1 files changed, 515 insertions, 0 deletions

diff --git a/arch/tile/kernel/stack.c b/arch/tile/kernel/stack.c
new file mode 100644
index 000000000..c42dce50a
--- /dev/null
+++ b/arch/tile/kernel/stack.c
@@ -0,0 +1,515 @@
+/*
+ * 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(&regs, 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(&regs, 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);