_regs(tsk);
-       save_context_stack(trace, sp, low, high, 1);
+       dump_trace(save_address_nosched, trace, tsk, sp);
        if (trace->nr_entries < trace->max_entries)
                trace->entries[trace->nr_entries++] = ULONG_MAX;
 }
@@ -106,7 +66,7 @@ void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
        unsigned long sp;
 
        sp = kernel_stack_pointer(regs);
-       __save_stack_trace(trace, sp);
+       dump_trace(save_address, trace, NULL, sp);
        if (trace->nr_entries < trace->max_entries)
                trace->entries[trace->nr_entries++] = ULONG_MAX;
 }

diff --git a/arch/s390/oprofile/Makefile b/arch/s390/oprofile/Makefile
index 1bd23017191e86fb528257d30cbc3e60e8339a5b..496e4a7ee00eb99a7d885acd4b7aff2c97eb4058 100644 (file)
--- a/arch/s390/oprofile/Makefile
+++ b/arch/s390/oprofile/Makefile
@@ -6,5 +6,5 @@ DRIVER_OBJS = $(addprefix ../../../drivers/oprofile/, \
                oprofilefs.o oprofile_stats.o  \
                timer_int.o )
 
-oprofile-y :=  $(DRIVER_OBJS) init.o backtrace.o
+oprofile-y :=  $(DRIVER_OBJS) init.o
 oprofile-y +=  hwsampler.o

diff --git a/arch/s390/oprofile/backtrace.c b/arch/s390/oprofile/backtrace.c
deleted file mode 100644 (file)
index 1884e17..0000000
--- a/arch/s390/oprofile/backtrace.c
+++ /dev/null
@@ -1,78 +0,0 @@
-/*
- * S390 Version
- *   Copyright IBM Corp. 2005
- *   Author(s): Andreas Krebbel <Andreas.Krebbel@de.ibm.com>
- */
-
-#include <linux/oprofile.h>
-
-#include <asm/processor.h> /* for struct stack_frame */
-
-static unsigned long
-__show_trace(unsigned int *depth, unsigned long sp,
-            unsigned long low, unsigned long high)
-{
-       struct stack_frame *sf;
-       struct pt_regs *regs;
-
-       while (*depth) {
-               if (sp < low || sp > high - sizeof(*sf))
-                       return sp;
-               sf = (struct stack_frame *) sp;
-               (*depth)--;
-               oprofile_add_trace(sf->gprs[8]);
-
-               /* Follow the backchain.  */
-               while (*depth) {
-                       low = sp;
-                       sp = sf->back_chain;
-                       if (!sp)
-                               break;
-                       if (sp <= low || sp > high - sizeof(*sf))
-                               return sp;
-                       sf = (struct stack_frame *) sp;
-                       (*depth)--;
-                       oprofile_add_trace(sf->gprs[8]);
-
-               }
-
-               if (*depth == 0)
-                       break;
-
-               /* Zero backchain detected, check for interrupt frame.  */
-               sp = (unsigned long) (sf + 1);
-               if (sp <= low || sp > high - sizeof(*regs))
-                       return sp;
-               regs = (struct pt_regs *) sp;
-               (*depth)--;
-               oprofile_add_trace(sf->gprs[8]);
-               low = sp;
-               sp = regs->gprs[15];
-       }
-       return sp;
-}
-
-void s390_backtrace(struct pt_regs * const regs, unsigned int depth)
-{
-       unsigned long head, frame_size;
-       struct stack_frame* head_sf;
-
-       if (user_mode(regs))
-               return;
-
-       frame_size = STACK_FRAME_OVERHEAD + sizeof(struct pt_regs);
-       head = regs->gprs[15];
-       head_sf = (struct stack_frame*)head;
-
-       if (!head_sf->back_chain)
-               return;
-
-       head = head_sf->back_chain;
-
-       head = __show_trace(&depth, head,
-                           S390_lowcore.async_stack + frame_size - ASYNC_SIZE,
-                           S390_lowcore.async_stack + frame_size);
-
-       __show_trace(&depth, head, S390_lowcore.thread_info,
-                    S390_lowcore.thread_info + THREAD_SIZE);
-}

diff --git a/arch/s390/oprofile/init.c b/arch/s390/oprofile/init.c
index 9cfa2ffaa9d6bb02dd29cb01d895a0feaf63bdb0..d85d1e6b1988875d0874eebb9e77d5c1b382c969 100644 (file)
--- a/arch/s390/oprofile/init.c
+++ b/arch/s390/oprofile/init.c
@@ -20,8 +20,6 @@
 
 #include "../../../drivers/oprofile/oprof.h"
 
-extern void s390_backtrace(struct pt_regs * const regs, unsigned int depth);
-
 #include "hwsampler.h"
 #include "op_counter.h"
 
@@ -494,6 +492,24 @@ static void oprofile_hwsampler_exit(void)
        hwsampler_shutdown();
 }
 
+static int __s390_backtrace(void *data, unsigned long address)
+{
+       unsigned int *depth = data;
+
+       if (*depth == 0)
+               return 1;
+       (*depth)--;
+       oprofile_add_trace(address);
+       return 0;
+}
+
+static void s390_backtrace(struct pt_regs *regs, unsigned int depth)
+{
+       if (user_mode(regs))
+               return;
+       dump_trace(__s390_backtrace, &depth, NULL, regs->gprs[15]);
+}
+
 int __init oprofile_arch_init(struct oprofile_operations *ops)
 {
        ops->backtrace = s390_backtrace;