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authorJon Medhurst <tixy@yxit.co.uk>2011-04-06 11:17:11 +0100
committerNicolas Pitre <nicolas.pitre@linaro.org>2011-04-28 23:40:55 -0400
commitad111ce46674a473370d302325db8f418ac4fe92 (patch)
treef99fc1a1dd357e431f8be4ca0b9784d8ad7797f8 /arch/arm/kernel
parenta539f5d46c868cb1f37b92e62e040b400571aed4 (diff)
ARM: kprobes: Fix emulation of CMP, CMN, TST and TEQ instructions.
Probing these instructions was corrupting R0 because the emulation code didn't account for the fact that they don't write a result to a register. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Diffstat (limited to 'arch/arm/kernel')
-rw-r--r--arch/arm/kernel/kprobes-decode.c55
1 files changed, 53 insertions, 2 deletions
diff --git a/arch/arm/kernel/kprobes-decode.c b/arch/arm/kernel/kprobes-decode.c
index f52fac0c59f0..ee29d3350437 100644
--- a/arch/arm/kernel/kprobes-decode.c
+++ b/arch/arm/kernel/kprobes-decode.c
@@ -808,6 +808,17 @@ emulate_alu_imm_rwflags(struct kprobe *p, struct pt_regs *regs)
}
static void __kprobes
+emulate_alu_tests_imm(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 rn = (insn >> 16) & 0xf;
+ long rnv = (rn == 15) ? (long)p->addr + 8 : regs->uregs[rn];
+
+ insnslot_1arg_rwflags(rnv, &regs->ARM_cpsr, i_fn);
+}
+
+static void __kprobes
emulate_alu_rflags(struct kprobe *p, struct pt_regs *regs)
{
insn_3arg_fn_t *i_fn = (insn_3arg_fn_t *)&p->ainsn.insn[0];
@@ -843,6 +854,22 @@ emulate_alu_rwflags(struct kprobe *p, struct pt_regs *regs)
insnslot_3arg_rwflags(rnv, rmv, rsv, &regs->ARM_cpsr, i_fn);
}
+static void __kprobes
+emulate_alu_tests(struct kprobe *p, struct pt_regs *regs)
+{
+ insn_3arg_fn_t *i_fn = (insn_3arg_fn_t *)&p->ainsn.insn[0];
+ kprobe_opcode_t insn = p->opcode;
+ long ppc = (long)p->addr + 8;
+ int rn = (insn >> 16) & 0xf;
+ int rs = (insn >> 8) & 0xf; /* rs/rsv may be invalid, don't care. */
+ int rm = insn & 0xf;
+ long rnv = (rn == 15) ? ppc : regs->uregs[rn];
+ long rmv = (rm == 15) ? ppc : regs->uregs[rm];
+ long rsv = regs->uregs[rs];
+
+ insnslot_3arg_rwflags(rnv, rmv, rsv, &regs->ARM_cpsr, i_fn);
+}
+
static enum kprobe_insn __kprobes
prep_emulate_ldr_str(kprobe_opcode_t insn, struct arch_specific_insn *asi)
{
@@ -1142,8 +1169,20 @@ space_cccc_000x(kprobe_opcode_t insn, struct arch_specific_insn *asi)
insn |= 0x00000200; /* Rs = r2 */
}
asi->insn[0] = insn;
- asi->insn_handler = (insn & (1 << 20)) ? /* S-bit */
+
+ if ((insn & 0x0f900000) == 0x01100000) {
+ /*
+ * TST : cccc 0001 0001 xxxx xxxx xxxx xxxx xxxx
+ * TEQ : cccc 0001 0011 xxxx xxxx xxxx xxxx xxxx
+ * CMP : cccc 0001 0101 xxxx xxxx xxxx xxxx xxxx
+ * CMN : cccc 0001 0111 xxxx xxxx xxxx xxxx xxxx
+ */
+ asi->insn_handler = emulate_alu_tests;
+ } else {
+ /* ALU ops which write to Rd */
+ asi->insn_handler = (insn & (1 << 20)) ? /* S-bit */
emulate_alu_rwflags : emulate_alu_rflags;
+ }
return INSN_GOOD;
}
@@ -1170,8 +1209,20 @@ space_cccc_001x(kprobe_opcode_t insn, struct arch_specific_insn *asi)
*/
insn &= 0xffff0fff; /* Rd = r0 */
asi->insn[0] = insn;
- asi->insn_handler = (insn & (1 << 20)) ? /* S-bit */
+
+ if ((insn & 0x0f900000) == 0x03100000) {
+ /*
+ * TST : cccc 0011 0001 xxxx xxxx xxxx xxxx xxxx
+ * TEQ : cccc 0011 0011 xxxx xxxx xxxx xxxx xxxx
+ * CMP : cccc 0011 0101 xxxx xxxx xxxx xxxx xxxx
+ * CMN : cccc 0011 0111 xxxx xxxx xxxx xxxx xxxx
+ */
+ asi->insn_handler = emulate_alu_tests_imm;
+ } else {
+ /* ALU ops which write to Rd */
+ asi->insn_handler = (insn & (1 << 20)) ? /* S-bit */
emulate_alu_imm_rwflags : emulate_alu_imm_rflags;
+ }
return INSN_GOOD;
}