revert buggy x86/mm: Expand static page table for fixmap space from 4.9

Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/queue-4.9/revert-x86-mm-expand-static-page-table-for-fixmap-sp.patch b/queue-4.9/revert-x86-mm-expand-static-page-table-for-fixmap-sp.patch
new file mode 100644 (file)
index 0000000..c19bbdf
--- /dev/null
+++ b/queue-4.9/revert-x86-mm-expand-static-page-table-for-fixmap-sp.patch
@@ -0,0 +1,158 @@
+From 37f8580bbc1aa098ef8826f4854450dc4667fb90 Mon Sep 17 00:00:00 2001
+From: Sasha Levin <sashal@kernel.org>
+Date: Fri, 2 Nov 2018 09:54:00 -0400
+Subject: Revert "x86/mm: Expand static page table for fixmap space"
+
+This reverts commit 3a8304b7ad2e291777e8499e39390145d932a2fd, which was
+upstream commit 05ab1d8a4b36ee912b7087c6da127439ed0a903e.
+
+Ben Hutchings writes:
+
+This backport is incorrect.  The part that updated __startup_64() in
+arch/x86/kernel/head64.c was dropped, presumably because that function
+doesn't exist in 4.9.  However that seems to be an essential of the
+fix.  In 4.9 the startup_64 routine in arch/x86/kernel/head_64.S would
+need to be changed instead.
+
+I also found that this introduces new boot-time warnings on some
+systems if CONFIG_DEBUG_WX is enabled.
+
+So, unless someone provides fixes for those issues, I think this should
+be reverted for the 4.9 branch.
+
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ arch/x86/include/asm/fixmap.h     | 10 ----------
+ 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.c                |  8 ++------
+ 5 files changed, 7 insertions(+), 39 deletions(-)
+
+diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h
+index 25152843dd1f..8554f960e21b 100644
+--- a/arch/x86/include/asm/fixmap.h
++++ b/arch/x86/include/asm/fixmap.h
+@@ -14,16 +14,6 @@
+ #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
+-/* fixmap starts downwards from the 507th entry in level2_fixmap_pgt */
+-#define FIXMAP_PMD_TOP        507
+-
+ #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 d5c4df98aac3..221a32ed1372 100644
+--- a/arch/x86/include/asm/pgtable_64.h
++++ b/arch/x86/include/asm/pgtable_64.h
+@@ -13,14 +13,13 @@
+ #include <asm/processor.h>
+ #include <linux/bitops.h>
+ #include <linux/threads.h>
+-#include <asm/fixmap.h>
+ 
+ extern pud_t level3_kernel_pgt[512];
+ 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 * FIXMAP_PMD_NUM];
++extern pte_t level1_fixmap_pgt[512];
+ extern pgd_t init_level4_pgt[];
+ 
+ #define swapper_pg_dir init_level4_pgt
+diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
+index b0d6697ab153..9d72cf547c88 100644
+--- a/arch/x86/kernel/head_64.S
++++ b/arch/x86/kernel/head_64.S
+@@ -23,7 +23,6 @@
+ #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>
+@@ -494,20 +493,13 @@ NEXT_PAGE(level2_kernel_pgt)
+               KERNEL_IMAGE_SIZE/PMD_SIZE)
+ 
+ NEXT_PAGE(level2_fixmap_pgt)
+-      .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;
+-      pgtno = pgtno + 1
+-      .endr
+-      /* 6 MB reserved space + a 2MB hole */
+-      .fill   4,8,0
++      .fill   506,8,0
++      .quad   level1_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE
++      /* 8MB reserved for vsyscalls + a 2MB hole = 4 + 1 entries */
++      .fill   5,8,0
+ 
+ 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 8cbed30feb67..e30baa8ad94f 100644
+--- a/arch/x86/mm/pgtable.c
++++ b/arch/x86/mm/pgtable.c
+@@ -536,15 +536,6 @@ 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.c b/arch/x86/xen/mmu.c
+index ebceaba20ad1..c92f75f7ae33 100644
+--- a/arch/x86/xen/mmu.c
++++ b/arch/x86/xen/mmu.c
+@@ -1936,7 +1936,7 @@ 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][508-FIXMAP_PMD_NUM ... 507] -> level1_fixmap_pgt */
++              /* L3_k[511][506] -> level1_fixmap_pgt */
+               convert_pfn_mfn(level2_fixmap_pgt);
+       }
+       /* We get [511][511] and have Xen's version of level2_kernel_pgt */
+@@ -1970,11 +1970,7 @@ 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);
+-
+-              for (i = 0; i < FIXMAP_PMD_NUM; i++) {
+-                      set_page_prot(level1_fixmap_pgt + i * PTRS_PER_PTE,
+-                                    PAGE_KERNEL_RO);
+-              }
++              set_page_prot(level1_fixmap_pgt, PAGE_KERNEL_RO);
+ 
+               /* Pin down new L4 */
+               pin_pagetable_pfn(MMUEXT_PIN_L4_TABLE,
+-- 
+2.17.1
+

diff --git a/queue-4.9/series b/queue-4.9/series
index cd6e67ddad34db3f5492c42acebe8445ee74020a..9a5daa2e3eb823613e7136ee0fb21d764d8e802d 100644 (file)
--- a/queue-4.9/series
+++ b/queue-4.9/series
@@ -152,3 +152,4 @@ net-drop-skb-on-failure-in-ip_check_defrag.patch
 net-fix-pskb_trim_rcsum_slow-with-odd-trim-offset.patch
 rtnetlink-disallow-fdb-configuration-for-non-ethernet-device.patch
 ip6_tunnel-fix-encapsulation-layout.patch
+revert-x86-mm-expand-static-page-table-for-fixmap-sp.patch