libbpf: fix USDT SIB argument handling causing unrecognized register error #5687
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…error On x86-64, USDT arguments can be specified using Scale-Index-Base (SIB) addressing, e.g. "1@-96(%rbp,%rax,8)". The current USDT implementation in libbpf cannot parse this format, causing `bpf_program__attach_usdt()` to fail with -ENOENT (unrecognized register). This patch fixes this by implementing the necessary changes: - add correct handling for SIB-addressed arguments in `bpf_usdt_arg`. - add adaptive support to `__bpf_usdt_arg_type` and `__bpf_usdt_arg_spec` to represent SIB addressing parameters. Signed-off-by: Jiawei Zhao <[email protected]>
When using GCC on x86-64 to compile an usdt prog with -O1 or higher optimization, the compiler will generate SIB addressing mode for global array and PC-relative addressing mode for global variable, e.g. "1@-96(%rbp,%rax,8)" and "-1@4+t1(%rip)". In this patch: - force -O2 optimization for usdt.test.o to generate SIB addressing usdt argument spec. - change the global variable t1 to a local variable, to avoid compiler generating PC-relative addressing mode for it. Signed-off-by: Jiawei Zhao <[email protected]>
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Pull request for series with
subject: libbpf: fix USDT SIB argument handling causing unrecognized register error
version: 6
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=987857