s390/dumpstack: fix call chain walking

dumpstack() did not always print a sane callchain when being called.
The reason is that show_trace() accessed register 15 directly to get
the current stack pointer and passed that pointer to __show_trace()
which expects a valid stack frame pointer as argument.
However due to tail call optimization the stack frame may not exist
anymore when __show_trace() gets called and therefore an invalid
stack frame pointer gets passed.
To prevent that disable tail call optimization for call chain walking
functions.
So move all the show_* functions to a dumpstack.c file like other
architectures have it already and add a -fno-optimize-sibling-calls
compile flag to both dumpstack.c and stacktrace.c to prevent tail
call optimization.

Fixes callchains that looked e.g. like this:

[   12.868258] Call Trace:
[   12.868262] ([<0000000000008000>] 0x8000)

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

1 files changed, 4 insertions, 246 deletions

diff --git a/arch/s390/kernel/traps.c b/arch/s390/kernel/traps.c
index 13dd63fba367..c5762324d9ee 100644
--- a/arch/s390/kernel/traps.c
+++ b/arch/s390/kernel/traps.c
@@ -12,49 +12,16 @@
  * 'Traps.c' handles hardware traps and faults after we have saved some
  * state in 'asm.s'.
  */
-#include <linux/sched.h>
-#include <linux/kernel.h>
-#include <linux/string.h>
-#include <linux/errno.h>
+#include <linux/kprobes.h>
+#include <linux/kdebug.h>
+#include <linux/module.h>
 #include <linux/ptrace.h>
-#include <linux/timer.h>
+#include <linux/sched.h>
 #include <linux/mm.h>
-#include <linux/smp.h>
-#include <linux/init.h>
-#include <linux/interrupt.h>
-#include <linux/seq_file.h>
-#include <linux/delay.h>
-#include <linux/module.h>
-#include <linux/kdebug.h>
-#include <linux/kallsyms.h>
-#include <linux/reboot.h>
-#include <linux/kprobes.h>
-#include <linux/bug.h>
-#include <linux/utsname.h>
-#include <asm/uaccess.h>
-#include <asm/io.h>
-#include <linux/atomic.h>
-#include <asm/mathemu.h>
-#include <asm/cpcmd.h>
-#include <asm/lowcore.h>
-#include <asm/debug.h>
-#include <asm/ipl.h>
 #include "entry.h"
 
 int show_unhandled_signals = 1;
 
-#define stack_pointer ({ void **sp; asm("la %0,0(15)" : "=&d" (sp)); sp; })
-
-#ifndef CONFIG_64BIT
-#define LONG "%08lx "
-#define FOURLONG "%08lx %08lx %08lx %08lx\n"
-static int kstack_depth_to_print = 12;
-#else /* CONFIG_64BIT */
-#define LONG "%016lx "
-#define FOURLONG "%016lx %016lx %016lx %016lx\n"
-static int kstack_depth_to_print = 20;
-#endif /* CONFIG_64BIT */
-
 static inline void __user *get_trap_ip(struct pt_regs *regs)
 {
 #ifdef CONFIG_64BIT
@@ -72,215 +39,6 @@ static inline void __user *get_trap_ip(struct pt_regs *regs)
 #endif
 }
 
-/*
- * For show_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
- * 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)
-{
-        struct stack_frame *sf;
-        struct pt_regs *regs;
-
-        while (1) {
-                sp = sp & PSW_ADDR_INSN;
-                if (sp < low || sp > high - sizeof(*sf))
-                        return sp;
-                sf = (struct stack_frame *) sp;
-                printk("([<%016lx>] ", sf->gprs[8] & PSW_ADDR_INSN);
-                print_symbol("%s)\n", sf->gprs[8] & PSW_ADDR_INSN);
-                /* Follow the backchain. */
-                while (1) {
-                        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;
-                        printk(" [<%016lx>] ", sf->gprs[8] & PSW_ADDR_INSN);
-                        print_symbol("%s\n", sf->gprs[8] & PSW_ADDR_INSN);
-                }
-                /* 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;
-                printk(" [<%016lx>] ", regs->psw.addr & PSW_ADDR_INSN);
-                print_symbol("%s\n", regs->psw.addr & PSW_ADDR_INSN);
-                low = sp;
-                sp = regs->gprs[15];
-        }
-}
-
-static void show_trace(struct task_struct *task, unsigned long *stack)
-{
-        register unsigned long __r15 asm ("15");
-        unsigned long sp;
-
-        sp = (unsigned long) stack;
-        if (!sp)
-                sp = task ? task->thread.ksp : __r15;
-        printk("Call Trace:\n");
-#ifdef CONFIG_CHECK_STACK
-        sp = __show_trace(sp, S390_lowcore.panic_stack - 4096,
-                          S390_lowcore.panic_stack);
-#endif
-        sp = __show_trace(sp, S390_lowcore.async_stack - ASYNC_SIZE,
-                          S390_lowcore.async_stack);
-        if (task)
-                __show_trace(sp, (unsigned long) task_stack_page(task),
-                             (unsigned long) task_stack_page(task) + THREAD_SIZE);
-        else
-                __show_trace(sp, S390_lowcore.thread_info,
-                             S390_lowcore.thread_info + THREAD_SIZE);
-        if (!task)
-                task = current;
-        debug_show_held_locks(task);
-}
-
-void show_stack(struct task_struct *task, unsigned long *sp)
-{
-        register unsigned long * __r15 asm ("15");
-        unsigned long *stack;
-        int i;
-
-        if (!sp)
-                stack = task ? (unsigned long *) task->thread.ksp : __r15;
-        else
-                stack = sp;
-
-        for (i = 0; i < kstack_depth_to_print; i++) {
-                if (((addr_t) stack & (THREAD_SIZE-1)) == 0)
-                        break;
-                if ((i * sizeof(long) % 32) == 0)
-                        printk("%s       ", i == 0 ? "" : "\n");
-                printk(LONG, *stack++);
-        }
-        printk("\n");
-        show_trace(task, sp);
-}
-
-static void show_last_breaking_event(struct pt_regs *regs)
-{
-#ifdef CONFIG_64BIT
-        printk("Last Breaking-Event-Address:\n");
-        printk(" [<%016lx>] ", regs->args[0] & PSW_ADDR_INSN);
-        print_symbol("%s\n", regs->args[0] & PSW_ADDR_INSN);
-#endif
-}
-
-/*
- * The architecture-independent dump_stack generator
- */
-void dump_stack(void)
-{
-        printk("CPU: %d %s %s %.*s\n",
-               task_thread_info(current)->cpu, print_tainted(),
-               init_utsname()->release,
-               (int)strcspn(init_utsname()->version, " "),
-               init_utsname()->version);
-        printk("Process %s (pid: %d, task: %p, ksp: %p)\n",
-               current->comm, current->pid, current,
-               (void *) current->thread.ksp);
-        show_stack(NULL, NULL);
-}
-EXPORT_SYMBOL(dump_stack);
-
-static inline int mask_bits(struct pt_regs *regs, unsigned long bits)
-{
-        return (regs->psw.mask & bits) / ((~bits + 1) & bits);
-}
-
-void show_registers(struct pt_regs *regs)
-{
-        char *mode;
-
-        mode = user_mode(regs) ? "User" : "Krnl";
-        printk("%s PSW : %p %p",
-               mode, (void *) regs->psw.mask,
-               (void *) regs->psw.addr);
-        print_symbol(" (%s)\n", regs->psw.addr & PSW_ADDR_INSN);
-        printk("           R:%x T:%x IO:%x EX:%x Key:%x M:%x W:%x "
-               "P:%x AS:%x CC:%x PM:%x", mask_bits(regs, PSW_MASK_PER),
-               mask_bits(regs, PSW_MASK_DAT), mask_bits(regs, PSW_MASK_IO),
-               mask_bits(regs, PSW_MASK_EXT), mask_bits(regs, PSW_MASK_KEY),
-               mask_bits(regs, PSW_MASK_MCHECK), mask_bits(regs, PSW_MASK_WAIT),
-               mask_bits(regs, PSW_MASK_PSTATE), mask_bits(regs, PSW_MASK_ASC),
-               mask_bits(regs, PSW_MASK_CC), mask_bits(regs, PSW_MASK_PM));
-#ifdef CONFIG_64BIT
-        printk(" EA:%x", mask_bits(regs, PSW_MASK_EA | PSW_MASK_BA));
-#endif
-        printk("\n%s GPRS: " FOURLONG, mode,
-               regs->gprs[0], regs->gprs[1], regs->gprs[2], regs->gprs[3]);
-        printk("           " FOURLONG,
-               regs->gprs[4], regs->gprs[5], regs->gprs[6], regs->gprs[7]);
-        printk("           " FOURLONG,
-               regs->gprs[8], regs->gprs[9], regs->gprs[10], regs->gprs[11]);
-        printk("           " FOURLONG,
-               regs->gprs[12], regs->gprs[13], regs->gprs[14], regs->gprs[15]);
-
-        show_code(regs);
-}       
-
-void show_regs(struct pt_regs *regs)
-{
-        printk("CPU: %d %s %s %.*s\n",
-               task_thread_info(current)->cpu, print_tainted(),
-               init_utsname()->release,
-               (int)strcspn(init_utsname()->version, " "),
-               init_utsname()->version);
-        printk("Process %s (pid: %d, task: %p, ksp: %p)\n",
-               current->comm, current->pid, current,
-               (void *) current->thread.ksp);
-        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_last_breaking_event(regs);
-}
-
-static DEFINE_SPINLOCK(die_lock);
-
-void die(struct pt_regs *regs, const char *str)
-{
-        static int die_counter;
-
-        oops_enter();
-        lgr_info_log();
-        debug_stop_all();
-        console_verbose();
-        spin_lock_irq(&die_lock);
-        bust_spinlocks(1);
-        printk("%s: %04x [#%d] ", str, regs->int_code & 0xffff, ++die_counter);
-#ifdef CONFIG_PREEMPT
-        printk("PREEMPT ");
-#endif
-#ifdef CONFIG_SMP
-        printk("SMP ");
-#endif
-#ifdef CONFIG_DEBUG_PAGEALLOC
-        printk("DEBUG_PAGEALLOC");
-#endif
-        printk("\n");
-        notify_die(DIE_OOPS, str, regs, 0, regs->int_code & 0xffff, SIGSEGV);
-        print_modules();
-        show_regs(regs);
-        bust_spinlocks(0);
-        add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
-        spin_unlock_irq(&die_lock);
-        if (in_interrupt())
-                panic("Fatal exception in interrupt");
-        if (panic_on_oops)
-                panic("Fatal exception: panic_on_oops");
-        oops_exit();
-        do_exit(SIGSEGV);
-}
-
 static inline void report_user_fault(struct pt_regs *regs, int signr)
 {
         if ((task_pid_nr(current) > 1) && !show_unhandled_signals)