From 6fe65f1b4db3fff305896e997c2804b7b42236ce Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Wed, 9 Feb 2022 15:19:58 -0800 Subject: libbpf: Prepare light skeleton for the kernel. Prepare light skeleton to be used in the kernel module and in the user space. The look and feel of lskel.h is mostly the same with the difference that for user space the skel->rodata is the same pointer before and after skel_load operation, while in the kernel the skel->rodata after skel_open and the skel->rodata after skel_load are different pointers. Typical usage of skeleton remains the same for kernel and user space: skel = my_bpf__open(); skel->rodata->my_global_var = init_val; err = my_bpf__load(skel); err = my_bpf__attach(skel); // access skel->rodata->my_global_var; // access skel->bss->another_var; Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Acked-by: Yonghong Song Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20220209232001.27490-3-alexei.starovoitov@gmail.com --- tools/lib/bpf/gen_loader.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) (limited to 'tools/lib/bpf/gen_loader.c') diff --git a/tools/lib/bpf/gen_loader.c b/tools/lib/bpf/gen_loader.c index 8ecef1088ba2..927745b08014 100644 --- a/tools/lib/bpf/gen_loader.c +++ b/tools/lib/bpf/gen_loader.c @@ -1043,18 +1043,27 @@ void bpf_gen__map_update_elem(struct bpf_gen *gen, int map_idx, void *pvalue, value = add_data(gen, pvalue, value_size); key = add_data(gen, &zero, sizeof(zero)); - /* if (map_desc[map_idx].initial_value) - * copy_from_user(value, initial_value, value_size); + /* if (map_desc[map_idx].initial_value) { + * if (ctx->flags & BPF_SKEL_KERNEL) + * bpf_probe_read_kernel(value, value_size, initial_value); + * else + * bpf_copy_from_user(value, value_size, initial_value); + * } */ emit(gen, BPF_LDX_MEM(BPF_DW, BPF_REG_3, BPF_REG_6, sizeof(struct bpf_loader_ctx) + sizeof(struct bpf_map_desc) * map_idx + offsetof(struct bpf_map_desc, initial_value))); - emit(gen, BPF_JMP_IMM(BPF_JEQ, BPF_REG_3, 0, 4)); + emit(gen, BPF_JMP_IMM(BPF_JEQ, BPF_REG_3, 0, 8)); emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE, 0, 0, 0, value)); emit(gen, BPF_MOV64_IMM(BPF_REG_2, value_size)); + emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_6, + offsetof(struct bpf_loader_ctx, flags))); + emit(gen, BPF_JMP_IMM(BPF_JSET, BPF_REG_0, BPF_SKEL_KERNEL, 2)); emit(gen, BPF_EMIT_CALL(BPF_FUNC_copy_from_user)); + emit(gen, BPF_JMP_IMM(BPF_JA, 0, 0, 1)); + emit(gen, BPF_EMIT_CALL(BPF_FUNC_probe_read_kernel)); map_update_attr = add_data(gen, &attr, attr_size); move_blob2blob(gen, attr_field(map_update_attr, map_fd), 4, -- cgit v1.2.3