Re: [RFC PATCH] Update the cachetlb.txt file WRTflush_dcache_pageand update_mmu_cache

[David Miller]

From: Catalin Marinas <catalin.marinas@xxxxxxx>
Date: Mon, 10 May 2010 15:00:10 +0100

> 3rd point above would help with the D-cache aliasing. Does the I/D cache
> coherency need to be handled differently? On PIPT Harvard architectures,
> we don't actually have D-cache aliasing but we may end up flushing too
> much in kunmap() just in case such page would be mapped in user space
> with executable permission.

You can handle this by having an "I-cache clean" bit in the page.
When you kmap/kunmap, simply force this bit clear.

In update_mmu_cache() or set_pte_at() you'll see when a page gets
into userspace with execute permission, and if the I-cache bit
is clear you can do the flush then and set the "I-cache clean"
bit.
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