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authorJon Medhurst <tixy@yxit.co.uk>2011-04-19 10:52:17 +0100
committerNicolas Pitre <nicolas.pitre@linaro.org>2011-04-28 23:40:59 -0400
commitc9836777d5f22e64eefc759d682511560b6d6d78 (patch)
tree37dbdb0ad5465fd1b290cc4742dd9f380b6f7ed6 /arch
parentf704a6e25bd07e1381af81f19fb1d123975807b1 (diff)
ARM: kprobes: Add emulation of MOVW and MOVT instructions
The MOVW and MOVT instructions account for approximately 7% of all instructions in a ARMv7 kernel as GCC uses them instead of a literal pool. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm/kernel/kprobes-decode.c30
1 files changed, 28 insertions, 2 deletions
diff --git a/arch/arm/kernel/kprobes-decode.c b/arch/arm/kernel/kprobes-decode.c
index 4715537b490c..a063f152d9b3 100644
--- a/arch/arm/kernel/kprobes-decode.c
+++ b/arch/arm/kernel/kprobes-decode.c
@@ -661,6 +661,17 @@ static void __kprobes emulate_nop(struct kprobe *p, struct pt_regs *regs)
{
}
+static void __kprobes
+emulate_rd12_modify(struct kprobe *p, struct pt_regs *regs)
+{
+ insn_1arg_fn_t *i_fn = (insn_1arg_fn_t *)&p->ainsn.insn[0];
+ kprobe_opcode_t insn = p->opcode;
+ int rd = (insn >> 12) & 0xf;
+ long rdv = regs->uregs[rd];
+
+ regs->uregs[rd] = insnslot_1arg_rflags(rdv, regs->ARM_cpsr, i_fn);
+}
+
static void __kprobes emulate_rd12rm0(struct kprobe *p, struct pt_regs *regs)
{
insn_1arg_fn_t *i_fn = (insn_1arg_fn_t *)&p->ainsn.insn[0];
@@ -847,6 +858,18 @@ prep_emulate_ldr_str(kprobe_opcode_t insn, struct arch_specific_insn *asi)
}
static enum kprobe_insn __kprobes
+prep_emulate_rd12_modify(kprobe_opcode_t insn, struct arch_specific_insn *asi)
+{
+ if (is_r15(insn, 12))
+ return INSN_REJECTED; /* Rd is PC */
+
+ insn &= 0xffff0fff; /* Rd = r0 */
+ asi->insn[0] = insn;
+ asi->insn_handler = emulate_rd12_modify;
+ return INSN_GOOD;
+}
+
+static enum kprobe_insn __kprobes
prep_emulate_rd12rm0(kprobe_opcode_t insn, struct arch_specific_insn *asi)
{
if (is_r15(insn, 12))
@@ -1170,14 +1193,17 @@ space_cccc_000x(kprobe_opcode_t insn, struct arch_specific_insn *asi)
static enum kprobe_insn __kprobes
space_cccc_001x(kprobe_opcode_t insn, struct arch_specific_insn *asi)
{
+ /* MOVW : cccc 0011 0000 xxxx xxxx xxxx xxxx xxxx */
+ /* MOVT : cccc 0011 0100 xxxx xxxx xxxx xxxx xxxx */
+ if ((insn & 0x0fb00000) == 0x03000000)
+ return prep_emulate_rd12_modify(insn, asi);
+
/*
* MSR : cccc 0011 0x10 xxxx xxxx xxxx xxxx xxxx
- * Undef : cccc 0011 0100 xxxx xxxx xxxx xxxx xxxx
* ALU op with S bit and Rd == 15 :
* cccc 001x xxx1 xxxx 1111 xxxx xxxx xxxx
*/
if ((insn & 0x0fb00000) == 0x03200000 || /* MSR */
- (insn & 0x0ff00000) == 0x03400000 || /* Undef */
(insn & 0x0e10f000) == 0x0210f000) /* ALU s-bit, R15 */
return INSN_REJECTED;