kprobes/arm: Fix ldrd/strd emulation
Currently emulate_ldrd and emulate_strd don't even have the adjustment
of the PC value, so in case of Rn == PC, it will not update the PC
incorrectly but instead load/store from the wrong address. Let's add
both the adjustment of the PC value and the check for PC == PC.
Signed-off-by: Viktor Rosendahl <viktor.rosendahl@nokia.com>
Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
diff --git a/arch/arm/kernel/kprobes-decode.c b/arch/arm/kernel/kprobes-decode.c
index 2389131..3b0cf90 100644
--- a/arch/arm/kernel/kprobes-decode.c
+++ b/arch/arm/kernel/kprobes-decode.c
@@ -540,9 +540,12 @@
{
insn_2arg_fn_t *i_fn = (insn_2arg_fn_t *)&p->ainsn.insn[0];
kprobe_opcode_t insn = p->opcode;
+ long ppc = (long)p->addr + 8;
int rd = (insn >> 12) & 0xf;
int rn = (insn >> 16) & 0xf;
int rm = insn & 0xf; /* rm may be invalid, don't care. */
+ long rmv = (rm == 15) ? ppc : regs->uregs[rm];
+ long rnv = (rn == 15) ? ppc : regs->uregs[rn];
/* Not following the C calling convention here, so need asm(). */
__asm__ __volatile__ (
@@ -554,29 +557,36 @@
"str r0, %[rn] \n\t" /* in case of writeback */
"str r2, %[rd0] \n\t"
"str r3, %[rd1] \n\t"
- : [rn] "+m" (regs->uregs[rn]),
+ : [rn] "+m" (rnv),
[rd0] "=m" (regs->uregs[rd]),
[rd1] "=m" (regs->uregs[rd+1])
- : [rm] "m" (regs->uregs[rm]),
+ : [rm] "m" (rmv),
[cpsr] "r" (regs->ARM_cpsr),
[i_fn] "r" (i_fn)
: "r0", "r1", "r2", "r3", "lr", "cc"
);
+ if (rn != 15)
+ regs->uregs[rn] = rnv; /* Save Rn in case of writeback. */
}
static void __kprobes emulate_strd(struct kprobe *p, struct pt_regs *regs)
{
insn_4arg_fn_t *i_fn = (insn_4arg_fn_t *)&p->ainsn.insn[0];
kprobe_opcode_t insn = p->opcode;
+ long ppc = (long)p->addr + 8;
int rd = (insn >> 12) & 0xf;
int rn = (insn >> 16) & 0xf;
int rm = insn & 0xf;
- 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];
+ /* rm/rmv may be invalid, don't care. */
+ long rmv = (rm == 15) ? ppc : regs->uregs[rm];
+ long rnv_wb;
- regs->uregs[rn] = insnslot_4arg_rflags(rnv, rmv, regs->uregs[rd],
+ rnv_wb = insnslot_4arg_rflags(rnv, rmv, regs->uregs[rd],
regs->uregs[rd+1],
regs->ARM_cpsr, i_fn);
+ if (rn != 15)
+ regs->uregs[rn] = rnv_wb; /* Save Rn in case of writeback. */
}
static void __kprobes emulate_ldr(struct kprobe *p, struct pt_regs *regs)