ba05fd36b8
Alexei reported a fd leak issue in gen loader (when invoked from bpftool) [0]. When adding ksym support, map fd allocation was moved from stack to loader map, however I missed closing these fds (relevant when cleanup label is jumped to on error). For the success case, the allocated fd is returned in loader ctx, hence this problem is not noticed. Make three changes, first MAX_USED_MAPS in MAX_FD_ARRAY_SZ instead of MAX_USED_PROGS, the braino was not a problem until now for this case as we didn't try to close map fds (otherwise use of it would have tried closing 32 additional fds in ksym btf fd range). Then, do a cleanup for all nr_maps fds in cleanup label code, so that in case of error all temporary map fds from bpf_gen__map_create are closed. Then, adjust the cleanup label to only generate code for the required number of program and map fds. To trim code for remaining program fds, lay out prog_fd array in stack in the end, so that we can directly skip the remaining instances. Still stack size remains same, since changing that would require changes in a lot of places (including adjustment of stack_off macro), so nr_progs_sz variable is only used to track required number of iterations (and jump over cleanup size calculated from that), stack offset calculation remains unaffected. The difference for test_ksyms_module.o is as follows: libbpf: //prog cleanup iterations: before = 34, after = 5 libbpf: //maps cleanup iterations: before = 64, after = 2 Also, move allocation of gen->fd_array offset to bpf_gen__init. Since offset can now be 0, and we already continue even if add_data returns 0 in case of failure, we do not need to distinguish between 0 offset and failure case 0, as we rely on bpf_gen__finish to check errors. We can also skip check for gen->fd_array in add_*_fd functions, since bpf_gen__init will take care of it. [0]: https://lore.kernel.org/bpf/CAADnVQJ6jSitKSNKyxOrUzwY2qDRX0sPkJ=VLGHuCLVJ=qOt9g@mail.gmail.com Fixes: 18f4fccbf314 ("libbpf: Update gen_loader to emit BTF_KIND_FUNC relocations") Reported-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211112232022.899074-1-memxor@gmail.com
62 lines
1.7 KiB
C
62 lines
1.7 KiB
C
/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
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/* Copyright (c) 2021 Facebook */
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#ifndef __BPF_GEN_INTERNAL_H
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#define __BPF_GEN_INTERNAL_H
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struct ksym_relo_desc {
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const char *name;
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int kind;
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int insn_idx;
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bool is_weak;
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bool is_typeless;
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};
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struct ksym_desc {
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const char *name;
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int ref;
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int kind;
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union {
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/* used for kfunc */
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int off;
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/* used for typeless ksym */
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bool typeless;
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};
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int insn;
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};
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struct bpf_gen {
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struct gen_loader_opts *opts;
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void *data_start;
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void *data_cur;
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void *insn_start;
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void *insn_cur;
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ssize_t cleanup_label;
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__u32 nr_progs;
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__u32 nr_maps;
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int log_level;
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int error;
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struct ksym_relo_desc *relos;
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int relo_cnt;
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char attach_target[128];
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int attach_kind;
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struct ksym_desc *ksyms;
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__u32 nr_ksyms;
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int fd_array;
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int nr_fd_array;
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};
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void bpf_gen__init(struct bpf_gen *gen, int log_level, int nr_progs, int nr_maps);
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int bpf_gen__finish(struct bpf_gen *gen, int nr_progs, int nr_maps);
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void bpf_gen__free(struct bpf_gen *gen);
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void bpf_gen__load_btf(struct bpf_gen *gen, const void *raw_data, __u32 raw_size);
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void bpf_gen__map_create(struct bpf_gen *gen, struct bpf_create_map_params *map_attr, int map_idx);
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struct bpf_prog_load_params;
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void bpf_gen__prog_load(struct bpf_gen *gen, struct bpf_prog_load_params *load_attr, int prog_idx);
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void bpf_gen__map_update_elem(struct bpf_gen *gen, int map_idx, void *value, __u32 value_size);
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void bpf_gen__map_freeze(struct bpf_gen *gen, int map_idx);
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void bpf_gen__record_attach_target(struct bpf_gen *gen, const char *name, enum bpf_attach_type type);
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void bpf_gen__record_extern(struct bpf_gen *gen, const char *name, bool is_weak,
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bool is_typeless, int kind, int insn_idx);
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#endif
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