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Re: R? min value is negative, either use unsigned or 'var &= const' #verifier

<ys114321=gmail.com@...> wrote: The reason for the failure is due spill/reload does not preserve the original register state for scalar value. Look at the kernel function: static bool

By Yonghong Song · #1611 ·

BCC support for ARM

Hi; We're trying to integrate bcc as a package in buildroot with the configuration shown below: - Target board : Raspberry PI 3. - Toolchain : Arm ARM 2018.11 - LLVM 7.0.1 However, buildroot

By Jugurtha BELKALEM · #1610 ·

bpf: Failed to load program: Permission denied

Hi, I'm new to BPF. I'm trying to write a program that analyses the structure o= f DNS requests. I keep getting the following error (bellow) at a certain point in the code (bellow). The error only

By Jacob Steadman · #1609 ·

Re: R? min value is negative, either use unsigned or 'var &= const' #verifier

Here a python 2 version.

By Simon · #1608 ·

Re: R? min value is negative, either use unsigned or 'var &= const' #verifier

I took a brief look. Indeed, it is very strange. I can see proper value of udp_len is stored into r10 - 40, but when it is retrieved later, the value became unkown.... I will try to experiment with

By Yonghong Song · #1607 ·

Re: R? min value is negative, either use unsigned or 'var &= const' #verifier

I tried to understand again this verifier error again and probably my previous post does not contain enough information. I understand that :93: (67) r0 <<= 32294: (c7) r0 s>>= 32295: (b7) r1 = 0296:

By Simon · #1606 ·

Re: math between pkt pointer and register with unbounded min value is not allowed #verifier

The be16 is to convert r3 with big endian encoding. If the host system is big endian, it will do nothing. Otherwise, it will convert from little endian to big endian. Yes, there is no documentation.

By Yonghong Song · #1605 ·

Re: minutes: IO Visor TSC/Dev Meeting

Hi Guys, My agenda for next meeting: 1) unifying and centralizing XDP statistics accounting [1]. 2) XDP resource management, User API [2]. 3) XDP meta data via btf (in kernel BTF registration). 4)

By Saeed Mahameed · #1604 ·

R? min value is negative, either use unsigned or 'var &= const' #verifier

I suspect I fall in another issue with verifier. This code (taking from katran : I just changed data_size type to __u32): __attribute__((__always_inline__))static inline void ipv4_l4_csum(void

By Simon · #1603 ·

Re: math between pkt pointer and register with unbounded min value is not allowed #verifier

Does it mean that r3 is considered as be16 ? I do not understand why as I explicitly convert it in u16. This output language is a readable format of bpf bytecode, right ? Is there any documentation

By Simon · #1602 ·

Re: math between pkt pointer and register with unbounded min value is not allowed #verifier

Yonghong Song writes: I had run into similar issue when debugging some other rejection before JMP32 introduced when LLVM was generating similar sequences under defult 64-bit mode, but IIRC LLVM

By Jiong Wang · #1601 ·

Re: math between pkt pointer and register with unbounded min value is not allowed #verifier

This is caused by compiler optimizations. r3 get the value from memory, its value could be any one as permitted by the type. test is done by r2. We indeed get better range for r2

By Yonghong Song · #1600 ·

Re: Sharing eBPF map between two eBPF kernel programs

You should be able to do the work with C as well. Just use APIs from libbpf.h, e.g., bpf_prog_get_next_id, bpf_prog_get_fd_by_id, bpf_map_get_fd_by_id. Yes, we may miss bpf_map_get_next_id and

By Yonghong Song · #1599 ·

minutes: IO Visor TSC/Dev Meeting

Hi All, Thank you for joining the call today. Here are my notes from the discussion. Thanks, Brenden === Discussion === Brenden: * Plan to tag release to coincide with kernel 5.0 Brendan: *

By Brenden Blanco · #1598 ·

math between pkt pointer and register with unbounded min value is not allowed #verifier

I'm playing with bcc to prototype an UDP load balancer. I'm facing an issue that I didn't succeed to understand... In my code I tried to validate my UDP packet using code like this : struct

By Simon · #1597 ·

reminder: IO Visor TSC/Dev Meeting

Please join us tomorrow for our bi-weekly call. As usual, this meeting is open to everybody and completely optional. You might be interested to join if: You want to know what is going on in BPF

By Brenden Blanco · #1596 ·

Re: Sharing eBPF map between two eBPF kernel programs

Thanks for that! I think those work because bcc has given utilities to do that. I am using C and we use libbpf to load programs and to do map operations. Do you know if we can achieve it in this way

By Kanthi P <Pavuluri.kanthi@...> · #1595 ·

Re: Sharing eBPF map between two eBPF kernel programs

In examples/cpp, we have UseExternalMap.cc, which gives an example of how to share maps between two processes with C++ interface. Basically, if you know the ID of the map in another application

By Yonghong Song · #1594 ·

Sharing eBPF map between two eBPF kernel programs

Hi, I have two eBPF programs, each with its own user and kernel programs. One of the programs defines an eBPF map. How do I access this map from another eBPF kernel program? PS: I can pin the map and

By Kanthi P <Pavuluri.kanthi@...> · #1593 ·

about kprobe/kretprobe matching

Hi, I'm trying to access the packet content in tcp_transmit_skb using eBPF/BCC. I defined kprobe____tcp_transmit_skb/kretprobe____tcp_transmit_skb functions. Since in kretprobe we cannot access the

By ovinee@... · #1592 ·

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