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linux-pinenote/arch/s390/kernel/traps.c
Heiko Carstens 1bca09f714 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>
2013-04-17 14:07:28 +02:00

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/*
* S390 version
* Copyright IBM Corp. 1999, 2000
* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
* Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com),
*
* Derived from "arch/i386/kernel/traps.c"
* Copyright (C) 1991, 1992 Linus Torvalds
*/
/*
* 'Traps.c' handles hardware traps and faults after we have saved some
* state in 'asm.s'.
*/
#include <linux/kprobes.h>
#include <linux/kdebug.h>
#include <linux/module.h>
#include <linux/ptrace.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include "entry.h"
int show_unhandled_signals = 1;
static inline void __user *get_trap_ip(struct pt_regs *regs)
{
#ifdef CONFIG_64BIT
unsigned long address;
if (regs->int_code & 0x200)
address = *(unsigned long *)(current->thread.trap_tdb + 24);
else
address = regs->psw.addr;
return (void __user *)
((address - (regs->int_code >> 16)) & PSW_ADDR_INSN);
#else
return (void __user *)
((regs->psw.addr - (regs->int_code >> 16)) & PSW_ADDR_INSN);
#endif
}
static inline void report_user_fault(struct pt_regs *regs, int signr)
{
if ((task_pid_nr(current) > 1) && !show_unhandled_signals)
return;
if (!unhandled_signal(current, signr))
return;
if (!printk_ratelimit())
return;
printk("User process fault: interruption code 0x%X ", regs->int_code);
print_vma_addr("in ", regs->psw.addr & PSW_ADDR_INSN);
printk("\n");
show_regs(regs);
}
int is_valid_bugaddr(unsigned long addr)
{
return 1;
}
static void __kprobes do_trap(struct pt_regs *regs,
int si_signo, int si_code, char *str)
{
siginfo_t info;
if (notify_die(DIE_TRAP, str, regs, 0,
regs->int_code, si_signo) == NOTIFY_STOP)
return;
if (user_mode(regs)) {
info.si_signo = si_signo;
info.si_errno = 0;
info.si_code = si_code;
info.si_addr = get_trap_ip(regs);
force_sig_info(si_signo, &info, current);
report_user_fault(regs, si_signo);
} else {
const struct exception_table_entry *fixup;
fixup = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
if (fixup)
regs->psw.addr = extable_fixup(fixup) | PSW_ADDR_AMODE;
else {
enum bug_trap_type btt;
btt = report_bug(regs->psw.addr & PSW_ADDR_INSN, regs);
if (btt == BUG_TRAP_TYPE_WARN)
return;
die(regs, str);
}
}
}
void __kprobes do_per_trap(struct pt_regs *regs)
{
siginfo_t info;
if (notify_die(DIE_SSTEP, "sstep", regs, 0, 0, SIGTRAP) == NOTIFY_STOP)
return;
if (!current->ptrace)
return;
info.si_signo = SIGTRAP;
info.si_errno = 0;
info.si_code = TRAP_HWBKPT;
info.si_addr =
(void __force __user *) current->thread.per_event.address;
force_sig_info(SIGTRAP, &info, current);
}
void default_trap_handler(struct pt_regs *regs)
{
if (user_mode(regs)) {
report_user_fault(regs, SIGSEGV);
do_exit(SIGSEGV);
} else
die(regs, "Unknown program exception");
}
#define DO_ERROR_INFO(name, signr, sicode, str) \
void name(struct pt_regs *regs) \
{ \
do_trap(regs, signr, sicode, str); \
}
DO_ERROR_INFO(addressing_exception, SIGILL, ILL_ILLADR,
"addressing exception")
DO_ERROR_INFO(execute_exception, SIGILL, ILL_ILLOPN,
"execute exception")
DO_ERROR_INFO(divide_exception, SIGFPE, FPE_INTDIV,
"fixpoint divide exception")
DO_ERROR_INFO(overflow_exception, SIGFPE, FPE_INTOVF,
"fixpoint overflow exception")
DO_ERROR_INFO(hfp_overflow_exception, SIGFPE, FPE_FLTOVF,
"HFP overflow exception")
DO_ERROR_INFO(hfp_underflow_exception, SIGFPE, FPE_FLTUND,
"HFP underflow exception")
DO_ERROR_INFO(hfp_significance_exception, SIGFPE, FPE_FLTRES,
"HFP significance exception")
DO_ERROR_INFO(hfp_divide_exception, SIGFPE, FPE_FLTDIV,
"HFP divide exception")
DO_ERROR_INFO(hfp_sqrt_exception, SIGFPE, FPE_FLTINV,
"HFP square root exception")
DO_ERROR_INFO(operand_exception, SIGILL, ILL_ILLOPN,
"operand exception")
DO_ERROR_INFO(privileged_op, SIGILL, ILL_PRVOPC,
"privileged operation")
DO_ERROR_INFO(special_op_exception, SIGILL, ILL_ILLOPN,
"special operation exception")
DO_ERROR_INFO(translation_exception, SIGILL, ILL_ILLOPN,
"translation exception")
#ifdef CONFIG_64BIT
DO_ERROR_INFO(transaction_exception, SIGILL, ILL_ILLOPN,
"transaction constraint exception")
#endif
static inline void do_fp_trap(struct pt_regs *regs, int fpc)
{
int si_code = 0;
/* FPC[2] is Data Exception Code */
if ((fpc & 0x00000300) == 0) {
/* bits 6 and 7 of DXC are 0 iff IEEE exception */
if (fpc & 0x8000) /* invalid fp operation */
si_code = FPE_FLTINV;
else if (fpc & 0x4000) /* div by 0 */
si_code = FPE_FLTDIV;
else if (fpc & 0x2000) /* overflow */
si_code = FPE_FLTOVF;
else if (fpc & 0x1000) /* underflow */
si_code = FPE_FLTUND;
else if (fpc & 0x0800) /* inexact */
si_code = FPE_FLTRES;
}
do_trap(regs, SIGFPE, si_code, "floating point exception");
}
void __kprobes illegal_op(struct pt_regs *regs)
{
siginfo_t info;
__u8 opcode[6];
__u16 __user *location;
int signal = 0;
location = get_trap_ip(regs);
if (user_mode(regs)) {
if (get_user(*((__u16 *) opcode), (__u16 __user *) location))
return;
if (*((__u16 *) opcode) == S390_BREAKPOINT_U16) {
if (current->ptrace) {
info.si_signo = SIGTRAP;
info.si_errno = 0;
info.si_code = TRAP_BRKPT;
info.si_addr = location;
force_sig_info(SIGTRAP, &info, current);
} else
signal = SIGILL;
#ifdef CONFIG_MATHEMU
} else if (opcode[0] == 0xb3) {
if (get_user(*((__u16 *) (opcode+2)), location+1))
return;
signal = math_emu_b3(opcode, regs);
} else if (opcode[0] == 0xed) {
if (get_user(*((__u32 *) (opcode+2)),
(__u32 __user *)(location+1)))
return;
signal = math_emu_ed(opcode, regs);
} else if (*((__u16 *) opcode) == 0xb299) {
if (get_user(*((__u16 *) (opcode+2)), location+1))
return;
signal = math_emu_srnm(opcode, regs);
} else if (*((__u16 *) opcode) == 0xb29c) {
if (get_user(*((__u16 *) (opcode+2)), location+1))
return;
signal = math_emu_stfpc(opcode, regs);
} else if (*((__u16 *) opcode) == 0xb29d) {
if (get_user(*((__u16 *) (opcode+2)), location+1))
return;
signal = math_emu_lfpc(opcode, regs);
#endif
} else
signal = SIGILL;
} else {
/*
* If we get an illegal op in kernel mode, send it through the
* kprobes notifier. If kprobes doesn't pick it up, SIGILL
*/
if (notify_die(DIE_BPT, "bpt", regs, 0,
3, SIGTRAP) != NOTIFY_STOP)
signal = SIGILL;
}
#ifdef CONFIG_MATHEMU
if (signal == SIGFPE)
do_fp_trap(regs, current->thread.fp_regs.fpc);
else if (signal == SIGSEGV)
do_trap(regs, signal, SEGV_MAPERR, "user address fault");
else
#endif
if (signal)
do_trap(regs, signal, ILL_ILLOPC, "illegal operation");
}
#ifdef CONFIG_MATHEMU
void specification_exception(struct pt_regs *regs)
{
__u8 opcode[6];
__u16 __user *location = NULL;
int signal = 0;
location = (__u16 __user *) get_trap_ip(regs);
if (user_mode(regs)) {
get_user(*((__u16 *) opcode), location);
switch (opcode[0]) {
case 0x28: /* LDR Rx,Ry */
signal = math_emu_ldr(opcode);
break;
case 0x38: /* LER Rx,Ry */
signal = math_emu_ler(opcode);
break;
case 0x60: /* STD R,D(X,B) */
get_user(*((__u16 *) (opcode+2)), location+1);
signal = math_emu_std(opcode, regs);
break;
case 0x68: /* LD R,D(X,B) */
get_user(*((__u16 *) (opcode+2)), location+1);
signal = math_emu_ld(opcode, regs);
break;
case 0x70: /* STE R,D(X,B) */
get_user(*((__u16 *) (opcode+2)), location+1);
signal = math_emu_ste(opcode, regs);
break;
case 0x78: /* LE R,D(X,B) */
get_user(*((__u16 *) (opcode+2)), location+1);
signal = math_emu_le(opcode, regs);
break;
default:
signal = SIGILL;
break;
}
} else
signal = SIGILL;
if (signal == SIGFPE)
do_fp_trap(regs, current->thread.fp_regs.fpc);
else if (signal)
do_trap(regs, signal, ILL_ILLOPN, "specification exception");
}
#else
DO_ERROR_INFO(specification_exception, SIGILL, ILL_ILLOPN,
"specification exception");
#endif
void data_exception(struct pt_regs *regs)
{
__u16 __user *location;
int signal = 0;
location = get_trap_ip(regs);
if (MACHINE_HAS_IEEE)
asm volatile("stfpc %0" : "=m" (current->thread.fp_regs.fpc));
#ifdef CONFIG_MATHEMU
else if (user_mode(regs)) {
__u8 opcode[6];
get_user(*((__u16 *) opcode), location);
switch (opcode[0]) {
case 0x28: /* LDR Rx,Ry */
signal = math_emu_ldr(opcode);
break;
case 0x38: /* LER Rx,Ry */
signal = math_emu_ler(opcode);
break;
case 0x60: /* STD R,D(X,B) */
get_user(*((__u16 *) (opcode+2)), location+1);
signal = math_emu_std(opcode, regs);
break;
case 0x68: /* LD R,D(X,B) */
get_user(*((__u16 *) (opcode+2)), location+1);
signal = math_emu_ld(opcode, regs);
break;
case 0x70: /* STE R,D(X,B) */
get_user(*((__u16 *) (opcode+2)), location+1);
signal = math_emu_ste(opcode, regs);
break;
case 0x78: /* LE R,D(X,B) */
get_user(*((__u16 *) (opcode+2)), location+1);
signal = math_emu_le(opcode, regs);
break;
case 0xb3:
get_user(*((__u16 *) (opcode+2)), location+1);
signal = math_emu_b3(opcode, regs);
break;
case 0xed:
get_user(*((__u32 *) (opcode+2)),
(__u32 __user *)(location+1));
signal = math_emu_ed(opcode, regs);
break;
case 0xb2:
if (opcode[1] == 0x99) {
get_user(*((__u16 *) (opcode+2)), location+1);
signal = math_emu_srnm(opcode, regs);
} else if (opcode[1] == 0x9c) {
get_user(*((__u16 *) (opcode+2)), location+1);
signal = math_emu_stfpc(opcode, regs);
} else if (opcode[1] == 0x9d) {
get_user(*((__u16 *) (opcode+2)), location+1);
signal = math_emu_lfpc(opcode, regs);
} else
signal = SIGILL;
break;
default:
signal = SIGILL;
break;
}
}
#endif
if (current->thread.fp_regs.fpc & FPC_DXC_MASK)
signal = SIGFPE;
else
signal = SIGILL;
if (signal == SIGFPE)
do_fp_trap(regs, current->thread.fp_regs.fpc);
else if (signal)
do_trap(regs, signal, ILL_ILLOPN, "data exception");
}
void space_switch_exception(struct pt_regs *regs)
{
/* Set user psw back to home space mode. */
if (user_mode(regs))
regs->psw.mask |= PSW_ASC_HOME;
/* Send SIGILL. */
do_trap(regs, SIGILL, ILL_PRVOPC, "space switch event");
}
void __kprobes kernel_stack_overflow(struct pt_regs * regs)
{
bust_spinlocks(1);
printk("Kernel stack overflow.\n");
show_regs(regs);
bust_spinlocks(0);
panic("Corrupt kernel stack, can't continue.");
}
void __init trap_init(void)
{
local_mcck_enable();
}
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