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a05c392032
The SMP flush_tlb_*() functions may clear the memory map's ASIDs for other CPUs if the mm has only a single user (the current CPU) in order to avoid SMP calls. However this makes it appear to has_valid_asid(), which is used by various cache flush functions, as if the CPUs have never run in the mm, and therefore can't have cached any of its memory. For flush_tlb_mm() this doesn't sound unreasonable. flush_tlb_range() corresponds to flush_cache_range() which does do full indexed cache flushes, but only on the icache if the specified mapping is executable, otherwise it doesn't guarantee that there are no cache contents left for the mm. flush_tlb_page() corresponds to flush_cache_page(), which will perform address based cache ops on the specified page only, and also only touches the icache if the page is executable. It does not guarantee that there are no cache contents left for the mm. For example, this affects flush_cache_range() which uses the has_valid_asid() optimisation. It is required to flush the icache when mappings are made executable (e.g. using mprotect) so they are immediately usable. If some code is changed to non executable in order to be modified then it will not be flushed from the icache during that time, but the ASID on other CPUs may still be cleared for TLB flushing. When the code is changed back to executable, flush_cache_range() will assume the code hasn't run on those other CPUs due to the zero ASID, and won't invalidate the icache on them. This is fixed by clearing the other CPUs ASIDs to 1 instead of 0 for the above two flush_tlb_*() functions when the corresponding cache flushes are likely to be incomplete (non executable range flush, or any page flush). This ASID appears valid to has_valid_asid(), but still triggers ASID regeneration due to the upper ASID version bits being 0, which is less than the minimum ASID version of 1 and so always treated as stale. Signed-off-by: James Hogan <james.hogan@imgtec.com> Cc: Paul Burton <paul.burton@imgtec.com> Cc: Leonid Yegoshin <leonid.yegoshin@imgtec.com> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/13795/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org> |
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