3 files changed, 96 insertions, 1 deletions

diff --git a/arch/arm/include/asm/kprobes.h b/arch/arm/include/asm/kprobes.h
index bb8a19bd5822..e46bdd0097eb 100644
--- a/arch/arm/include/asm/kprobes.h
+++ b/arch/arm/include/asm/kprobes.h
@@ -39,10 +39,13 @@ typedef u32 kprobe_opcode_t;
 struct kprobe;
 typedef void (kprobe_insn_handler_t)(struct kprobe *, struct pt_regs *);
 
+typedef unsigned long (kprobe_check_cc)(unsigned long);
+
 /* Architecture specific copy of original instruction. */
 struct arch_specific_insn {
         kprobe_opcode_t         *insn;
         kprobe_insn_handler_t   *insn_handler;
+        kprobe_check_cc         *insn_check_cc;
 };
 
 struct prev_kprobe {
diff --git a/arch/arm/kernel/kprobes-decode.c b/arch/arm/kernel/kprobes-decode.c
index 3b0cf90cb449..2e84169b9e91 100644
--- a/arch/arm/kernel/kprobes-decode.c
+++ b/arch/arm/kernel/kprobes-decode.c
@@ -1396,6 +1396,96 @@ space_cccc_111x(kprobe_opcode_t insn, struct arch_specific_insn *asi)
         return INSN_GOOD;
 }
 
+static unsigned long __kprobes __check_eq(unsigned long cpsr)
+{
+        return cpsr & PSR_Z_BIT;
+}
+
+static unsigned long __kprobes __check_ne(unsigned long cpsr)
+{
+        return (~cpsr) & PSR_Z_BIT;
+}
+
+static unsigned long __kprobes __check_cs(unsigned long cpsr)
+{
+        return cpsr & PSR_C_BIT;
+}
+
+static unsigned long __kprobes __check_cc(unsigned long cpsr)
+{
+        return (~cpsr) & PSR_C_BIT;
+}
+
+static unsigned long __kprobes __check_mi(unsigned long cpsr)
+{
+        return cpsr & PSR_N_BIT;
+}
+
+static unsigned long __kprobes __check_pl(unsigned long cpsr)
+{
+        return (~cpsr) & PSR_N_BIT;
+}
+
+static unsigned long __kprobes __check_vs(unsigned long cpsr)
+{
+        return cpsr & PSR_V_BIT;
+}
+
+static unsigned long __kprobes __check_vc(unsigned long cpsr)
+{
+        return (~cpsr) & PSR_V_BIT;
+}
+
+static unsigned long __kprobes __check_hi(unsigned long cpsr)
+{
+        cpsr &= ~(cpsr >> 1); /* PSR_C_BIT &= ~PSR_Z_BIT */
+        return cpsr & PSR_C_BIT;
+}
+
+static unsigned long __kprobes __check_ls(unsigned long cpsr)
+{
+        cpsr &= ~(cpsr >> 1); /* PSR_C_BIT &= ~PSR_Z_BIT */
+        return (~cpsr) & PSR_C_BIT;
+}
+
+static unsigned long __kprobes __check_ge(unsigned long cpsr)
+{
+        cpsr ^= (cpsr << 3); /* PSR_N_BIT ^= PSR_V_BIT */
+        return (~cpsr) & PSR_N_BIT;
+}
+
+static unsigned long __kprobes __check_lt(unsigned long cpsr)
+{
+        cpsr ^= (cpsr << 3); /* PSR_N_BIT ^= PSR_V_BIT */
+        return cpsr & PSR_N_BIT;
+}
+
+static unsigned long __kprobes __check_gt(unsigned long cpsr)
+{
+        unsigned long temp = cpsr ^ (cpsr << 3); /* PSR_N_BIT ^= PSR_V_BIT */
+        temp |= (cpsr << 1);                     /* PSR_N_BIT |= PSR_Z_BIT */
+        return (~temp) & PSR_N_BIT;
+}
+
+static unsigned long __kprobes __check_le(unsigned long cpsr)
+{
+        unsigned long temp = cpsr ^ (cpsr << 3); /* PSR_N_BIT ^= PSR_V_BIT */
+        temp |= (cpsr << 1);                     /* PSR_N_BIT |= PSR_Z_BIT */
+        return temp & PSR_N_BIT;
+}
+
+static unsigned long __kprobes __check_al(unsigned long cpsr)
+{
+        return true;
+}
+
+static kprobe_check_cc * const condition_checks[16] = {
+        &__check_eq, &__check_ne, &__check_cs, &__check_cc,
+        &__check_mi, &__check_pl, &__check_vs, &__check_vc,
+        &__check_hi, &__check_ls, &__check_ge, &__check_lt,
+        &__check_gt, &__check_le, &__check_al, &__check_al
+};
+
 /* Return:
  *   INSN_REJECTED     If instruction is one not allowed to kprobe,
  *   INSN_GOOD         If instruction is supported and uses instruction slot,
@@ -1411,6 +1501,7 @@ space_cccc_111x(kprobe_opcode_t insn, struct arch_specific_insn *asi)
 enum kprobe_insn __kprobes
 arm_kprobe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi)
 {
+        asi->insn_check_cc = condition_checks[insn>>28];
         asi->insn[1] = KPROBE_RETURN_INSTRUCTION;
 
         if ((insn & 0xf0000000) == 0xf0000000) {
diff --git a/arch/arm/kernel/kprobes.c b/arch/arm/kernel/kprobes.c
index 2ba7deb3072e..1656c87501c0 100644
--- a/arch/arm/kernel/kprobes.c
+++ b/arch/arm/kernel/kprobes.c
@@ -134,7 +134,8 @@ static void __kprobes singlestep(struct kprobe *p, struct pt_regs *regs,
                                  struct kprobe_ctlblk *kcb)
 {
         regs->ARM_pc += 4;
-        p->ainsn.insn_handler(p, regs);
+        if (p->ainsn.insn_check_cc(regs->ARM_cpsr))
+                p->ainsn.insn_handler(p, regs);
 }
 
 /*