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

From: Robin Murphy
Date: Tue Dec 06 2016 - 11:38:35 EST


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@xxxxxxxxxxx>
>> Signed-off-by: Vaneet Narang <v.narang@xxxxxxxxxxx>
>> ---
>> 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
>
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