linux-kernel - [PATCH v1 1/3] x86/mm: Adapt MODULES

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Message-Id: <20170120164126.27624-1-thgarnie@google.com>
Date:   Fri, 20 Jan 2017 08:41:24 -0800
From:   Thomas Garnier <thgarnie@...gle.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>,
        Thomas Garnier <thgarnie@...gle.com>,
        Kees Cook <keescook@...omium.org>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Pavel Machek <pavel@....cz>, Andy Lutomirski <luto@...nel.org>,
        Borislav Petkov <bp@...e.de>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Brian Gerst <brgerst@...il.com>,
        He Chen <he.chen@...ux.intel.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Chen Yucong <slaoub@...il.com>, Baoquan He <bhe@...hat.com>,
        Paul Gortmaker <paul.gortmaker@...driver.com>,
        Joerg Roedel <joro@...tes.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Fenghua Yu <fenghua.yu@...el.com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, kvm@...r.kernel.org,
        kernel-hardening@...ts.openwall.com
Subject: [PATCH v1 1/3] x86/mm: Adapt MODULES_END based on Fixmap section size

This patch aligns MODULES_END to the beginning of the Fixmap section.
It optimizes the space available for both sections. The address is
pre-computed based on the number of pages required by the Fixmap
section.

It will allow GDT remapping in the Fixmap section. The current
MODULES_END static address does not provide enough space for the kernel
to support a large number of processors.

Signed-off-by: Thomas Garnier <thgarnie@...gle.com>
---
Based on next-20170119
---
 arch/x86/include/asm/fixmap.h           | 8 ++++++++
 arch/x86/include/asm/pgtable_64_types.h | 3 ---
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h
index 8554f960e21b..c46289799b02 100644
--- a/arch/x86/include/asm/fixmap.h
+++ b/arch/x86/include/asm/fixmap.h
@@ -132,6 +132,14 @@ enum fixed_addresses {
 
 extern void reserve_top_address(unsigned long reserve);
 
+/* On 64bit, the module sections ends with the start of the fixmap */
+#ifdef CONFIG_X86_64
+#define MODULES_VADDR    (__START_KERNEL_map + KERNEL_IMAGE_SIZE)
+#define MODULES_END   __fix_to_virt(__end_of_fixed_addresses + 1)
+#define MODULES_LEN   (MODULES_END - MODULES_VADDR)
+#endif /* CONFIG_X86_64 */
+
+
 #define FIXADDR_SIZE	(__end_of_permanent_fixed_addresses << PAGE_SHIFT)
 #define FIXADDR_START		(FIXADDR_TOP - FIXADDR_SIZE)
 
diff --git a/arch/x86/include/asm/pgtable_64_types.h b/arch/x86/include/asm/pgtable_64_types.h
index 3a264200c62f..de8bace10200 100644
--- a/arch/x86/include/asm/pgtable_64_types.h
+++ b/arch/x86/include/asm/pgtable_64_types.h
@@ -66,9 +66,6 @@ typedef struct { pteval_t pte; } pte_t;
 #define VMEMMAP_START	__VMEMMAP_BASE
 #endif /* CONFIG_RANDOMIZE_MEMORY */
 #define VMALLOC_END	(VMALLOC_START + _AC((VMALLOC_SIZE_TB << 40) - 1, UL))
-#define MODULES_VADDR    (__START_KERNEL_map + KERNEL_IMAGE_SIZE)
-#define MODULES_END      _AC(0xffffffffff000000, UL)
-#define MODULES_LEN   (MODULES_END - MODULES_VADDR)
 #define ESPFIX_PGD_ENTRY _AC(-2, UL)
 #define ESPFIX_BASE_ADDR (ESPFIX_PGD_ENTRY << PGDIR_SHIFT)
 #define EFI_VA_START	 ( -4 * (_AC(1, UL) << 30))
-- 
2.11.0.483.g087da7b7c-goog