[PATCH v3 06/12] objtool/klp: Add LoongArch jump opcode bytes support
From: George Guo <hidden>
Date: 2026-07-07 07:22:54
Also in:
lkml, llvm, loongarch
Subsystem:
objtool, the rest · Maintainers:
Josh Poimboeuf, Peter Zijlstra, Linus Torvalds
From: George Guo <redacted> Implement arch_jump_opcode_bytes() for LoongArch so that klp checksums for jump/call instructions with non-relocated destination offsets are position-independent, mirroring the x86 and arm64 implementations. Mask out the embedded branch offset while preserving the opcode and the register operands, which differ per instruction format: - B/BL (reg0i26): no regs -> 0xfc000000 - BEQZ/BNEZ/BCEQZ/BCNEZ (reg1i21): keep rj/cj -> 0xfc0003e0 - JIRL/BEQ/BNE/.../BGEU (reg2i16): keep rj/rd -> 0xfc0003ff Co-developed-by: Kexin Liu <redacted> Signed-off-by: Kexin Liu <redacted> Signed-off-by: George Guo <redacted> --- tools/objtool/arch/loongarch/decode.c | 41 +++++++++++++++++++++++++++ 1 file changed, 41 insertions(+)
diff --git a/tools/objtool/arch/loongarch/decode.c b/tools/objtool/arch/loongarch/decode.c
index 674e4efd138f..12facd0cc8d1 100644
--- a/tools/objtool/arch/loongarch/decode.c
+++ b/tools/objtool/arch/loongarch/decode.c@@ -432,6 +432,47 @@ unsigned long arch_jump_table_sym_offset(struct reloc *reloc, struct reloc *tabl } } +size_t arch_jump_opcode_bytes(struct objtool_file *file, struct instruction *insn, + unsigned char *buf) +{ + union loongarch_instruction *code; + u32 insn_word; + + insn_word = le32toh(*(u32 *)(insn->sec->data->d_buf + insn->offset)); + code = (union loongarch_instruction *)&insn_word; + + switch (code->reg0i26_format.opcode) { + case b_op: + case bl_op: + /* reg0i26: 26-bit offset, no register operands */ + insn_word &= 0xfc000000; + break; + case beqz_op: + case bnez_op: + case bceqz_op: /* == bcnez_op */ + /* reg1i21: keep opcode + rj/cj at bits[9:5] */ + insn_word &= 0xfc0003e0; + break; + case jirl_op: + case beq_op: + case bne_op: + case blt_op: + case bge_op: + case bltu_op: + case bgeu_op: + /* reg2i16: keep opcode + rj/rd at bits[9:0] */ + insn_word &= 0xfc0003ff; + break; + default: + break; + } + + insn_word = htole32(insn_word); + memcpy(buf, &insn_word, sizeof(insn_word)); + + return LOONGARCH_INSN_SIZE; +} + #ifdef DISAS int arch_disas_info_init(struct disassemble_info *dinfo)
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2.25.1