arch/arc/kernel/troubleshoot.c

/*
 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 */

#include <linux/ptrace.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/kdev_t.h>
#include <linux/fs_struct.h>
#include <linux/proc_fs.h>
#include <linux/file.h>
#include <asm/arcregs.h>

/*
 * Common routine to print scratch regs (r0-r12) or callee regs (r13-r25)
 *   -Prints 3 regs per line and a CR.
 *   -To continue, callee regs right after scratch, special handling of CR
 */
static noinline void print_reg_file(long *reg_rev, int start_num)
{
	unsigned int i;
	char buf[512];
	int n = 0, len = sizeof(buf);

	/* weird loop because pt_regs regs rev r12..r0, r25..r13 */
	for (i = start_num; i < start_num + 13; i++) {
		n += scnprintf(buf + n, len - n, "r%02u: 0x%08lx\t",
			       i, (unsigned long)*reg_rev);

		if (((i + 1) % 3) == 0)
			n += scnprintf(buf + n, len - n, "\n");

		reg_rev--;
	}

	if (start_num != 0)
		n += scnprintf(buf + n, len - n, "\n\n");

	pr_info("%s", buf);
}

static void show_callee_regs(struct callee_regs *cregs)
{
	print_reg_file(&(cregs->r13), 13);
}

void print_task_path_n_nm(struct task_struct *tsk, char *buf)
{
	struct path path;
	char *path_nm = NULL;
	struct mm_struct *mm;
	struct file *exe_file;

	mm = get_task_mm(tsk);
	if (!mm)
		goto done;

	exe_file = get_mm_exe_file(mm);
	mmput(mm);

	if (exe_file) {
		path = exe_file->f_path;
		path_get(&exe_file->f_path);
		fput(exe_file);
		path_nm = d_path(&path, buf, 255);
		path_put(&path);
	}

done:
	pr_info("Path: %s\n", path_nm);
}
EXPORT_SYMBOL(print_task_path_n_nm);

static void show_faulting_vma(unsigned long address, char *buf)
{
	struct vm_area_struct *vma;
	struct inode *inode;
	unsigned long ino = 0;
	dev_t dev = 0;
	char *nm = buf;

	vma = find_vma(current->active_mm, address);

	/* check against the find_vma( ) behaviour which returns the next VMA
	 * if the container VMA is not found
	 */
	if (vma && (vma->vm_start <= address)) {
		struct file *file = vma->vm_file;
		if (file) {
			struct path *path = &file->f_path;
			nm = d_path(path, buf, PAGE_SIZE - 1);
			inode = vma->vm_file->f_path.dentry->d_inode;
			dev = inode->i_sb->s_dev;
			ino = inode->i_ino;
		}
		pr_info("    @off 0x%lx in [%s]\n"
			"    VMA: 0x%08lx to 0x%08lx\n\n",
		       address - vma->vm_start, nm, vma->vm_start, vma->vm_end);
	} else
		pr_info("    @No matching VMA found\n");
}

static void show_ecr_verbose(struct pt_regs *regs)
{
	unsigned int vec, cause_code, cause_reg;
	unsigned long address;

	cause_reg = current->thread.cause_code;
	pr_info("\n[ECR]: 0x%08x => ", cause_reg);

	/* For Data fault, this is data address not instruction addr */
	address = current->thread.fault_address;

	vec = cause_reg >> 16;
	cause_code = (cause_reg >> 8) & 0xFF;

	/* For DTLB Miss or ProtV, display the memory involved too */
	if (vec == ECR_V_DTLB_MISS) {
		pr_cont("Invalid (%s) @ 0x%08lx by insn @ 0x%08lx\n",
		       (cause_code == 0x01) ? "Read From" :
		       ((cause_code == 0x02) ? "Write to" : "EX"),
		       address, regs->ret);
	} else if (vec == ECR_V_ITLB_MISS) {
		pr_cont("Insn could not be fetched\n");
	} else if (vec == ECR_V_MACH_CHK) {
		pr_cont("%s\n", (cause_code == 0x0) ?
					"Double Fault" : "Other Fatal Err");

	} else if (vec == ECR_V_PROTV) {
		if (cause_code == ECR_C_PROTV_INST_FETCH)
			pr_cont("Execute from Non-exec Page\n");
		else if (cause_code == ECR_C_PROTV_LOAD)
			pr_cont("Read from Non-readable Page\n");
		else if (cause_code == ECR_C_PROTV_STORE)
			pr_cont("Write to Non-writable Page\n");
		else if (cause_code == ECR_C_PROTV_XCHG)
			pr_cont("Data exchange protection violation\n");
		else if (cause_code == ECR_C_PROTV_MISALIG_DATA)
			pr_cont("Misaligned r/w from 0x%08lx\n", address);
	} else if (vec == ECR_V_INSN_ERR) {
		pr_cont("Illegal Insn\n");
	} else {
		pr_cont("Check Programmer's Manual\n");
	}
}

/************************************************************************
 *  API called by rest of kernel
 ***********************************************************************/

void show_regs(struct pt_regs *regs)
{
	struct task_struct *tsk = current;
	struct callee_regs *cregs;
	char *buf;

	buf = (char *)__get_free_page(GFP_TEMPORARY);
	if (!buf)
		return;

	print_task_path_n_nm(tsk, buf);
	show_regs_print_info(KERN_INFO);

	if (current->thread.cause_code)
		show_ecr_verbose(regs);

	pr_info("[EFA]: 0x%08lx\n", current->thread.fault_address);
	pr_info("[ERET]: 0x%08lx (PC of Faulting Instr)\n", regs->ret);

	show_faulting_vma(regs->ret, buf);	/* faulting code, not data */

	/* can't use print_vma_addr() yet as it doesn't check for
	 * non-inclusive vma
	 */

	/* print special regs */
	pr_info("status32: 0x%08lx\n", regs->status32);
	pr_info(" SP: 0x%08lx\tFP: 0x%08lx\n", regs->sp, regs->fp);
	pr_info("BTA: 0x%08lx\tBLINK: 0x%08lx\n",
		regs->bta, regs->blink);
	pr_info("LPS: 0x%08lx\tLPE: 0x%08lx\tLPC: 0x%08lx\n",
	       regs->lp_start, regs->lp_end, regs->lp_count);

	/* print regs->r0 thru regs->r12
	 * Sequential printing was generating horrible code
	 */
	print_reg_file(&(regs->r0), 0);

	/* If Callee regs were saved, display them too */
	cregs = (struct callee_regs *)current->thread.callee_reg;
	if (cregs)
		show_callee_regs(cregs);

	free_page((unsigned long)buf);
}

void show_kernel_fault_diag(const char *str, struct pt_regs *regs,
			    unsigned long address, unsigned long cause_reg)
{
	current->thread.fault_address = address;
	current->thread.cause_code = cause_reg;

	/* Caller and Callee regs */
	show_regs(regs);

	/* Show stack trace if this Fatality happened in kernel mode */
	if (!user_mode(regs))
		show_stacktrace(current, regs);
}

#ifdef CONFIG_DEBUG_FS

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/pagemap.h>
#include <linux/init.h>
#include <linux/namei.h>
#include <linux/debugfs.h>

static struct dentry *test_dentry;
static struct dentry *test_dir;
static struct dentry *test_u32_dentry;

static u32 clr_on_read = 1;

#ifdef CONFIG_ARC_DBG_TLB_MISS_COUNT
u32 numitlb, numdtlb, num_pte_not_present;

static int fill_display_data(char *kbuf)
{
	size_t num = 0;
	num += sprintf(kbuf + num, "I-TLB Miss %x\n", numitlb);
	num += sprintf(kbuf + num, "D-TLB Miss %x\n", numdtlb);
	num += sprintf(kbuf + num, "PTE not present %x\n", num_pte_not_present);

	if (clr_on_read)
		numitlb = numdtlb = num_pte_not_present = 0;

	return num;
}

static int tlb_stats_open(struct inode *inode, struct file *file)
{
	file->private_data = (void *)__get_free_page(GFP_KERNEL);
	return 0;
}

/* called on user read(): display the couters */
static ssize_t tlb_stats_output(struct file *file,	/* file descriptor */
				char __user *user_buf,	/* user buffer */
				size_t len,		/* length of buffer */
				loff_t *offset)		/* offset in the file */
{
	size_t num;
	char *kbuf = (char *)file->private_data;

	/* All of the data can he shoved in one iteration */
	if (*offset != 0)
		return 0;

	num = fill_display_data(kbuf);

	/* simple_read_from_buffer() is helper for copy to user space
	   It copies up to @2 (num) bytes from kernel buffer @4 (kbuf) at offset
	   @3 (offset) into the user space address starting at @1 (user_buf).
	   @5 (len) is max size of user buffer
	 */
	return simple_read_from_buffer(user_buf, num, offset, kbuf, len);
}

/* called on user write : clears the counters */
static ssize_t tlb_stats_clear(struct file *file, const char __user *user_buf,
			       size_t length, loff_t *offset)
{
	numitlb = numdtlb = num_pte_not_present = 0;
	return length;
}

static int tlb_stats_close(struct inode *inode, struct file *file)
{
	free_page((unsigned long)(file->private_data));
	return 0;
}

static const struct file_operations tlb_stats_file_ops = {
	.read = tlb_stats_output,
	.write = tlb_stats_clear,
	.open = tlb_stats_open,
	.release = tlb_stats_close
};
#endif

static int __init arc_debugfs_init(void)
{
	test_dir = debugfs_create_dir("arc", NULL);

#ifdef CONFIG_ARC_DBG_TLB_MISS_COUNT
	test_dentry = debugfs_create_file("tlb_stats", 0444, test_dir, NULL,
					  &tlb_stats_file_ops);
#endif

	test_u32_dentry =
	    debugfs_create_u32("clr_on_read", 0444, test_dir, &clr_on_read);

	return 0;
}

module_init(arc_debugfs_init);

static void __exit arc_debugfs_exit(void)
{
	debugfs_remove(test_u32_dentry);
	debugfs_remove(test_dentry);
	debugfs_remove(test_dir);
}
module_exit(arc_debugfs_exit);

#endif