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/*
* Copyright 2010 Tilera Corporation. 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
* as published by the Free Software Foundation, version 2.
*
* 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, GOOD TITLE or
* NON INFRINGEMENT. See the GNU General Public License for
* more details.
*/
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/kprobes.h>
#include <linux/module.h>
#include <linux/pfn.h>
#include <linux/kallsyms.h>
#include <linux/stacktrace.h>
#include <linux/uaccess.h>
#include <linux/mmzone.h>
#include <linux/dcache.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <asm/backtrace.h>
#include <asm/page.h>
#include <asm/ucontext.h>
#include <asm/switch_to.h>
#include <asm/sigframe.h>
#include <asm/stack.h>
#include <asm/vdso.h>
#include <arch/abi.h>
#include <arch/interrupts.h>
#define KBT_ONGOING 0 /* Backtrace still ongoing */
#define KBT_DONE 1 /* Backtrace cleanly completed */
#define KBT_RUNNING 2 /* Can't run backtrace on a running task */
#define KBT_LOOP 3 /* Backtrace entered a loop */
/* Is address on the specified kernel stack? */
static int in_kernel_stack(struct KBacktraceIterator *kbt, unsigned long sp)
{
ulong kstack_base = (ulong) kbt->task->stack;
if (kstack_base == 0) /* corrupt task pointer; just follow stack... */
return sp >= PAGE_OFFSET && sp < (unsigned long)high_memory;
return sp >= kstack_base && sp < kstack_base + THREAD_SIZE;
}
/* Callback for backtracer; basically a glorified memcpy */
static bool read_memory_func(void *result, unsigned long address,
unsigned int size, void *vkbt)
{
int retval;
struct KBacktraceIterator *kbt = (struct KBacktraceIterator *)vkbt;
if (address == 0)
return 0;
if (__kernel_text_address(address)) {
/* OK to read kernel code. */
} else if (address >= PAGE_OFFSET) {
/* We only tolerate kernel-space reads of this task's stack */
if (!in_kernel_stack(kbt, address))
return 0;
} else if (!kbt->is_current) {
return 0; /* can't read from other user address spaces */
}
pagefault_disable();
retval = __copy_from_user_inatomic(result,
(void __user __force *)address,
size);
pagefault_enable();
return (retval == 0);
}
/* Return a pt_regs pointer for a valid fault handler frame */
static struct pt_regs *valid_fault_handler(struct KBacktraceIterator* kbt)
{
const char *fault = NULL; /* happy compiler */
char fault_buf[64];
unsigned long sp = kbt->it.sp;
struct pt_regs *p;
if (sp % sizeof(long) != 0)
return NULL;
if (!in_kernel_stack(kbt, sp))
return NULL;
if (!in_kernel_stack(kbt, sp + C_ABI_SAVE_AREA_SIZE + PTREGS_SIZE-1))
return NULL;
p = (struct pt_regs *)(sp + C_ABI_SAVE_AREA_SIZE);
if (p->faultnum == INT_SWINT_1 || p->faultnum == INT_SWINT_1_SIGRETURN)
fault = "syscall";
else {
if (kbt->verbose) { /* else we aren't going to use it */
snprintf(fault_buf, sizeof(fault_buf),
"interrupt %ld", p->faultnum);
fault = fault_buf;
}
}
if (EX1_PL(p->ex1) == KERNEL_PL &&
__kernel_text_address(p->pc) &&
in_kernel_stack(kbt, p->sp) &&
p->sp >= sp) {
if (kbt->verbose)
pr_err(" <%s while in kernel mode>\n", fault);
} else if (user_mode(p) &&
p->sp < PAGE_OFFSET && p->sp != 0) {
if (kbt->verbose)
pr_err(" <%s while in user mode>\n", fault);
} else if (kbt->verbose) {
pr_err(" (odd fault: pc %#lx, sp %#lx, ex1 %#lx?)\n",
p->pc, p->sp, p->ex1);
p = NULL;
}
if (!kbt->profile || ((1ULL << p->faultnum) & QUEUED_INTERRUPTS) == 0)
return p;
return NULL;
}
/* Is the pc pointing to a sigreturn trampoline? */
static int is_sigreturn(unsigned long pc)
{
return current->mm && (pc == VDSO_SYM(&__vdso_rt_sigreturn));
}
/* Return a pt_regs pointer for a valid signal handler frame */
static struct pt_regs *valid_sigframe(struct KBacktraceIterator* kbt,
struct rt_sigframe* kframe)
{
BacktraceIterator *b = &kbt->it;
if (is_sigreturn(b->pc) && b->sp < PAGE_OFFSET &&
b->sp % sizeof(long) == 0) {
int retval;
pagefault_disable();
retval = __copy_from_user_inatomic(
kframe, (void __user __force *)b->sp,
sizeof(*kframe));
pagefault_enable();
if (retval != 0 ||
(unsigned int)(kframe->info.si_signo) >= _NSIG)
return NULL;
if (kbt->verbose) {
pr_err(" <received signal %d>\n",
kframe->info.si_signo);
}
return (struct pt_regs *)&kframe->uc.uc_mcontext;
}
return NULL;
}
static int KBacktraceIterator_is_sigreturn(struct KBacktraceIterator *kbt)
{
return is_sigreturn(kbt->it.pc);
}
static int KBacktraceIterator_restart(struct KBacktraceIterator *kbt)
{
struct pt_regs *p;
struct rt_sigframe kframe;
p = valid_fault_handler(kbt);
if (p == NULL)
p = valid_sigframe(kbt, &kframe);
if (p == NULL)
return 0;
backtrace_init(&kbt->it, read_memory_func, kbt,
p->pc, p->lr, p->sp, p->regs[52]);
kbt->new_context = 1;
return 1;
}
/* Find a frame that isn't a sigreturn, if there is one. */
static int KBacktraceIterator_next_item_inclusive(
struct KBacktraceIterator *kbt)
{
for (;;) {
do {
if (!KBacktraceIterator_is_sigreturn(kbt))
return KBT_ONGOING;
} while (backtrace_next(&kbt->it));
if (!KBacktraceIterator_restart(kbt))
return KBT_DONE;
}
}
/*
* If the current sp is on a page different than what we recorded
* as the top-of-kernel-stack last time we context switched, we have
* probably blown the stack, and nothing is going to work out well.
* If we can at least get out a warning, that may help the debug,
* though we probably won't be able to backtrace into the code that
* actually did the recursive damage.
*/
static void validate_stack(struct pt_regs *regs)
{
int cpu = raw_smp_processor_id();
unsigned long ksp0 = get_current_ksp0();
unsigned long ksp0_base = ksp0 & -THREAD_SIZE;
unsigned long sp = stack_pointer;
if (EX1_PL(regs->ex1) == KERNEL_PL && regs->sp >= ksp0) {
pr_err("WARNING: cpu %d: kernel stack %#lx..%#lx underrun!\n"
" sp %#lx (%#lx in caller), caller pc %#lx, lr %#lx\n",
cpu, ksp0_base, ksp0, sp, regs->sp, regs->pc, regs->lr);
}
else if (
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