On Tue, Sep 08, 2020 at 03:58:07PM +0200, Andrey Konovalov wrote:

On Thu, Aug 27, 2020 at 12:38 PM Catalin Marinas
[off-list ref] wrote:

quoted

On Fri, Aug 14, 2020 at 07:27:06PM +0200, Andrey Konovalov wrote:

quoted

@@ -957,6 +984,7 @@ SYM_FUNC_START(cpu_switch_to)
      mov     sp, x9
      msr     sp_el0, x1
      ptrauth_keys_install_kernel x1, x8, x9, x10
+     mte_restore_gcr 1, x1, x8, x9
      scs_save x0, x8
      scs_load x1, x8
      ret

Since we set GCR_EL1 on exception entry and return, why is this needed?
We don't have a per-kernel thread GCR_EL1, it's global to all threads,
so I think cpu_switch_to() should not be touched.

Dropping this line from the diff leads to many false-positives... I'll
leave this to Vincenzo.

I wouldn't expect this to have any effect but maybe the
mte_thread_switch() code still touches GCR_EL1 (it does this in the
user-space support, Vincenzo's patches should move that to exception
entry/return).

-- 
Catalin

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