Is LKL usage of setjmp correct? #266
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Yes, your are right. In the initial implementation I used a different host ops API for setjmp to avoid this issue, but during cleanups I've forgot why I did it that way and scraped it :( I will post a PR to fix this issue soon. |
rodionov
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Add a new test case which performs double query of the bpf_mprog through libbpf API, but also via raw bpf(2) syscall. This is testing to gather first the count and then in a subsequent probe the full information with the program array without clearing passed structs in between. # ./vmtest.sh -- ./test_progs -t tc_opts [...] ./test_progs -t tc_opts [ 1.398818] tsc: Refined TSC clocksource calibration: 3407.999 MHz [ 1.400263] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x311fd336761, max_idle_ns: 440795243819 ns [ 1.402734] clocksource: Switched to clocksource tsc [ 1.426639] bpf_testmod: loading out-of-tree module taints kernel. [ 1.428112] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel lkl#252 tc_opts_after:OK lkl#253 tc_opts_append:OK lkl#254 tc_opts_basic:OK lkl#255 tc_opts_before:OK lkl#256 tc_opts_chain_classic:OK lkl#257 tc_opts_chain_mixed:OK lkl#258 tc_opts_delete_empty:OK lkl#259 tc_opts_demixed:OK lkl#260 tc_opts_detach:OK lkl#261 tc_opts_detach_after:OK lkl#262 tc_opts_detach_before:OK lkl#263 tc_opts_dev_cleanup:OK lkl#264 tc_opts_invalid:OK lkl#265 tc_opts_max:OK lkl#266 tc_opts_mixed:OK lkl#267 tc_opts_prepend:OK lkl#268 tc_opts_query:OK <--- (new test) lkl#269 tc_opts_replace:OK lkl#270 tc_opts_revision:OK Summary: 19/0 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Daniel Borkmann <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Martin KaFai Lau <[email protected]>
rodionov
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Jan 2, 2025
Add a new test case to query on an empty bpf_mprog and pass the revision directly into expected_revision for attachment to assert that this does succeed. ./test_progs -t tc_opts [ 1.406778] tsc: Refined TSC clocksource calibration: 3407.990 MHz [ 1.408863] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x311fcaf6eb0, max_idle_ns: 440795321766 ns [ 1.412419] clocksource: Switched to clocksource tsc [ 1.428671] bpf_testmod: loading out-of-tree module taints kernel. [ 1.430260] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel lkl#252 tc_opts_after:OK lkl#253 tc_opts_append:OK lkl#254 tc_opts_basic:OK lkl#255 tc_opts_before:OK lkl#256 tc_opts_chain_classic:OK lkl#257 tc_opts_chain_mixed:OK lkl#258 tc_opts_delete_empty:OK lkl#259 tc_opts_demixed:OK lkl#260 tc_opts_detach:OK lkl#261 tc_opts_detach_after:OK lkl#262 tc_opts_detach_before:OK lkl#263 tc_opts_dev_cleanup:OK lkl#264 tc_opts_invalid:OK lkl#265 tc_opts_max:OK lkl#266 tc_opts_mixed:OK lkl#267 tc_opts_prepend:OK lkl#268 tc_opts_query:OK lkl#269 tc_opts_query_attach:OK <--- (new test) lkl#270 tc_opts_replace:OK lkl#271 tc_opts_revision:OK Summary: 20/0 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Daniel Borkmann <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Martin KaFai Lau <[email protected]>
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As far as I know, setjmp must be used inline so the the stack is still alive when long jmp happens. "And some esoteric tasks (generally requiring the use of assembly code, such as setjmp and certain kinds of locking) must be performed inline or they won't work right."
But the way we use setjmp in LKL is not inlined so I'm worried this may be cause of segment fault I observed (at very low frequency). I can't explain why it works though.
Also I don't find a way to inline the setjmp into LKL kernel code.
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