From 734aea1ccebd70639af43c84d4f86f3d5456abe3 Mon Sep 17 00:00:00 2001
From: San Mehat <san@google.com>
Date: Tue, 25 Aug 2009 16:52:22 -0700
Subject: [PATCH] ARM: process: Add display of memory around registers when
 displaying regs.

This is extremely useful in diagnosing remote crashes, and is based heavily
on original work by <md@google.com>.

Signed-off-by: San Mehat <san@google.com>
Cc: Michael Davidson <md@google.com>

[ARM] process: Use uber-safe probe_kernel_address() to read mem when dumping.

This prevents the dump from taking pagefaults / external aborts.

Signed-off-by: San Mehat <san@google.com>
Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
Change-Id: I7586677c4ea0e064b5a38c7972102db3b5771500
---
 arch/arm/kernel/process.c | 84 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 84 insertions(+)

diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index ae60679939a4..cb49744c6d46 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -112,6 +112,88 @@ void __show_regs_alloc_free(struct pt_regs *regs)
 	}
 }
 
+static int arm_insn_read(void *addr, u32 *insnp)
+{
+	int ret;
+	__le32 val;
+
+	ret = copy_from_kernel_nofault(&val, addr, 4);
+	if (!ret)
+		*insnp = le32_to_cpu(val);
+
+	return ret;
+}
+
+/*
+ * dump a block of kernel memory from around the given address
+ */
+static void show_data(unsigned long addr, int nbytes, const char *name)
+{
+	int	i, j;
+	int	nlines;
+	u32	*p;
+
+	/*
+	 * don't attempt to dump non-kernel addresses or
+	 * values that are probably just small negative numbers
+	 */
+	if (addr < PAGE_OFFSET || addr > -4096UL)
+		return;
+
+	printk("\n%s: %#lx:\n", name, addr);
+
+	/*
+	 * round address down to a 32 bit boundary
+	 * and always dump a multiple of 32 bytes
+	 */
+	p = (u32 *)(addr & ~(sizeof(u32) - 1));
+	nbytes += (addr & (sizeof(u32) - 1));
+	nlines = (nbytes + 31) / 32;
+
+	for (i = 0; i < nlines; i++) {
+		/*
+		 * just display low 16 bits of address to keep
+		 * each line of the dump < 80 characters
+		 */
+		if (i == (nlines / 2))
+			printk("%04lx*", (unsigned long)p & 0xffff);
+		else
+			printk("%04lx ", (unsigned long)p & 0xffff);
+
+		for (j = 0; j < 8; j++) {
+			u32	data;
+
+			if (arm_insn_read(p, &data)) {
+				pr_cont(" ********");
+			} else {
+				pr_cont(" %08x", data);
+			}
+			++p;
+		}
+		pr_cont("\n");
+	}
+}
+
+static void show_extra_register_data(struct pt_regs *regs, int nbytes)
+{
+	show_data(regs->ARM_pc - nbytes, nbytes * 2, "PC");
+	show_data(regs->ARM_lr - nbytes, nbytes * 2, "LR");
+	show_data(regs->ARM_sp - nbytes, nbytes * 2, "SP");
+	show_data(regs->ARM_ip - nbytes, nbytes * 2, "IP");
+	show_data(regs->ARM_fp - nbytes, nbytes * 2, "FP");
+	show_data(regs->ARM_r0 - nbytes, nbytes * 2, "R0");
+	show_data(regs->ARM_r1 - nbytes, nbytes * 2, "R1");
+	show_data(regs->ARM_r2 - nbytes, nbytes * 2, "R2");
+	show_data(regs->ARM_r3 - nbytes, nbytes * 2, "R3");
+	show_data(regs->ARM_r4 - nbytes, nbytes * 2, "R4");
+	show_data(regs->ARM_r5 - nbytes, nbytes * 2, "R5");
+	show_data(regs->ARM_r6 - nbytes, nbytes * 2, "R6");
+	show_data(regs->ARM_r7 - nbytes, nbytes * 2, "R7");
+	show_data(regs->ARM_r8 - nbytes, nbytes * 2, "R8");
+	show_data(regs->ARM_r9 - nbytes, nbytes * 2, "R9");
+	show_data(regs->ARM_r10 - nbytes, nbytes * 2, "R10");
+}
+
 void __show_regs(struct pt_regs *regs)
 {
 	unsigned long flags;
@@ -198,6 +280,8 @@ void __show_regs(struct pt_regs *regs)
 		printk("Control: %08x%s\n", ctrl, buf);
 	}
 #endif
+	if (!user_mode(regs))
+		show_extra_register_data(regs, 512);
 }
 
 void show_regs(struct pt_regs * regs)