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arm64: mm: Simplify __flush_tlb_range_limit_excess()

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__flush_tlb_range_limit_excess() is unnecessarily complicated:

  - It takes a 'start', 'end' and 'pages' argument, whereas it only
    needs 'pages' (which the caller has computed from the other two
    arguments!).

  - It erroneously compares 'pages' with MAX_TLBI_RANGE_PAGES when
    the system doesn't support range-based invalidation but the range to
    be invalidated would result in fewer than MAX_DVM_OPS invalidations.

Simplify the function so that it no longer takes the 'start' and 'end'
arguments and only considers the MAX_TLBI_RANGE_PAGES threshold on
systems that implement range-based invalidation.

Signed-off-by: Will Deacon <will@kernel.org>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Will Deacon 2026-03-02 13:55:55 +00:00 committed by Catalin Marinas
parent 057bbd8e06
commit c753d667d9
1 changed files with 11 additions and 13 deletions
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24
arch/arm64/include/asm/tlbflush.h
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@ -537,21 +537,19 @@ static __always_inline void __flush_tlb_range_op(tlbi_op lop, tlbi_op rop,
#define __flush_s2_tlb_range_op(op, start, pages, stride, tlb_level) \
__flush_tlb_range_op(op, r##op, start, pages, stride, 0, tlb_level, kvm_lpa2_is_enabled())
static inline bool __flush_tlb_range_limit_excess(unsigned long start,
unsigned long end, unsigned long pages, unsigned long stride)
static inline bool __flush_tlb_range_limit_excess(unsigned long pages,
unsigned long stride)
{
/*
* When the system does not support TLB range based flush
* operation, (MAX_DVM_OPS - 1) pages can be handled. But
* with TLB range based operation, MAX_TLBI_RANGE_PAGES
* pages can be handled.
* Assume that the worst case number of DVM ops required to flush a
* given range on a system that supports tlb-range is 20 (4 scales, 1
* final page, 15 for alignment on LPA2 systems), which is much smaller
* than MAX_DVM_OPS.
*/
if ((!system_supports_tlb_range() &&
(end - start) >= (MAX_DVM_OPS * stride)) ||
pages > MAX_TLBI_RANGE_PAGES)
return true;
if (system_supports_tlb_range())
return pages > MAX_TLBI_RANGE_PAGES;
return false;
return pages >= (MAX_DVM_OPS * stride) >> PAGE_SHIFT;
}
static inline void __flush_tlb_range_nosync(struct mm_struct *mm,
@ -565,7 +563,7 @@ static inline void __flush_tlb_range_nosync(struct mm_struct *mm,
end = round_up(end, stride);
pages = (end - start) >> PAGE_SHIFT;
if (__flush_tlb_range_limit_excess(start, end, pages, stride)) {
if (__flush_tlb_range_limit_excess(pages, stride)) {
flush_tlb_mm(mm);
return;
}
@ -629,7 +627,7 @@ static inline void flush_tlb_kernel_range(unsigned long start, unsigned long end
end = round_up(end, stride);
pages = (end - start) >> PAGE_SHIFT;
if (__flush_tlb_range_limit_excess(start, end, pages, stride)) {
if (__flush_tlb_range_limit_excess(pages, stride)) {
flush_tlb_all();
return;
}