Unverified Commit b7d2be48 authored by Chen Lifu's avatar Chen Lifu Committed by Palmer Dabbelt
Browse files

riscv: kprobes: implement the auipc instruction 



This has been tested by probing a module that contains an auipc
instruction.

Signed-off-by: default avatarChen Lifu <chenlifu@huawei.com>
[Palmer: commit message]
Signed-off-by: default avatarPalmer Dabbelt <palmerdabbelt@google.com>
parent e73f0f0e

arch/riscv/kernel/probes/decode-insn.c

+1 −1
Original line number Diff line number Diff line
@@ -38,11 +38,11 @@ riscv_probe_decode_insn(probe_opcode_t *addr, struct arch_probe_insn *api) 
	RISCV_INSN_REJECTED(c_ebreak,		insn);

#endif



	RISCV_INSN_REJECTED(auipc,		insn);

	RISCV_INSN_REJECTED(branch,		insn);



	RISCV_INSN_SET_SIMULATE(jal,		insn);

	RISCV_INSN_SET_SIMULATE(jalr,		insn);

	RISCV_INSN_SET_SIMULATE(auipc,		insn);



	return INSN_GOOD;

}

arch/riscv/kernel/probes/simulate-insn.c

+34 −0
Original line number Diff line number Diff line
@@ -83,3 +83,37 @@ bool __kprobes simulate_jalr(u32 opcode, unsigned long addr, struct pt_regs *reg 


	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;

}