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

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Date:   Tue, 6 Dec 2016 17:11:16 +0100
From:   Christoffer Dall <christoffer.dall@...aro.org>
To:     Maninder Singh <maninder1.s@...sung.com>
Cc:     catalin.marinas@....com, will.deacon@....com, marc.zyngier@....com,
        pbonzini@...hat.com, rkrcmar@...hat.com, cmetcalf@...lanox.com,
        panand@...hat.com, mark.rutland@....com, james.morse@....com,
        akpm@...ux-foundation.org, sandeepa.s.prabhu@...il.com,
        labbott@...hat.com, shijie.huang@....com,
        ard.biesheuvel@...aro.org, wangkefeng.wang@...wei.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kvmarm@...ts.cs.columbia.edu, kvm@...r.kernel.org,
        pankaj.m@...sung.com, ajeet.y@...sung.com, cpgs@...sung.com,
        Vaneet Narang <v.narang@...sung.com>
Subject: Re: [PATCH 1/1] arm64: Correcting format specifier for printing 64
 bit addresses

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.

>  	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