From 20e8155e24ba5c04558780d0a8da13c39f98c002 Mon Sep 17 00:00:00 2001 From: Jon Medhurst Date: Tue, 19 Apr 2011 10:52:18 +0100 Subject: [PATCH] ARM: kprobes: Add emulation of SBFX, UBFX, BFI and BFC instructions These bit field manipulation instructions occur several thousand times in an ARMv7 kernel. Signed-off-by: Jon Medhurst Signed-off-by: Nicolas Pitre --- arch/arm/kernel/kprobes-decode.c | 42 ++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) diff --git a/arch/arm/kernel/kprobes-decode.c b/arch/arm/kernel/kprobes-decode.c index a063f152d9b..6bed8b089af 100644 --- a/arch/arm/kernel/kprobes-decode.c +++ b/arch/arm/kernel/kprobes-decode.c @@ -672,6 +672,19 @@ emulate_rd12_modify(struct kprobe *p, struct pt_regs *regs) regs->uregs[rd] = insnslot_1arg_rflags(rdv, regs->ARM_cpsr, i_fn); } +static void __kprobes +emulate_rd12rn0_modify(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; + int rd = (insn >> 12) & 0xf; + int rn = insn & 0xf; + long rdv = regs->uregs[rd]; + long rnv = regs->uregs[rn]; + + regs->uregs[rd] = insnslot_2arg_rflags(rdv, rnv, 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]; @@ -869,6 +882,20 @@ prep_emulate_rd12_modify(kprobe_opcode_t insn, struct arch_specific_insn *asi) return INSN_GOOD; } +static enum kprobe_insn __kprobes +prep_emulate_rd12rn0_modify(kprobe_opcode_t insn, + struct arch_specific_insn *asi) +{ + if (is_r15(insn, 12)) + return INSN_REJECTED; /* Rd is PC */ + + insn &= 0xffff0ff0; /* Rd = r0 */ + insn |= 0x00000001; /* Rn = r1 */ + asi->insn[0] = insn; + asi->insn_handler = emulate_rd12rn0_modify; + return INSN_GOOD; +} + static enum kprobe_insn __kprobes prep_emulate_rd12rm0(kprobe_opcode_t insn, struct arch_specific_insn *asi) { @@ -1396,6 +1423,21 @@ space_cccc_0111__1(kprobe_opcode_t insn, struct arch_specific_insn *asi) if ((insn & 0x0ff000d0) == 0x075000d0) return prep_emulate_rd16rn12rs8rm0_wflags(insn, asi); + /* SBFX : cccc 0111 101x xxxx xxxx xxxx x101 xxxx : */ + /* UBFX : cccc 0111 111x xxxx xxxx xxxx x101 xxxx : */ + if ((insn & 0x0fa00070) == 0x07a00050) + return prep_emulate_rd12rm0(insn, asi); + + /* BFI : cccc 0111 110x xxxx xxxx xxxx x001 xxxx : */ + /* BFC : cccc 0111 110x xxxx xxxx xxxx x001 1111 : */ + if ((insn & 0x0fe00070) == 0x07c00010) { + + if ((insn & 0x0000000f) == 0x0000000f) + return prep_emulate_rd12_modify(insn, asi); + else + return prep_emulate_rd12rn0_modify(insn, asi); + } + return INSN_REJECTED; } -- 2.41.0