summaryrefslogtreecommitdiffstats
path: root/arch/arm64/kernel/probes/simulate-insn.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/arm64/kernel/probes/simulate-insn.c')
-rw-r--r--arch/arm64/kernel/probes/simulate-insn.c201
1 files changed, 201 insertions, 0 deletions
diff --git a/arch/arm64/kernel/probes/simulate-insn.c b/arch/arm64/kernel/probes/simulate-insn.c
new file mode 100644
index 000000000..25f67ec59
--- /dev/null
+++ b/arch/arm64/kernel/probes/simulate-insn.c
@@ -0,0 +1,201 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * arch/arm64/kernel/probes/simulate-insn.c
+ *
+ * Copyright (C) 2013 Linaro Limited.
+ */
+
+#include <linux/bitops.h>
+#include <linux/kernel.h>
+#include <linux/kprobes.h>
+
+#include <asm/ptrace.h>
+
+#include "simulate-insn.h"
+
+#define bbl_displacement(insn) \
+ sign_extend32(((insn) & 0x3ffffff) << 2, 27)
+
+#define bcond_displacement(insn) \
+ sign_extend32(((insn >> 5) & 0x7ffff) << 2, 20)
+
+#define cbz_displacement(insn) \
+ sign_extend32(((insn >> 5) & 0x7ffff) << 2, 20)
+
+#define tbz_displacement(insn) \
+ sign_extend32(((insn >> 5) & 0x3fff) << 2, 15)
+
+#define ldr_displacement(insn) \
+ sign_extend32(((insn >> 5) & 0x7ffff) << 2, 20)
+
+static inline void set_x_reg(struct pt_regs *regs, int reg, u64 val)
+{
+ pt_regs_write_reg(regs, reg, val);
+}
+
+static inline void set_w_reg(struct pt_regs *regs, int reg, u64 val)
+{
+ pt_regs_write_reg(regs, reg, lower_32_bits(val));
+}
+
+static inline u64 get_x_reg(struct pt_regs *regs, int reg)
+{
+ return pt_regs_read_reg(regs, reg);
+}
+
+static inline u32 get_w_reg(struct pt_regs *regs, int reg)
+{
+ return lower_32_bits(pt_regs_read_reg(regs, reg));
+}
+
+static bool __kprobes check_cbz(u32 opcode, struct pt_regs *regs)
+{
+ int xn = opcode & 0x1f;
+
+ return (opcode & (1 << 31)) ?
+ (get_x_reg(regs, xn) == 0) : (get_w_reg(regs, xn) == 0);
+}
+
+static bool __kprobes check_cbnz(u32 opcode, struct pt_regs *regs)
+{
+ int xn = opcode & 0x1f;
+
+ return (opcode & (1 << 31)) ?
+ (get_x_reg(regs, xn) != 0) : (get_w_reg(regs, xn) != 0);
+}
+
+static bool __kprobes check_tbz(u32 opcode, struct pt_regs *regs)
+{
+ int xn = opcode & 0x1f;
+ int bit_pos = ((opcode & (1 << 31)) >> 26) | ((opcode >> 19) & 0x1f);
+
+ return ((get_x_reg(regs, xn) >> bit_pos) & 0x1) == 0;
+}
+
+static bool __kprobes check_tbnz(u32 opcode, struct pt_regs *regs)
+{
+ int xn = opcode & 0x1f;
+ int bit_pos = ((opcode & (1 << 31)) >> 26) | ((opcode >> 19) & 0x1f);
+
+ return ((get_x_reg(regs, xn) >> bit_pos) & 0x1) != 0;
+}
+
+/*
+ * instruction simulation functions
+ */
+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_extend64(imm, 20);
+ if (opcode & 0x80000000)
+ val = (imm<<12) + (addr & 0xfffffffffffff000);
+ else
+ val = imm + addr;
+
+ set_x_reg(regs, xn, val);
+
+ instruction_pointer_set(regs, 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))
+ set_x_reg(regs, 30, addr + 4);
+
+ instruction_pointer_set(regs, addr + disp);
+}
+
+void __kprobes
+simulate_b_cond(u32 opcode, long addr, struct pt_regs *regs)
+{
+ int disp = 4;
+
+ if (aarch32_opcode_cond_checks[opcode & 0xf](regs->pstate & 0xffffffff))
+ disp = bcond_displacement(opcode);
+
+ instruction_pointer_set(regs, addr + disp);
+}
+
+void __kprobes
+simulate_br_blr_ret(u32 opcode, long addr, struct pt_regs *regs)
+{
+ int xn = (opcode >> 5) & 0x1f;
+
+ /* update pc first in case we're doing a "blr lr" */
+ instruction_pointer_set(regs, get_x_reg(regs, xn));
+
+ /* Link register is x30 */
+ if (((opcode >> 21) & 0x3) == 1)
+ set_x_reg(regs, 30, addr + 4);
+}
+
+void __kprobes
+simulate_cbz_cbnz(u32 opcode, long addr, struct pt_regs *regs)
+{
+ int disp = 4;
+
+ if (opcode & (1 << 24)) {
+ if (check_cbnz(opcode, regs))
+ disp = cbz_displacement(opcode);
+ } else {
+ if (check_cbz(opcode, regs))
+ disp = cbz_displacement(opcode);
+ }
+ instruction_pointer_set(regs, addr + disp);
+}
+
+void __kprobes
+simulate_tbz_tbnz(u32 opcode, long addr, struct pt_regs *regs)
+{
+ int disp = 4;
+
+ if (opcode & (1 << 24)) {
+ if (check_tbnz(opcode, regs))
+ disp = tbz_displacement(opcode);
+ } else {
+ if (check_tbz(opcode, regs))
+ disp = tbz_displacement(opcode);
+ }
+ instruction_pointer_set(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;
+
+ disp = ldr_displacement(opcode);
+ load_addr = (u64 *) (addr + disp);
+
+ if (opcode & (1 << 30)) /* x0-x30 */
+ set_x_reg(regs, xn, *load_addr);
+ else /* w0-w30 */
+ set_w_reg(regs, xn, *load_addr);
+
+ instruction_pointer_set(regs, 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;
+
+ disp = ldr_displacement(opcode);
+ load_addr = (s32 *) (addr + disp);
+
+ set_x_reg(regs, xn, *load_addr);
+
+ instruction_pointer_set(regs, instruction_pointer(regs) + 4);
+}