linux-kernel - Re: [PATCH] powerpc/xmon: symbol lookup length fixed

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Message-ID: <zkm6fcxaef4gnvvsvykv7po7joytakyhqnmt2j72ej3r4wffn2@j5p6h6h2bwnw>
Date: Fri, 25 Oct 2024 00:33:41 +0530
From: Mukesh Kumar Chaurasiya <mchauras@...ux.ibm.com>
To: Michael Ellerman <mpe@...erman.id.au>
Cc: npiggin@...il.com, christophe.leroy@...roup.eu, naveen@...nel.org,
        maddy@...ux.ibm.com, peterx@...hat.com, groug@...d.org,
        sshegde@...ux.ibm.com, linuxppc-dev@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] powerpc/xmon: symbol lookup length fixed

On Thu, Oct 24, 2024 at 10:42:12AM +0530, Mukesh Kumar Chaurasiya wrote:
> On Thu, Oct 24, 2024 at 12:00:53PM +1100, Michael Ellerman wrote:
> > Mukesh Kumar Chaurasiya <mchauras@...ux.ibm.com> writes:
> > > Currently xmon cannot lookup symbol beyond 64 characters in some cases.
> > 
> > Can you mention which commands? It looks like it's "ls" and "lp".
> Sure.
> > 
> > > Fix this by using KSYM_NAME_LEN instead of fixed 64 characters.
> > >
> > > Signed-off-by: Mukesh Kumar Chaurasiya <mchauras@...ux.ibm.com>
> > > ---
> > >  arch/powerpc/xmon/xmon.c | 6 +++---
> > >  1 file changed, 3 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
> > > index e6cddbb2305f..22b8b5cc4df0 100644
> > > --- a/arch/powerpc/xmon/xmon.c
> > > +++ b/arch/powerpc/xmon/xmon.c
> > > @@ -3662,7 +3662,7 @@ symbol_lookup(void)
> > >  	int type = inchar();
> > >  	unsigned long addr, cpu;
> > >  	void __percpu *ptr = NULL;
> > > -	static char tmp[64];
> > > +	static char tmp[KSYM_NAME_LEN];
> >   
> > I think you could use the existing tmpstr buffer.
> > 
> > It is global so it's a little hard to track down all the users, but I
> > think it's only used briefly in get_function_bounds(),
> > xmon_print_symbol() and scanhex(). ie. none of the uses persist across
> > function calls.
> > 
> > We don't want to have two 512 byte static arrays lying around if we can
> > get by with one.
> > 
> > cheers
> Sure.
For now i don't think so we can get by with only one. There is a lookup being
done when the scanhex is using the tmpstr for another lookup.

I'll send a V2 with commit message change.
> 
> Will send out V2.
> > >  	switch (type) {
> > >  	case 'a':
> > > @@ -3671,7 +3671,7 @@ symbol_lookup(void)
> > >  		termch = 0;
> > >  		break;
> > >  	case 's':
> > > -		getstring(tmp, 64);
> > > +		getstring(tmp, KSYM_NAME_LEN);
> > >  		if (setjmp(bus_error_jmp) == 0) {
> > >  			catch_memory_errors = 1;
> > >  			sync();
> > > @@ -3686,7 +3686,7 @@ symbol_lookup(void)
> > >  		termch = 0;
> > >  		break;
> > >  	case 'p':
> > > -		getstring(tmp, 64);
> > > +		getstring(tmp, KSYM_NAME_LEN);
> > >  		if (setjmp(bus_error_jmp) == 0) {
> > >  			catch_memory_errors = 1;
> > >  			sync();
> > > -- 
> > > 2.47.0
>