From: dave.long@linaro.org (David Long)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v11 1/9] arm64: Add HAVE_REGS_AND_STACK_ACCESS_API feature
Date: Fri, 18 Mar 2016 09:06:06 -0400 [thread overview]
Message-ID: <56EBFD3E.5070600@linaro.org> (raw)
In-Reply-To: <56E3094E.5010906@arm.com>
On 03/11/2016 01:07 PM, James Morse wrote:
> Hi David,
>
> On 09/03/16 05:32, David Long wrote:
>> From: "David A. Long" <dave.long@linaro.org>
>>
>> Add HAVE_REGS_AND_STACK_ACCESS_API feature for arm64.
>>
>> Signed-off-by: David A. Long <dave.long@linaro.org>
>
>> diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
>> index ff7f132..efebf0f 100644
>> --- a/arch/arm64/kernel/ptrace.c
>> +++ b/arch/arm64/kernel/ptrace.c
>
> [ ... SNIP ... ]
>
>> +/**
>> + * 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)));
>
> I'm not sure where this is called from, but if kernel_stack_pointer(regs) could
> ever point into an irq_stack you will get the wrong result.
>
> arch/arm64/include/asm/irq.h has 'on_irq_stack(sp, cpu)' which should help,
> although you will need to check the bounds of the irq_stack separately.
>
>
> The horrible details...
>
> From arch/arm64/kernel/irq.c:20
>> /* irq stack only needs to be 16 byte aligned - not IRQ_STACK_SIZE aligned. */
>> DEFINE_PER_CPU(unsigned long [IRQ_STACK_SIZE/sizeof(long)], irq_stack)
>> __aligned(16);
>
> This was because per-cpu variables can be at-most page aligned.
> 6cdf9c7ca687 ("arm64: Store struct thread_info in sp_el0") changed
> current_thread_info() to work on these weirdly aligned irq_stacks.
>
>
> Thanks,
>
> James
>
>
It looks like this is ultimately used (currently) only by the
arch-independent kprobes tracing code. But it does seem like this will
be recording the wrong data when stack contents are being traced from
interrupt routine probes. I will put a fix in for the next spin.
Thanks,
-dl
next prev parent reply other threads:[~2016-03-18 13:06 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-09 5:32 [PATCH v11 0/9] arm64: Add kernel probes (kprobes) support David Long
2016-03-09 5:32 ` [PATCH v11 1/9] arm64: Add HAVE_REGS_AND_STACK_ACCESS_API feature David Long
2016-03-11 18:07 ` James Morse
2016-03-18 13:06 ` David Long [this message]
2016-03-15 11:04 ` Marc Zyngier
2016-03-21 7:08 ` David Long
2016-03-09 5:32 ` [PATCH v11 2/9] arm64: Add more test functions to insn.c David Long
2016-03-09 5:32 ` [PATCH v11 3/9] arm64: add copy_to/from_user to kprobes blacklist David Long
2016-03-15 18:47 ` James Morse
2016-03-16 5:43 ` Pratyush Anand
2016-03-16 10:27 ` James Morse
2016-03-17 7:57 ` Pratyush Anand
2016-03-18 13:29 ` Pratyush Anand
2016-03-18 14:02 ` James Morse
2016-03-18 14:43 ` Pratyush Anand
2016-03-18 18:12 ` James Morse
2016-03-21 5:17 ` Pratyush Anand
2016-03-21 14:52 ` Will Deacon
2016-03-22 16:51 ` Pratyush Anand
2016-03-17 12:04 ` 平松雅巳 / HIRAMATU，MASAMI
2016-03-09 5:32 ` [PATCH v11 4/9] arm64: add conditional instruction simulation support David Long
2016-03-13 12:09 ` Marc Zyngier
2016-03-14 4:04 ` Pratyush Anand
2016-03-14 7:38 ` Marc Zyngier
2016-03-21 8:35 ` David Long
2016-03-09 5:32 ` [PATCH v11 5/9] arm64: Kprobes with single stepping support David Long
2016-04-20 1:29 ` Li Bin
2016-03-09 5:32 ` [PATCH v11 6/9] arm64: kprobes instruction simulation support David Long
2016-03-12 3:56 ` Marc Zyngier
2016-03-21 9:39 ` David Long
2016-03-09 5:32 ` [PATCH v11 7/9] arm64: Add trampoline code for kretprobes David Long
2016-03-13 13:52 ` Marc Zyngier
2016-03-21 13:30 ` David Long
2016-03-09 5:32 ` [PATCH v11 8/9] arm64: Add kernel return probes support (kretprobes) David Long
2016-03-17 12:22 ` 平松雅巳 / HIRAMATU，MASAMI
2016-03-17 12:58 ` 平松雅巳 / HIRAMATU，MASAMI
2016-03-21 13:33 ` David Long
2016-03-09 5:32 ` [PATCH v11 9/9] kprobes: Add arm64 case in kprobe example module David Long
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