# Re: \[PATCH v11 18/39\] arm64/traps: Handle GCS exceptions

- From: Mark Brown \<broonie@kernel.org\>
- Date: 2024-08-22 16:31:21 
- List: linux-arm-kernel
- Page: https://ratatoskr.run/linux-arm-kernel/2024/08/289776
- Thread: https://ratatoskr.run/linux-arm-kernel/2024/08/289561/t.md

```text
On Thu, Aug 22, 2024 at 04:44:12PM +0100, Catalin Marinas wrote:
> On Thu, Aug 22, 2024 at 02:15:21AM +0100, Mark Brown wrote:

> > +void do_el0_gcs(struct pt_regs *regs, unsigned long esr)
> > +{
> > +	force_signal_inject(SIGSEGV, SEGV_CPERR, regs->pc, 0);
> > +}

> Just double checking: a GCSPOPM (for example, it can be a RET) from a
> non-GCS page would generate a classic permission fault with ISS2.GCS set
> rather than a GCS exception. That's my reading from the Arm ARM
> pseudocode, the text isn't clear to me.

Yes, we only generate GCS exceptions on checking values that have
successfully been loaded from memory or other GCS logic errors - memory
accesses generate data aborts.
```

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