[PATCH] arm64: Fix map_range() not splitting mapped blocks

[Pierre-Clément Tosi]

Hi Marc,

On Tue, Mar 19, 2024 at 09:43:03AM +0000, Marc Zyngier wrote:
> This seems pretty reasonable, thanks for looking into this. However, I
> can't help but notice that this is done without any BBM, and no TLBI
> either.
> 
> Are we guaranteed that the updated page tables are not live at the
> point of update?

This means gd->arch.tlb_addr pointing to the live PTs during setup_pgtables().

In arch/arm/cpu/armv8, setup_all_pgtables() runs with SCTLR_ELx.M unset.

In arch/arm/cpu/armv8/fsl-layerscape, setup_pgtables() is called twice:

 - early_mmu_setup() calls it with SCTLR_ELx.M unset;
 - final_mmu_setup() overwrites gd->arch.tlb_addr before calling it iff
   CFG_SYS_MEM_RESERVE_SECURE is defined i.e. if CONFIG_SYS_SOC="fsl-layerscape"
   so that <asm/arch-fsl-layerscape/config.h> gets auto-included through
   <include/config.h>.

So can CONFIG_FSL_LAYERSCAPE be set while CONFIG_SYS_SOC != "fsl-layerscape"?

I suppose Fabio and Stefano can answer this and/or help with ensuring that
setup_pgtables() is never called on live PTs.

Thanks,

-- 
Pierre