Messages in this thread | | | Date | Fri, 11 Mar 2016 18:07:10 +0000 | From | James Morse <> | Subject | Re: [PATCH v11 1/9] arm64: Add HAVE_REGS_AND_STACK_ACCESS_API feature |
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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
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