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riscv: kprobes: implement the auipc instruction

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

Signed-off-by: Chen Lifu <chenlifu@huawei.com>
[Palmer: commit message]
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
This commit is contained in:
Chen Lifu 2021-06-29 10:34:54 +08:00 committed by Palmer Dabbelt
parent e73f0f0ee7
commit b7d2be48cc
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GPG Key ID: 2E1319F35FBB1889
2 changed files with 35 additions and 1 deletions
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2
arch/riscv/kernel/probes/decode-insn.c
View File

@ -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;
}

34
arch/riscv/kernel/probes/simulate-insn.c
View File

@ -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;
}