ARM: 6226/1: fix kprobe bug in ldr instruction emulation

commit 0ebe25f9 upstream.

From: Bin Yang <bin.yang@marvell.com>
Signed-off-by: Bin Yang <bin.yang@marvell.com>
Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

arch/arm/kernel/kprobes-decode.c

@@ -583,13 +583,14 @@ static void __kprobes emulate_ldr(struct kprobe *p, struct pt_regs *regs)
 {
 	insn_llret_3arg_fn_t *i_fn = (insn_llret_3arg_fn_t *)&p->ainsn.insn[0];
 	kprobe_opcode_t insn = p->opcode;
+	long ppc = (long)p->addr + 8;
 	union reg_pair fnr;
 	int rd = (insn >> 12) & 0xf;
 	int rn = (insn >> 16) & 0xf;
 	int rm = insn & 0xf;
 	long rdv;
-	long rnv  = regs->uregs[rn];
-	long rmv  = regs->uregs[rm]; /* rm/rmv may be invalid, don't care. */
+	long rnv = (rn == 15) ? ppc : regs->uregs[rn];
+	long rmv = (rm == 15) ? ppc : regs->uregs[rm];
 	long cpsr = regs->ARM_cpsr;
 
 	fnr.dr = insnslot_llret_3arg_rflags(rnv, 0, rmv, cpsr, i_fn);