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Commit cf3cc1aa authored by Viktor Rosendahl's avatar Viktor Rosendahl Committed by Nicolas Pitre
Browse files

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: default avatarViktor Rosendahl <viktor.rosendahl@nokia.com>
Signed-off-by: default avatarNicolas Pitre <nicolas.pitre@linaro.org>
parent 6221f222

arch/arm/kernel/kprobes-decode.c

+15 −5
Original line number Diff line number Diff line
@@ -540,9 +540,12 @@ static void __kprobes emulate_ldrd(struct kprobe *p, struct pt_regs *regs) 
{

	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 @@ static void __kprobes emulate_ldrd(struct kprobe *p, struct pt_regs *regs) 
		"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)