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riscv: kprobes: simulate c.j instruction

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kprobes currently rejects c.j instruction. Implement it.

Signed-off-by: Nam Cao <namcaov@gmail.com>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Link: https://lore.kernel.org/r/6ef76cd9984b8015826649d13f870f8ac45a2d0d.1690704360.git.namcaov@gmail.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Nam Cao 2023-07-30 10:27:07 +02:00 committed by Palmer Dabbelt
parent 06c2afb862
commit a93892974f
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GPG Key ID: 2E1319F35FBB1889
3 changed files with 27 additions and 1 deletions
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3
arch/riscv/kernel/probes/decode-insn.c
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@ -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);

24
arch/riscv/kernel/probes/simulate-insn.c
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@ -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;
}

1
arch/riscv/kernel/probes/simulate-insn.h
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@ -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 */