| Message ID | 1434395229-6654-5-git-send-email-dave.long@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 15 June 2015 at 20:07, David Long <dave.long@linaro.org> wrote: > From: Sandeepa Prabhu <sandeepa.prabhu@linaro.org> > > Kprobes needs simulation of instructions that cannot be stepped > from different memory location, e.g.: those instructions > that uses PC-relative addressing. In simulation, the behaviour > of the instruction is implemented using a copy of pt_regs. > > Following instruction catagories are simulated: > - All branching instructions(conditional, register, and immediate) > - Literal access instructions(load-literal, adr/adrp) > > Conditional execution is limited to branching instructions in > ARM v8. If conditions at PSTATE do not match the condition fields > of opcode, the instruction is effectively NOP. Kprobes considers > this case as 'miss'. > > Thanks to Will Cohen for assorted suggested changes. > > Signed-off-by: Sandeepa Prabhu <sandeepa.prabhu@linaro.org> > Signed-off-by: William Cohen <wcohen@redhat.com> > Signed-off-by: David A. Long <dave.long@linaro.org> > --- > arch/arm64/kernel/Makefile | 4 +- > arch/arm64/kernel/kprobes-arm64.c | 98 +++++++++++++++++ > arch/arm64/kernel/kprobes-arm64.h | 2 + > arch/arm64/kernel/kprobes.c | 35 ++++++- > arch/arm64/kernel/probes-condn-check.c | 122 ++++++++++++++++++++++ > arch/arm64/kernel/probes-simulate-insn.c | 174 +++++++++++++++++++++++++++++++ > arch/arm64/kernel/probes-simulate-insn.h | 33 ++++++ > 7 files changed, 464 insertions(+), 4 deletions(-) > create mode 100644 arch/arm64/kernel/probes-condn-check.c > create mode 100644 arch/arm64/kernel/probes-simulate-insn.c > create mode 100644 arch/arm64/kernel/probes-simulate-insn.h > > diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile > index 1319872..5e9d54f 100644 > --- a/arch/arm64/kernel/Makefile > +++ b/arch/arm64/kernel/Makefile > @@ -32,7 +32,9 @@ arm64-obj-$(CONFIG_CPU_PM) += sleep.o suspend.o > arm64-obj-$(CONFIG_CPU_IDLE) += cpuidle.o > arm64-obj-$(CONFIG_JUMP_LABEL) += jump_label.o > arm64-obj-$(CONFIG_KGDB) += kgdb.o > -arm64-obj-$(CONFIG_KPROBES) += kprobes.o kprobes-arm64.o > +arm64-obj-$(CONFIG_KPROBES) += kprobes.o kprobes-arm64.o \ > + probes-simulate-insn.o \ > + probes-condn-check.o > arm64-obj-$(CONFIG_EFI) += efi.o efi-stub.o efi-entry.o > arm64-obj-$(CONFIG_PCI) += pci.o > arm64-obj-$(CONFIG_ARMV8_DEPRECATED) += armv8_deprecated.o > diff --git a/arch/arm64/kernel/kprobes-arm64.c b/arch/arm64/kernel/kprobes-arm64.c > index f958c52..8a7e6b0 100644 > --- a/arch/arm64/kernel/kprobes-arm64.c > +++ b/arch/arm64/kernel/kprobes-arm64.c > @@ -20,6 +20,76 @@ > #include <asm/insn.h> > > #include "kprobes-arm64.h" > +#include "probes-simulate-insn.h" > + > +/* > + * condition check functions for kprobes simulation > + */ > +static unsigned long __kprobes > +__check_pstate(struct kprobe *p, struct pt_regs *regs) > +{ > + struct arch_specific_insn *asi = &p->ainsn; > + unsigned long pstate = regs->pstate & 0xffffffff; > + > + return asi->pstate_cc(pstate); > +} > + > +static unsigned long __kprobes > +__check_cbz(struct kprobe *p, struct pt_regs *regs) > +{ > + return check_cbz((u32)p->opcode, regs); > +} > + > +static unsigned long __kprobes > +__check_cbnz(struct kprobe *p, struct pt_regs *regs) > +{ > + return check_cbnz((u32)p->opcode, regs); > +} > + > +static unsigned long __kprobes > +__check_tbz(struct kprobe *p, struct pt_regs *regs) > +{ > + return check_tbz((u32)p->opcode, regs); > +} > + > +static unsigned long __kprobes > +__check_tbnz(struct kprobe *p, struct pt_regs *regs) > +{ > + return check_tbnz((u32)p->opcode, regs); > +} > + > +/* > + * prepare functions for instruction simulation > + */ > +static void __kprobes > +prepare_none(struct kprobe *p, struct arch_specific_insn *asi) > +{ > +} > + > +static void __kprobes > +prepare_bcond(struct kprobe *p, struct arch_specific_insn *asi) > +{ > + kprobe_opcode_t insn = p->opcode; > + > + asi->check_condn = __check_pstate; > + asi->pstate_cc = kprobe_condition_checks[insn & 0xf]; > +} > + > +static void __kprobes > +prepare_cbz_cbnz(struct kprobe *p, struct arch_specific_insn *asi) > +{ > + kprobe_opcode_t insn = p->opcode; > + > + asi->check_condn = (insn & (1 << 24)) ? __check_cbnz : __check_cbz; > +} > + > +static void __kprobes > +prepare_tbz_tbnz(struct kprobe *p, struct arch_specific_insn *asi) > +{ > + kprobe_opcode_t insn = p->opcode; > + > + asi->check_condn = (insn & (1 << 24)) ? __check_tbnz : __check_tbz; > +} > > static bool __kprobes aarch64_insn_is_steppable(u32 insn) > { > @@ -63,6 +133,34 @@ arm_kprobe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi) > */ > if (aarch64_insn_is_steppable(insn)) > return INSN_GOOD; > + > + asi->prepare = prepare_none; > + > + if (aarch64_insn_is_bcond(insn)) { > + asi->prepare = prepare_bcond; > + asi->handler = simulate_b_cond; > + } else if (aarch64_insn_is_cb(insn)) { > + asi->prepare = prepare_cbz_cbnz; > + asi->handler = simulate_cbz_cbnz; > + } else if (aarch64_insn_is_tb(insn)) { > + asi->prepare = prepare_tbz_tbnz; > + asi->handler = simulate_tbz_tbnz; > + } else if (aarch64_insn_is_adr_adrp(insn)) > + asi->handler = simulate_adr_adrp; > + else if (aarch64_insn_is_b_bl(insn)) > + asi->handler = simulate_b_bl; > + else if (aarch64_insn_is_br_blr(insn) || aarch64_insn_is_ret(insn)) > + asi->handler = simulate_br_blr_ret; > + else if (aarch64_insn_is_ldr_lit(insn)) > + asi->handler = simulate_ldr_literal; > + else if (aarch64_insn_is_ldrsw_lit(insn)) > + asi->handler = simulate_ldrsw_literal; > else > + /* > + * Instruction cannot be stepped out-of-line and we don't > + * (yet) simulate it. > + */ > return INSN_REJECTED; > + > + return INSN_GOOD_NO_SLOT; > } > diff --git a/arch/arm64/kernel/kprobes-arm64.h b/arch/arm64/kernel/kprobes-arm64.h > index 87e7891..ff8a55f 100644 > --- a/arch/arm64/kernel/kprobes-arm64.h > +++ b/arch/arm64/kernel/kprobes-arm64.h > @@ -22,6 +22,8 @@ enum kprobe_insn { > INSN_GOOD, > }; > > +extern kprobes_pstate_check_t * const kprobe_condition_checks[16]; > + > enum kprobe_insn __kprobes > arm_kprobe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi); > > diff --git a/arch/arm64/kernel/kprobes.c b/arch/arm64/kernel/kprobes.c > index 601d2c6..6255814 100644 > --- a/arch/arm64/kernel/kprobes.c > +++ b/arch/arm64/kernel/kprobes.c > @@ -38,6 +38,9 @@ > DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; > DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); > > +static void __kprobes > +post_kprobe_handler(struct kprobe_ctlblk *, struct pt_regs *); > + > static void __kprobes arch_prepare_ss_slot(struct kprobe *p) > { > /* prepare insn slot */ > @@ -54,6 +57,27 @@ static void __kprobes arch_prepare_ss_slot(struct kprobe *p) > p->ainsn.restore.type = RESTORE_PC; > } > > +static void __kprobes arch_prepare_simulate(struct kprobe *p) > +{ > + if (p->ainsn.prepare) > + p->ainsn.prepare(p, &p->ainsn); > + > + /* This instructions is not executed xol. No need to adjust the PC */ > + p->ainsn.restore.addr = 0; > + p->ainsn.restore.type = NO_RESTORE; > +} > + > +static void __kprobes arch_simulate_insn(struct kprobe *p, struct pt_regs *regs) > +{ > + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); > + > + if (p->ainsn.handler) > + p->ainsn.handler((u32)p->opcode, (long)p->addr, regs); > + > + /* single step simulated, now go for post processing */ > + post_kprobe_handler(kcb, regs); > +} > + > int __kprobes arch_prepare_kprobe(struct kprobe *p) > { > kprobe_opcode_t insn; > @@ -72,7 +96,8 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p) > return -EINVAL; > > case INSN_GOOD_NO_SLOT: /* insn need simulation */ > - return -EINVAL; > + p->ainsn.insn = NULL; > + break; > > case INSN_GOOD: /* instruction uses slot */ > p->ainsn.insn = get_insn_slot(); > @@ -82,7 +107,10 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p) > }; > > /* prepare the instruction */ > - arch_prepare_ss_slot(p); > + if (p->ainsn.insn) > + arch_prepare_ss_slot(p); > + else > + arch_prepare_simulate(p); > > return 0; > } > @@ -231,7 +259,8 @@ static void __kprobes setup_singlestep(struct kprobe *p, > kernel_enable_single_step(regs); > instruction_pointer(regs) = slot; > } else { > - BUG(); > + /* insn simulation */ > + arch_simulate_insn(p, regs); > } > } > > diff --git a/arch/arm64/kernel/probes-condn-check.c b/arch/arm64/kernel/probes-condn-check.c > new file mode 100644 > index 0000000..e68aa0c > --- /dev/null > +++ b/arch/arm64/kernel/probes-condn-check.c > @@ -0,0 +1,122 @@ > +/* > + * arch/arm64/kernel/probes-condn-check.c > + * > + * Copyright (C) 2013 Linaro Limited > + * > + * Copied from: arch/arm/kernel/kprobes-common.c > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License version 2 as > + * published by the Free Software Foundation. > + * > + * This program is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > + * General Public License for more details. > + * > + * Description: > + * > + * AArch64 and AArch32 shares same conditional(CNZV) flags encoding. > + * This file implements conditional check helpers compatible with > + * both AArch64 and AArch32 modes. Uprobes on v8 can handle both 32-bit > + * & 64-bit user-space instructions, so we abstract the common functions > + * in this file. While AArch64 and AArch32 specific instruction handling > + * are implemented in separate files, this file contains common bits. > + */ > +#include <linux/kernel.h> > +#include <linux/module.h> > +#include <asm/probes.h> > + > +static unsigned long __kprobes __check_eq(unsigned long pstate) > +{ > + return pstate & PSR_Z_BIT; > +} > + > +static unsigned long __kprobes __check_ne(unsigned long pstate) > +{ > + return (~pstate) & PSR_Z_BIT; > +} > + > +static unsigned long __kprobes __check_cs(unsigned long pstate) > +{ > + return pstate & PSR_C_BIT; > +} > + > +static unsigned long __kprobes __check_cc(unsigned long pstate) > +{ > + return (~pstate) & PSR_C_BIT; > +} > + > +static unsigned long __kprobes __check_mi(unsigned long pstate) > +{ > + return pstate & PSR_N_BIT; > +} > + > +static unsigned long __kprobes __check_pl(unsigned long pstate) > +{ > + return (~pstate) & PSR_N_BIT; > +} > + > +static unsigned long __kprobes __check_vs(unsigned long pstate) > +{ > + return pstate & PSR_V_BIT; > +} > + > +static unsigned long __kprobes __check_vc(unsigned long pstate) > +{ > + return (~pstate) & PSR_V_BIT; > +} > + > +static unsigned long __kprobes __check_hi(unsigned long pstate) > +{ > + pstate &= ~(pstate >> 1); /* PSR_C_BIT &= ~PSR_Z_BIT */ > + return pstate & PSR_C_BIT; > +} > + > +static unsigned long __kprobes __check_ls(unsigned long pstate) > +{ > + pstate &= ~(pstate >> 1); /* PSR_C_BIT &= ~PSR_Z_BIT */ > + return (~pstate) & PSR_C_BIT; > +} > + > +static unsigned long __kprobes __check_ge(unsigned long pstate) > +{ > + pstate ^= (pstate << 3); /* PSR_N_BIT ^= PSR_V_BIT */ > + return (~pstate) & PSR_N_BIT; > +} > + > +static unsigned long __kprobes __check_lt(unsigned long pstate) > +{ > + pstate ^= (pstate << 3); /* PSR_N_BIT ^= PSR_V_BIT */ > + return pstate & PSR_N_BIT; > +} > + > +static unsigned long __kprobes __check_gt(unsigned long pstate) > +{ > + /*PSR_N_BIT ^= PSR_V_BIT */ > + unsigned long temp = pstate ^ (pstate << 3); > + > + temp |= (pstate << 1); /*PSR_N_BIT |= PSR_Z_BIT */ > + return (~temp) & PSR_N_BIT; > +} > + > +static unsigned long __kprobes __check_le(unsigned long pstate) > +{ > + /*PSR_N_BIT ^= PSR_V_BIT */ > + unsigned long temp = pstate ^ (pstate << 3); > + > + temp |= (pstate << 1); /*PSR_N_BIT |= PSR_Z_BIT */ > + return temp & PSR_N_BIT; > +} > + > +static unsigned long __kprobes __check_al(unsigned long pstate) > +{ > + return true; > +} > + > +kprobes_pstate_check_t * const kprobe_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 > +}; > diff --git a/arch/arm64/kernel/probes-simulate-insn.c b/arch/arm64/kernel/probes-simulate-insn.c > new file mode 100644 > index 0000000..a224c91 > --- /dev/null > +++ b/arch/arm64/kernel/probes-simulate-insn.c > @@ -0,0 +1,174 @@ > +/* > + * arch/arm64/kernel/probes-simulate-insn.c > + * > + * Copyright (C) 2013 Linaro Limited. > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License version 2 as > + * published by the Free Software Foundation. > + * > + * This program is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > + * General Public License for more details. > + */ > + > +#include <linux/kernel.h> > +#include <linux/kprobes.h> > +#include <linux/module.h> > + > +#include "probes-simulate-insn.h" > + > +#define sign_extend(x, signbit) \ > + ((x) | (0 - ((x) & (1 << (signbit))))) > + > +#define bbl_displacement(insn) \ > + sign_extend(((insn) & 0x3ffffff) << 2, 27) > + > +#define bcond_displacement(insn) \ > + sign_extend(((insn >> 5) & 0x7ffff) << 2, 21) > + > +#define cbz_displacement(insn) \ > + sign_extend(((insn >> 5) & 0x7ffff) << 2, 21) > + > +#define tbz_displacement(insn) \ > + sign_extend(((insn >> 5) & 0x3fff) << 2, 15) > + > +#define ldr_displacement(insn) \ > + sign_extend(((insn >> 5) & 0x7ffff) << 2, 21) > + > + > +unsigned long __kprobes check_cbz(u32 opcode, struct pt_regs *regs) > +{ > + int xn = opcode & 0x1f; > + > + return (opcode & (1 << 31)) ? > + !(regs->regs[xn]) : !(regs->regs[xn] & 0xffffffff); > +} > + > +unsigned long __kprobes check_cbnz(u32 opcode, struct pt_regs *regs) > +{ > + int xn = opcode & 0x1f; > + > + return (opcode & (1 << 31)) ? > + (regs->regs[xn]) : (regs->regs[xn] & 0xffffffff); > +} > + > +unsigned long __kprobes check_tbz(u32 opcode, struct pt_regs *regs) > +{ > + int xn = opcode & 0x1f; > + int bit_pos = ((opcode & (1 << 31)) >> 26) | ((opcode >> 19) & 0x1f); > + > + return ~((regs->regs[xn] >> bit_pos) & 0x1); > +} > + > +unsigned long __kprobes check_tbnz(u32 opcode, struct pt_regs *regs) > +{ > + int xn = opcode & 0x1f; > + int bit_pos = ((opcode & (1 << 31)) >> 26) | ((opcode >> 19) & 0x1f); > + > + return (regs->regs[xn] >> bit_pos) & 0x1; > +} > + > +/* > + * instruction simulate functions > + */ > +void __kprobes simulate_none(u32 opcode, long addr, struct pt_regs *regs) > +{ > +} I can't see anything that references simulate_none? > + > +void __kprobes > +simulate_adr_adrp(u32 opcode, long addr, struct pt_regs *regs) > +{ > + long imm, xn, val; > + > + xn = opcode & 0x1f; > + imm = ((opcode >> 3) & 0x1ffffc) | ((opcode >> 29) & 0x3); > + imm = sign_extend(imm, 20); > + if (opcode & 0x80000000) > + val = (imm<<12) + (addr & 0xfffffffffffff000); > + else > + val = imm + addr; > + > + regs->regs[xn] = val; > + > + instruction_pointer(regs) += 4; > +} > + > +void __kprobes > +simulate_b_bl(u32 opcode, long addr, struct pt_regs *regs) > +{ > + int disp = bbl_displacement(opcode); > + > + /* Link register is x30 */ > + if (opcode & (1 << 31)) > + regs->regs[30] = addr + 4; > + > + instruction_pointer(regs) = addr + disp; > +} > + > +void __kprobes > +simulate_b_cond(u32 opcode, long addr, struct pt_regs *regs) > +{ > + int disp = bcond_displacement(opcode); > + > + instruction_pointer(regs) = addr + disp; > +} > + > +void __kprobes > +simulate_br_blr_ret(u32 opcode, long addr, struct pt_regs *regs) > +{ > + int xn = (opcode >> 5) & 0x1f; > + > + /* Link register is x30 */ > + if (((opcode >> 21) & 0x3) == 1) > + regs->regs[30] = addr + 4; > + > + instruction_pointer(regs) = regs->regs[xn]; > +} > + > +void __kprobes > +simulate_cbz_cbnz(u32 opcode, long addr, struct pt_regs *regs) > +{ > + int disp = cbz_displacement(opcode); > + > + instruction_pointer(regs) = addr + disp; > +} > + > +void __kprobes > +simulate_tbz_tbnz(u32 opcode, long addr, struct pt_regs *regs) > +{ > + int disp = tbz_displacement(opcode); > + > + instruction_pointer(regs) = addr + disp; > +} > + > +void __kprobes > +simulate_ldr_literal(u32 opcode, long addr, struct pt_regs *regs) > +{ > + u64 *load_addr; > + int xn = opcode & 0x1f; > + int disp = ldr_displacement(opcode); > + > + load_addr = (u64 *) (addr + disp); > + > + if (opcode & (1 << 30)) /* x0-x31 */ > + regs->regs[xn] = *load_addr; > + else /* w0-w31 */ > + *(u32 *) (®s->regs[xn]) = (*(u32 *) (load_addr)); This looks wrong to me. The casting on the LHS will mean we set the bottom 32 bits of regs[xn] whilst leaving the upper-bits preserved. Loading into a w register should clear the upper 32 bits. I think we want instead something like: regs->regs[xn] = (u32) (*load_addr); > + > + instruction_pointer(regs) += 4; > +} > + > +void __kprobes > +simulate_ldrsw_literal(u32 opcode, long addr, struct pt_regs *regs) > +{ > + s32 *load_addr; > + int xn = opcode & 0x1f; > + int disp = ldr_displacement(opcode); > + > + load_addr = (s32 *) (addr + disp); > + regs->regs[xn] = *load_addr; > + > + instruction_pointer(regs) += 4; > +} > diff --git a/arch/arm64/kernel/probes-simulate-insn.h b/arch/arm64/kernel/probes-simulate-insn.h > new file mode 100644 > index 0000000..406f5c2 > --- /dev/null > +++ b/arch/arm64/kernel/probes-simulate-insn.h > @@ -0,0 +1,33 @@ > +/* > + * arch/arm64/kernel/probes-simulate-insn.h > + * > + * Copyright (C) 2013 Linaro Limited > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License version 2 as > + * published by the Free Software Foundation. > + * > + * This program is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > + * General Public License for more details. > + */ > + > +#ifndef _ARM_KERNEL_PROBES_SIMULATE_INSN_H > +#define _ARM_KERNEL_PROBES_SIMULATE_INSN_H > + > +unsigned long check_cbz(u32 opcode, struct pt_regs *regs); > +unsigned long check_cbnz(u32 opcode, struct pt_regs *regs); > +unsigned long check_tbz(u32 opcode, struct pt_regs *regs); > +unsigned long check_tbnz(u32 opcode, struct pt_regs *regs); > +void simulate_none(u32 opcode, long addr, struct pt_regs *regs); > +void simulate_adr_adrp(u32 opcode, long addr, struct pt_regs *regs); > +void simulate_b_bl(u32 opcode, long addr, struct pt_regs *regs); > +void simulate_b_cond(u32 opcode, long addr, struct pt_regs *regs); > +void simulate_br_blr_ret(u32 opcode, long addr, struct pt_regs *regs); > +void simulate_cbz_cbnz(u32 opcode, long addr, struct pt_regs *regs); > +void simulate_tbz_tbnz(u32 opcode, long addr, struct pt_regs *regs); > +void simulate_ldr_literal(u32 opcode, long addr, struct pt_regs *regs); > +void simulate_ldrsw_literal(u32 opcode, long addr, struct pt_regs *regs); > + > +#endif /* _ARM_KERNEL_PROBES_SIMULATE_INSN_H */ > -- > 1.8.1.2 >
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index 1319872..5e9d54f 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -32,7 +32,9 @@ arm64-obj-$(CONFIG_CPU_PM) += sleep.o suspend.o arm64-obj-$(CONFIG_CPU_IDLE) += cpuidle.o arm64-obj-$(CONFIG_JUMP_LABEL) += jump_label.o arm64-obj-$(CONFIG_KGDB) += kgdb.o -arm64-obj-$(CONFIG_KPROBES) += kprobes.o kprobes-arm64.o +arm64-obj-$(CONFIG_KPROBES) += kprobes.o kprobes-arm64.o \ + probes-simulate-insn.o \ + probes-condn-check.o arm64-obj-$(CONFIG_EFI) += efi.o efi-stub.o efi-entry.o arm64-obj-$(CONFIG_PCI) += pci.o arm64-obj-$(CONFIG_ARMV8_DEPRECATED) += armv8_deprecated.o diff --git a/arch/arm64/kernel/kprobes-arm64.c b/arch/arm64/kernel/kprobes-arm64.c index f958c52..8a7e6b0 100644 --- a/arch/arm64/kernel/kprobes-arm64.c +++ b/arch/arm64/kernel/kprobes-arm64.c @@ -20,6 +20,76 @@ #include <asm/insn.h> #include "kprobes-arm64.h" +#include "probes-simulate-insn.h" + +/* + * condition check functions for kprobes simulation + */ +static unsigned long __kprobes +__check_pstate(struct kprobe *p, struct pt_regs *regs) +{ + struct arch_specific_insn *asi = &p->ainsn; + unsigned long pstate = regs->pstate & 0xffffffff; + + return asi->pstate_cc(pstate); +} + +static unsigned long __kprobes +__check_cbz(struct kprobe *p, struct pt_regs *regs) +{ + return check_cbz((u32)p->opcode, regs); +} + +static unsigned long __kprobes +__check_cbnz(struct kprobe *p, struct pt_regs *regs) +{ + return check_cbnz((u32)p->opcode, regs); +} + +static unsigned long __kprobes +__check_tbz(struct kprobe *p, struct pt_regs *regs) +{ + return check_tbz((u32)p->opcode, regs); +} + +static unsigned long __kprobes +__check_tbnz(struct kprobe *p, struct pt_regs *regs) +{ + return check_tbnz((u32)p->opcode, regs); +} + +/* + * prepare functions for instruction simulation + */ +static void __kprobes +prepare_none(struct kprobe *p, struct arch_specific_insn *asi) +{ +} + +static void __kprobes +prepare_bcond(struct kprobe *p, struct arch_specific_insn *asi) +{ + kprobe_opcode_t insn = p->opcode; + + asi->check_condn = __check_pstate; + asi->pstate_cc = kprobe_condition_checks[insn & 0xf]; +} + +static void __kprobes +prepare_cbz_cbnz(struct kprobe *p, struct arch_specific_insn *asi) +{ + kprobe_opcode_t insn = p->opcode; + + asi->check_condn = (insn & (1 << 24)) ? __check_cbnz : __check_cbz; +} + +static void __kprobes +prepare_tbz_tbnz(struct kprobe *p, struct arch_specific_insn *asi) +{ + kprobe_opcode_t insn = p->opcode; + + asi->check_condn = (insn & (1 << 24)) ? __check_tbnz : __check_tbz; +} static bool __kprobes aarch64_insn_is_steppable(u32 insn) { @@ -63,6 +133,34 @@ arm_kprobe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi) */ if (aarch64_insn_is_steppable(insn)) return INSN_GOOD; + + asi->prepare = prepare_none; + + if (aarch64_insn_is_bcond(insn)) { + asi->prepare = prepare_bcond; + asi->handler = simulate_b_cond; + } else if (aarch64_insn_is_cb(insn)) { + asi->prepare = prepare_cbz_cbnz; + asi->handler = simulate_cbz_cbnz; + } else if (aarch64_insn_is_tb(insn)) { + asi->prepare = prepare_tbz_tbnz; + asi->handler = simulate_tbz_tbnz; + } else if (aarch64_insn_is_adr_adrp(insn)) + asi->handler = simulate_adr_adrp; + else if (aarch64_insn_is_b_bl(insn)) + asi->handler = simulate_b_bl; + else if (aarch64_insn_is_br_blr(insn) || aarch64_insn_is_ret(insn)) + asi->handler = simulate_br_blr_ret; + else if (aarch64_insn_is_ldr_lit(insn)) + asi->handler = simulate_ldr_literal; + else if (aarch64_insn_is_ldrsw_lit(insn)) + asi->handler = simulate_ldrsw_literal; else + /* + * Instruction cannot be stepped out-of-line and we don't + * (yet) simulate it. + */ return INSN_REJECTED; + + return INSN_GOOD_NO_SLOT; } diff --git a/arch/arm64/kernel/kprobes-arm64.h b/arch/arm64/kernel/kprobes-arm64.h index 87e7891..ff8a55f 100644 --- a/arch/arm64/kernel/kprobes-arm64.h +++ b/arch/arm64/kernel/kprobes-arm64.h @@ -22,6 +22,8 @@ enum kprobe_insn { INSN_GOOD, }; +extern kprobes_pstate_check_t * const kprobe_condition_checks[16]; + enum kprobe_insn __kprobes arm_kprobe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi); diff --git a/arch/arm64/kernel/kprobes.c b/arch/arm64/kernel/kprobes.c index 601d2c6..6255814 100644 --- a/arch/arm64/kernel/kprobes.c +++ b/arch/arm64/kernel/kprobes.c @@ -38,6 +38,9 @@ DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); +static void __kprobes +post_kprobe_handler(struct kprobe_ctlblk *, struct pt_regs *); + static void __kprobes arch_prepare_ss_slot(struct kprobe *p) { /* prepare insn slot */ @@ -54,6 +57,27 @@ static void __kprobes arch_prepare_ss_slot(struct kprobe *p) p->ainsn.restore.type = RESTORE_PC; } +static void __kprobes arch_prepare_simulate(struct kprobe *p) +{ + if (p->ainsn.prepare) + p->ainsn.prepare(p, &p->ainsn); + + /* This instructions is not executed xol. No need to adjust the PC */ + p->ainsn.restore.addr = 0; + p->ainsn.restore.type = NO_RESTORE; +} + +static void __kprobes arch_simulate_insn(struct kprobe *p, struct pt_regs *regs) +{ + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + + if (p->ainsn.handler) + p->ainsn.handler((u32)p->opcode, (long)p->addr, regs); + + /* single step simulated, now go for post processing */ + post_kprobe_handler(kcb, regs); +} + int __kprobes arch_prepare_kprobe(struct kprobe *p) { kprobe_opcode_t insn; @@ -72,7 +96,8 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p) return -EINVAL; case INSN_GOOD_NO_SLOT: /* insn need simulation */ - return -EINVAL; + p->ainsn.insn = NULL; + break; case INSN_GOOD: /* instruction uses slot */ p->ainsn.insn = get_insn_slot(); @@ -82,7 +107,10 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p) }; /* prepare the instruction */ - arch_prepare_ss_slot(p); + if (p->ainsn.insn) + arch_prepare_ss_slot(p); + else + arch_prepare_simulate(p); return 0; } @@ -231,7 +259,8 @@ static void __kprobes setup_singlestep(struct kprobe *p, kernel_enable_single_step(regs); instruction_pointer(regs) = slot; } else { - BUG(); + /* insn simulation */ + arch_simulate_insn(p, regs); } } diff --git a/arch/arm64/kernel/probes-condn-check.c b/arch/arm64/kernel/probes-condn-check.c new file mode 100644 index 0000000..e68aa0c --- /dev/null +++ b/arch/arm64/kernel/probes-condn-check.c @@ -0,0 +1,122 @@ +/* + * arch/arm64/kernel/probes-condn-check.c + * + * Copyright (C) 2013 Linaro Limited + * + * Copied from: arch/arm/kernel/kprobes-common.c + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * Description: + * + * AArch64 and AArch32 shares same conditional(CNZV) flags encoding. + * This file implements conditional check helpers compatible with + * both AArch64 and AArch32 modes. Uprobes on v8 can handle both 32-bit + * & 64-bit user-space instructions, so we abstract the common functions + * in this file. While AArch64 and AArch32 specific instruction handling + * are implemented in separate files, this file contains common bits. + */ +#include <linux/kernel.h> +#include <linux/module.h> +#include <asm/probes.h> + +static unsigned long __kprobes __check_eq(unsigned long pstate) +{ + return pstate & PSR_Z_BIT; +} + +static unsigned long __kprobes __check_ne(unsigned long pstate) +{ + return (~pstate) & PSR_Z_BIT; +} + +static unsigned long __kprobes __check_cs(unsigned long pstate) +{ + return pstate & PSR_C_BIT; +} + +static unsigned long __kprobes __check_cc(unsigned long pstate) +{ + return (~pstate) & PSR_C_BIT; +} + +static unsigned long __kprobes __check_mi(unsigned long pstate) +{ + return pstate & PSR_N_BIT; +} + +static unsigned long __kprobes __check_pl(unsigned long pstate) +{ + return (~pstate) & PSR_N_BIT; +} + +static unsigned long __kprobes __check_vs(unsigned long pstate) +{ + return pstate & PSR_V_BIT; +} + +static unsigned long __kprobes __check_vc(unsigned long pstate) +{ + return (~pstate) & PSR_V_BIT; +} + +static unsigned long __kprobes __check_hi(unsigned long pstate) +{ + pstate &= ~(pstate >> 1); /* PSR_C_BIT &= ~PSR_Z_BIT */ + return pstate & PSR_C_BIT; +} + +static unsigned long __kprobes __check_ls(unsigned long pstate) +{ + pstate &= ~(pstate >> 1); /* PSR_C_BIT &= ~PSR_Z_BIT */ + return (~pstate) & PSR_C_BIT; +} + +static unsigned long __kprobes __check_ge(unsigned long pstate) +{ + pstate ^= (pstate << 3); /* PSR_N_BIT ^= PSR_V_BIT */ + return (~pstate) & PSR_N_BIT; +} + +static unsigned long __kprobes __check_lt(unsigned long pstate) +{ + pstate ^= (pstate << 3); /* PSR_N_BIT ^= PSR_V_BIT */ + return pstate & PSR_N_BIT; +} + +static unsigned long __kprobes __check_gt(unsigned long pstate) +{ + /*PSR_N_BIT ^= PSR_V_BIT */ + unsigned long temp = pstate ^ (pstate << 3); + + temp |= (pstate << 1); /*PSR_N_BIT |= PSR_Z_BIT */ + return (~temp) & PSR_N_BIT; +} + +static unsigned long __kprobes __check_le(unsigned long pstate) +{ + /*PSR_N_BIT ^= PSR_V_BIT */ + unsigned long temp = pstate ^ (pstate << 3); + + temp |= (pstate << 1); /*PSR_N_BIT |= PSR_Z_BIT */ + return temp & PSR_N_BIT; +} + +static unsigned long __kprobes __check_al(unsigned long pstate) +{ + return true; +} + +kprobes_pstate_check_t * const kprobe_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 +}; diff --git a/arch/arm64/kernel/probes-simulate-insn.c b/arch/arm64/kernel/probes-simulate-insn.c new file mode 100644 index 0000000..a224c91 --- /dev/null +++ b/arch/arm64/kernel/probes-simulate-insn.c @@ -0,0 +1,174 @@ +/* + * arch/arm64/kernel/probes-simulate-insn.c + * + * Copyright (C) 2013 Linaro Limited. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + */ + +#include <linux/kernel.h> +#include <linux/kprobes.h> +#include <linux/module.h> + +#include "probes-simulate-insn.h" + +#define sign_extend(x, signbit) \ + ((x) | (0 - ((x) & (1 << (signbit))))) + +#define bbl_displacement(insn) \ + sign_extend(((insn) & 0x3ffffff) << 2, 27) + +#define bcond_displacement(insn) \ + sign_extend(((insn >> 5) & 0x7ffff) << 2, 21) + +#define cbz_displacement(insn) \ + sign_extend(((insn >> 5) & 0x7ffff) << 2, 21) + +#define tbz_displacement(insn) \ + sign_extend(((insn >> 5) & 0x3fff) << 2, 15) + +#define ldr_displacement(insn) \ + sign_extend(((insn >> 5) & 0x7ffff) << 2, 21) + + +unsigned long __kprobes check_cbz(u32 opcode, struct pt_regs *regs) +{ + int xn = opcode & 0x1f; + + return (opcode & (1 << 31)) ? + !(regs->regs[xn]) : !(regs->regs[xn] & 0xffffffff); +} + +unsigned long __kprobes check_cbnz(u32 opcode, struct pt_regs *regs) +{ + int xn = opcode & 0x1f; + + return (opcode & (1 << 31)) ? + (regs->regs[xn]) : (regs->regs[xn] & 0xffffffff); +} + +unsigned long __kprobes check_tbz(u32 opcode, struct pt_regs *regs) +{ + int xn = opcode & 0x1f; + int bit_pos = ((opcode & (1 << 31)) >> 26) | ((opcode >> 19) & 0x1f); + + return ~((regs->regs[xn] >> bit_pos) & 0x1); +} + +unsigned long __kprobes check_tbnz(u32 opcode, struct pt_regs *regs) +{ + int xn = opcode & 0x1f; + int bit_pos = ((opcode & (1 << 31)) >> 26) | ((opcode >> 19) & 0x1f); + + return (regs->regs[xn] >> bit_pos) & 0x1; +} + +/* + * instruction simulate functions + */ +void __kprobes simulate_none(u32 opcode, long addr, struct pt_regs *regs) +{ +} + +void __kprobes +simulate_adr_adrp(u32 opcode, long addr, struct pt_regs *regs) +{ + long imm, xn, val; + + xn = opcode & 0x1f; + imm = ((opcode >> 3) & 0x1ffffc) | ((opcode >> 29) & 0x3); + imm = sign_extend(imm, 20); + if (opcode & 0x80000000) + val = (imm<<12) + (addr & 0xfffffffffffff000); + else + val = imm + addr; + + regs->regs[xn] = val; + + instruction_pointer(regs) += 4; +} + +void __kprobes +simulate_b_bl(u32 opcode, long addr, struct pt_regs *regs) +{ + int disp = bbl_displacement(opcode); + + /* Link register is x30 */ + if (opcode & (1 << 31)) + regs->regs[30] = addr + 4; + + instruction_pointer(regs) = addr + disp; +} + +void __kprobes +simulate_b_cond(u32 opcode, long addr, struct pt_regs *regs) +{ + int disp = bcond_displacement(opcode); + + instruction_pointer(regs) = addr + disp; +} + +void __kprobes +simulate_br_blr_ret(u32 opcode, long addr, struct pt_regs *regs) +{ + int xn = (opcode >> 5) & 0x1f; + + /* Link register is x30 */ + if (((opcode >> 21) & 0x3) == 1) + regs->regs[30] = addr + 4; + + instruction_pointer(regs) = regs->regs[xn]; +} + +void __kprobes +simulate_cbz_cbnz(u32 opcode, long addr, struct pt_regs *regs) +{ + int disp = cbz_displacement(opcode); + + instruction_pointer(regs) = addr + disp; +} + +void __kprobes +simulate_tbz_tbnz(u32 opcode, long addr, struct pt_regs *regs) +{ + int disp = tbz_displacement(opcode); + + instruction_pointer(regs) = addr + disp; +} + +void __kprobes +simulate_ldr_literal(u32 opcode, long addr, struct pt_regs *regs) +{ + u64 *load_addr; + int xn = opcode & 0x1f; + int disp = ldr_displacement(opcode); + + load_addr = (u64 *) (addr + disp); + + if (opcode & (1 << 30)) /* x0-x31 */ + regs->regs[xn] = *load_addr; + else /* w0-w31 */ + *(u32 *) (®s->regs[xn]) = (*(u32 *) (load_addr)); + + instruction_pointer(regs) += 4; +} + +void __kprobes +simulate_ldrsw_literal(u32 opcode, long addr, struct pt_regs *regs) +{ + s32 *load_addr; + int xn = opcode & 0x1f; + int disp = ldr_displacement(opcode); + + load_addr = (s32 *) (addr + disp); + regs->regs[xn] = *load_addr; + + instruction_pointer(regs) += 4; +} diff --git a/arch/arm64/kernel/probes-simulate-insn.h b/arch/arm64/kernel/probes-simulate-insn.h new file mode 100644 index 0000000..406f5c2 --- /dev/null +++ b/arch/arm64/kernel/probes-simulate-insn.h @@ -0,0 +1,33 @@ +/* + * arch/arm64/kernel/probes-simulate-insn.h + * + * Copyright (C) 2013 Linaro Limited + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + */ + +#ifndef _ARM_KERNEL_PROBES_SIMULATE_INSN_H +#define _ARM_KERNEL_PROBES_SIMULATE_INSN_H + +unsigned long check_cbz(u32 opcode, struct pt_regs *regs); +unsigned long check_cbnz(u32 opcode, struct pt_regs *regs); +unsigned long check_tbz(u32 opcode, struct pt_regs *regs); +unsigned long check_tbnz(u32 opcode, struct pt_regs *regs); +void simulate_none(u32 opcode, long addr, struct pt_regs *regs); +void simulate_adr_adrp(u32 opcode, long addr, struct pt_regs *regs); +void simulate_b_bl(u32 opcode, long addr, struct pt_regs *regs); +void simulate_b_cond(u32 opcode, long addr, struct pt_regs *regs); +void simulate_br_blr_ret(u32 opcode, long addr, struct pt_regs *regs); +void simulate_cbz_cbnz(u32 opcode, long addr, struct pt_regs *regs); +void simulate_tbz_tbnz(u32 opcode, long addr, struct pt_regs *regs); +void simulate_ldr_literal(u32 opcode, long addr, struct pt_regs *regs); +void simulate_ldrsw_literal(u32 opcode, long addr, struct pt_regs *regs); + +#endif /* _ARM_KERNEL_PROBES_SIMULATE_INSN_H */