Unverified Commit a9389297 authored by Nam Cao's avatar Nam Cao Committed by Palmer Dabbelt
Browse files

riscv: kprobes: simulate c.j instruction 



kprobes currently rejects c.j instruction. Implement it.

Signed-off-by: default avatarNam Cao <namcaov@gmail.com>
Reviewed-by: default avatarCharlie Jenkins <charlie@rivosinc.com>
Link: https://lore.kernel.org/r/6ef76cd9984b8015826649d13f870f8ac45a2d0d.1690704360.git.namcaov@gmail.com


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent 06c2afb8

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

+2 −1
Original line number Diff line number Diff line
@@ -29,13 +29,14 @@ riscv_probe_decode_insn(probe_opcode_t *addr, struct arch_probe_insn *api) 
	 * TODO: the REJECTED ones below need to be implemented

	 */

#ifdef CONFIG_RISCV_ISA_C

	RISCV_INSN_REJECTED(c_j,		insn);

	RISCV_INSN_REJECTED(c_jr,		insn);

	RISCV_INSN_REJECTED(c_jal,		insn);

	RISCV_INSN_REJECTED(c_jalr,		insn);

	RISCV_INSN_REJECTED(c_beqz,		insn);

	RISCV_INSN_REJECTED(c_bnez,		insn);

	RISCV_INSN_REJECTED(c_ebreak,		insn);



	RISCV_INSN_SET_SIMULATE(c_j,		insn);

#endif



	RISCV_INSN_SET_SIMULATE(jal,		insn);

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

+24 −0
Original line number Diff line number Diff line
@@ -188,3 +188,27 @@ bool __kprobes simulate_branch(u32 opcode, unsigned long addr, struct pt_regs *r 


	return true;

}



bool __kprobes simulate_c_j(u32 opcode, unsigned long addr, struct pt_regs *regs)

{

	/*

	 *  15    13 12                            2 1      0

	 * | funct3 | offset[11|4|9:8|10|6|7|3:1|5] | opcode |

	 *     3                   11                    2

	 */



	s32 offset;



	offset  = ((opcode >> 3)  & 0x7) << 1;

	offset |= ((opcode >> 11) & 0x1) << 4;

	offset |= ((opcode >> 2)  & 0x1) << 5;

	offset |= ((opcode >> 7)  & 0x1) << 6;

	offset |= ((opcode >> 6)  & 0x1) << 7;

	offset |= ((opcode >> 9)  & 0x3) << 8;

	offset |= ((opcode >> 8)  & 0x1) << 10;

	offset |= ((opcode >> 12) & 0x1) << 11;



	instruction_pointer_set(regs, addr + sign_extend32(offset, 11));



	return true;

}

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

+1 −0
Original line number Diff line number Diff line
@@ -24,5 +24,6 @@ bool simulate_auipc(u32 opcode, unsigned long addr, struct pt_regs *regs); 
bool simulate_branch(u32 opcode, unsigned long addr, struct pt_regs *regs);

bool simulate_jal(u32 opcode, unsigned long addr, struct pt_regs *regs);

bool simulate_jalr(u32 opcode, unsigned long addr, struct pt_regs *regs);

bool simulate_c_j(u32 opcode, unsigned long addr, struct pt_regs *regs);



#endif /* _RISCV_KERNEL_PROBES_SIMULATE_INSN_H */