linux-kernel - Re: [PATCH 1/1] arm64: Correcting format specifier for printing 64 bit addresses

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Message-ID: <dbf5af31-2a36-5216-4544-13ade6dddd3a@arm.com>
Date:   Tue, 6 Dec 2016 16:32:18 +0000
From:   Robin Murphy <robin.murphy@....com>
To:     Christoffer Dall <christoffer.dall@...aro.org>,
        Maninder Singh <maninder1.s@...sung.com>
Cc:     mark.rutland@....com, wangkefeng.wang@...wei.com,
        kvm@...r.kernel.org, rkrcmar@...hat.com, catalin.marinas@....com,
        will.deacon@....com, kvmarm@...ts.cs.columbia.edu,
        panand@...hat.com, cpgs@...sung.com, shijie.huang@....com,
        labbott@...hat.com, Vaneet Narang <v.narang@...sung.com>,
        cmetcalf@...lanox.com, marc.zyngier@....com, ajeet.y@...sung.com,
        sandeepa.s.prabhu@...il.com, linux-arm-kernel@...ts.infradead.org,
        pankaj.m@...sung.com, ard.biesheuvel@...aro.org,
        linux-kernel@...r.kernel.org, james.morse@....com,
        pbonzini@...hat.com, akpm@...ux-foundation.org
Subject: Re: [PATCH 1/1] arm64: Correcting format specifier for printing 64
 bit addresses

On 06/12/16 16:11, Christoffer Dall wrote:
> On Mon, Dec 05, 2016 at 01:39:53PM +0530, Maninder Singh wrote:
>> This patch corrects format specifier for printing 64 bit addresses.
>>
>> Signed-off-by: Maninder Singh <maninder1.s@...sung.com>
>> Signed-off-by: Vaneet Narang <v.narang@...sung.com>
>> ---
>>  arch/arm64/kernel/signal.c |  2 +-
>>  arch/arm64/kvm/sys_regs.c  |  8 ++++++--
>>  arch/arm64/mm/fault.c      | 15 ++++++++++-----
>>  arch/arm64/mm/mmu.c        |  4 ++--
>>  4 files changed, 19 insertions(+), 10 deletions(-)
>>
>> diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
>> index c7b6de6..c89d5fd 100644
>> --- a/arch/arm64/kernel/signal.c
>> +++ b/arch/arm64/kernel/signal.c
>> @@ -155,7 +155,7 @@ asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
>>  
>>  badframe:
>>  	if (show_unhandled_signals)
>> -		pr_info_ratelimited("%s[%d]: bad frame in %s: pc=%08llx sp=%08llx\n",
>> +		pr_info_ratelimited("%s[%d]: bad frame in %s: pc=%016llx sp=%016llx\n",
>>  				    current->comm, task_pid_nr(current), __func__,
>>  				    regs->pc, regs->sp);
>>  	force_sig(SIGSEGV, current);
>> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
>> index 87e7e66..89bf5c1 100644
>> --- a/arch/arm64/kvm/sys_regs.c
>> +++ b/arch/arm64/kvm/sys_regs.c
>> @@ -1554,8 +1554,12 @@ static void unhandled_cp_access(struct kvm_vcpu *vcpu,
>>  		WARN_ON(1);
>>  	}
>>  
>> -	kvm_err("Unsupported guest CP%d access at: %08lx\n",
>> -		cp, *vcpu_pc(vcpu));
>> +	if (params->is_32bit)
>> +		kvm_err("Unsupported guest CP%d access at: %08lx\n",
>> +			cp, *vcpu_pc(vcpu));
>> +	else
>> +		kvm_err("Unsupported guest CP%d access at: %016lx\n",
>> +			cp, *vcpu_pc(vcpu));
> 
> It feels a bit much to me to have an if-statement to differentiate the
> number of leading zeros, so if it's important to always have fixed
> widths then I would just use %016lx in both cases.

Actually, it looks like vsnprintf does support the '*' field width
specifier, so even if the format _is_ critical there's still no reason
to have such duplicated code.

Robin.

>>  	print_sys_reg_instr(params);
>>  	kvm_inject_undefined(vcpu);
>>  }
>> diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
>> index a78a5c4..d96a42a 100644
>> --- a/arch/arm64/mm/fault.c
>> +++ b/arch/arm64/mm/fault.c
>> @@ -77,7 +77,7 @@ void show_pte(struct mm_struct *mm, unsigned long addr)
>>  
>>  	pr_alert("pgd = %p\n", mm->pgd);
>>  	pgd = pgd_offset(mm, addr);
>> -	pr_alert("[%08lx] *pgd=%016llx", addr, pgd_val(*pgd));
>> +	pr_alert("[%016lx] *pgd=%016llx", addr, pgd_val(*pgd));
>>  
>>  	do {
>>  		pud_t *pud;
>> @@ -177,7 +177,7 @@ static void __do_kernel_fault(struct mm_struct *mm, unsigned long addr,
>>  	 * No handler, we'll have to terminate things with extreme prejudice.
>>  	 */
>>  	bust_spinlocks(1);
>> -	pr_alert("Unable to handle kernel %s at virtual address %08lx\n",
>> +	pr_alert("Unable to handle kernel %s at virtual address %016lx\n",
>>  		 (addr < PAGE_SIZE) ? "NULL pointer dereference" :
>>  		 "paging request", addr);
>>  
>> @@ -198,9 +198,14 @@ static void __do_user_fault(struct task_struct *tsk, unsigned long addr,
>>  	struct siginfo si;
>>  
>>  	if (unhandled_signal(tsk, sig) && show_unhandled_signals_ratelimited()) {
>> -		pr_info("%s[%d]: unhandled %s (%d) at 0x%08lx, esr 0x%03x\n",
>> -			tsk->comm, task_pid_nr(tsk), fault_name(esr), sig,
>> -			addr, esr);
>> +		if (compat_user_mode(regs))
>> +			pr_info("%s[%d]: unhandled %s (%d) at 0x%08lx, esr 0x%03x\n",
>> +				tsk->comm, task_pid_nr(tsk), fault_name(esr), sig,
>> +				addr, esr);
>> +		else
>> +			pr_info("%s[%d]: unhandled %s (%d) at 0x%016lx, esr 0x%03x\n",
>> +				tsk->comm, task_pid_nr(tsk), fault_name(esr), sig,
>> +				addr, esr);
> 
> same here.
> 
> Thanks,
> -Christoffer
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 

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