Re: [PATCH v12 07/10] arm64: kprobes instruction simulation support
From: David Long
Date: Thu May 26 2016 - 15:28:40 EST
On 05/18/2016 09:52 PM, Huang Shijie wrote:
On Wed, Apr 27, 2016 at 02:53:02PM -0400, David Long wrote:
From: Sandeepa Prabhu <sandeepa.s.prabhu@xxxxxxxxx>
Kprobes needs simulation of instructions that cannot be stepped
from a 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.
The following instruction categories 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.
Thanks to Will Cohen for assorted suggested changes.
Signed-off-by: Sandeepa Prabhu <sandeepa.s.prabhu@xxxxxxxxx>
Signed-off-by: William Cohen <wcohen@xxxxxxxxxx>
Signed-off-by: David A. Long <dave.long@xxxxxxxxxx>
---
arch/arm64/include/asm/insn.h | 1 +
arch/arm64/include/asm/probes.h | 5 +-
arch/arm64/kernel/Makefile | 3 +-
arch/arm64/kernel/insn.c | 1 +
arch/arm64/kernel/kprobes-arm64.c | 29 ++++
arch/arm64/kernel/kprobes.c | 32 ++++-
arch/arm64/kernel/probes-simulate-insn.c | 218 +++++++++++++++++++++++++++++++
arch/arm64/kernel/probes-simulate-insn.h | 28 ++++
8 files changed, 311 insertions(+), 6 deletions(-)
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/include/asm/insn.h b/arch/arm64/include/asm/insn.h
index b9567a1..26cee10 100644
--- a/arch/arm64/include/asm/insn.h
+++ b/arch/arm64/include/asm/insn.h
@@ -410,6 +410,7 @@ u32 aarch32_insn_mcr_extract_crm(u32 insn);
typedef bool (pstate_check_t)(unsigned long);
extern pstate_check_t * const opcode_condition_checks[16];
+
#endif /* __ASSEMBLY__ */
#endif /* __ASM_INSN_H */
diff --git a/arch/arm64/include/asm/probes.h b/arch/arm64/include/asm/probes.h
index c5fcbe6..d524f7d 100644
--- a/arch/arm64/include/asm/probes.h
+++ b/arch/arm64/include/asm/probes.h
@@ -15,11 +15,12 @@
#ifndef _ARM_PROBES_H
#define _ARM_PROBES_H
+#include <asm/opcodes.h>
+
struct kprobe;
struct arch_specific_insn;
typedef u32 kprobe_opcode_t;
-typedef unsigned long (kprobes_pstate_check_t)(unsigned long);
typedef void (kprobes_handler_t) (u32 opcode, long addr, struct pt_regs *);
enum pc_restore_type {
@@ -35,7 +36,7 @@ struct kprobe_pc_restore {
/* architecture specific copy of original instruction */
struct arch_specific_insn {
kprobe_opcode_t *insn;
- kprobes_pstate_check_t *pstate_cc;
+ pstate_check_t *pstate_cc;
kprobes_handler_t *handler;
/* restore address after step xol */
struct kprobe_pc_restore restore;
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index 8816de2..43bf6cc 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -37,7 +37,8 @@ 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
arm64-obj-$(CONFIG_EFI) += efi.o efi-entry.stub.o
arm64-obj-$(CONFIG_PCI) += pci.o
arm64-obj-$(CONFIG_ARMV8_DEPRECATED) += armv8_deprecated.o
diff --git a/arch/arm64/kernel/insn.c b/arch/arm64/kernel/insn.c
index f79e72e..bb2738c 100644
--- a/arch/arm64/kernel/insn.c
+++ b/arch/arm64/kernel/insn.c
@@ -30,6 +30,7 @@
#include <asm/cacheflush.h>
#include <asm/debug-monitors.h>
#include <asm/fixmap.h>
+#include <asm/opcodes.h>
#include <asm/insn.h>
#define AARCH64_INSN_SF_BIT BIT(31)
diff --git a/arch/arm64/kernel/kprobes-arm64.c b/arch/arm64/kernel/kprobes-arm64.c
index e07727a..487238a 100644
--- a/arch/arm64/kernel/kprobes-arm64.c
+++ b/arch/arm64/kernel/kprobes-arm64.c
@@ -21,6 +21,7 @@
#include <asm/sections.h>
#include "kprobes-arm64.h"
+#include "probes-simulate-insn.h"
static bool __kprobes aarch64_insn_is_steppable(u32 insn)
{
@@ -62,8 +63,36 @@ arm_probe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi)
*/
if (aarch64_insn_is_steppable(insn))
return INSN_GOOD;
+
+ if (aarch64_insn_is_bcond(insn)) {
+ asi->handler = simulate_b_cond;
+ } else if (aarch64_insn_is_cbz(insn) ||
+ aarch64_insn_is_cbnz(insn)) {
+ asi->handler = simulate_cbz_cbnz;
+ } else if (aarch64_insn_is_tbz(insn) ||
+ aarch64_insn_is_tbnz(insn)) {
+ asi->handler = simulate_tbz_tbnz;
+ } else if (aarch64_insn_is_adr_adrp(insn))
+ asi->handler = simulate_adr_adrp;
+ else if (aarch64_insn_is_b(insn) ||
+ aarch64_insn_is_bl(insn))
+ asi->handler = simulate_b_bl;
For the same codingstyle, we'd better add more "{}" here and below.
thanks
Huang Shijie
+ else if (aarch64_insn_is_br(insn) ||
+ aarch64_insn_is_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;
}
I've made this change for the next version of the patch.
Thanks,
-dl