/*
* arch/xtensa/kernel/traps.c
*
* Exception handling.
*
* Derived from code with the following copyrights:
* Copyright (C) 1994 - 1999 by Ralf Baechle
* Modified for R3000 by Paul M. Antoine, 1995, 1996
* Complete output from die() by Ulf Carlsson, 1998
* Copyright (C) 1999 Silicon Graphics, Inc.
*
* Essentially rewritten for the Xtensa architecture port.
*
* Copyright (C) 2001 - 2013 Tensilica Inc.
*
* Joe Taylor <joe@tensilica.com, joetylr@yahoo.com>
* Chris Zankel <chris@zankel.net>
* Marc Gauthier<marc@tensilica.com, marc@alumni.uwaterloo.ca>
* Kevin Chea
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*/
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/stringify.h>
#include <linux/kallsyms.h>
#include <linux/delay.h>
#include <linux/hardirq.h>
#include <asm/stacktrace.h>
#include <asm/ptrace.h>
#include <asm/timex.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
#include <asm/traps.h>
#ifdef CONFIG_KGDB
extern int gdb_enter;
extern int return_from_debug_flag;
#endif
/*
* Machine specific interrupt handlers
*/
extern void kernel_exception(void);
extern void user_exception(void);
extern void fast_syscall_kernel(void);
extern void fast_syscall_user(void);
extern void fast_alloca(void);
extern void fast_unaligned(void);
extern void fast_second_level_miss(void);
extern void fast_store_prohibited(void);
extern void fast_coprocessor(void);
extern void do_illegal_instruction (struct pt_regs*);
extern void do_interrupt (struct pt_regs*);
extern void do_unaligned_user (struct pt_regs*);
extern void do_multihit (struct pt_regs*, unsigned long);
extern void do_page_fault (struct pt_regs*, unsigned long);
extern void do_debug (struct pt_regs*);
extern void system_call (struct pt_regs*);
/*
* The vector table must be preceded by a save area (which
* implies it must be in RAM, unless one places RAM immediately
* before a ROM and puts the vector at the start of the ROM (!))
*/
#define KRNL 0x01
#define USER 0x02
#define COPROCESSOR(x) \
{ EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER, fast_coprocessor }
typedef struct {
int cause;
int fast;
void* handler;
} dispatch_init_table_t;
static dispatch_init_table_t __initdata dispatch_init_table[] = {
{ EXCCAUSE_ILLEGAL_INSTRUCTION, 0, do_illegal_instruction},
{ EXCCAUSE_SYSTEM_CALL, KRNL, fast_syscall_kernel },
{ EXCCAUSE_SYSTEM_CALL, USER, fast_syscall_user },
{ EXCCAUSE_SYSTEM_CALL, 0, system_call },
/* EXCCAUSE_INSTRUCTION_FETCH unhandled */
/* EXCCAUSE_LOAD_STORE_ERROR unhandled*/
{ EXCCAUSE_LEVEL1_INTERRUPT, 0, do_interrupt },
{ EXCCAUSE_ALLOCA, USER|KRNL, fast_alloca },
/* EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */
/* EXCCAUSE_PRIVILEGED unhandled */
#if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
#ifdef CONFIG_XTENSA_UNALIGNED_USER
{ EXCCAUSE_UNALIGNED, USER, fast_unaligned },
#endif
{ EXCCAUSE_UNALIGNED, 0, do_unaligned_user },
{ EXCCAUSE_UNALIGNED, KRNL, fast_unaligned },
#endif
#ifdef CONFIG_MMU
{ EXCCAUSE_ITLB_MISS, 0, do_page_fault },
{ EXCCAUSE_ITLB_MISS, USER|KRNL, fast_second_level_miss},
{ EXCCAUSE_ITLB_MULTIHIT, 0, do_multihit },
{ EXCCAUSE_ITLB_PRIVILEGE, 0, do_page_fault },
/* EXCCAUSE_SIZE_RESTRICTION unhandled */
{ EXCCAUSE_FETCH_CACHE_ATTRIBUTE, 0, do_page_fault },
{ EXCCAUSE_DTLB_MISS, USER|KRNL, fast_second_level_miss},
{ EXCCAUSE_DTLB_MISS, 0, do_page_fault },
{ EXCCAUSE_DTLB_MULTIHIT, 0, do_multihit },
{ EXCCAUSE_DTLB_PRIVILEGE, 0, do_page_fault },
/* EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */
{ EXCCAUSE_STORE_CACHE_ATTRIBUTE, USER|KRNL, fast_store_prohibited },
{ EXCCAUSE_STORE_CACHE_ATTRIBUTE, 0, do_page_fault },
{ EXCCAUSE_LOAD_CACHE_ATTRIBUTE, 0, do_page_fault },
#endif /* CONFIG_MMU */
/* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */
#if XTENSA_HAVE_COPROCESSOR(0)
COPROCESSOR(0),
#endif
#if XTENSA_HAVE_COPROCESSOR(1)
COPROCESSOR(1),
#endif
#if XTENSA_HAVE_COPROCESSOR(2)
COPROCESSOR(2),
#endif
#if XTENSA_HAVE_COPROCESSOR(3)
COPROCESSOR(3),
#endif
#if XTENSA_HAVE_COPROCESSOR(4)
COPROCESSOR(4),
#endif
#if XTENSA_HAVE_COPROCESSOR(5)
COPROCESSOR(5),
#endif
#if XTENSA_HAVE_COPROCESSOR(6)
COPROCESSOR(6),
#endif
#if XTENSA_HAVE_COPROCESSOR(7)
COPROCESSOR(7),
#endif
{ EXCCAUSE_MAPPED_DEBUG, 0, do_debug },
{ -1, -1, 0 }
};
/* The exception table <exc_table> serves two functions:
* 1. it contains three dispatch tables (fast_user, fast_kernel, default-c)
* 2. it is a temporary memory buffer for the exception handlers.
*/
DEFINE_PER_CPU(unsigned long, exc_table[EXC_TABLE_SIZE/4]);
void die(const char*, struct pt_regs*, long);
static inline void
__die_if_kernel(const char *str, struct pt_regs *regs, long err)
{
if (!user_mode(regs))
die(str, regs, err);
}
/*
* Unhandled Exceptions. Kill user task or panic if in kernel space.
*/
void do_unhandled(struct pt_regs *regs, unsigned long exccause)
{
__die_if_kernel("Caught unhandled exception - should not happen",
regs, SIGKILL);
/* If in user mode, send SIGILL signal to current process */
printk("Caught unhandled exception in '%s' "
"(pid = %d, pc = %#010lx) - should not happen\n"
"\tEXCCAUSE is %ld\n",
current->comm, task_pid_nr(current), regs->pc, exccause);
force_sig(SIGILL, current);
}
/*
* Multi-hit exception. This if fatal!
*/
void do_multihit(struct pt_regs *regs, unsigned long exccause)
{
die("Caught multihit exception", regs, SIGKILL);
}
/*
* IRQ handler.
*/
extern void do_IRQ(int, struct pt_regs *);
void do_interrupt(struct pt_regs *regs)
{
static const unsigned int_level_mask[] = {
0,
XCHAL_INTLEVEL1_MASK,
XCHAL_INTLEVEL2_MASK,
XCHAL_INTLEVEL3_MASK,
XCHAL_INTLEVEL4_MASK,
XCHAL_INTLEVEL5_MASK,
XCHAL_INTLEVEL6_MASK,
XCHAL_INTLEVEL7_MASK,
};
struct pt_regs *old_regs = set_irq_regs(regs);
irq_enter();
for (;;) {
unsigned intread = get_sr(interrupt);
unsigned intenable = get_sr(intenable);
unsigned int_at_level = intread & intenable;
unsigned level;
for (level = LOCKLEVEL; level > 0; --level) {
if (int_at_level & int_level_mask[level]) {
int_at_level &= int_level_mask[level];
break;
}
}
if (level == 0)
break;
do_IRQ(__ffs(int_at_level), regs);
}
irq_exit();
set_irq_regs(old_regs);
}
/*
* Illegal instruction. Fatal if in kernel space.
*/
void
do_illegal_instruction(struct pt_regs *regs)
{
__die_if_kernel("Illegal instruction in kernel", regs, SIGKILL);
/* If in user mode, send SIGILL signal to current process. */
printk("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n",
current->comm, task_pid_nr(current), regs->pc);
force_sig(SIGILL, current);
}
/*
* Handle unaligned memory accesses from user space. Kill task.
*
* If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory
* accesses causes from user space.
*/
#if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
void
do_unaligned_user (struct pt_regs *regs)
{
siginfo_t info;
__die_if_kernel("Unhandled unaligned exception in kernel",
regs, SIGKILL);
current->thread.bad_vaddr = regs->excvaddr;
current->thread.error_code = -3;
printk("Unaligned memory access to %08lx in '%s' "
"(pid = %d, pc = %#010lx)\n",
regs->excvaddr, current->comm, task_pid_nr(current), regs->pc);
info.si_signo = SIGBUS;
info.si_errno = 0;
info.si_code = BUS_ADRALN;
info.si_addr = (void *) regs->excvaddr;
force_sig_info(SIGSEGV, &info, current);
}
#endif
void
do_debug(struct pt_regs *regs)
{
#ifdef CONFIG_KGDB
/* If remote debugging is configured AND enabled, we give control to
* kgdb. Otherwise, we fall through, perhaps giving control to the
* native debugger.
*/
if (gdb_enter) {
extern void gdb_handle_exception(struct pt_regs *);
gdb_handle_exception(regs);
return_from_debug_flag = 1;
return;
}
#endif
__die_if_kernel("Breakpoint in kernel", regs, SIGKILL);
/* If in user mode, send SIGTRAP signal to current process */
force_sig(SIGTRAP, current);
}
static void set_handler(int idx, void *handler)
{
unsigned int cpu;
for_each_possible_cpu(cpu)
per_cpu(exc_table, cpu)[idx] = (unsigned long)handler;
}
/* Set exception C handler - for temporary use when probing exceptions */
void * __init trap_set_handler(int cause, void *handler)
{
void *previous = (void *)per_cpu(exc_table, 0)[
EXC_TABLE_DEFAULT / 4 + cause];
set_handler(EXC_TABLE_DEFAULT / 4 + cause, handler);
return previous;
}
static void trap_init_excsave(void)
{
unsigned long excsave1 = (unsigned long)this_cpu_ptr(exc_table);
__asm__ __volatile__("wsr %0, excsave1\n" : : "a" (excsave1));
}
/*
* Initialize dispatch tables.
*
* The exception vectors are stored compressed the __init section in the
* dispatch_init_table. This function initializes the following three tables
* from that compressed table:
* - fast user first dispatch table for user exceptions
* - fast kernel first dispatch table for kernel exceptions
* - default C-handler C-handler called by the default fast handler.
*
* See vectors.S for more details.
*/
void __init trap_init(void)
{
int i;
/* Setup default vectors. */
for(i = 0; i < 64; i++) {
set_handler(EXC_TABLE_FAST_USER/4 + i, user_exception);
set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception);
set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled);
}
/* Setup specific handlers. */
for(i = 0; dispatch_init_table[i].cause >= 0; i++) {
int fast = dispatch_init_table[i].fast;
int cause = dispatch_init_table[i].cause;
void *handler = dispatch_init_table[i].handler;
if (fast == 0)
set_handler (EXC_TABLE_DEFAULT/4 + cause, handler);
if (fast && fast & USER)
set_handler (EXC_TABLE_FAST_USER/4 + cause, handler);
if (fast && fast & KRNL)
set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler);
}
/* Initialize EXCSAVE_1 to hold the address of the exception table. */
trap_init_excsave();
}
#ifdef CONFIG_SMP
void secondary_trap_init(void)
{
trap_init_excsave();
}
#endif
/*
* This function dumps the current valid window frame and other base registers.
*/
void show_regs(struct pt_regs * regs)
{
int i, wmask;
show_regs_print_info(KERN_DEFAULT);
wmask = regs->wmask & ~1;
for (i = 0; i < 16; i++) {
if ((i % 8) == 0)
printk(KERN_INFO "a%02d:", i);
printk(KERN_CONT " %08lx", regs->areg[i]);
}
printk(KERN_CONT "\n");
printk("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n",
regs->pc, regs->ps, regs->depc, regs->excvaddr);
printk("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n",
regs->lbeg, regs->lend, regs->lcount, regs->sar);
if (user_mode(regs))
printk("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n",
regs->windowbase, regs->windowstart, regs->wmask,
regs->syscall);
}
static int show_trace_cb(struct stackframe *frame, void *data)
{
if (kernel_text_address(frame->pc)) {
printk(" [<%08lx>] ", frame->pc);
print_symbol("%s\n", frame->pc);
}
return 0;
}
void show_trace(struct task_struct *task, unsigned long *sp)
{
if (!sp)
sp = stack_pointer(task);
printk("Call Trace:");
#ifdef CONFIG_KALLSYMS
printk("\n");
#endif
walk_stackframe(sp, show_trace_cb, NULL);
printk("\n");
}
/*
* This routine abuses get_user()/put_user() to reference pointers
* with at least a bit of error checking ...
*/
static int kstack_depth_to_print = 24;
void show_stack(struct task_struct *task, unsigned long *sp)
{
int i = 0;
unsigned long *stack;
if (!sp)
sp = stack_pointer(task);
stack = sp;
printk("\nStack: ");
for (i = 0; i < kstack_depth_to_print; i++) {
if (kstack_end(sp))
break;
if (i && ((i % 8) == 0))
printk("\n ");
printk("%08lx ", *sp++);
}
printk("\n");
show_trace(task, stack);
}
void show_code(unsigned int *pc)
{
long i;
printk("\nCode:");
for(i = -3 ; i < 6 ; i++) {
unsigned long insn;
if (__get_user(insn, pc + i)) {
printk(" (Bad address in pc)\n");
break;
}
printk("%c%08lx%c",(i?' ':'<'),insn,(i?' ':'>'));
}
}
DEFINE_SPINLOCK(die_lock);
void die(const char * str, struct pt_regs * regs, long err)
{
static int die_counter;
int nl = 0;
console_verbose();
spin_lock_irq(&die_lock);
printk("%s: sig: %ld [#%d]\n", str, err, ++die_counter);
#ifdef CONFIG_PREEMPT
printk("PREEMPT ");
nl = 1;
#endif
if (nl)
printk("\n");
show_regs(regs);
if (!user_mode(regs))
show_stack(NULL, (unsigned long*)regs->areg[1]);
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");
do_exit(err);
}