Commit-ID: b17a5f97d413c9bd882ea5011462f7a530d37ae0
Gitweb: http://git.kernel.org/tip/b17a5f97d413c9bd882ea5011462f7a530d37ae0
Author: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
AuthorDate: Wed, 20 Jul 2011 17:07:54 +0100
Committer: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
CommitDate: Fri, 22 Jul 2011 11:45:55 -0700
x86_32: Calculate additional memory needed by the fixmap
When NR_CPUS increases the fixmap might need more than the page
allocated by head_32.S.
This patch introduces the logic to calculate the additional memory that
is going to be required by early_ioremap_page_table_range_init:
- enough memory to allocate the pte pages needed to cover the fixmap
virtual memory range, minus the single page allocated by head_32.S;
- account for the page already allocated by early_ioremap_init;
- account for the two additional pages that might be needed to make sure
that the kmap's ptes are contiguous.
Changes to v1:
- refactor the fixmap space calculation in a new function to make it
easier to read and avoid compilation warnings on x86_64.
Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1311178074-16833-1-git-send-email-stefano.stabellini@xxxxxxxxxxxxx
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Reported-and-Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
---
arch/x86/mm/init.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 53 insertions(+), 0 deletions(-)
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index e72c9f8..a90ccc4 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -28,6 +28,57 @@ int direct_gbpages
#endif
;
+static unsigned long __init find_early_fixmap_space(void)
+{
+ unsigned long size = 0;
+#ifdef CONFIG_X86_32
+ int kmap_begin_pmd_idx, kmap_end_pmd_idx;
+ int fixmap_begin_pmd_idx, fixmap_end_pmd_idx;
+ int btmap_begin_pmd_idx;
+
+ fixmap_begin_pmd_idx =
+ __fix_to_virt(__end_of_fixed_addresses - 1) >> PMD_SHIFT;
+ /*
+ * fixmap_end_pmd_idx is the end of the fixmap minus the PMD that
+ * has been defined in the data section by head_32.S (see
+ * initial_pg_fixmap).
+ * Note: This is similar to what early_ioremap_page_table_range_init
+ * does except that the "end" has PMD_SIZE expunged as per previous
+ * comment.
+ */
+ fixmap_end_pmd_idx = (FIXADDR_TOP - 1) >> PMD_SHIFT;
+ btmap_begin_pmd_idx = __fix_to_virt(FIX_BTMAP_BEGIN) >> PMD_SHIFT;
+ kmap_begin_pmd_idx = __fix_to_virt(FIX_KMAP_END) >> PMD_SHIFT;
+ kmap_end_pmd_idx = __fix_to_virt(FIX_KMAP_BEGIN) >> PMD_SHIFT;
+
+ size = fixmap_end_pmd_idx - fixmap_begin_pmd_idx;
+ /*
+ * early_ioremap_init has already allocated a PMD at
+ * btmap_begin_pmd_idx
+ */
+ if (btmap_begin_pmd_idx < fixmap_end_pmd_idx)
+ size--;
+
+#ifdef CONFIG_HIGHMEM
+ /*
+ * see page_table_kmap_check: if the kmap spans multiple PMDs, make
+ * sure the pte pages are allocated contiguously. It might need up
+ * to two additional pte pages to replace the page declared by
+ * head_32.S and the one allocated by early_ioremap_init, if they
+ * are even partially used for the kmap.
+ */
+ if (kmap_begin_pmd_idx != kmap_end_pmd_idx) {
+ if (kmap_end_pmd_idx == fixmap_end_pmd_idx)
+ size++;
+ if (btmap_begin_pmd_idx >= kmap_begin_pmd_idx &&
+ btmap_begin_pmd_idx <= kmap_end_pmd_idx)
+ size++;
+ }
+#endif
+#endif
+ return (size * PMD_SIZE + PAGE_SIZE - 1) >> PAGE_SHIFT;
+}
+
static void __init find_early_table_space(unsigned long start,
unsigned long end, int use_pse, int use_gbpages)
{
@@ -92,6 +143,8 @@ static void __init find_early_table_space(unsigned long start,
} else
ptes = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ ptes += find_early_fixmap_space();
+
tables += roundup(ptes * sizeof(pte_t), PAGE_SIZE);
if (!tables)
--
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