Re: [RFC PATCH v2 1/4] arm64: Implement infrastructure for stack trace reliability checks

From: Mark Brown
Date: Fri Apr 09 2021 - 07:57:30 EST


On Thu, Apr 08, 2021 at 06:30:22PM -0500, Madhavan T. Venkataraman wrote:
> On 4/8/21 2:30 PM, Madhavan T. Venkataraman wrote:

> > 1. Create a common section (I will have to come up with an appropriate name) and put
> > all such functions in that one section.

> > 2. Create one section for each logical type (exception section, ftrace section and
> > kprobe section) or some such.

> For now, I will start with idea 2. I will create a special section for each class of
> functions (EL1 exception handlers, FTRACE trampolines, KPROBE trampolines). Instead of a
> special functions array, I will implement a special_sections array. The rest of the code
> should just fall into place.

> Let me know if you prefer something different.

It might be safer to start off by just putting all SYM_CODE into a
section then pulling bits we know to be safe out of the section as
needed - we know that anything that's SYM_CODE is doing something
non-standard and needs checking to verify that the unwinder will be
happy with it and I that should cover most if not all of the cases above
as well as anything else we didn't explicitly think of.

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