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

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Message-ID: <878que2u2i.fsf@mail.lhotse>
Date: Thu, 24 Oct 2024 12:00:53 +1100
From: Michael Ellerman <mpe@...erman.id.au>
To: Mukesh Kumar Chaurasiya <mchauras@...ux.ibm.com>
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, mchauras@...ux.ibm.com,
 linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] powerpc/xmon: symbol lookup length fixed

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".

> 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

>  	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