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ARM: kprobes: Reject probing of instructions which write to PC unpredictably.

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Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
This commit is contained in:
Jon Medhurst 2011-04-07 13:25:17 +01:00 committed by Nicolas Pitre
parent c412aba2a1
commit 983ebd9365
1 changed files with 28 additions and 0 deletions
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28
arch/arm/kernel/kprobes-decode.c
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@ -68,6 +68,8 @@
#define branch_displacement(insn) sign_extend(((insn) & 0xffffff) << 2, 25)
#define is_r15(insn, bitpos) (((insn) & (0xf << bitpos)) == (0xf << bitpos))
#define PSR_fs (PSR_f|PSR_s)
#define KPROBE_RETURN_INSTRUCTION 0xe1a0f00e /* mov pc, lr */
@ -897,6 +899,9 @@ prep_emulate_ldr_str(kprobe_opcode_t insn, struct arch_specific_insn *asi)
static enum kprobe_insn __kprobes
prep_emulate_rd12rm0(kprobe_opcode_t insn, struct arch_specific_insn *asi)
{
if (is_r15(insn, 12))
return INSN_REJECTED; /* Rd is PC */
insn &= 0xffff0ff0; /* Rd = r0, Rm = r0 */
asi->insn[0] = insn;
asi->insn_handler = emulate_rd12rm0;
@ -907,6 +912,9 @@ static enum kprobe_insn __kprobes
prep_emulate_rd12rn16rm0_wflags(kprobe_opcode_t insn,
struct arch_specific_insn *asi)
{
if (is_r15(insn, 12))
return INSN_REJECTED; /* Rd is PC */
insn &= 0xfff00ff0; /* Rd = r0, Rn = r0 */
insn |= 0x00000001; /* Rm = r1 */
asi->insn[0] = insn;
@ -918,6 +926,9 @@ static enum kprobe_insn __kprobes
prep_emulate_rd16rs8rm0_wflags(kprobe_opcode_t insn,
struct arch_specific_insn *asi)
{
if (is_r15(insn, 16))
return INSN_REJECTED; /* Rd is PC */
insn &= 0xfff0f0f0; /* Rd = r0, Rs = r0 */
insn |= 0x00000001; /* Rm = r1 */
asi->insn[0] = insn;
@ -929,6 +940,9 @@ static enum kprobe_insn __kprobes
prep_emulate_rd16rn12rs8rm0_wflags(kprobe_opcode_t insn,
struct arch_specific_insn *asi)
{
if (is_r15(insn, 16))
return INSN_REJECTED; /* Rd is PC */
insn &= 0xfff000f0; /* Rd = r0, Rn = r0 */
insn |= 0x00000102; /* Rs = r1, Rm = r2 */
asi->insn[0] = insn;
@ -940,6 +954,9 @@ static enum kprobe_insn __kprobes
prep_emulate_rdhi16rdlo12rs8rm0_wflags(kprobe_opcode_t insn,
struct arch_specific_insn *asi)
{
if (is_r15(insn, 16) || is_r15(insn, 12))
return INSN_REJECTED; /* RdHi or RdLo is PC */
insn &= 0xfff000f0; /* RdHi = r0, RdLo = r1 */
insn |= 0x00001203; /* Rs = r2, Rm = r3 */
asi->insn[0] = insn;
@ -1035,6 +1052,8 @@ space_cccc_000x(kprobe_opcode_t insn, struct arch_specific_insn *asi)
/* MRS cpsr : cccc 0001 0000 xxxx xxxx xxxx 0000 xxxx */
if ((insn & 0x0ff000f0) == 0x01000000) {
if (is_r15(insn, 12))
return INSN_REJECTED; /* Rd is PC */
asi->insn_handler = simulate_mrs;
return INSN_GOOD_NO_SLOT;
}
@ -1065,6 +1084,8 @@ space_cccc_000x(kprobe_opcode_t insn, struct arch_specific_insn *asi)
/* BLX(2) : cccc 0001 0010 xxxx xxxx xxxx 0011 xxxx */
/* BX : cccc 0001 0010 xxxx xxxx xxxx 0001 xxxx */
if ((insn & 0x0ff000d0) == 0x01200010) {
if ((insn & 0x0ff000ff) == 0x0120003f)
return INSN_REJECTED; /* BLX pc */
asi->insn_handler = simulate_blx2bx;
return INSN_GOOD_NO_SLOT;
}
@ -1234,6 +1255,8 @@ space_cccc_0110__1(kprobe_opcode_t insn, struct arch_specific_insn *asi)
{
/* SEL : cccc 0110 1000 xxxx xxxx xxxx 1011 xxxx GE: !!! */
if ((insn & 0x0ff000f0) == 0x068000b0) {
if (is_r15(insn, 12))
return INSN_REJECTED; /* Rd is PC */
insn &= 0xfff00ff0; /* Rd = r0, Rn = r0 */
insn |= 0x00000001; /* Rm = r1 */
asi->insn[0] = insn;
@ -1247,6 +1270,8 @@ space_cccc_0110__1(kprobe_opcode_t insn, struct arch_specific_insn *asi)
/* USAT16 : cccc 0110 1110 xxxx xxxx xxxx 0011 xxxx :Q */
if ((insn & 0x0fa00030) == 0x06a00010 ||
(insn & 0x0fb000f0) == 0x06a00030) {
if (is_r15(insn, 12))
return INSN_REJECTED; /* Rd is PC */
insn &= 0xffff0ff0; /* Rd = r0, Rm = r0 */
asi->insn[0] = insn;
asi->insn_handler = emulate_sat;
@ -1384,6 +1409,9 @@ space_cccc_1100_010x(kprobe_opcode_t insn, struct arch_specific_insn *asi)
{
/* MCRR : cccc 1100 0100 xxxx xxxx xxxx xxxx xxxx : (Rd!=Rn) */
/* MRRC : cccc 1100 0101 xxxx xxxx xxxx xxxx xxxx : (Rd!=Rn) */
if (is_r15(insn, 16) || is_r15(insn, 12))
return INSN_REJECTED; /* Rn or Rd is PC */
insn &= 0xfff00fff;
insn |= 0x00001000; /* Rn = r0, Rd = r1 */
asi->insn[0] = insn;