bpf, x64: allow not-converged images when BPF_JIT_ALWAYS_ON is set #343
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The x64 bpf jit expects the bpf images converge within the given passes.
However there is a corner case:
l0: ldh [4]
l1: jeq #0x537d, l2, l40
l2: ld [0]
l3: jeq #0xfa163e0d, l4, l40
l4: ldh [12]
l5: ldx #0xe
l6: jeq #0x86dd, l41, l7
l7: jeq #0x800, l8, l41
l8: ld [x+16]
l9: ja 41
[... repeated ja 41 ]
l40: ja 41
l41: ret #0
l42: ld #len
l43: ret a
The bpf program contains 32 "ja 41" and do_jit() only removes one "ja 41"
right before "l41: ret #0" for offset==0 in each pass, so
bpf_int_jit_compile() needs to run do_jit() at least 32 times to
eliminate those JMP instructions. Since the current max number of passes
is 20, the bpf program couldn't converge within 20 passes and got rejected
when BPF_JIT_ALWAYS_ON is set even though it's legit as a classic socket
filter.
A not-converged image may be not optimal but at least the bpf
instructions are translated into x64 machine code. Maybe we could just
issue a warning instead so that the program is still loaded and the user
is also notified.
On the other hand, if the size convergence is mandatory, then it
deserves a document to collect the corner cases so that the user could
know the limitations and how to work around them.
Signed-off-by: Gary Lin <glin@suse.com>
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Master branch: 9602182 |
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At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=383431 expired. Closing PR. |
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Add a test case which replaces an active ingress qdisc while keeping the miniq in-tact during the transition period to the new clsact qdisc. # ./vmtest.sh -- ./test_progs -t tc_link [...] ./test_progs -t tc_link [ 3.412871] bpf_testmod: loading out-of-tree module taints kernel. [ 3.413343] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel #332 tc_links_after:OK #333 tc_links_append:OK #334 tc_links_basic:OK #335 tc_links_before:OK #336 tc_links_chain_classic:OK #337 tc_links_chain_mixed:OK #338 tc_links_dev_chain0:OK #339 tc_links_dev_cleanup:OK #340 tc_links_dev_mixed:OK #341 tc_links_ingress:OK #342 tc_links_invalid:OK #343 tc_links_prepend:OK #344 tc_links_replace:OK #345 tc_links_revision:OK Summary: 14/0 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Cc: Martin KaFai Lau <martin.lau@kernel.org>
kernel-patches-daemon-bpf bot
pushed a commit
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Jul 8, 2024
Add a test case which replaces an active ingress qdisc while keeping the miniq in-tact during the transition period to the new clsact qdisc. # ./vmtest.sh -- ./test_progs -t tc_link [...] ./test_progs -t tc_link [ 3.412871] bpf_testmod: loading out-of-tree module taints kernel. [ 3.413343] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel #332 tc_links_after:OK #333 tc_links_append:OK #334 tc_links_basic:OK #335 tc_links_before:OK #336 tc_links_chain_classic:OK #337 tc_links_chain_mixed:OK #338 tc_links_dev_chain0:OK #339 tc_links_dev_cleanup:OK #340 tc_links_dev_mixed:OK #341 tc_links_ingress:OK #342 tc_links_invalid:OK #343 tc_links_prepend:OK #344 tc_links_replace:OK #345 tc_links_revision:OK Summary: 14/0 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Cc: Martin KaFai Lau <martin.lau@kernel.org>
kernel-patches-daemon-bpf bot
pushed a commit
that referenced
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Jul 8, 2024
Add a test case which replaces an active ingress qdisc while keeping the miniq in-tact during the transition period to the new clsact qdisc. # ./vmtest.sh -- ./test_progs -t tc_link [...] ./test_progs -t tc_link [ 3.412871] bpf_testmod: loading out-of-tree module taints kernel. [ 3.413343] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel #332 tc_links_after:OK #333 tc_links_append:OK #334 tc_links_basic:OK #335 tc_links_before:OK #336 tc_links_chain_classic:OK #337 tc_links_chain_mixed:OK #338 tc_links_dev_chain0:OK #339 tc_links_dev_cleanup:OK #340 tc_links_dev_mixed:OK #341 tc_links_ingress:OK #342 tc_links_invalid:OK #343 tc_links_prepend:OK #344 tc_links_replace:OK #345 tc_links_revision:OK Summary: 14/0 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Cc: Martin KaFai Lau <martin.lau@kernel.org> Link: https://lore.kernel.org/r/20240708133130.11609-2-daniel@iogearbox.net Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
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Pull request for series with
subject: bpf, x64: allow not-converged images when BPF_JIT_ALWAYS_ON is set
version: 1
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=383431