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authorBenjamin Herrenschmidt <benh@kernel.crashing.org>2013-10-11 18:23:53 +1100
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2013-10-11 18:23:53 +1100
commit3ad26e5c4459d3793ad65bc8929037c70515df83 (patch)
tree434327df7942878383e372988eb5f3bccb25de12 /arch/powerpc/mm
parent5293bf97a27e1be8ac6096aa198ff6a9e3e6837c (diff)
parent18461960cbf50bf345ef0667d45d5f64de8fb893 (diff)
downloadop-kernel-dev-3ad26e5c4459d3793ad65bc8929037c70515df83.zip
op-kernel-dev-3ad26e5c4459d3793ad65bc8929037c70515df83.tar.gz
Merge branch 'for-kvm' into next
Topic branch for commits that the KVM tree might want to pull in separately. Hand merged a few files due to conflicts with the LE stuff Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/mm')
-rw-r--r--arch/powerpc/mm/init_64.c51
1 files changed, 50 insertions, 1 deletions
diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
index 8ed035d..e3734ed 100644
--- a/arch/powerpc/mm/init_64.c
+++ b/arch/powerpc/mm/init_64.c
@@ -304,5 +304,54 @@ void register_page_bootmem_memmap(unsigned long section_nr,
struct page *start_page, unsigned long size)
{
}
-#endif /* CONFIG_SPARSEMEM_VMEMMAP */
+/*
+ * We do not have access to the sparsemem vmemmap, so we fallback to
+ * walking the list of sparsemem blocks which we already maintain for
+ * the sake of crashdump. In the long run, we might want to maintain
+ * a tree if performance of that linear walk becomes a problem.
+ *
+ * realmode_pfn_to_page functions can fail due to:
+ * 1) As real sparsemem blocks do not lay in RAM continously (they
+ * are in virtual address space which is not available in the real mode),
+ * the requested page struct can be split between blocks so get_page/put_page
+ * may fail.
+ * 2) When huge pages are used, the get_page/put_page API will fail
+ * in real mode as the linked addresses in the page struct are virtual
+ * too.
+ */
+struct page *realmode_pfn_to_page(unsigned long pfn)
+{
+ struct vmemmap_backing *vmem_back;
+ struct page *page;
+ unsigned long page_size = 1 << mmu_psize_defs[mmu_vmemmap_psize].shift;
+ unsigned long pg_va = (unsigned long) pfn_to_page(pfn);
+
+ for (vmem_back = vmemmap_list; vmem_back; vmem_back = vmem_back->list) {
+ if (pg_va < vmem_back->virt_addr)
+ continue;
+
+ /* Check that page struct is not split between real pages */
+ if ((pg_va + sizeof(struct page)) >
+ (vmem_back->virt_addr + page_size))
+ return NULL;
+
+ page = (struct page *) (vmem_back->phys + pg_va -
+ vmem_back->virt_addr);
+ return page;
+ }
+
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(realmode_pfn_to_page);
+
+#elif defined(CONFIG_FLATMEM)
+
+struct page *realmode_pfn_to_page(unsigned long pfn)
+{
+ struct page *page = pfn_to_page(pfn);
+ return page;
+}
+EXPORT_SYMBOL_GPL(realmode_pfn_to_page);
+
+#endif /* CONFIG_SPARSEMEM_VMEMMAP/CONFIG_FLATMEM */
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