GitHub pull request #2950 of commit 4d38e35e5c1572e2ee0e16f2ea5d790a314f5ec3, no merge conflicts.sha1origin/pr/2950/mergeghprbActualCommit4d38e35e5c1572e2ee0e16f2ea5d790a314f5ec3ghprbActualCommitAuthorYonghong SongghprbActualCommitAuthorEmailyhs@fb.comghprbAuthorRepoGitUrlhttps://github.com/iovisor/bcc.gitghprbTriggerAuthorghprbTriggerAuthorEmailghprbTriggerAuthorLoginghprbTriggerAuthorLoginMentionghprbPullId2950ghprbTargetBranchmasterghprbSourceBranchyhs_devGIT_BRANCHyhs_devghprbPullAuthorEmailghprbPullAuthorLoginyonghong-songghprbPullAuthorLoginMention@yonghong-songghprbPullDescriptionGitHub pull request #2950 of commit 4d38e35e5c1572e2ee0e16f2ea5d790a314f5ec3, no merge conflicts.ghprbPullTitleturn off x86 jump table optimization during jit compilationghprbPullLinkhttps://github.com/iovisor/bcc/pull/2950ghprbPullLongDescriptionjump table optimization tries to optimize switch statements\r\ninto an array access. But such optimization will place certain\r\ninformation, acted as the array, in the read-only section.\r\nCurrently, bcc does not support read-only section, so\r\njump table optimized code will fail during kernel verification.\r\nThis is what happened to biolatpcts.py in my environment with\r\nlatest llvm.\r\n```\r\n -bash-4.4$ sudo ./biolatpcts.py console\r\n bpf: Failed to load program: Invalid argument\r\n unknown opcode 60\r\n processed 0 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0\r\n\r\n HINT: The 'unknown opcode' can happen if you reference a global or static variable,\r\n or data in read-only section. For example, 'char *p = \"hello\"' will result in p\r\n referencing a read-only section, and 'char p[] = \"hello\"' will have \"hello\" stored on the stack.\r\n```\r\nThis patch disabled jump table optimization on x64. The jump table\r\noptimization is introduced in llvm 3.9, I presume all bcc users\r\nshould already start to use recent llvm, so I go ahead to disable\r\nit without guarding based on llvm version. We can disable jump\r\ntable on other architectures if needed. A test case, developed\r\nbased biolatpcts.py tool, is added to ensure it pass the verifier.\r\n\r\nSigned-off-by: Yonghong Song <yhs@fb.com>ghprbCommentBodynullghprbGhRepositoryiovisor/bccghprbCredentialsId6d3daf13-69b8-48b1-9c8f-ec5353264113false<a title="turn off x86 jump table optimization during jit compilation" href="https://github.com/iovisor/bcc/pull/2950">PR #2950</a>: turn off x86 jump table opt...#52715615607460664bcc-pr #527527false5274224FAILURE1591251159882https://buildbot.iovisor.org/jenkins/user/davemarchevsky/my-views/view/all/job/bcc-pr/527/git527https://buildbot.iovisor.org/jenkins/user/davemarchevsky/my-views/view/all/job/bcc-pr/label=fc25/527/527https://buildbot.iovisor.org/jenkins/user/davemarchevsky/my-views/view/all/job/bcc-pr/label=fc26/527/527https://buildbot.iovisor.org/jenkins/user/davemarchevsky/my-views/view/all/job/bcc-pr/label=fc27/527/527https://buildbot.iovisor.org/jenkins/user/davemarchevsky/my-views/view/all/job/bcc-pr/label=fc28/527/527https://buildbot.iovisor.org/jenkins/user/davemarchevsky/my-views/view/all/job/bcc-pr/label=ubuntu1604/527/527https://buildbot.iovisor.org/jenkins/user/davemarchevsky/my-views/view/all/job/bcc-pr/label=ubuntu1710/527/527https://buildbot.iovisor.org/jenkins/user/davemarchevsky/my-views/view/all/job/bcc-pr/label=ubuntu1804/527/