@@ -24,23 +24,26 @@
#endif
/*
- * The idmap and swapper page tables need some space reserved in the kernel
- * image. Both require pgd, pud (4 levels only) and pmd tables to (section)
- * map the kernel. With the 64K page configuration, swapper and idmap need to
+ * The swapper page table needs some space reserved in the kernel
+ * image. It require pgd, pud (4 levels only) and pmd tables to (section)
+ * map the kernel. With the 64K page configuration, swapper needs to
* map to pte level. The swapper also maps the FDT (see __create_page_tables
- * for more information). Note that the number of ID map translation levels
- * could be increased on the fly if system RAM is out of reach for the default
- * VA range, so pages required to map highest possible PA are reserved in all
- * cases.
+ * for more information).
*/
#if ARM64_SWAPPER_USES_SECTION_MAPS
#define SWAPPER_PGTABLE_LEVELS (CONFIG_PGTABLE_LEVELS - 1)
-#define IDMAP_PGTABLE_LEVELS (ARM64_HW_PGTABLE_LEVELS(PHYS_MASK_SHIFT) - 1)
#else
#define SWAPPER_PGTABLE_LEVELS (CONFIG_PGTABLE_LEVELS)
-#define IDMAP_PGTABLE_LEVELS (ARM64_HW_PGTABLE_LEVELS(PHYS_MASK_SHIFT))
#endif
+/*
+ * idmap also needs some space reserved in the kernel image. Since ".idmap.text"
+ * only occupies less than a page, idmap needs to map to pte level.
+ * Note that the number of ID map translation levels could be increased on the fly
+ * if system RAM is out of reach for the default VA range, so pages required to
+ * map highest possible PA are reserved in all cases.
+ */
+#define IDMAP_PGTABLE_LEVELS (ARM64_HW_PGTABLE_LEVELS(PHYS_MASK_SHIFT))
/*
* If KASLR is enabled, then an offset K is added to the kernel address
After commit 5dfe9d7d23c2 ("arm64: reduce ID map to a single page"), idmap only costs a page. While with 4K page, the current code enforces section mapping (2MB) on it due to the prot SWAPPER_MM_MMUFLAGS. But if switching to __create_pgd_mapping() to create pgtable, the code will decide the proper mapping level by itself, as the code snippet in init_pmd(): if (((addr | next | phys) & ~SECTION_MASK) == 0 && (flags & NO_BLOCK_MAPPINGS) == 0) pmd_set_huge(pmdp, phys, prot); As the case of .idmap.text, it requires pgtable up to pte level. Hence IDMAP_PGTABLE_LEVELS should be large enough to assure the capacity of IDMAP_DIR_SIZE. Signed-off-by: Pingfan Liu <kernelfans@gmail.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Ard Biesheuvel <ardb@kernel.org> Cc: Marc Zyngier <maz@kernel.org> Cc: Kristina Martsenko <kristina.martsenko@arm.com> Cc: James Morse <james.morse@arm.com> Cc: Steven Price <steven.price@arm.com> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Atish Patra <atish.patra@wdc.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Logan Gunthorpe <logang@deltatee.com> Cc: Mark Brown <broonie@kernel.org> To: linux-arm-kernel@lists.infradead.org --- arch/arm64/include/asm/kernel-pgtable.h | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-)