hollalinux
/
linux-sg2042
mirror of https://github.com/sophgo/linux-riscv.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

libbpf: Avoid reload of imm for weak, unresolved, repeating ksym 

Alexei pointed out that we can use BPF_REG_0 which already contains imm
from move_blob2blob computation. Note that we now compare the second
insn's imm, but this should not matter, since both will be zeroed out
for the error case for the insn populated earlier.

Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20211122235733.634914-4-memxor@gmail.com
This commit is contained in:
Kumar Kartikeya Dwivedi 2021-11-23 05:27:33 +05:30 committed by Andrii Nakryiko
parent 0270090d39
commit d995816b77
1 changed files with 2 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
tools/lib/bpf/gen_loader.c
View File

@ -795,9 +795,8 @@ static void emit_relo_ksym_btf(struct bpf_gen *gen, struct ksym_relo_desc *relo,
kdesc->insn + offsetof(struct bpf_insn, imm));
move_blob2blob(gen, insn + sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm), 4,
kdesc->insn + sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm));
emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_9, BPF_REG_8, offsetof(struct bpf_insn, imm)));
/* jump over src_reg adjustment if imm is not 0 */
emit(gen, BPF_JMP_IMM(BPF_JNE, BPF_REG_9, 0, 3));
/* jump over src_reg adjustment if imm is not 0, reuse BPF_REG_0 from move_blob2blob */
emit(gen, BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 3));
goto clear_src_reg;
}
/* remember insn offset, so we can copy BTF ID and FD later */