linux-kernel - Re: linux-next: changed messages in qemu boot

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Message-Id: <1653375606.b65qo262yf.naveen@linux.ibm.com>
Date:   Tue, 24 May 2022 12:41:27 +0530
From:   "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>
To:     Michael Ellerman <mpe@...erman.id.au>,
        Stephen Rothwell <sfr@...b.auug.org.au>
Cc:     Christophe Leroy <christophe.leroy@...roup.eu>,
        Linux Kernel
 Mailing List 
        <linux-kernel@...r.kernel.org>,
        Linux Next Mailing List <linux-next@...r.kernel.org>,
        PowerPC <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: linux-next: changed messages in qemu boot

Michael Ellerman wrote:
> "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com> writes:
>> Stephen Rothwell wrote:
> 
>> The below diff fixes it for me:
>>
>> diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c
>> index 46c002a8388804..7418da705d43ac 100644
>> --- a/arch/powerpc/kernel/trace/ftrace.c
>> +++ b/arch/powerpc/kernel/trace/ftrace.c
>> @@ -746,7 +746,7 @@ int __init ftrace_dyn_arch_init(void)
>>  
>>         reladdr = addr - kernel_toc_addr();
>>  
>> -       if (reladdr >= SZ_2G || reladdr < -SZ_2G) {
>> +       if (reladdr >= SZ_2G || reladdr < -_UL(SZ_2G)) {
>>                 pr_err("Address of %ps out of range of kernel_toc.\n",
>>                                 (void *)addr);
>>                 return -1;
> 
> I did:
> 
> 	if (reladdr >= SZ_2G || reladdr < -(long)SZ_2G) {

That was my first attempt.

> Which more closely matches what the old code did, and I think is more
> obvious? ie. we don't want to negate the unsigned value, we want a
> signed value, and then the negative of that.

When you put it like that... :D
In hindsight, I agree though -- _UL() isn't necessarily better.


Thanks,
Naveen