[PATCH] objtool: Move objtool_file struct off the stack

[PATCH] objtool: Move objtool_file struct off the stack

[Josh Poimboeuf]

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@gmail.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.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;
+
 int check(const char *_objname, bool orc)
 {
-	struct objtool_file file;
 	int ret, warnings = 0;
 
 	objname = _objname;
-- 
2.17.2

Re: [PATCH] objtool: Move objtool_file struct off the stack

[moosotc]

Josh Poimboeuf <jpoimboe@redhat.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@gmail.com>
> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.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)?

>  int check(const char *_objname, bool orc)
>  {
> -	struct objtool_file file;
>  	int ret, warnings = 0;
>  
>  	objname = _objname;

-- 
mailto:moosotc@gmail.com

Re: [PATCH] objtool: Move objtool_file struct off the stack

[Josh Poimboeuf]

On Thu, Mar 14, 2019 at 06:31:37PM +0300, moosotc@gmail.com wrote:
> Josh Poimboeuf <jpoimboe@redhat.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@gmail.com>
> > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.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@gmail.com

-- 
Josh