Date: Wed, 13 May 2015 18:52:18 +0000 (UTC) From: Stanislav Sedov <stas@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r282866 - head/usr.sbin/pmcstat Message-ID: <201505131852.t4DIqILs046320@svn.freebsd.org>
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Author: stas Date: Wed May 13 18:52:18 2015 New Revision: 282866 URL: https://svnweb.freebsd.org/changeset/base/282866 Log: Fix pmcstat symbol resolution for userland processes. When examining existing processes pmcstat fails to correctly determine the locations of executable sections of the process due to a miscalculated virtual load address. This does not affect the newly launched processes as the same value passed as a "start address" to the pmcstat_image_link() thus nullifying the effect of it. The issue manifests itself in processes not being reported in the pmcstat(8) output and "dubious frames" being reported. Fix it for now by ignoring all the sections except the executable one. This won't fix the issue for objects with multiple executable sections but helps in majority of real world usecases. The real solution would be to modify the MAP-IN event to include the appropriate load address so pmcstat(8) won't have to manually parse object files to try to determine it. PR: 198147, 198148 Reviewed by: jhb, rpaulo MFC after: 2 weeks Modified: head/usr.sbin/pmcstat/pmcstat_log.c Modified: head/usr.sbin/pmcstat/pmcstat_log.c ============================================================================== --- head/usr.sbin/pmcstat/pmcstat_log.c Wed May 13 17:38:07 2015 (r282865) +++ head/usr.sbin/pmcstat/pmcstat_log.c Wed May 13 18:52:18 2015 (r282866) @@ -716,7 +716,8 @@ pmcstat_image_get_elf_params(struct pmcs ph.p_offset); break; case PT_LOAD: - if ((ph.p_offset & (-ph.p_align)) == 0) + if ((ph.p_flags & PF_X) != 0 && + (ph.p_offset & (-ph.p_align)) == 0) image->pi_vaddr = ph.p_vaddr & (-ph.p_align); break; }
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