/*
* Kernel traps/events for Hexagon processor
*
* Copyright (c) 2010-2014, The Linux Foundation. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 and
* only version 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/module.h>
#include <linux/kallsyms.h>
#include <linux/kdebug.h>
#include <linux/syscalls.h>
#include <linux/signal.h>
#include <linux/tracehook.h>
#include <asm/traps.h>
#include <asm/vm_fault.h>
#include <asm/syscall.h>
#include <asm/registers.h>
#include <asm/unistd.h>
#include <asm/sections.h>
#ifdef CONFIG_KGDB
# include <linux/kgdb.h>
#endif
#define TRAP_SYSCALL 1
#define TRAP_DEBUG 0xdb
void __init trap_init(void)
{
}
#ifdef CONFIG_GENERIC_BUG
/* Maybe should resemble arch/sh/kernel/traps.c ?? */
int is_valid_bugaddr(unsigned long addr)
{
return 1;
}
#endif /* CONFIG_GENERIC_BUG */
static const char *ex_name(int ex)
{
switch (ex) {
case HVM_GE_C_XPROT:
case HVM_GE_C_XUSER:
return "Execute protection fault";
case HVM_GE_C_RPROT:
case HVM_GE_C_RUSER:
return "Read protection fault";
case HVM_GE_C_WPROT:
case HVM_GE_C_WUSER:
return "Write protection fault";
case HVM_GE_C_XMAL:
return "Misaligned instruction";
case HVM_GE_C_WREG:
return "Multiple writes to same register in packet";
case HVM_GE_C_PCAL:
return "Program counter values that are not properly aligned";
case HVM_GE_C_RMAL:
return "Misaligned data load";
case HVM_GE_C_WMAL:
return "Misaligned data store";
case HVM_GE_C_INVI:
case HVM_GE_C_PRIVI:
return "Illegal instruction";
case HVM_GE_C_BUS:
return "Precise bus error";
case HVM_GE_C_CACHE:
return "Cache error";
case 0xdb:
return "Debugger trap";
default:
return "Unrecognized exception";
}
}
static void do_show_stack(struct task_struct *task, unsigned long *fp,
unsigned long ip)
{
int kstack_depth_to_print = 24;
unsigned long offset, size;
const char *name = NULL;
unsigned long *newfp;
unsigned long low, high;
char tmpstr[128];
char *modname;
int i;
if (task == NULL)
task = current;
printk(KERN_INFO "CPU#%d, %s/%d, Call Trace:\n",
raw_smp_processor_id(), task->comm,
task_pid_nr(task));
if (fp == NULL) {
if (task == current) {
asm("%0 = r30" : "=r" (fp));
} else {
fp = (unsigned long *)
((struct hexagon_switch_stack *)
task->thread.switch_sp)->fp;
}
}
if ((((unsigned long) fp) & 0x3) || ((unsigned long) fp < 0x1000)) {
printk(KERN_INFO "-- Corrupt frame pointer %p\n", fp);
return;
}
/* Saved link reg is one word above FP */
if (!ip)
ip = *(fp+1);
/* Expect kernel stack to be in-bounds */
low = (unsigned long)task_stack_page(task);
high = low + THREAD_SIZE - 8;
low += sizeof(struct thread_info);
for (i = 0; i < kstack_depth_to_print; i++) {
name = kallsyms_lookup(ip, &size, &offset, &modname, tmpstr);
printk(KERN_INFO "[%p] 0x%lx: %s + 0x%lx", fp, ip, name,
offset);
if (((unsigned long) fp < low) || (high < (unsigned long) fp))
printk(KERN_CONT " (FP out of bounds!)");
if (modname)
printk(KERN_CONT " [%s] ", modname);
printk(KERN_CONT "\n");
newfp = (unsigned long *) *fp;
if (((unsigned long) newfp) & 0x3) {
printk(KERN_INFO "-- Corrupt frame pointer %p\n",
newfp);
break;
}
/* Attempt to continue past exception. */
if (0 == newfp) {
struct pt_regs *regs = (struct pt_regs *) (((void *)fp)
+ 8);
if (regs->syscall_nr != -1) {
printk(KERN_INFO "-- trap0 -- syscall_nr: %ld",
regs->syscall_nr);
printk(KERN_CONT " psp: %lx elr: %lx\n",
pt_psp(regs), pt_elr(regs));
break;
} else {
/* really want to see more ... */
kstack_depth_to_print += 6;
printk(KERN_INFO "-- %s (0x%lx) badva: %lx\n",
ex_name(pt_cause(regs)), pt_cause(regs),
pt_badva(regs));
}
newfp = (unsigned long *) regs->r30;
ip = pt_elr(regs);
} else {
ip = *(newfp + 1);
}
/* If link reg is null, we are done. */
if (ip == 0x0)
break;
/* If newfp isn't larger, we're tracing garbage. */
if (newfp > fp)
fp = newfp;
else
break;
}
}
void show_stack(struct task_struct *task, unsigned long *fp)
{
/* Saved link reg is one word above FP */
do_show_stack(task, fp, 0);
}
int die(const char *str, struct pt_regs *regs, long err)
{
static struct {
spinlock_t lock;
int counter;
} die = {
.lock = __SPIN_LOCK_UNLOCKED(die.lock),
.counter = 0
};
console_verbose();
oops_enter();
spin_lock_irq(&die.lock);
bust_spinlocks(1);
printk(KERN_EMERG "Oops: %s[#%d]:\n", str, ++die.counter);
if (notify_die(DIE_OOPS, str, regs, err, pt_cause(regs), SIGSEGV) ==
NOTIFY_STOP)
return 1;
print_modules();
show_regs(regs);
do_show_stack(current, ®s->r30, pt_elr(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");
oops_exit();
do_exit(err);
return 0;
}
int die_if_kernel(char *str, struct pt_regs *regs, long err)
{
if (!user_mode(regs))
return die(str, regs, err);
else
return 0;
}
/*
* It's not clear that misaligned fetches are ever recoverable.
*/
static void misaligned_instruction(struct pt_regs *regs)
{
die_if_kernel("Misaligned Instruction", regs, 0);
force_sig(SIGBUS, current);
}
/*
* Misaligned loads and stores, on the other hand, can be
* emulated, and probably should be, some day. But for now
* they will be considered fatal.
*/
static void misaligned_data_load(struct pt_regs *regs)
{
die_if_kernel("Misaligned Data Load", regs, 0);
force_sig(SIGBUS, current);
}
static void misaligned_data_store(struct pt_regs *regs)
{
die_if_kernel("Misaligned Data Store", regs, 0);
force_sig(SIGBUS, current);
}
static void illegal_instruction(struct pt_regs *regs)
{
die_if_kernel("Illegal Instruction", regs, 0);
force_sig(SIGILL, current);
}
/*
* Precise bus errors may be recoverable with a a retry,
* but for now, treat them as irrecoverable.
*/
static void precise_bus_error(struct pt_regs *regs)
{
die_if_kernel("Precise Bus Error", regs, 0);
force_sig(SIGBUS, current);
}
/*
* If anything is to be done here other than panic,
* it will probably be complex and migrate to another
* source module. For now, just die.
*/
static void cache_error(struct pt_regs *regs)
{
die("Cache Error", regs, 0);
}
/*
* General exception handler
*/
void do_genex(struct pt_regs *regs)
{
/*
* Decode Cause and Dispatch
*/
switch (pt_cause(regs)) {
case HVM_GE_C_XPROT:
case HVM_GE_C_XUSER:
execute_protection_fault(regs);
break;
case HVM_GE_C_RPROT:
case HVM_GE_C_RUSER:
read_protection_fault(regs);
break;
case HVM_GE_C_WPROT:
case HVM_GE_C_WUSER:
write_protection_fault(regs);
break;
case HVM_GE_C_XMAL:
misaligned_instruction(regs);
break;
case HVM_GE_C_WREG:
illegal_instruction(regs);
break;
case HVM_GE_C_PCAL:
misaligned_instruction(regs);
break;
case HVM_GE_C_RMAL:
misaligned_data_load(regs);
break;
case HVM_GE_C_WMAL:
misaligned_data_store(regs);
break;
case HVM_GE_C_INVI:
case HVM_GE_C_PRIVI:
illegal_instruction(regs);
break;
case HVM_GE_C_BUS:
precise_bus_error(regs);
break;
case HVM_GE_C_CACHE:
cache_error(regs);
break;
default:
/* Halt and catch fire */
panic("Unrecognized exception 0x%lx\n", pt_cause(regs));
break;
}
}
/* Indirect system call dispatch */
long sys_syscall(void)
{
printk(KERN_ERR "sys_syscall invoked!\n");
return -ENOSYS;
}
void do_trap0(struct pt_regs *regs)
{
syscall_fn syscall;
switch (pt_cause(regs)) {
case TRAP_SYSCALL:
/* System call is trap0 #1 */
/* allow strace to catch syscall args */
if (unlikely(test_thread_flag(TIF_SYSCALL_TRACE) &&
tracehook_report_syscall_entry(regs)))
return; /* return -ENOSYS somewhere? */
/* Interrupts should be re-enabled for syscall processing */
__vmsetie(VM_INT_ENABLE);
/*
* System call number is in r6, arguments in r0..r5.
* Fortunately, no Linux syscall has more than 6 arguments,
* and Hexagon ABI passes first 6 arguments in registers.
* 64-bit arguments are passed in odd/even register pairs.
* Fortunately, we have no system calls that take more
* than three arguments with more than one 64-bit value.
* Should that change, we'd need to redesign to copy
* between user and kernel stacks.
*/
regs->syscall_nr = regs->r06;
/*
* GPR R0 carries the first parameter, and is also used
* to report the return value. We need a backup of
* the user's value in case we need to do a late restart
* of the system call.
*/
regs->restart_r0 = regs->r00;
if ((unsigned long) regs->syscall_nr >= __NR_syscalls) {
regs->r00 = -1;
} else {
syscall = (syscall_fn)
(sys_call_table[regs->syscall_nr]);
regs->r00 = syscall(regs->r00, regs->r01,
regs->r02, regs->r03,
regs->r04, regs->r05);
}
/* allow strace to get the syscall return state */
if (unlikely(test_thread_flag(TIF_SYSCALL_TRACE)))
tracehook_report_syscall_exit(regs, 0);
break;
case TRAP_DEBUG:
/* Trap0 0xdb is debug breakpoint */
if (user_mode(regs)) {
struct siginfo info;
info.si_signo = SIGTRAP;
info.si_errno = 0;
/*
* Some architecures add some per-thread state
* to distinguish between breakpoint traps and
* trace traps. We may want to do that, and
* set the si_code value appropriately, or we
* may want to use a different trap0 flavor.
*/
info.si_code = TRAP_BRKPT;
info.si_addr = (void __user *) pt_elr(regs);
force_sig_info(SIGTRAP, &info, current);
} else {
#ifdef CONFIG_KGDB
kgdb_handle_exception(pt_cause(regs), SIGTRAP,
TRAP_BRKPT, regs);
#endif
}
break;
}
/* Ignore other trap0 codes for now, especially 0 (Angel calls) */
}
/*
* Machine check exception handler
*/
void do_machcheck(struct pt_regs *regs)
{
/* Halt and catch fire */
__vmstop();
}
/*
* Treat this like the old 0xdb trap.
*/
void do_debug_exception(struct pt_regs *regs)
{
regs->hvmer.vmest &= ~HVM_VMEST_CAUSE_MSK;
regs->hvmer.vmest |= (TRAP_DEBUG << HVM_VMEST_CAUSE_SFT);
do_trap0(regs);
}