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d1d3aa98b1
Add __TLBI_VADDR_RANGE macro and rewrite __flush_tlb_range(). When cpu supports TLBI feature, the minimum range granularity is decided by 'scale', so we can not flush all pages by one instruction in some cases. For example, when the pages = 0xe81a, let's start 'scale' from maximum, and find right 'num' for each 'scale': 1. scale = 3, we can flush no pages because the minimum range is 2^(5*3 + 1) = 0x10000. 2. scale = 2, the minimum range is 2^(5*2 + 1) = 0x800, we can flush 0xe800 pages this time, the num = 0xe800/0x800 - 1 = 0x1c. Remaining pages is 0x1a; 3. scale = 1, the minimum range is 2^(5*1 + 1) = 0x40, no page can be flushed. 4. scale = 0, we flush the remaining 0x1a pages, the num = 0x1a/0x2 - 1 = 0xd. However, in most scenarios, the pages = 1 when flush_tlb_range() is called. Start from scale = 3 or other proper value (such as scale = ilog2(pages)), will incur extra overhead. So increase 'scale' from 0 to maximum, the flush order is exactly opposite to the example. Signed-off-by: Zhenyu Ye <yezhenyu2@huawei.com> Link: https://lore.kernel.org/r/20200715071945.897-4-yezhenyu2@huawei.com [catalin.marinas@arm.com: removed unnecessary masks in __TLBI_VADDR_RANGE] [catalin.marinas@arm.com: __TLB_RANGE_NUM subtracts 1] [catalin.marinas@arm.com: minor adjustments to the comments] [catalin.marinas@arm.com: introduce system_supports_tlb_range()] Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.