powerpc/32: Allow __ioremap on RAM addresses for kdump kernel
While for debugging it is good to catch bogus users of ioremap, though for kdump support it is more convenient to use __ioremap for copy_oldmem_page() (exactly as we do for PPC64 currently). Note that copy_oldmem_page() calls __ioremap with flags set to '0', so it should be safe with the regard to the caches. The other option is to use kmap_atomic_pfn()[1], but it will not work for kernels compiled without HIGHMEM. That is, on a board with 256MB RAM and crashkernel=64M@32M case, the !HIGHMEM capturing kernel maps 0-96M range, which does not include all the memory needed to capture the dump. And, obviously, accessing anything upper than 96M will cause faults. [1] http://ozlabs.org/pipermail/linuxppc-dev/2007-November/046747.html Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com> Signed-off-by: Paul Mackerras <paulus@samba.org>
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@ -173,6 +173,7 @@ __ioremap(phys_addr_t addr, unsigned long size, unsigned long flags)
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if (p < 16*1024*1024)
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p += _ISA_MEM_BASE;
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#ifndef CONFIG_CRASH_DUMP
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/*
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* Don't allow anybody to remap normal RAM that we're using.
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* mem_init() sets high_memory so only do the check after that.
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@ -182,6 +183,7 @@ __ioremap(phys_addr_t addr, unsigned long size, unsigned long flags)
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(unsigned long long)p, __builtin_return_address(0));
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return NULL;
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}
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#endif
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if (size == 0)
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return NULL;
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