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This works with: $ clang -v clang version 14.0.5 (Fedora 14.0.5-2.fc36) $ But not with: $ clang -v clang version 16.0.6 (Fedora 16.0.6-2.fc38) $ [root@quaco ~]# perf trace -e connect*,sendto* ping -c 10 localhost libbpf: prog 'sys_enter_sendto': BPF program load failed: Permission denied libbpf: prog 'sys_enter_sendto': -- BEGIN PROG LOAD LOG -- reg type unsupported for arg#0 function sys_enter_sendto#59 0: R1=ctx(off=0,imm=0) R10=fp0 ; int sys_enter_sendto(struct syscall_enter_args *args) 0: (bf) r6 = r1 ; R1=ctx(off=0,imm=0) R6_w=ctx(off=0,imm=0) 1: (b7) r1 = 0 ; R1_w=0 ; int key = 0; 2: (63) *(u32 *)(r10 -4) = r1 ; R1_w=0 R10=fp0 fp-8=0000???? 3: (bf) r2 = r10 ; R2_w=fp0 R10=fp0 ; 4: (07) r2 += -4 ; R2_w=fp-4 ; return bpf_map_lookup_elem(&augmented_args_tmp, &key); 5: (18) r1 = 0xffff8de5a5b8bc00 ; R1_w=map_ptr(off=0,ks=4,vs=8272,imm=0) 7: (85) call bpf_map_lookup_elem#1 ; R0_w=map_value_or_null(id=1,off=0,ks=4,vs=8272,imm=0) 8: (bf) r7 = r0 ; R0_w=map_value_or_null(id=1,off=0,ks=4,vs=8272,imm=0) R7_w=map_value_or_null(id=1,off=0,ks=4,vs=8272,imm=0) 9: (b7) r0 = 1 ; R0_w=1 ; if (augmented_args == NULL) 10: (15) if r7 == 0x0 goto pc+25 ; R7_w=map_value(off=0,ks=4,vs=8272,imm=0) ; unsigned int socklen = args->args[5]; 11: (79) r1 = *(u64 *)(r6 +56) ; R1_w=scalar() R6_w=ctx(off=0,imm=0) ; 12: (bf) r2 = r1 ; R1_w=scalar(id=2) R2_w=scalar(id=2) 13: (67) r2 <<= 32 ; R2_w=scalar(smax=9223372032559808512,umax=18446744069414584320,var_off=(0x0; 0xffffffff00000000),s32_min=0,s32_max=0,u32_max=0) 14: (77) r2 >>= 32 ; R2_w=scalar(umax=4294967295,var_off=(0x0; 0xffffffff)) 15: (b7) r8 = 128 ; R8=128 ; if (socklen > sizeof(augmented_args->saddr)) 16: (25) if r2 > 0x80 goto pc+1 ; R2=scalar(umax=128,var_off=(0x0; 0xff)) 17: (bf) r8 = r1 ; R1=scalar(id=2) R8_w=scalar(id=2) ; const void *sockaddr_arg = (const void *)args->args[4]; 18: (79) r3 = *(u64 *)(r6 +48) ; R3_w=scalar() R6=ctx(off=0,imm=0) ; bpf_probe_read(&augmented_args->saddr, socklen, sockaddr_arg); 19: (bf) r1 = r7 ; R1_w=map_value(off=0,ks=4,vs=8272,imm=0) R7=map_value(off=0,ks=4,vs=8272,imm=0) 20: (07) r1 += 64 ; R1_w=map_value(off=64,ks=4,vs=8272,imm=0) ; bpf_probe_read(&augmented_args->saddr, socklen, sockaddr_arg); 21: (bf) r2 = r8 ; R2_w=scalar(id=2) R8_w=scalar(id=2) 22: (85) call bpf_probe_read#4 R2 min value is negative, either use unsigned or 'var &= const' processed 22 insns (limit 1000000) max_states_per_insn 0 total_states 1 peak_states 1 mark_read 1 -- END PROG LOAD LOG -- libbpf: prog 'sys_enter_sendto': failed to load: -13 libbpf: failed to load object 'augmented_raw_syscalls_bpf' libbpf: failed to load BPF skeleton 'augmented_raw_syscalls_bpf': -13 So use the suggested &= variant since sizeof(saddr) == 128 bytes. Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Ian Rogers <irogers@google.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.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.