Date: Mon, 05 Dec 2016 16:42:15 -0800 From: John Baldwin <jhb@freebsd.org> To: src-committers@freebsd.org Cc: svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r309589 - head/usr.bin/truss Message-ID: <18568727.ZCvfzOzSEO@ralph.baldwin.cx> In-Reply-To: <201612060039.uB60d0eE075130@repo.freebsd.org> References: <201612060039.uB60d0eE075130@repo.freebsd.org>
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On Tuesday, December 06, 2016 12:39:00 AM John Baldwin wrote: > Author: jhb > Date: Tue Dec 6 00:39:00 2016 > New Revision: 309589 > URL: https://svnweb.freebsd.org/changeset/base/309589 > > Log: > Rework syscall structure lookups. > > Avoid always using an O(n^2) loop over known syscall structures with > strcmp() on each system call. Instead, use a per-ABI cache indexed by > the system call number. The first 1024 system calls (which should cover > all of the normal system calls in currently-supported ABIs) use a flat array > indexed by the system call number to find system call structure. For other > system calls, a linked list of structures storing an integer to structure > mapping is stored in the ABI. The linked list isn't very smart, but it > should only be used by buggy applications invoking unknown system calls. > > This also fixes handling of unknown system calls which currently trigger > a NULL pointer dereference. > > Reviewed by: kib > MFC after: 2 weeks I of course forgot: Differential Revision: https://reviews.freebsd.org/D8639 The table + linked-list could perhaps be replaced by a hash table, but I don't quite feel like writing a new hash table from scratch. One option would be to make truss a C++ program and use unordered_map<>. We could then turn the procabi thing into a class which might look a bit nicer (and use constructors to initialize the hash table instead of the inline STAILQ_HEAD_INITIALIZER). -- John Baldwin
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