linux-kernel - Re: [PATCH] objtool: Move objtool

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Message-ID: <20190314161503.67ti3ikrw6uydcqd@treble>
Date:   Thu, 14 Mar 2019 11:15:03 -0500
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     moosotc@...il.com
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH] objtool: Move objtool_file struct off the stack

On Thu, Mar 14, 2019 at 06:31:37PM +0300, moosotc@...il.com wrote:
> Josh Poimboeuf <jpoimboe@...hat.com> writes:
> 
> > Objtool uses over 512k of stack, thanks to the hash table embedded in
> > the objtool_file struct.  This causes an unnecessarily large stack
> > allocation and breaks users with low stack limits.
> >
> > Move the struct off the stack.
> >
> > Fixes: 042ba73fe7eb ("objtool: Add several performance improvements")
> > Reported-by: Vassili Karpov <moosotc@...il.com>
> > Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
> > ---
> >  tools/objtool/check.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/objtool/check.c b/tools/objtool/check.c
> > index 0414a0d52262..91c4799192e1 100644
> > --- a/tools/objtool/check.c
> > +++ b/tools/objtool/check.c
> > @@ -2184,9 +2184,10 @@ static void cleanup(struct objtool_file *file)
> >  	elf_close(file->elf);
> >  }
> >  
> > +struct objtool_file file;
> > +
> 
> Maybe it also deserves a "static" storage duration (if nothing else this
> would prevent possible name clashes)?

Yeah, good point.

> 
> >  int check(const char *_objname, bool orc)
> >  {
> > -	struct objtool_file file;
> >  	int ret, warnings = 0;
> >  
> >  	objname = _objname;
> 
> -- 
> mailto:moosotc@...il.com

-- 
Josh