kernel/linux.git/samples/bpf, branch v6.6.40

work around gcc bugs with 'asm goto' with outputs

2024-02-23T08:24:47+00:00

commit 4356e9f841f7fbb945521cef3577ba394c65f3fc upstream. We've had issues with gcc and 'asm goto' before, and we created a 'asm_volatile_goto()' macro for that in the past: see commits 3f0116c3238a ("compiler/gcc4: Add quirk for 'asm goto' miscompilation bug") and a9f180345f53 ("compiler/gcc4: Make quirk for asm_volatile_goto() unconditional"). Then, much later, we ended up removing the workaround in commit 43c249ea0b1e ("compiler-gcc.h: remove ancient workaround for gcc PR 58670") because we no longer supported building the kernel with the affected gcc versions, but we left the macro uses around. Now, Sean Christopherson reports a new version of a very similar problem, which is fixed by re-applying that ancient workaround. But the problem in question is limited to only the 'asm goto with outputs' cases, so instead of re-introducing the old workaround as-is, let's rename and limit the workaround to just that much less common case. It looks like there are at least two separate issues that all hit in this area: (a) some versions of gcc don't mark the asm goto as 'volatile' when it has outputs: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98619 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110420 which is easy to work around by just adding the 'volatile' by hand. (b) Internal compiler errors: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110422 which are worked around by adding the extra empty 'asm' as a barrier, as in the original workaround. but the problem Sean sees may be a third thing since it involves bad code generation (not an ICE) even with the manually added 'volatile'. but the same old workaround works for this case, even if this feels a bit like voodoo programming and may only be hiding the issue. Reported-and-tested-by: Sean Christopherson Link: https://lore.kernel.org/all/20240208220604.140859-1-seanjc@google.com/ Cc: Nick Desaulniers Cc: Uros Bizjak Cc: Jakub Jelinek Cc: Andrew Pinski Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

samples/bpf: syscall_tp_user: Fix array out-of-bound access

2023-11-28T17:19:48+00:00

[ Upstream commit 9220c3ef6fefbf18f24aeedb1142a642b3de0596 ] Commit 06744f24696e ("samples/bpf: Add openat2() enter/exit tracepoint to syscall_tp sample") added two more eBPF programs to support the openat2() syscall. However, it did not increase the size of the array that holds the corresponding bpf_links. This leads to an out-of-bound access on that array in the bpf_object__for_each_program loop and could corrupt other variables on the stack. On our testing QEMU, it corrupts the map1_fds array and causes the sample to fail: # ./syscall_tp prog #0: map ids 4 5 verify map:4 val: 5 map_lookup failed: Bad file descriptor Dynamically allocate the array based on the number of programs reported by libbpf to prevent similar inconsistencies in the future Fixes: 06744f24696e ("samples/bpf: Add openat2() enter/exit tracepoint to syscall_tp sample") Signed-off-by: Jinghao Jia Signed-off-by: Ruowen Qin Signed-off-by: Jinghao Jia Link: https://lore.kernel.org/r/20230917214220.637721-4-jinghao7@illinois.edu Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin

samples/bpf: syscall_tp_user: Rename num_progs into nr_tests

2023-11-28T17:19:48+00:00

[ Upstream commit 0ee352fe0d28015cab161b04d202fa3231c0ba3b ] The variable name num_progs causes confusion because that variable really controls the number of rounds the test should be executed. Rename num_progs into nr_tests for the sake of clarity. Signed-off-by: Jinghao Jia Signed-off-by: Ruowen Qin Signed-off-by: Jinghao Jia Link: https://lore.kernel.org/r/20230917214220.637721-3-jinghao7@illinois.edu Signed-off-by: Alexei Starovoitov Stable-dep-of: 9220c3ef6fef ("samples/bpf: syscall_tp_user: Fix array out-of-bound access") Signed-off-by: Sasha Levin

samples/bpf: Add note to README about the XDP utilities moved to xdp-tools

2023-08-24T15:43:50+00:00

To help users find the XDP utilities, add a note to the README about the new location and the conversion documentation in the commit messages. Signed-off-by: Toke Høiland-Jørgensen Link: https://lore.kernel.org/r/20230824102255.1561885-8-toke@redhat.com Signed-off-by: Alexei Starovoitov

samples/bpf: Cleanup .gitignore

2023-08-24T15:43:50+00:00

Remove no longer present XDP utilities from .gitignore. Apart from the recently removed XDP utilities this also includes the previously removed xdpsock and xsk utilities. Signed-off-by: Toke Høiland-Jørgensen Link: https://lore.kernel.org/r/20230824102255.1561885-7-toke@redhat.com Signed-off-by: Alexei Starovoitov

samples/bpf: Remove the xdp_sample_pkts utility

2023-08-24T15:43:50+00:00

The functionality of this utility is covered by the xdpdump utility in xdp-tools. There's a slight difference in usage as the xdpdump utility's main focus is to dump packets before or after they are processed by an existing XDP program. However, xdpdump also has the --load-xdp-program switch, which will make it attach its own program if no existing program is loaded. With this, xdp_sample_pkts usage can be converted as: xdp_sample_pkts eth0 --> xdpdump --load-xdp-program eth0 To get roughly equivalent behaviour. Signed-off-by: Toke Høiland-Jørgensen Link: https://lore.kernel.org/r/20230824102255.1561885-6-toke@redhat.com Signed-off-by: Alexei Starovoitov

samples/bpf: Remove the xdp1 and xdp2 utilities

2023-08-24T15:43:50+00:00

The functionality of these utilities have been incorporated into the xdp-bench utility in xdp-tools. Equivalent functionality is: xdp1 eth0 --> xdp-bench drop -p parse-ip -l load-bytes eth0 xdp2 eth0 --> xdp-bench drop -p swap-macs eth0 Note that there's a slight difference in behaviour of those examples: the swap-macs operation of xdp-bench doesn't use the bpf_xdp_load_bytes() helper to load the packet data, whereas the xdp2 utility did so unconditionally. For the parse-ip action the use of bpf_xdp_load_bytes() can be selected by the '-l load-bytes' switch, with the difference that the xdp-bench utility will perform two separate calls to the helper, one to load the ethernet header and another to load the IP header; where the xdp1 utility only performed one call always loading 60 bytes of data. Signed-off-by: Toke Høiland-Jørgensen Link: https://lore.kernel.org/r/20230824102255.1561885-5-toke@redhat.com Signed-off-by: Alexei Starovoitov

samples/bpf: Remove the xdp_rxq_info utility

2023-08-24T15:43:50+00:00

The functionality of this utility has been incorporated into the xdp-bench utility in xdp-tools, by way of the --rxq-stats argument to the 'drop', 'pass' and 'tx' commands of xdp-bench. Some examples of how to convert xdp_rxq_info invocations into equivalent xdp-bench commands: xdp_rxq_info -d eth0 --> xdp-bench pass --rxq-stats eth0 xdp_rxq_info -d eth0 -a XDP_DROP -m --> xdp-bench drop --rxq-stats -p swap-macs eth0 Signed-off-by: Toke Høiland-Jørgensen Link: https://lore.kernel.org/r/20230824102255.1561885-4-toke@redhat.com Signed-off-by: Alexei Starovoitov

samples/bpf: Remove the xdp_redirect* utilities

2023-08-24T15:43:50+00:00

These utilities have all been ported to xdp-tools as functions of the xdp-bench utility. The four different utilities in samples are incorporated as separate subcommands to xdp-bench, with most of the command line parameters left intact, except that mandatory arguments are always positional in xdp-bench. For full usage details see the --help output of each command, or the xdp-bench man page. Some examples of how to convert usage to xdp-bench are: xdp_redirect eth0 eth1 --> xdp-bench redirect eth0 eth1 xdp_redirect_map eth0 eth1 --> xdp-bench redirect-map eth0 eth1 xdp_redirect_map_multi eth0 eth1 eth2 eth3 --> xdp-bench redirect-multi eth0 eth1 eth2 eth3 xdp_redirect_cpu -d eth0 -c 0 -c 1 --> xdp-bench redirect-cpu -c 0 -c 1 eth0 xdp_redirect_cpu -d eth0 -c 0 -c 1 -r eth1 --> xdp-bench redirect-cpu -c 0 -c 1 eth0 -r redirect -D eth1 Signed-off-by: Toke Høiland-Jørgensen Link: https://lore.kernel.org/r/20230824102255.1561885-3-toke@redhat.com Signed-off-by: Alexei Starovoitov

samples/bpf: Remove the xdp_monitor utility

2023-08-24T15:43:50+00:00

This utility has been ported as-is to xdp-tools as 'xdp-monitor'. The only difference in usage between the samples and xdp-tools versions is that the '-v' command line parameter has been changed to '-e' in the xdp-tools version for consistency with the other utilities. Signed-off-by: Toke Høiland-Jørgensen Link: https://lore.kernel.org/r/20230824102255.1561885-2-toke@redhat.com Signed-off-by: Alexei Starovoitov