From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752812AbaHIAL3 (ORCPT ); Fri, 8 Aug 2014 20:11:29 -0400 Received: from mail-ob0-f172.google.com ([209.85.214.172]:39126 "EHLO mail-ob0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751400AbaHIAL1 (ORCPT ); Fri, 8 Aug 2014 20:11:27 -0400 MIME-Version: 1.0 In-Reply-To: References: <1407423713-4160-1-git-send-email-keescook@chromium.org> <1407423713-4160-4-git-send-email-keescook@chromium.org> Date: Fri, 8 Aug 2014 17:11:27 -0700 X-Google-Sender-Auth: 2i6Yl6mM-jrjmWnlcSSZ_aySOIo Message-ID: Subject: Re: [PATCH 3/8] arm: mm: reduce fixmap kmap from 32 to 16 CPUS From: Kees Cook To: Rob Herring Cc: "linux-kernel@vger.kernel.org" , Liu hua , Mark Salter , Rabin Vincent , Nikolay Borisov , Nicolas Pitre , Leif Lindholm , Tomasz Figa , Doug Anderson , Jason Wessel , Will Deacon , Laura Abbott , Catalin Marinas , Russell King - ARM Linux , "linux-arm-kernel@lists.infradead.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 7, 2014 at 3:18 PM, Rob Herring wrote: > On Thu, Aug 7, 2014 at 10:01 AM, Kees Cook wrote: >> More room is needed in the fixmap range for non-kmap fixmap entries. This >> reduces the kmap range from 32 to 16 CPUs. > > Do you want this merged or just doing this to get the rest of your > series working? I'll post my patch for making the fixmap region 3MB > (it adds back the first 1MB of the top pmd). Excellent, thanks for sending this, I'll get it tested as part of the series. >> Additionally, add PTE entry for >> fixmap regardless of CONFIG_HIGHMEM. > > "Additionally" is a good flag for this patch should be split-up. It > seems like we would want to apply this part to stable. Does anyone have use-cases that broke in 3.16 due to this bug? If so, it absolutely should be split out and CCed to -stable. I'll split it out regardless, and if someone can speak up with a broken situation, I'll add the CC. Thanks! -Kees > > Rob > >> >> Signed-off-by: Kees Cook >> --- >> arch/arm/include/asm/fixmap.h | 12 ++++++++++-- >> arch/arm/mm/highmem.c | 2 -- >> arch/arm/mm/mm.h | 3 +++ >> arch/arm/mm/mmu.c | 5 ++++- >> 4 files changed, 17 insertions(+), 5 deletions(-) >> >> diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h >> index 8ee7cb4f62ca..3ed08232be55 100644 >> --- a/arch/arm/include/asm/fixmap.h >> +++ b/arch/arm/include/asm/fixmap.h >> @@ -1,16 +1,24 @@ >> #ifndef _ASM_FIXMAP_H >> #define _ASM_FIXMAP_H >> >> +/* >> + * The fixmap uses 2MB. The KMAP fixmap needs 64k per CPU, so make room for >> + * 16 CPUs (taking 1MB) and leave the rest for additional fixmap areas. >> + */ >> #define FIXADDR_START 0xffc00000UL >> #define FIXADDR_END 0xffe00000UL >> #define FIXADDR_TOP (FIXADDR_END - PAGE_SIZE) >> #define FIXADDR_SIZE (FIXADDR_END - FIXADDR_START) >> >> -#define FIX_KMAP_NR_PTES (FIXADDR_SIZE >> PAGE_SHIFT) >> +/* 16 PTEs per CPU (64k of 4k pages). */ >> +#define FIX_KMAP_NR_PTES 16 >> +#define FIX_KMAP_NR_CPUS 16 >> >> enum fixed_addresses { >> + /* Support 16 CPUs for kmap as the first region of fixmap entries. */ >> FIX_KMAP_BEGIN, >> - FIX_KMAP_END = FIX_KMAP_NR_PTES - 1, >> + FIX_KMAP_END = (FIX_KMAP_NR_PTES * FIX_KMAP_NR_CPUS) - 1, >> + >> __end_of_fixed_addresses >> }; >> >> diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c >> index a1241ee8425e..adf264fb700b 100644 >> --- a/arch/arm/mm/highmem.c >> +++ b/arch/arm/mm/highmem.c >> @@ -18,8 +18,6 @@ >> #include >> #include "mm.h" >> >> -pte_t *fixmap_page_table; >> - >> static inline void set_fixmap_pte(int idx, pte_t pte) >> { >> unsigned long vaddr = __fix_to_virt(idx); >> diff --git a/arch/arm/mm/mm.h b/arch/arm/mm/mm.h >> index ce727d47275c..c8b5b2d05b55 100644 >> --- a/arch/arm/mm/mm.h >> +++ b/arch/arm/mm/mm.h >> @@ -7,6 +7,9 @@ >> /* the upper-most page table pointer */ >> extern pmd_t *top_pmd; >> >> +/* The fixmap PTE. */ >> +extern pte_t *fixmap_page_table; >> + >> /* >> * 0xffff8000 to 0xffffffff is reserved for any ARM architecture >> * specific hacks for copying pages efficiently, while 0xffff4000 >> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c >> index e881ed817a8b..a7a756603775 100644 >> --- a/arch/arm/mm/mmu.c >> +++ b/arch/arm/mm/mmu.c >> @@ -53,6 +53,9 @@ EXPORT_SYMBOL(empty_zero_page); >> */ >> pmd_t *top_pmd; >> >> +/* The fixmap PTE. */ >> +pte_t *fixmap_page_table; >> + >> #define CPOLICY_UNCACHED 0 >> #define CPOLICY_BUFFERED 1 >> #define CPOLICY_WRITETHROUGH 2 >> @@ -1342,10 +1345,10 @@ static void __init kmap_init(void) >> #ifdef CONFIG_HIGHMEM >> pkmap_page_table = early_pte_alloc(pmd_off_k(PKMAP_BASE), >> PKMAP_BASE, _PAGE_KERNEL_TABLE); >> +#endif >> >> fixmap_page_table = early_pte_alloc(pmd_off_k(FIXADDR_START), >> FIXADDR_START, _PAGE_KERNEL_TABLE); >> -#endif >> } >> >> static void __init map_lowmem(void) >> -- >> 1.9.1 >> -- Kees Cook Chrome OS Security From mboxrd@z Thu Jan 1 00:00:00 1970 From: keescook@chromium.org (Kees Cook) Date: Fri, 8 Aug 2014 17:11:27 -0700 Subject: [PATCH 3/8] arm: mm: reduce fixmap kmap from 32 to 16 CPUS In-Reply-To: References: <1407423713-4160-1-git-send-email-keescook@chromium.org> <1407423713-4160-4-git-send-email-keescook@chromium.org> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, Aug 7, 2014 at 3:18 PM, Rob Herring wrote: > On Thu, Aug 7, 2014 at 10:01 AM, Kees Cook wrote: >> More room is needed in the fixmap range for non-kmap fixmap entries. This >> reduces the kmap range from 32 to 16 CPUs. > > Do you want this merged or just doing this to get the rest of your > series working? I'll post my patch for making the fixmap region 3MB > (it adds back the first 1MB of the top pmd). Excellent, thanks for sending this, I'll get it tested as part of the series. >> Additionally, add PTE entry for >> fixmap regardless of CONFIG_HIGHMEM. > > "Additionally" is a good flag for this patch should be split-up. It > seems like we would want to apply this part to stable. Does anyone have use-cases that broke in 3.16 due to this bug? If so, it absolutely should be split out and CCed to -stable. I'll split it out regardless, and if someone can speak up with a broken situation, I'll add the CC. Thanks! -Kees > > Rob > >> >> Signed-off-by: Kees Cook >> --- >> arch/arm/include/asm/fixmap.h | 12 ++++++++++-- >> arch/arm/mm/highmem.c | 2 -- >> arch/arm/mm/mm.h | 3 +++ >> arch/arm/mm/mmu.c | 5 ++++- >> 4 files changed, 17 insertions(+), 5 deletions(-) >> >> diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h >> index 8ee7cb4f62ca..3ed08232be55 100644 >> --- a/arch/arm/include/asm/fixmap.h >> +++ b/arch/arm/include/asm/fixmap.h >> @@ -1,16 +1,24 @@ >> #ifndef _ASM_FIXMAP_H >> #define _ASM_FIXMAP_H >> >> +/* >> + * The fixmap uses 2MB. The KMAP fixmap needs 64k per CPU, so make room for >> + * 16 CPUs (taking 1MB) and leave the rest for additional fixmap areas. >> + */ >> #define FIXADDR_START 0xffc00000UL >> #define FIXADDR_END 0xffe00000UL >> #define FIXADDR_TOP (FIXADDR_END - PAGE_SIZE) >> #define FIXADDR_SIZE (FIXADDR_END - FIXADDR_START) >> >> -#define FIX_KMAP_NR_PTES (FIXADDR_SIZE >> PAGE_SHIFT) >> +/* 16 PTEs per CPU (64k of 4k pages). */ >> +#define FIX_KMAP_NR_PTES 16 >> +#define FIX_KMAP_NR_CPUS 16 >> >> enum fixed_addresses { >> + /* Support 16 CPUs for kmap as the first region of fixmap entries. */ >> FIX_KMAP_BEGIN, >> - FIX_KMAP_END = FIX_KMAP_NR_PTES - 1, >> + FIX_KMAP_END = (FIX_KMAP_NR_PTES * FIX_KMAP_NR_CPUS) - 1, >> + >> __end_of_fixed_addresses >> }; >> >> diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c >> index a1241ee8425e..adf264fb700b 100644 >> --- a/arch/arm/mm/highmem.c >> +++ b/arch/arm/mm/highmem.c >> @@ -18,8 +18,6 @@ >> #include >> #include "mm.h" >> >> -pte_t *fixmap_page_table; >> - >> static inline void set_fixmap_pte(int idx, pte_t pte) >> { >> unsigned long vaddr = __fix_to_virt(idx); >> diff --git a/arch/arm/mm/mm.h b/arch/arm/mm/mm.h >> index ce727d47275c..c8b5b2d05b55 100644 >> --- a/arch/arm/mm/mm.h >> +++ b/arch/arm/mm/mm.h >> @@ -7,6 +7,9 @@ >> /* the upper-most page table pointer */ >> extern pmd_t *top_pmd; >> >> +/* The fixmap PTE. */ >> +extern pte_t *fixmap_page_table; >> + >> /* >> * 0xffff8000 to 0xffffffff is reserved for any ARM architecture >> * specific hacks for copying pages efficiently, while 0xffff4000 >> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c >> index e881ed817a8b..a7a756603775 100644 >> --- a/arch/arm/mm/mmu.c >> +++ b/arch/arm/mm/mmu.c >> @@ -53,6 +53,9 @@ EXPORT_SYMBOL(empty_zero_page); >> */ >> pmd_t *top_pmd; >> >> +/* The fixmap PTE. */ >> +pte_t *fixmap_page_table; >> + >> #define CPOLICY_UNCACHED 0 >> #define CPOLICY_BUFFERED 1 >> #define CPOLICY_WRITETHROUGH 2 >> @@ -1342,10 +1345,10 @@ static void __init kmap_init(void) >> #ifdef CONFIG_HIGHMEM >> pkmap_page_table = early_pte_alloc(pmd_off_k(PKMAP_BASE), >> PKMAP_BASE, _PAGE_KERNEL_TABLE); >> +#endif >> >> fixmap_page_table = early_pte_alloc(pmd_off_k(FIXADDR_START), >> FIXADDR_START, _PAGE_KERNEL_TABLE); >> -#endif >> } >> >> static void __init map_lowmem(void) >> -- >> 1.9.1 >> -- Kees Cook Chrome OS Security