--- /dev/null
+/*
+ * 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);
+ return NULL;
+ }
+ if (kbt->profile && ((1ULL << p->faultnum) & QUEUED_INTERRUPTS) != 0)
+ return NULL;
+ return p;
+}
+
+/* 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 (sp < ksp0_base + sizeof(struct thread_info)) {
+ pr_err("WARNING: cpu %d: kernel stack %#lx..%#lx overrun!\n"
+ " sp %#lx (%#lx in caller), caller pc %#lx, lr %#lx\n",
+ cpu, ksp0_base, ksp0, sp, regs->sp, regs->pc, regs->lr);
+ }
+}
+
+void KBacktraceIterator_init(struct KBacktraceIterator *kbt,
+ struct task_struct *t, struct pt_regs *regs)
+{
+ unsigned long pc, lr, sp, r52;
+ int is_current;
+
+ /*
+ * Set up callback information. We grab the kernel stack base
+ * so we will allow reads of that address range.
+ */
+ is_current = (t == NULL || t == current);
+ kbt->is_current = is_current;
+ if (is_current)
+ t = validate_current();
+ kbt->task = t;
+ kbt->verbose = 0; /* override in caller if desired */
+ kbt->profile = 0; /* override in caller if desired */
+ kbt->end = KBT_ONGOING;
+ kbt->new_context = 1;
+ if (is_current)
+ validate_stack(regs);
+
+ if (regs == NULL) {
+ if (is_current || t->state == TASK_RUNNING) {
+ /* Can't do this; we need registers */
+ kbt->end = KBT_RUNNING;
+ return;
+ }
+ pc = get_switch_to_pc();
+ lr = t->thread.pc;
+ sp = t->thread.ksp;
+ r52 = 0;
+ } else {
+ pc = regs->pc;
+ lr = regs->lr;
+ sp = regs->sp;
+ r52 = regs->regs[52];
+ }
+
+ backtrace_init(&kbt->it, read_memory_func, kbt, pc, lr, sp, r52);
+ kbt->end = KBacktraceIterator_next_item_inclusive(kbt);
+}
+EXPORT_SYMBOL(KBacktraceIterator_init);
+
+int KBacktraceIterator_end(struct KBacktraceIterator *kbt)
+{
+ return kbt->end != KBT_ONGOING;
+}
+EXPORT_SYMBOL(KBacktraceIterator_end);
+
+void KBacktraceIterator_next(struct KBacktraceIterator *kbt)
+{
+ unsigned long old_pc = kbt->it.pc, old_sp = kbt->it.sp;
+ kbt->new_context = 0;
+ if (!backtrace_next(&kbt->it) && !KBacktraceIterator_restart(kbt)) {
+ kbt->end = KBT_DONE;
+ return;
+ }
+ kbt->end = KBacktraceIterator_next_item_inclusive(kbt);
+ if (old_pc == kbt->it.pc && old_sp == kbt->it.sp) {
+ /* Trapped in a loop; give up. */
+ kbt->end = KBT_LOOP;
+ }
+}
+EXPORT_SYMBOL(KBacktraceIterator_next);
+
+static void describe_addr(struct KBacktraceIterator *kbt,
+ unsigned long address,
+ int have_mmap_sem, char *buf, size_t bufsize)
+{
+ struct vm_area_struct *vma;
+ size_t namelen, remaining;
+ unsigned long size, offset, adjust;
+ char *p, *modname;
+ const char *name;
+ int rc;
+
+ /*
+ * Look one byte back for every caller frame (i.e. those that
+ * aren't a new context) so we look up symbol data for the
+ * call itself, not the following instruction, which may be on
+ * a different line (or in a different function).
+ */
+ adjust = !kbt->new_context;
+ address -= adjust;
+
+ if (address >= PAGE_OFFSET) {
+ /* Handle kernel symbols. */
+ BUG_ON(bufsize < KSYM_NAME_LEN);
+ name = kallsyms_lookup(address, &size, &offset,
+ &modname, buf);
+ if (name == NULL) {
+ buf[0] = '\0';
+ return;
+ }
+ namelen = strlen(buf);
+ remaining = (bufsize - 1) - namelen;
+ p = buf + namelen;
+ rc = snprintf(p, remaining, "+%#lx/%#lx ",
+ offset + adjust, size);
+ if (modname && rc < remaining)
+ snprintf(p + rc, remaining - rc, "[%s] ", modname);
+ buf[bufsize-1] = '\0';
+ return;
+ }
+
+ /* If we don't have the mmap_sem, we can't show any more info. */
+ buf[0] = '\0';
+ if (!have_mmap_sem)
+ return;
+
+ /* Find vma info. */
+ vma = find_vma(kbt->task->mm, address);
+ if (vma == NULL || address < vma->vm_start) {
+ snprintf(buf, bufsize, "[unmapped address] ");
+ return;
+ }
+
+ if (vma->vm_file) {
+ p = d_path(&vma->vm_file->f_path, buf, bufsize);
+ if (IS_ERR(p))
+ p = "?";
+ name = kbasename(p);
+ } else {
+ name = "anon";
+ }
+
+ /* Generate a string description of the vma info. */
+ namelen = strlen(name);
+ remaining = (bufsize - 1) - namelen;
+ memmove(buf, name, namelen);
+ snprintf(buf + namelen, remaining, "[%lx+%lx] ",
+ vma->vm_start, vma->vm_end - vma->vm_start);
+}
+
+/*
+ * Avoid possible crash recursion during backtrace. If it happens, it
+ * makes it easy to lose the actual root cause of the failure, so we
+ * put a simple guard on all the backtrace loops.
+ */
+static bool start_backtrace(void)
+{
+ if (current->thread.in_backtrace) {
+ pr_err("Backtrace requested while in backtrace!\n");
+ return false;
+ }
+ current->thread.in_backtrace = true;
+ return true;
+}
+
+static void end_backtrace(void)
+{
+ current->thread.in_backtrace = false;
+}
+
+/*
+ * This method wraps the backtracer's more generic support.
+ * It is only invoked from the architecture-specific code; show_stack()
+ * and dump_stack() (in entry.S) are architecture-independent entry points.
+ */
+void tile_show_stack(struct KBacktraceIterator *kbt, int headers)
+{
+ int i;
+ int have_mmap_sem = 0;
+
+ if (!start_backtrace())
+ return;
+ if (headers) {
+ /*
+ * Add a blank line since if we are called from panic(),
+ * then bust_spinlocks() spit out a space in front of us
+ * and it will mess up our KERN_ERR.
+ */
+ pr_err("Starting stack dump of tid %d, pid %d (%s) on cpu %d at cycle %lld\n",
+ kbt->task->pid, kbt->task->tgid, kbt->task->comm,
+ raw_smp_processor_id(), get_cycles());
+ }
+ kbt->verbose = 1;
+ i = 0;
+ for (; !KBacktraceIterator_end(kbt); KBacktraceIterator_next(kbt)) {
+ char namebuf[KSYM_NAME_LEN+100];
+ unsigned long address = kbt->it.pc;
+
+ /* Try to acquire the mmap_sem as we pass into userspace. */
+ if (address < PAGE_OFFSET && !have_mmap_sem && kbt->task->mm)
+ have_mmap_sem =
+ down_read_trylock(&kbt->task->mm->mmap_sem);
+
+ describe_addr(kbt, address, have_mmap_sem,
+ namebuf, sizeof(namebuf));
+
+ pr_err(" frame %d: 0x%lx %s(sp 0x%lx)\n",
+ i++, address, namebuf, (unsigned long)(kbt->it.sp));
+
+ if (i >= 100) {
+ pr_err("Stack dump truncated (%d frames)\n", i);
+ break;
+ }
+ }
+ if (kbt->end == KBT_LOOP)
+ pr_err("Stack dump stopped; next frame identical to this one\n");
+ if (headers)
+ pr_err("Stack dump complete\n");
+ if (have_mmap_sem)
+ up_read(&kbt->task->mm->mmap_sem);
+ end_backtrace();
+}
+EXPORT_SYMBOL(tile_show_stack);
+
+
+/* This is called from show_regs() and _dump_stack() */
+void dump_stack_regs(struct pt_regs *regs)
+{
+ struct KBacktraceIterator kbt;
+ KBacktraceIterator_init(&kbt, NULL, regs);
+ tile_show_stack(&kbt, 1);
+}
+EXPORT_SYMBOL(dump_stack_regs);
+
+static struct pt_regs *regs_to_pt_regs(struct pt_regs *regs,
+ ulong pc, ulong lr, ulong sp, ulong r52)
+{
+ memset(regs, 0, sizeof(struct pt_regs));
+ regs->pc = pc;
+ regs->lr = lr;
+ regs->sp = sp;
+ regs->regs[52] = r52;
+ return regs;
+}
+
+/* This is called from dump_stack() and just converts to pt_regs */
+void _dump_stack(int dummy, ulong pc, ulong lr, ulong sp, ulong r52)
+{
+ struct pt_regs regs;
+ dump_stack_regs(regs_to_pt_regs(®s, pc, lr, sp, r52));
+}
+
+/* This is called from KBacktraceIterator_init_current() */
+void _KBacktraceIterator_init_current(struct KBacktraceIterator *kbt, ulong pc,
+ ulong lr, ulong sp, ulong r52)
+{
+ struct pt_regs regs;
+ KBacktraceIterator_init(kbt, NULL,
+ regs_to_pt_regs(®s, pc, lr, sp, r52));
+}
+
+/* This is called only from kernel/sched/core.c, with esp == NULL */
+void show_stack(struct task_struct *task, unsigned long *esp)
+{
+ struct KBacktraceIterator kbt;
+ if (task == NULL || task == current)
+ KBacktraceIterator_init_current(&kbt);
+ else
+ KBacktraceIterator_init(&kbt, task, NULL);
+ tile_show_stack(&kbt, 0);
+}
+
+#ifdef CONFIG_STACKTRACE
+
+/* Support generic Linux stack API too */
+
+void save_stack_trace_tsk(struct task_struct *task, struct stack_trace *trace)
+{
+ struct KBacktraceIterator kbt;
+ int skip = trace->skip;
+ int i = 0;
+
+ if (!start_backtrace())
+ goto done;
+ if (task == NULL || task == current)
+ KBacktraceIterator_init_current(&kbt);
+ else
+ KBacktraceIterator_init(&kbt, task, NULL);
+ for (; !KBacktraceIterator_end(&kbt); KBacktraceIterator_next(&kbt)) {
+ if (skip) {
+ --skip;
+ continue;
+ }
+ if (i >= trace->max_entries || kbt.it.pc < PAGE_OFFSET)
+ break;
+ trace->entries[i++] = kbt.it.pc;
+ }
+ end_backtrace();
+done:
+ trace->nr_entries = i;
+}
+EXPORT_SYMBOL(save_stack_trace_tsk);
+
+void save_stack_trace(struct stack_trace *trace)
+{
+ save_stack_trace_tsk(NULL, trace);
+}
+EXPORT_SYMBOL_GPL(save_stack_trace);
+
+#endif
+
+/* In entry.S */
+EXPORT_SYMBOL(KBacktraceIterator_init_current);
Code Review / kvmfornfv.git / blobdiff