[PATCH] lockdep: stacktrace subsystem, s390 support

stacktrace interface for s390 as needed by lock validator.

[clg@fr.ibm.com: build fix]
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Cedric Le Goater <clg@fr.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 95 insertions, 0 deletions

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 821a141889de..5b28da4ad809 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -7,6 +7,10 @@ config MMU
         bool
         default y
 
+config STACKTRACE_SUPPORT
+        bool
+        default y
+
 config RWSEM_GENERIC_SPINLOCK
         bool
 
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/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;
+}