arm64: process: dump memory around registers when displaying regs

A port of 8608d7c4418c75841c562a90cddd9beae5798a48 to ARM64.  Both the
original code and this port are limited to dumping kernel addresses, so
don't bother if the registers are from a userspace process.

Change-Id: Idc76804c54efaaeb70311cbb500c54db6dac4525
Signed-off-by: Greg Hackmann <ghackmann@google.com>

1 files changed, 66 insertions, 0 deletions

diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index f75b540bc3b4..62068ded1e90 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -164,6 +164,70 @@ void machine_restart(char *cmd)
 	while (1);
 }
 
+/*
+ * 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 > -256UL)
+		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
+		 */
+		printk("%04lx ", (unsigned long)p & 0xffff);
+		for (j = 0; j < 8; j++) {
+			u32	data;
+			if (probe_kernel_address(p, data)) {
+				printk(" ********");
+			} else {
+				printk(" %08x", data);
+			}
+			++p;
+		}
+		printk("\n");
+	}
+}
+
+static void show_extra_register_data(struct pt_regs *regs, int nbytes)
+{
+	mm_segment_t fs;
+	unsigned int i;
+
+	fs = get_fs();
+	set_fs(KERNEL_DS);
+	show_data(regs->pc - nbytes, nbytes * 2, "PC");
+	show_data(regs->regs[30] - nbytes, nbytes * 2, "LR");
+	show_data(regs->sp - nbytes, nbytes * 2, "SP");
+	for (i = 0; i < 30; i++) {
+		char name[4];
+		snprintf(name, sizeof(name), "X%u", i);
+		show_data(regs->regs[i] - nbytes, nbytes * 2, name);
+	}
+	set_fs(fs);
+}
+
 void __show_regs(struct pt_regs *regs)
 {
 	int i, top_reg;
@@ -190,6 +254,8 @@ void __show_regs(struct pt_regs *regs)
 		if (i % 2 == 0)
 			printk("\n");
 	}
+	if (!user_mode(regs))
+		show_extra_register_data(regs, 128);
 	printk("\n");
 }