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Message-ID: <573E8FFB.3000107@linaro.org>
Date: Fri, 20 May 2016 00:18:03 -0400
From: David Long <dave.long@...aro.org>
To: Huang Shijie <shijie.huang@....com>
Cc: Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will.deacon@....com>,
Sandeepa Prabhu <sandeepa.s.prabhu@...il.com>,
William Cohen <wcohen@...hat.com>,
Pratyush Anand <panand@...hat.com>,
Steve Capper <steve.capper@...aro.org>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
Marc Zyngier <marc.zyngier@....com>,
Mark Rutland <mark.rutland@....com>,
Petr Mladek <pmladek@...e.com>,
Viresh Kumar <viresh.kumar@...aro.org>,
John Blackwood <john.blackwood@...r.com>,
Feng Kan <fkan@....com>, Zi Shen Lim <zlim.lnx@...il.com>,
Dave P Martin <Dave.Martin@....com>,
Yang Shi <yang.shi@...aro.org>,
Vladimir Murzin <Vladimir.Murzin@....com>,
Kees Cook <keescook@...omium.org>,
"Suzuki K. Poulose" <suzuki.poulose@....com>,
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Alex Bennée <alex.bennee@...aro.org>,
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Christoffer Dall <christoffer.dall@...aro.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Robin Murphy <Robin.Murphy@....com>,
Jens Wiklander <jens.wiklander@...aro.org>,
Balamurugan Shanmugam <bshanmugam@....com>, nd@....com
Subject: Re: [PATCH v12 01/10] arm64: Add HAVE_REGS_AND_STACK_ACCESS_API
feature
On 05/17/2016 05:14 AM, Huang Shijie wrote:
> On Wed, Apr 27, 2016 at 02:52:56PM -0400, David Long wrote:
>> From: "David A. Long" <dave.long@...aro.org>
>> +/**
>> + * regs_within_kernel_stack() - check the address in the stack
>> + * @regs: pt_regs which contains kernel stack pointer.
>> + * @addr: address which is checked.
>> + *
>> + * regs_within_kernel_stack() checks @addr is within the kernel stack page(s).
>> + * If @addr is within the kernel stack, it returns true. If not, returns false.
>> + */
>> +bool regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr)
>> +{
>> + return ((addr & ~(THREAD_SIZE - 1)) ==
>> + (kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1))) ||
>> + on_irq_stack(addr, raw_smp_processor_id());
>> +}
>> +
>> +/**
>> + * regs_get_kernel_stack_nth() - get Nth entry of the stack
>> + * @regs: pt_regs which contains kernel stack pointer.
>> + * @n: stack entry number.
>> + *
>> + * regs_get_kernel_stack_nth() returns @n th entry of the kernel stack which
>> + * is specified by @regs. If the @n th entry is NOT in the kernel stack,
>> + * this returns 0.
>> + */_
>> +unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs, unsigned int n)
>> +{
>> + unsigned long *addr = (unsigned long *)kernel_stack_pointer(regs);
>> +
>> + addr += n;
>> + if (regs_within_kernel_stack(regs, (unsigned long)addr))
> If the @addr fall in the interrupt stack, the regs_within_kernel_stack()
> will return true. But Is it what we want?
>
Yes, I think it is. The function is used in regs_get_kernel_stack_nth()
to make sure the data being asked for (based on the pt_regs saved stack
pointer) is actually on the stack, whether it's "kernel" stack or "irq"
stack.
Thanks,
-dl
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