Messages in this thread | | | Date | Wed, 7 May 2014 18:34:43 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH] perf x86: Fix perf to use non-executable stack, again |
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* Mathias Krause <minipli@googlemail.com> wrote:
> On 27 April 2014 18:16, Jiri Olsa <jolsa@redhat.com> wrote: > > On Sun, Apr 27, 2014 at 06:07:30PM +0200, Mathias Krause wrote: > >> On 27 April 2014 12:39, Jiri Olsa <jolsa@redhat.com> wrote: > >> > On Sun, Apr 27, 2014 at 12:03:50PM +0200, Mathias Krause wrote: > >> > [...] > >> >> 2/ What if somebody tries to add/link code to perf that makes use of > >> >> nested functions? That'll make perf fail as the trampoline code > >> >> generated by gcc won't be executable due to the enforced > >> >> non-executable stack by -Wl,-z,noexecstack. > >> > > >> > I guess in that case he would change the Makefile as well? > >> > >> Not necessarily. What if a later version of a library already used by > >> perf needs an executable stack because it now makes use of nested > >> functions? Unlikely, though in that case no change to perf would be > >> made, but perf would then require an executable stack, too. > > > > I tried you can run binary with noexecstack having dynamic > > library dependency wit execstack > > Well, it might work on your system but it won't work on mine. See this > bug, why: https://sourceware.org/bugzilla/show_bug.cgi?id=12492 > > > [...] > >> > >> > or insert test case for perf's executable stack to 'perf test' > >> > >> That won't work for systems preventing processes getting an executable > >> stack in the first place. That was the reason I stumbled about the > > > > could be disabled on such systems > > Of course, it could be disabled, i.e. I could allow perf to get an > executable stack. Though, I don't like my stacks to be executable ;)
Absolutely. Using an executable stack is really just a legacy thing, it should be avoided (and I'd say it must be avoided) in any modern application.
Thanks,
Ingo
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