From: Carlo Arenas <firstname.lastname@example.org> To: "Ævar Arnfjörð Bjarmason" <email@example.com> Cc: firstname.lastname@example.org, email@example.com Subject: Re: [RFC PATCH] grep: allow for run time disabling of JIT in PCRE Date: Mon, 29 Jul 2019 03:26:42 -0700 [thread overview] Message-ID: <CAPUEspgQNCENviPYP6X790DvSgj_RpJVo2KP_39voLQnVc65pQ@mail.gmail.com> (raw) In-Reply-To: <firstname.lastname@example.org> On Mon, Jul 29, 2019 at 1:55 AM Ævar Arnfjörð Bjarmason <email@example.com> wrote: > > On Mon, Jul 29 2019, Carlo Marcelo Arenas Belón wrote: > > > PCRE1 allowed for a compile time flag to disable JIT, but PCRE2 never > > had one, forcing the use of JIT if -P was requested. > > What's that PCRE1 compile-time flag? NO_LIBPCRE1_JIT at GIT compile time (regardless of JIT support in the PCRE1 library you are using) > > After ed0479ce3d (Merge branch 'ab/no-kwset' into next, 2019-07-15) > > the PCRE2 engine will be used more broadly and therefore adding this > > knob will give users a fallback for situations like the one observed > > in OpenBSD with a JIT enabled PCRE2, because of W^X restrictions: > > > > $ git grep 'foo bar' > > fatal: Couldn't JIT the PCRE2 pattern 'foo bar', got '-48' > > $ git grep -G 'foo bar' > > fatal: Couldn't JIT the PCRE2 pattern 'foo bar', got '-48' > > $ git grep -E 'foo bar' > > fatal: Couldn't JIT the PCRE2 pattern 'foo bar', got '-48' > > $ git grep -F 'foo bar' > > fatal: Couldn't JIT the PCRE2 pattern 'foo bar', got '-48' > > Yeah that obviously sucks more with ab/no-kwset, but that seems like a > case where -P would have been completely broken before, and therefore I > can't imagine the package ever passed "make test". Or is W^X also > exposed as some run-time option on OpenBSD? ironically, you could use PCRE1 since that is not using the JIT fast path and therefore will fallback automatically to the interpreter there is also a convoluted way to make your binary work by moving it into a mount point that has been specially exempted from that W^X restriction. > I.e. aside from the merits of such a setting in general these examples > seem like just working around something that should be fixed at make > all/test time, or maybe I'm missing something. 1) before you could just avoid using -P and still be able to grep 2) there is no way to tell PCRE2 to get out of the way even if you are not using -P you are right though that this is not a new problem and was reported before with patches and the last comment saying a configuration should be provided. > To the extent that we'd want to make this sort of thing configurable, I > wonder if a continuation of my (*NO_JIT) patch isn't better, i.e. just > adding the ability to configure some string we'd inject at the start of > every pattern. looking at the number of lines of code, it would seem the configuration approach is simpler. > That would allow for setting any other number of options in > pcre2syntax(3) without us needing to carry config for each one, > e.g. (*LIMIT_HEAP=d), (*LIMIT_DEPTH=d) etc. It does present a larger > foot-gun surface though... the parameters I suspect users might need are not really accessible through that (ex: jit stacksize). it is important to note that currently we are not preventing any user to use those flags themselves in their patterns either. Carlo
next prev parent reply other threads:[~2019-07-29 10:26 UTC|newest] Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-07-28 23:54 Carlo Marcelo Arenas Belón 2019-07-29 0:09 ` Carlo Arenas 2019-07-29 4:57 ` Junio C Hamano 2019-07-29 5:29 ` Carlo Arenas 2019-07-29 8:55 ` Ævar Arnfjörð Bjarmason 2019-07-29 10:26 ` Carlo Arenas [this message] 2019-07-29 12:38 ` Ævar Arnfjörð Bjarmason 2019-07-30 13:01 ` Carlo Arenas 2019-07-29 10:59 ` [RFC PATCH v2] " Carlo Marcelo Arenas Belón 2019-07-29 11:33 ` Carlo Arenas 2019-07-29 15:11 ` René Scharfe 2019-07-29 17:47 ` Junio C Hamano 2019-07-30 0:49 ` Carlo Arenas 2019-07-30 17:55 ` René Scharfe 2019-07-31 12:36 ` Johannes Schindelin 2019-07-31 16:18 ` Junio C Hamano 2019-07-31 12:32 ` Johannes Schindelin 2019-07-31 14:57 ` Ævar Arnfjörð Bjarmason 2019-08-04 0:25 ` Carlo Arenas 2019-08-04 3:14 ` [RFC PATCH v3] grep: treat PCRE2 jit compilation memory error as non fatal Carlo Marcelo Arenas Belón 2019-08-04 7:43 ` Carlo Arenas 2019-08-05 20:16 ` Junio C Hamano 2019-07-31 12:24 ` [RFC PATCH] grep: allow for run time disabling of JIT in PCRE Johannes Schindelin
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style List information: http://vger.kernel.org/majordomo-info.html * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=CAPUEspgQNCENviPYP6X790DvSgj_RpJVo2KP_39voLQnVc65pQ@mail.gmail.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --subject='Re: [RFC PATCH] grep: allow for run time disabling of JIT in PCRE' \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: link
Code repositories for project(s) associated with this inbox: https://80x24.org/mirrors/git.git This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).