[bpftool] remove BPF_OBJ_NAME_LEN restriction when looking up bpf#32
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chantra wants to merge 1 commit intolibbpf:masterfrom
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[bpftool] remove BPF_OBJ_NAME_LEN restriction when looking up bpf#32chantra wants to merge 1 commit intolibbpf:masterfrom
chantra wants to merge 1 commit intolibbpf:masterfrom
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program by name bpftool was limiting the length of names to [BPF_OBJ_NAME_LEN](https://github.com/libbpf/bpftool/blob/2d7bba1e8c17dd0422879c856cda66723b209952/src/common.c#L823-L826). Since libbpf@61833a2 we can get the full program name from BTF. This diffs remove the restriction of name length when running `bpftool prog show name ${name}`. Test: Tested against some internal program names that were longer than `BPF_OBJ_NAME_LEN`, here a redacted example of what was ran to test. ``` $ sudo bpftool prog show name some_long_program_name Error: can't parse name $ sudo ./bpftool prog show name some_long_program_name 123456789: tracing name some_long_program_name tag taghexa gpl .... ... ... ... ```
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Thanks a lot! As you figured by yourself, this is going to the BPF mailing list :) |
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The LLVM disassembler needs ISA extension features enabled to correctly decode instructions from those extensions. On aarch64, without these features, instructions like LSE atomics (e.g. ldaddal) are silently decoded as incorrect instructions and disassembly is truncated. Use LLVMCreateDisasmCPUFeatures() with "+all" features for aarch64 targets so that the disassembler can handle any instruction the kernel JIT might emit. Before: int bench_trigger_uprobe(void * ctx): bpf_prog_538c6a43d1c6b84c_bench_trigger_uprobe: ; int cpu = bpf_get_smp_processor_id(); 0: mov x9, x30 4: nop 8: stp x29, x30, [sp, #-16]! c: mov x29, sp 10: stp xzr, x26, [sp, #-16]! 14: mov x26, sp 18: mrs x10, SP_EL0 1c: ldr w7, [x10, libbpf#16] ; __sync_add_and_fetch(&hits[cpu & CPU_MASK].value, 1); 20: and w7, w7, #0xff ; __sync_add_and_fetch(&hits[cpu & CPU_MASK].value, 1); 24: lsl x7, x7, libbpf#7 28: mov x0, #-281474976710656 2c: movk x0, #32768, lsl libbpf#32 30: movk x0, #35407, lsl libbpf#16 34: add x0, x0, x7 38: mov x1, #1 ; __sync_add_and_fetch(&hits[cpu & CPU_MASK].value, 1); 3c: mov x1, #1 After: int bench_trigger_uprobe(void * ctx): bpf_prog_538c6a43d1c6b84c_bench_trigger_uprobe: ; int cpu = bpf_get_smp_processor_id(); 0: mov x9, x30 4: nop 8: stp x29, x30, [sp, #-16]! c: mov x29, sp 10: stp xzr, x26, [sp, #-16]! 14: mov x26, sp 18: mrs x10, SP_EL0 1c: ldr w7, [x10, libbpf#16] ; __sync_add_and_fetch(&hits[cpu & CPU_MASK].value, 1); 20: and w7, w7, #0xff ; __sync_add_and_fetch(&hits[cpu & CPU_MASK].value, 1); 24: lsl x7, x7, libbpf#7 28: mov x0, #-281474976710656 2c: movk x0, #32768, lsl libbpf#32 30: movk x0, #35407, lsl libbpf#16 34: add x0, x0, x7 38: mov x1, #1 ; __sync_add_and_fetch(&hits[cpu & CPU_MASK].value, 1); 3c: ldaddal x1, x1, [x0] ; return 0; 40: mov w7, #0 44: ldp xzr, x26, [sp], libbpf#16 48: ldp x29, x30, [sp], libbpf#16 4c: mov x0, x7 50: ret 54: nop 58: ldr x10, libbpf#8 5c: br x10 Signed-off-by: Puranjay Mohan <puranjay@kernel.org> Acked-by: Yonghong Song <yonghong.song@linux.dev> Acked-by: Leon Hwang <leon.hwang@linux.dev> Acked-by: Quentin Monnet <qmo@kernel.org> Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com> Link: https://lore.kernel.org/r/20260318172259.2882792-1-puranjay@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
qmonnet
pushed a commit
that referenced
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Apr 10, 2026
The LLVM disassembler needs ISA extension features enabled to correctly decode instructions from those extensions. On aarch64, without these features, instructions like LSE atomics (e.g. ldaddal) are silently decoded as incorrect instructions and disassembly is truncated. Use LLVMCreateDisasmCPUFeatures() with "+all" features for aarch64 targets so that the disassembler can handle any instruction the kernel JIT might emit. Before: int bench_trigger_uprobe(void * ctx): bpf_prog_538c6a43d1c6b84c_bench_trigger_uprobe: ; int cpu = bpf_get_smp_processor_id(); 0: mov x9, x30 4: nop 8: stp x29, x30, [sp, #-16]! c: mov x29, sp 10: stp xzr, x26, [sp, #-16]! 14: mov x26, sp 18: mrs x10, SP_EL0 1c: ldr w7, [x10, #16] ; __sync_add_and_fetch(&hits[cpu & CPU_MASK].value, 1); 20: and w7, w7, #0xff ; __sync_add_and_fetch(&hits[cpu & CPU_MASK].value, 1); 24: lsl x7, x7, #7 28: mov x0, #-281474976710656 2c: movk x0, #32768, lsl #32 30: movk x0, #35407, lsl #16 34: add x0, x0, x7 38: mov x1, #1 ; __sync_add_and_fetch(&hits[cpu & CPU_MASK].value, 1); 3c: mov x1, #1 After: int bench_trigger_uprobe(void * ctx): bpf_prog_538c6a43d1c6b84c_bench_trigger_uprobe: ; int cpu = bpf_get_smp_processor_id(); 0: mov x9, x30 4: nop 8: stp x29, x30, [sp, #-16]! c: mov x29, sp 10: stp xzr, x26, [sp, #-16]! 14: mov x26, sp 18: mrs x10, SP_EL0 1c: ldr w7, [x10, #16] ; __sync_add_and_fetch(&hits[cpu & CPU_MASK].value, 1); 20: and w7, w7, #0xff ; __sync_add_and_fetch(&hits[cpu & CPU_MASK].value, 1); 24: lsl x7, x7, #7 28: mov x0, #-281474976710656 2c: movk x0, #32768, lsl #32 30: movk x0, #35407, lsl #16 34: add x0, x0, x7 38: mov x1, #1 ; __sync_add_and_fetch(&hits[cpu & CPU_MASK].value, 1); 3c: ldaddal x1, x1, [x0] ; return 0; 40: mov w7, #0 44: ldp xzr, x26, [sp], #16 48: ldp x29, x30, [sp], #16 4c: mov x0, x7 50: ret 54: nop 58: ldr x10, #8 5c: br x10 Signed-off-by: Puranjay Mohan <puranjay@kernel.org> Acked-by: Yonghong Song <yonghong.song@linux.dev> Acked-by: Leon Hwang <leon.hwang@linux.dev> Acked-by: Quentin Monnet <qmo@kernel.org> Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com> Link: https://lore.kernel.org/r/20260318172259.2882792-1-puranjay@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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program by name
bpftool was limiting the length of names to
BPF_OBJ_NAME_LEN.
Since
61833a2
we can get the full program name from BTF.
This diffs remove the restriction of name length when running
bpftool prog show name ${name}.Test:
Tested against some internal program names that were longer than
BPF_OBJ_NAME_LEN, here a redacted example of what was ran to test.