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b991fc5207
This commit adds a utility function to get disassembled text for jited
representation of a BPF program designated by file descriptor.
Function prototype looks as follows:
int get_jited_program_text(int fd, char *text, size_t text_sz)
Where 'fd' is a file descriptor for the program, 'text' and 'text_sz'
refer to a destination buffer for disassembled text.
Output format looks as follows:
18: 77 06 ja L0
1a: 50 pushq %rax
1b: 48 89 e0 movq %rsp, %rax
1e: eb 01 jmp L1
20: 50 L0: pushq %rax
21: 50 L1: pushq %rax
^ ^^^^^^^^ ^ ^^^^^^^^^^^^^^^^^^
| binary insn | textual insn
| representation | representation
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instruction offset inferred local label name
The code and makefile changes are inspired by jit_disasm.c from bpftool.
Use llvm libraries to disassemble BPF program instead of libbfd to avoid
issues with disassembly output stability pointed out in [1].
Selftests makefile uses Makefile.feature to detect if LLVM libraries
are available. If that is not the case selftests build proceeds but
the function returns -EOPNOTSUPP at runtime.
[1] commit eb9d1acf63 ("bpftool: Add LLVM as default library for disassembling JIT-ed programs")
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20240820102357.3372779-6-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
10 lines
244 B
C
10 lines
244 B
C
/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
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#ifndef __JIT_DISASM_HELPERS_H
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#define __JIT_DISASM_HELPERS_H
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#include <stddef.h>
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int get_jited_program_text(int fd, char *text, size_t text_sz);
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#endif /* __JIT_DISASM_HELPERS_H */
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