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-rw-r--r--arch/riscv/kernel/probes/simulate-insn.c197
1 files changed, 197 insertions, 0 deletions
diff --git a/arch/riscv/kernel/probes/simulate-insn.c b/arch/riscv/kernel/probes/simulate-insn.c
new file mode 100644
index 000000000..41bf1eb01
--- /dev/null
+++ b/arch/riscv/kernel/probes/simulate-insn.c
@@ -0,0 +1,197 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+#include <linux/bitops.h>
+#include <linux/kernel.h>
+#include <linux/kprobes.h>
+
+#include "decode-insn.h"
+#include "simulate-insn.h"
+
+static inline bool rv_insn_reg_get_val(struct pt_regs *regs, u32 index,
+ unsigned long *ptr)
+{
+ if (index == 0)
+ *ptr = 0;
+ else if (index <= 31)
+ *ptr = *((unsigned long *)regs + index);
+ else
+ return false;
+
+ return true;
+}
+
+static inline bool rv_insn_reg_set_val(struct pt_regs *regs, u32 index,
+ unsigned long val)
+{
+ if (index == 0)
+ return true;
+ else if (index <= 31)
+ *((unsigned long *)regs + index) = val;
+ else
+ return false;
+
+ return true;
+}
+
+bool __kprobes simulate_jal(u32 opcode, unsigned long addr, struct pt_regs *regs)
+{
+ /*
+ * 31 30 21 20 19 12 11 7 6 0
+ * imm [20] | imm[10:1] | imm[11] | imm[19:12] | rd | opcode
+ * 1 10 1 8 5 JAL/J
+ */
+ bool ret;
+ u32 imm;
+ u32 index = (opcode >> 7) & 0x1f;
+
+ ret = rv_insn_reg_set_val(regs, index, addr + 4);
+ if (!ret)
+ return ret;
+
+ imm = ((opcode >> 21) & 0x3ff) << 1;
+ imm |= ((opcode >> 20) & 0x1) << 11;
+ imm |= ((opcode >> 12) & 0xff) << 12;
+ imm |= ((opcode >> 31) & 0x1) << 20;
+
+ instruction_pointer_set(regs, addr + sign_extend32((imm), 20));
+
+ return ret;
+}
+
+bool __kprobes simulate_jalr(u32 opcode, unsigned long addr, struct pt_regs *regs)
+{
+ /*
+ * 31 20 19 15 14 12 11 7 6 0
+ * offset[11:0] | rs1 | 010 | rd | opcode
+ * 12 5 3 5 JALR/JR
+ */
+ bool ret;
+ unsigned long base_addr;
+ u32 imm = (opcode >> 20) & 0xfff;
+ u32 rd_index = (opcode >> 7) & 0x1f;
+ u32 rs1_index = (opcode >> 15) & 0x1f;
+
+ ret = rv_insn_reg_get_val(regs, rs1_index, &base_addr);
+ if (!ret)
+ return ret;
+
+ ret = rv_insn_reg_set_val(regs, rd_index, addr + 4);
+ if (!ret)
+ return ret;
+
+ instruction_pointer_set(regs, (base_addr + sign_extend32((imm), 11))&~1);
+
+ return ret;
+}
+
+#define auipc_rd_idx(opcode) \
+ ((opcode >> 7) & 0x1f)
+
+#define auipc_imm(opcode) \
+ ((((opcode) >> 12) & 0xfffff) << 12)
+
+#if __riscv_xlen == 64
+#define auipc_offset(opcode) sign_extend64(auipc_imm(opcode), 31)
+#elif __riscv_xlen == 32
+#define auipc_offset(opcode) auipc_imm(opcode)
+#else
+#error "Unexpected __riscv_xlen"
+#endif
+
+bool __kprobes simulate_auipc(u32 opcode, unsigned long addr, struct pt_regs *regs)
+{
+ /*
+ * auipc instruction:
+ * 31 12 11 7 6 0
+ * | imm[31:12] | rd | opcode |
+ * 20 5 7
+ */
+
+ u32 rd_idx = auipc_rd_idx(opcode);
+ unsigned long rd_val = addr + auipc_offset(opcode);
+
+ if (!rv_insn_reg_set_val(regs, rd_idx, rd_val))
+ return false;
+
+ instruction_pointer_set(regs, addr + 4);
+
+ return true;
+}
+
+#define branch_rs1_idx(opcode) \
+ (((opcode) >> 15) & 0x1f)
+
+#define branch_rs2_idx(opcode) \
+ (((opcode) >> 20) & 0x1f)
+
+#define branch_funct3(opcode) \
+ (((opcode) >> 12) & 0x7)
+
+#define branch_imm(opcode) \
+ (((((opcode) >> 8) & 0xf ) << 1) | \
+ ((((opcode) >> 25) & 0x3f) << 5) | \
+ ((((opcode) >> 7) & 0x1 ) << 11) | \
+ ((((opcode) >> 31) & 0x1 ) << 12))
+
+#define branch_offset(opcode) \
+ sign_extend32((branch_imm(opcode)), 12)
+
+#define BRANCH_BEQ 0x0
+#define BRANCH_BNE 0x1
+#define BRANCH_BLT 0x4
+#define BRANCH_BGE 0x5
+#define BRANCH_BLTU 0x6
+#define BRANCH_BGEU 0x7
+
+bool __kprobes simulate_branch(u32 opcode, unsigned long addr, struct pt_regs *regs)
+{
+ /*
+ * branch instructions:
+ * 31 30 25 24 20 19 15 14 12 11 8 7 6 0
+ * | imm[12] | imm[10:5] | rs2 | rs1 | funct3 | imm[4:1] | imm[11] | opcode |
+ * 1 6 5 5 3 4 1 7
+ * imm[12|10:5] rs2 rs1 000 imm[4:1|11] 1100011 BEQ
+ * imm[12|10:5] rs2 rs1 001 imm[4:1|11] 1100011 BNE
+ * imm[12|10:5] rs2 rs1 100 imm[4:1|11] 1100011 BLT
+ * imm[12|10:5] rs2 rs1 101 imm[4:1|11] 1100011 BGE
+ * imm[12|10:5] rs2 rs1 110 imm[4:1|11] 1100011 BLTU
+ * imm[12|10:5] rs2 rs1 111 imm[4:1|11] 1100011 BGEU
+ */
+
+ s32 offset;
+ s32 offset_tmp;
+ unsigned long rs1_val;
+ unsigned long rs2_val;
+
+ if (!rv_insn_reg_get_val(regs, branch_rs1_idx(opcode), &rs1_val) ||
+ !rv_insn_reg_get_val(regs, branch_rs2_idx(opcode), &rs2_val))
+ return false;
+
+ offset_tmp = branch_offset(opcode);
+ switch (branch_funct3(opcode)) {
+ case BRANCH_BEQ:
+ offset = (rs1_val == rs2_val) ? offset_tmp : 4;
+ break;
+ case BRANCH_BNE:
+ offset = (rs1_val != rs2_val) ? offset_tmp : 4;
+ break;
+ case BRANCH_BLT:
+ offset = ((long)rs1_val < (long)rs2_val) ? offset_tmp : 4;
+ break;
+ case BRANCH_BGE:
+ offset = ((long)rs1_val >= (long)rs2_val) ? offset_tmp : 4;
+ break;
+ case BRANCH_BLTU:
+ offset = (rs1_val < rs2_val) ? offset_tmp : 4;
+ break;
+ case BRANCH_BGEU:
+ offset = (rs1_val >= rs2_val) ? offset_tmp : 4;
+ break;
+ default:
+ return false;
+ }
+
+ instruction_pointer_set(regs, addr + offset);
+
+ return true;
+}