Paul Burton 523402fa91 MIPS: Fix ioremap() RAM check ... We currently attempt to check whether a physical address range provided to __ioremap() may be in use by the page allocator by examining the value of PageReserved for each page in the region - lowmem pages not marked reserved are presumed to be in use by the page allocator, and requests to ioremap them fail. The way we check this has been broken since commit 92923ca3aa ("mm: meminit: only set page reserved in the memblock region"), because memblock will typically not have any knowledge of non-RAM pages and therefore those pages will not have the PageReserved flag set. Thus when we attempt to ioremap a region outside of RAM we incorrectly fail believing that the region is RAM that may be in use. In most cases ioremap() on MIPS will take a fast-path to use the unmapped kseg1 or xkphys virtual address spaces and never hit this path, so the only way to hit it is for a MIPS32 system to attempt to ioremap() an address range in lowmem with flags other than _CACHE_UNCACHED. Perhaps the most straightforward way to do this is using ioremap_uncached_accelerated(), which is how the problem was discovered. Fix this by making use of walk_system_ram_range() to test the address range provided to __ioremap() against only RAM pages, rather than all lowmem pages. This means that if we have a lowmem I/O region, which is very common for MIPS systems, we're free to ioremap() address ranges within it. A nice bonus is that the test is no longer limited to lowmem. The approach here matches the way x86 performed the same test after commit c81c8a1eee ("x86, ioremap: Speed up check for RAM pages") until x86 moved towards a slightly more complicated check using walk_mem_res() for unrelated reasons with commit 0e4c12b45a ("x86/mm, resource: Use PAGE_KERNEL protection for ioremap of memory pages"). Signed-off-by: Paul Burton <paul.burton@mips.com> Reported-by: Serge Semin <fancer.lancer@gmail.com> Tested-by: Serge Semin <fancer.lancer@gmail.com> Fixes: 92923ca3aa ("mm: meminit: only set page reserved in the memblock region") Cc: James Hogan <jhogan@kernel.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: linux-mips@linux-mips.org Cc: stable@vger.kernel.org # v4.2+ Patchwork: https://patchwork.linux-mips.org/patch/19786/		2018-07-05 14:43:21 -07:00
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alchemy	…
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ath25	…
ath79	MIPS: pb44: Fix i2c-gpio GPIO descriptor table	2018-06-18 22:19:50 +01:00
bcm47xx	MIPS: BCM47XX: Enable 74K Core ExternalSync for PCIe erratum	2018-06-18 22:19:50 +01:00
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include	MIPS: Wire up io_pgetevents syscall	2018-06-19 21:14:29 -07:00
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kernel	MIPS: Use async IPIs for arch_trigger_cpumask_backtrace()	2018-06-28 14:14:41 -07:00
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mm	MIPS: Fix ioremap() RAM check	2018-07-05 14:43:21 -07:00
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Kconfig	MIPS: Add support for restartable sequences	2018-06-19 21:13:17 -07:00
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