Commit-ID: 31217900acbaf66249b8befd06c975aa897b4deb Gitweb: https://git.kernel.org/tip/31217900acbaf66249b8befd06c975aa897b4deb Author: Feng Tang <feng.t...@intel.com> AuthorDate: Mon, 17 Sep 2018 17:14:23 +0800 Committer: Thomas Gleixner <t...@linutronix.de> CommitDate: Wed, 19 Sep 2018 00:09:10 +0200
x86/mm: Expand static page table for fixmap space We met a kernel panic when enabling earlycon, which is due to the fixmap address of earlycon is not statically setup. Currently the static fixmap setup in head_64.S only covers 2M virtual address space, while it acutually could be in 4M space with different kernel configurations. So increase the static space to 4M for now by defining FIXMAP_PMD_NUM to 2, and add a build time check to ensure that the fixmap is covered by the intial static page tables. [ tglx: s/PTRS_PER_PMD/PTRS_PER_PTE/ and add the missing brackets ] Suggested-by: Thomas Gleixner <t...@linutronix.de> Signed-off-by: Feng Tang <feng.t...@intel.com> Signed-off-by: Thomas Gleixner <t...@linutronix.de> Reviewed-by: Juergen Gross <jgr...@suse.com> (Xen parts) Cc: H Peter Anvin <h...@linux.intel.com> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Michal Hocko <mho...@kernel.org> Cc: Yinghai Lu <ying...@kernel.org> Cc: Dave Hansen <dave.han...@intel.com> Cc: Andi Kleen <a...@linux.intel.com> Link: https://lkml.kernel.org/r/20180917091423.16069-1-feng.t...@intel.com --- arch/x86/include/asm/fixmap.h | 8 ++++++++ arch/x86/include/asm/pgtable_64.h | 3 ++- arch/x86/kernel/head_64.S | 16 ++++++++++++---- arch/x86/mm/pgtable.c | 9 +++++++++ arch/x86/xen/mmu_pv.c | 8 ++++++-- 5 files changed, 37 insertions(+), 7 deletions(-) diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h index e203169931c7..01e8da740293 100644 --- a/arch/x86/include/asm/fixmap.h +++ b/arch/x86/include/asm/fixmap.h @@ -14,6 +14,14 @@ #ifndef _ASM_X86_FIXMAP_H #define _ASM_X86_FIXMAP_H +/* + * Exposed to assembly code for setting up initial page tables. Cannot be + * calculated in assembly code (fixmap entries are an enum), but is sanity + * checked in the actual fixmap C code to make sure that the fixmap is + * covered fully. + */ +#define FIXMAP_PMD_NUM 2 + #ifndef __ASSEMBLY__ #include <linux/kernel.h> #include <asm/acpi.h> diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h index ce2b59047cb8..9c85b54bf03c 100644 --- a/arch/x86/include/asm/pgtable_64.h +++ b/arch/x86/include/asm/pgtable_64.h @@ -14,6 +14,7 @@ #include <asm/processor.h> #include <linux/bitops.h> #include <linux/threads.h> +#include <asm/fixmap.h> extern p4d_t level4_kernel_pgt[512]; extern p4d_t level4_ident_pgt[512]; @@ -22,7 +23,7 @@ extern pud_t level3_ident_pgt[512]; extern pmd_t level2_kernel_pgt[512]; extern pmd_t level2_fixmap_pgt[512]; extern pmd_t level2_ident_pgt[512]; -extern pte_t level1_fixmap_pgt[512]; +extern pte_t level1_fixmap_pgt[512 * FIXMAP_PMD_NUM]; extern pgd_t init_top_pgt[]; #define swapper_pg_dir init_top_pgt diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 15ebc2fc166e..a3618cf04cf6 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -24,6 +24,7 @@ #include "../entry/calling.h" #include <asm/export.h> #include <asm/nospec-branch.h> +#include <asm/fixmap.h> #ifdef CONFIG_PARAVIRT #include <asm/asm-offsets.h> @@ -445,13 +446,20 @@ NEXT_PAGE(level2_kernel_pgt) KERNEL_IMAGE_SIZE/PMD_SIZE) NEXT_PAGE(level2_fixmap_pgt) - .fill 506,8,0 - .quad level1_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC - /* 8MB reserved for vsyscalls + a 2MB hole = 4 + 1 entries */ - .fill 5,8,0 + .fill (512 - 4 - FIXMAP_PMD_NUM),8,0 + pgtno = 0 + .rept (FIXMAP_PMD_NUM) + .quad level1_fixmap_pgt + (pgtno << PAGE_SHIFT) - __START_KERNEL_map \ + + _PAGE_TABLE_NOENC; + pgtno = pgtno + 1 + .endr + /* 6 MB reserved space + a 2MB hole */ + .fill 4,8,0 NEXT_PAGE(level1_fixmap_pgt) + .rept (FIXMAP_PMD_NUM) .fill 512,8,0 + .endr #undef PMDS diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index ae394552fb94..089e78c4effd 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -637,6 +637,15 @@ void __native_set_fixmap(enum fixed_addresses idx, pte_t pte) { unsigned long address = __fix_to_virt(idx); +#ifdef CONFIG_X86_64 + /* + * Ensure that the static initial page tables are covering the + * fixmap completely. + */ + BUILD_BUG_ON(__end_of_permanent_fixed_addresses > + (FIXMAP_PMD_NUM * PTRS_PER_PTE)); +#endif + if (idx >= __end_of_fixed_addresses) { BUG(); return; diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c index 2fe5c9b1816b..dd461c0167ef 100644 --- a/arch/x86/xen/mmu_pv.c +++ b/arch/x86/xen/mmu_pv.c @@ -1907,7 +1907,7 @@ void __init xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn) /* L3_k[511] -> level2_fixmap_pgt */ convert_pfn_mfn(level3_kernel_pgt); - /* L3_k[511][506] -> level1_fixmap_pgt */ + /* L3_k[511][508-FIXMAP_PMD_NUM ... 507] -> level1_fixmap_pgt */ convert_pfn_mfn(level2_fixmap_pgt); /* We get [511][511] and have Xen's version of level2_kernel_pgt */ @@ -1952,7 +1952,11 @@ void __init xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn) set_page_prot(level2_ident_pgt, PAGE_KERNEL_RO); set_page_prot(level2_kernel_pgt, PAGE_KERNEL_RO); set_page_prot(level2_fixmap_pgt, PAGE_KERNEL_RO); - set_page_prot(level1_fixmap_pgt, PAGE_KERNEL_RO); + + for (i = 0; i < FIXMAP_PMD_NUM; i++) { + set_page_prot(level1_fixmap_pgt + i * PTRS_PER_PTE, + PAGE_KERNEL_RO); + } /* Pin down new L4 */ pin_pagetable_pfn(MMUEXT_PIN_L4_TABLE,
