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authorJessica Clarke <jrtc27@jrtc27.com>2020-08-11 19:24:57 +0100
committerMike Rapoport <rppt@linux.ibm.com>2020-08-17 21:50:54 +0300
commitbd05220c7be3356046861c317d9c287ca50445ba (patch)
tree3fe1105c202525965c492ca880e3417f9e3b152b /arch
parent9123e3a74ec7b934a4a099e98af6a61c2f80bbf5 (diff)
arch/ia64: Restore arch-specific pgd_offset_k implementation
IA-64 is special and treats pgd_offset_k() differently to pgd_offset(), using different formulae to calculate the indices into the kernel and user PGDs. The index into the user PGDs takes into account the region number, but the index into the kernel (init_mm) PGD always assumes a predefined kernel region number. Commit 974b9b2c68f3 ("mm: consolidate pte_index() and pte_offset_*() definitions") made IA-64 use a generic pgd_offset_k() which incorrectly used pgd_index() for kernel page tables. As a result, the index into the kernel PGD was going out of bounds and the kernel hung during early boot. Allow overrides of pgd_offset_k() and override it on IA-64 with the old implementation that will correctly index the kernel PGD. Fixes: 974b9b2c68f3 ("mm: consolidate pte_index() and pte_offset_*() definitions") Reported-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> Signed-off-by: Jessica Clarke <jrtc27@jrtc27.com> Tested-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> Acked-by: Tony Luck <tony.luck@intel.com> Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/ia64/include/asm/pgtable.h9
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/ia64/include/asm/pgtable.h b/arch/ia64/include/asm/pgtable.h
index 10850897a91c..779b6972aa84 100644
--- a/arch/ia64/include/asm/pgtable.h
+++ b/arch/ia64/include/asm/pgtable.h
@@ -366,6 +366,15 @@ pgd_index (unsigned long address)
}
#define pgd_index pgd_index
+/*
+ * In the kernel's mapped region we know everything is in region number 5, so
+ * as an optimisation its PGD already points to the area for that region.
+ * However, this also means that we cannot use pgd_index() and we must
+ * never add the region here.
+ */
+#define pgd_offset_k(addr) \
+ (init_mm.pgd + (((addr) >> PGDIR_SHIFT) & (PTRS_PER_PGD - 1)))
+
/* Look up a pgd entry in the gate area. On IA-64, the gate-area
resides in the kernel-mapped segment, hence we use pgd_offset_k()
here. */