9 files changed, 158 insertions, 9 deletions

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 821a141889de..224fbff79969 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -7,6 +7,14 @@ config MMU
         bool
         default y
 
+config LOCKDEP_SUPPORT
+        bool
+        default y
+
+config STACKTRACE_SUPPORT
+        bool
+        default y
+
 config RWSEM_GENERIC_SPINLOCK
         bool
 
diff --git a/arch/s390/Kconfig.debug b/arch/s390/Kconfig.debug
index f53b6d5300e5..2283933a9a93 100644
--- a/arch/s390/Kconfig.debug
+++ b/arch/s390/Kconfig.debug
@@ -1,5 +1,9 @@
 menu "Kernel hacking"
 
+config TRACE_IRQFLAGS_SUPPORT
+        bool
+        default y
+
 source "lib/Kconfig.debug"
 
 endmenu
diff --git a/arch/s390/Makefile b/arch/s390/Makefile
index b3791fb094a8..74ef57dcfa60 100644
--- a/arch/s390/Makefile
+++ b/arch/s390/Makefile
@@ -34,6 +34,11 @@ cflags-$(CONFIG_MARCH_G5)   += $(call cc-option,-march=g5)
 cflags-$(CONFIG_MARCH_Z900) += $(call cc-option,-march=z900)
 cflags-$(CONFIG_MARCH_Z990) += $(call cc-option,-march=z990)
 
+#
+# Prevent tail-call optimizations, to get clearer backtraces:
+#
+cflags-$(CONFIG_FRAME_POINTER) += -fno-optimize-sibling-calls
+
 # old style option for packed stacks
 ifeq ($(call cc-option-yn,-mkernel-backchain),y)
 cflags-$(CONFIG_PACK_STACK)  += -mkernel-backchain -D__PACK_STACK
diff --git a/arch/s390/kernel/Makefile b/arch/s390/kernel/Makefile
index 9269b5788fac..eabf00a6f770 100644
--- a/arch/s390/kernel/Makefile
+++ b/arch/s390/kernel/Makefile
@@ -21,6 +21,7 @@ obj-$(CONFIG_COMPAT)		+= compat_linux.o compat_signal.o \
 obj-$(CONFIG_BINFMT_ELF32)      += binfmt_elf32.o
 
 obj-$(CONFIG_VIRT_TIMER)        += vtime.o
+obj-$(CONFIG_STACKTRACE)        += stacktrace.o
 
 # Kexec part
 S390_KEXEC_OBJS := machine_kexec.o crash.o
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index d8948c342caf..5b5799ac8f83 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -58,6 +58,21 @@ STACK_SIZE  = 1 << STACK_SHIFT
 
 #define BASED(name) name-system_call(%r13)
 
+#ifdef CONFIG_TRACE_IRQFLAGS
+        .macro  TRACE_IRQS_ON
+        l       %r1,BASED(.Ltrace_irq_on)
+        basr    %r14,%r1
+        .endm
+
+        .macro  TRACE_IRQS_OFF
+        l       %r1,BASED(.Ltrace_irq_off)
+        basr    %r14,%r1
+        .endm
+#else
+#define TRACE_IRQS_ON
+#define TRACE_IRQS_OFF
+#endif
+
 /*
  * Register usage in interrupt handlers:
  *    R9  - pointer to current task structure
@@ -361,6 +376,7 @@ ret_from_fork:
         st      %r15,SP_R15(%r15)       # store stack pointer for new kthread
 0:      l       %r1,BASED(.Lschedtail)
         basr    %r14,%r1
+        TRACE_IRQS_ON
         stosm   __SF_EMPTY(%r15),0x03     # reenable interrupts
         b       BASED(sysc_return)
 
@@ -516,6 +532,7 @@ pgm_no_vtime3:
         mvc     __THREAD_per+__PER_address(4,%r1),__LC_PER_ADDRESS
         mvc     __THREAD_per+__PER_access_id(1,%r1),__LC_PER_ACCESS_ID
         oi      __TI_flags+3(%r9),_TIF_SINGLE_STEP # set TIF_SINGLE_STEP
+        TRACE_IRQS_ON
         stosm   __SF_EMPTY(%r15),0x03   # reenable interrupts
         b       BASED(sysc_do_svc)
 
@@ -539,9 +556,11 @@ io_int_handler:
 io_no_vtime:
 #endif
         l       %r9,__LC_THREAD_INFO    # load pointer to thread_info struct
+        TRACE_IRQS_OFF
         l       %r1,BASED(.Ldo_IRQ)        # load address of do_IRQ
         la      %r2,SP_PTREGS(%r15) # address of register-save area
         basr    %r14,%r1          # branch to standard irq handler
+        TRACE_IRQS_ON
 
 io_return:
         tm      SP_PSW+1(%r15),0x01    # returning to user ?
@@ -651,10 +670,12 @@ ext_int_handler:
 ext_no_vtime:
 #endif
         l       %r9,__LC_THREAD_INFO    # load pointer to thread_info struct
+        TRACE_IRQS_OFF
         la      %r2,SP_PTREGS(%r15)    # address of register-save area
         lh      %r3,__LC_EXT_INT_CODE  # get interruption code
         l       %r1,BASED(.Ldo_extint)
         basr    %r14,%r1
+        TRACE_IRQS_ON
         b       BASED(io_return)
 
 __critical_end:
@@ -731,8 +752,10 @@ mcck_no_vtime:
         stosm   __SF_EMPTY(%r15),0x04   # turn dat on
         tm      __TI_flags+3(%r9),_TIF_MCCK_PENDING
         bno     BASED(mcck_return)
+        TRACE_IRQS_OFF
         l       %r1,BASED(.Ls390_handle_mcck)
         basr    %r14,%r1                # call machine check handler
+        TRACE_IRQS_ON
 mcck_return:
         mvc     __LC_RETURN_MCCK_PSW(8),SP_PSW(%r15) # move return PSW
         ni      __LC_RETURN_MCCK_PSW+1,0xfd # clear wait state bit
@@ -1012,7 +1035,11 @@ cleanup_io_leave_insn:
 .Lvfork:       .long  sys_vfork
 .Lschedtail:   .long  schedule_tail
 .Lsysc_table:  .long  sys_call_table
-
+#ifdef CONFIG_TRACE_IRQFLAGS
+.Ltrace_irq_on:.long  trace_hardirqs_on
+.Ltrace_irq_off:
+               .long  trace_hardirqs_off
+#endif
 .Lcritical_start:
                .long  __critical_start + 0x80000000
 .Lcritical_end:
diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index 1ca499fa54b4..56f5f613b868 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -58,6 +58,19 @@ _TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK | _TIF_NEED_RESCHED | \
 
 #define BASED(name) name-system_call(%r13)
 
+#ifdef CONFIG_TRACE_IRQFLAGS
+        .macro  TRACE_IRQS_ON
+         brasl  %r14,trace_hardirqs_on
+        .endm
+
+        .macro  TRACE_IRQS_OFF
+         brasl  %r14,trace_hardirqs_off
+        .endm
+#else
+#define TRACE_IRQS_ON
+#define TRACE_IRQS_OFF
+#endif
+
         .macro  STORE_TIMER lc_offset
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
         stpt    \lc_offset
@@ -354,6 +367,7 @@ ret_from_fork:
         jo      0f
         stg     %r15,SP_R15(%r15)       # store stack pointer for new kthread
 0:      brasl   %r14,schedule_tail
+        TRACE_IRQS_ON
         stosm   24(%r15),0x03     # reenable interrupts
         j       sysc_return
 
@@ -535,6 +549,7 @@ pgm_no_vtime3:
         mvc     __THREAD_per+__PER_address(8,%r1),__LC_PER_ADDRESS
         mvc     __THREAD_per+__PER_access_id(1,%r1),__LC_PER_ACCESS_ID
         oi      __TI_flags+7(%r9),_TIF_SINGLE_STEP # set TIF_SINGLE_STEP
+        TRACE_IRQS_ON
         stosm   __SF_EMPTY(%r15),0x03   # reenable interrupts
         j       sysc_do_svc
 
@@ -557,8 +572,10 @@ io_int_handler:
 io_no_vtime:
 #endif
         lg      %r9,__LC_THREAD_INFO    # load pointer to thread_info struct
+        TRACE_IRQS_OFF
         la      %r2,SP_PTREGS(%r15)    # address of register-save area
         brasl   %r14,do_IRQ            # call standard irq handler
+        TRACE_IRQS_ON
 
 io_return:
         tm      SP_PSW+1(%r15),0x01    # returning to user ?
@@ -665,9 +682,11 @@ ext_int_handler:
 ext_no_vtime:
 #endif
         lg      %r9,__LC_THREAD_INFO    # load pointer to thread_info struct
+        TRACE_IRQS_OFF
         la      %r2,SP_PTREGS(%r15)    # address of register-save area
         llgh    %r3,__LC_EXT_INT_CODE  # get interruption code
         brasl   %r14,do_extint
+        TRACE_IRQS_ON
         j       io_return
 
 __critical_end:
@@ -743,7 +762,9 @@ mcck_no_vtime:
         stosm   __SF_EMPTY(%r15),0x04   # turn dat on
         tm      __TI_flags+7(%r9),_TIF_MCCK_PENDING
         jno     mcck_return
+        TRACE_IRQS_OFF
         brasl   %r14,s390_handle_mcck
+        TRACE_IRQS_ON
 mcck_return:
         mvc     __LC_RETURN_MCCK_PSW(16),SP_PSW(%r15) # move return PSW
         ni      __LC_RETURN_MCCK_PSW+1,0xfd # clear wait state bit
diff --git a/arch/s390/kernel/irq.c b/arch/s390/kernel/irq.c
index 480b6a5fef3a..1eef50918615 100644
--- a/arch/s390/kernel/irq.c
+++ b/arch/s390/kernel/irq.c
@@ -69,10 +69,6 @@ asmlinkage void do_softirq(void)
 
         local_irq_save(flags);
 
-        account_system_vtime(current);
-
-        local_bh_disable();
-
         if (local_softirq_pending()) {
                 /* Get current stack pointer. */
                 asm volatile("la %0,0(15)" : "=a" (old));
@@ -95,10 +91,6 @@ asmlinkage void do_softirq(void)
                         __do_softirq();
         }
 
-        account_system_vtime(current);
-
-        __local_bh_enable();
-
         local_irq_restore(flags);
 }
 
diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index 1f9399191794..78c8e5548caf 100644
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -142,6 +142,7 @@ static void default_idle(void)
                 return;
         }
 
+        trace_hardirqs_on();
         /* Wait for external, I/O or machine check interrupt. */
         __load_psw_mask(PSW_KERNEL_BITS | PSW_MASK_WAIT |
                         PSW_MASK_IO | PSW_MASK_EXT);
diff --git a/arch/s390/kernel/stacktrace.c b/arch/s390/kernel/stacktrace.c
new file mode 100644
index 000000000000..de83f38288d0
--- /dev/null
+++ b/arch/s390/kernel/stacktrace.c
@@ -0,0 +1,90 @@
+/*
+ * arch/s390/kernel/stacktrace.c
+ *
+ * Stack trace management functions
+ *
+ *  Copyright (C) IBM Corp. 2006
+ *  Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>
+ */
+
+#include <linux/sched.h>
+#include <linux/stacktrace.h>
+#include <linux/kallsyms.h>
+
+static inline unsigned long save_context_stack(struct stack_trace *trace,
+                                               unsigned int *skip,
+                                               unsigned long sp,
+                                               unsigned long low,
+                                               unsigned long high)
+{
+        struct stack_frame *sf;
+        struct pt_regs *regs;
+        unsigned long addr;
+
+        while(1) {
+                sp &= PSW_ADDR_INSN;
+                if (sp < low || sp > high)
+                        return sp;
+                sf = (struct stack_frame *)sp;
+                while(1) {
+                        addr = sf->gprs[8] & PSW_ADDR_INSN;
+                        if (!(*skip))
+                                trace->entries[trace->nr_entries++] = addr;
+                        else
+                                (*skip)--;
+                        if (trace->nr_entries >= trace->max_entries)
+                                return sp;
+                        low = sp;
+                        sp = sf->back_chain & PSW_ADDR_INSN;
+                        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 & PSW_ADDR_INSN;
+                if (!(*skip))
+                        trace->entries[trace->nr_entries++] = addr;
+                else
+                        (*skip)--;
+                if (trace->nr_entries >= trace->max_entries)
+                        return sp;
+                low = sp;
+                sp = regs->gprs[15];
+        }
+}
+
+void save_stack_trace(struct stack_trace *trace,
+                      struct task_struct *task, int all_contexts,
+                      unsigned int skip)
+{
+        register unsigned long sp asm ("15");
+        unsigned long orig_sp;
+
+        sp &= PSW_ADDR_INSN;
+        orig_sp = sp;
+
+        sp = save_context_stack(trace, &skip, sp,
+                                S390_lowcore.panic_stack - PAGE_SIZE,
+                                S390_lowcore.panic_stack);
+        if ((sp != orig_sp) && !all_contexts)
+                return;
+        sp = save_context_stack(trace, &skip, sp,
+                                S390_lowcore.async_stack - ASYNC_SIZE,
+                                S390_lowcore.async_stack);
+        if ((sp != orig_sp) && !all_contexts)
+                return;
+        if (task)
+                save_context_stack(trace, &skip, sp,
+                                   (unsigned long) task_stack_page(task),
+                                   (unsigned long) task_stack_page(task) + THREAD_SIZE);
+        else
+                save_context_stack(trace, &skip, sp, S390_lowcore.thread_info,
+                                   S390_lowcore.thread_info + THREAD_SIZE);
+        return;
+}