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Make -d flag functional for gen_loader style program loading. For example: $ bpftool prog load -L -d test_d_path.o ... // will print: libbpf: loading ./test_d_path.o libbpf: elf: section(3) fentry/security_inode_getattr, size 280, link 0, flags 6, type=1 ... libbpf: prog 'prog_close': found data map 0 (test_d_p.bss, sec 7, off 0) for insn 30 libbpf: gen: load_btf: size 5376 libbpf: gen: map_create: test_d_p.bss idx 0 type 2 value_type_id 118 libbpf: map 'test_d_p.bss': created successfully, fd=0 libbpf: gen: map_update_elem: idx 0 libbpf: sec 'fentry/filp_close': found 1 CO-RE relocations libbpf: record_relo_core: prog 1 insn[15] struct file 0:1 final insn_idx 15 libbpf: gen: prog_load: type 26 insns_cnt 35 progi_idx 0 libbpf: gen: find_attach_tgt security_inode_getattr 12 libbpf: gen: prog_load: type 26 insns_cnt 37 progi_idx 1 libbpf: gen: find_attach_tgt filp_close 12 libbpf: gen: finish 0 ... // at this point libbpf finished generating loader program 0: (bf) r6 = r1 1: (bf) r1 = r10 2: (07) r1 += -136 3: (b7) r2 = 136 4: (b7) r3 = 0 5: (85) call bpf_probe_read_kernel#113 6: (05) goto pc+104 ... // this is the assembly dump of the loader program 390: (63) *(u32 *)(r6 +44) = r0 391: (18) r1 = map[idx:0]+5584 393: (61) r0 = *(u32 *)(r1 +0) 394: (63) *(u32 *)(r6 +24) = r0 395: (b7) r0 = 0 396: (95) exit err 0 // the loader program was loaded and executed successfully (null) func#0 @0 ... // CO-RE in the kernel logs: CO-RE relocating STRUCT file: found target candidate [500] prog '': relo #0: kind <byte_off> (0), spec is [8] STRUCT file.f_path (0:1 @ offset 16) prog '': relo #0: matching candidate #0 [500] STRUCT file.f_path (0:1 @ offset 16) prog '': relo #0: patched insn #15 (ALU/ALU64) imm 16 -> 16 vmlinux_cand_cache:[11]file(500), module_cand_cache: ... // verifier logs when it was checking test_d_path.o program: R1 type=ctx expected=fp 0: R1=ctx(id=0,off=0,imm=0) R10=fp0 ; int BPF_PROG(prog_close, struct file *file, void *id) 0: (79) r6 = *(u64 *)(r1 +0) func 'filp_close' arg0 has btf_id 500 type STRUCT 'file' 1: R1=ctx(id=0,off=0,imm=0) R6_w=ptr_file(id=0,off=0,imm=0) R10=fp0 ; pid_t pid = bpf_get_current_pid_tgid() >> 32; 1: (85) call bpf_get_current_pid_tgid#14 ... // if there are multiple programs being loaded by the loader program ... // only the last program in the elf file will be printed, since ... // the same verifier log_buf is used for all PROG_LOAD commands. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20211204194623.27779-1-alexei.starovoitov@gmail.com
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.