Date:	Mon, 12 Nov 2012 17:18:57 +0530
From:	<Vineet.Gupta1@...opsys.com>
To:	<linux-arch@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:	<tglx@...utronix.de>, <arnd@...db.de>,
	Vineet Gupta <Vineet.Gupta1@...opsys.com>
Subject: [RFC Patch v1 39/55] ARC: kernel diagnostics: show_regs() etc

From: Vineet Gupta <vgupta@...opsys.com>

Signed-off-by: Vineet Gupta <vgupta@...opsys.com>
---
 arch/arc/kernel/troubleshoot.c |  304 ++++++++++++++++++++++++++++++++++++++++
 arch/arc/mm/tlbex.S            |   20 +++
 2 files changed, 324 insertions(+), 0 deletions(-)

diff --git a/arch/arc/kernel/troubleshoot.c b/arch/arc/kernel/troubleshoot.c
index 80bfe2a..8a816f2 100644
--- a/arch/arc/kernel/troubleshoot.c
+++ b/arch/arc/kernel/troubleshoot.c
@@ -6,12 +6,316 @@
  */
 
 #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>
+#include <asm/event-log.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 *task, char *buf)
+{
+	struct path path;
+	char *nm = NULL;
+	struct mm_struct *mm;
+	struct file *exe_file;
+	char comm_buf[TASK_COMM_LEN];
+
+	mm = get_task_mm(task);
+	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);
+		nm = d_path(&path, buf, 255);
+		path_put(&path);
+	}
+
+done:
+	pr_info("task = %s '%s', TGID %u PID = %u\n", nm,
+		get_task_comm(comm_buf, task), task->tgid, task->pid);
+}
+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 {
+		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);
+
+	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);
+
+	sort_snaps(1);
 }
+
+#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;
+
+	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
diff --git a/arch/arc/mm/tlbex.S b/arch/arc/mm/tlbex.S
index 86804d3..a95d0f7 100644
--- a/arch/arc/mm/tlbex.S
+++ b/arch/arc/mm/tlbex.S
@@ -134,6 +134,14 @@ ex_saved_reg1:
 	lsr     r0, r2, (PAGE_SHIFT - 2)
 	and     r0, r0, ( (PTRS_PER_PTE - 1) << 2)
 	ld.aw   r0, [r1, r0]            ; get PTE and PTE ptr for fault addr
+#ifdef CONFIG_ARC_DBG_TLB_MISS_COUNT
+	and.f 0, r0, _PAGE_PRESENT
+	bz   1f
+	ld   r2, [num_pte_not_present]
+	add  r2, r2, 1
+	st   r2, [num_pte_not_present]
+1:
+#endif
 
 .endm
 
@@ -223,6 +231,12 @@ ARC_ENTRY EV_TLBMissI
 
 	TLBMISS_FREEUP_REGS
 
+#ifdef CONFIG_ARC_DBG_TLB_MISS_COUNT
+	ld  r0, [@numitlb]
+	add r0, r0, 1
+	st  r0, [@numitlb]
+#endif
+
 	;----------------------------------------------------------------
 	; Get the PTE corresponding to V-addr accessed
 	LOAD_FAULT_PTE
@@ -256,6 +270,12 @@ ARC_ENTRY EV_TLBMissD
 
 	TLBMISS_FREEUP_REGS
 
+#ifdef CONFIG_ARC_DBG_TLB_MISS_COUNT
+	ld  r0, [@numdtlb]
+	add r0, r0, 1
+	st  r0, [@numdtlb]
+#endif
+
 	;----------------------------------------------------------------
 	; Get the PTE corresponding to V-addr accessed
 	; If PTE exists, it will setup, r0 = PTE, r1 = Ptr to PTE
-- 
1.7.4.1

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