| Message ID | 20170907173609.22696-6-tycho@docker.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
> +/* > + * Lookup the page table entry for a virtual address and return a pointer to > + * the entry. Based on x86 tree. > + */ > +static pte_t *lookup_address(unsigned long addr) Seems like this should be moved to common arm64 mm code and used by kernel_page_present.
Hi, On Thu, Sep 07, 2017 at 11:36:03AM -0600, Tycho Andersen wrote: > From: Juerg Haefliger <juerg.haefliger@canonical.com> > > Enable support for eXclusive Page Frame Ownership (XPFO) for arm64 and > provide a hook for updating a single kernel page table entry (which is > required by the generic XPFO code). > > v6: use flush_tlb_kernel_range() instead of __flush_tlb_one() > > CC: linux-arm-kernel@lists.infradead.org > Signed-off-by: Juerg Haefliger <juerg.haefliger@canonical.com> > Signed-off-by: Tycho Andersen <tycho@docker.com> > --- > arch/arm64/Kconfig | 1 + > arch/arm64/mm/Makefile | 2 ++ > arch/arm64/mm/xpfo.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 61 insertions(+) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index dfd908630631..44fa44ef02ec 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -121,6 +121,7 @@ config ARM64 > select SPARSE_IRQ > select SYSCTL_EXCEPTION_TRACE > select THREAD_INFO_IN_TASK > + select ARCH_SUPPORTS_XPFO A bit of a nit, but this list is (intended to be) organised alphabetically. Could you please try to retain that? i.e. place this between ARCH_SUPPORTS_NUMA_BALANCING and ARCH_WANT_COMPAT_IPC_PARSE_VERSION. > help > ARM 64-bit (AArch64) Linux support. > > diff --git a/arch/arm64/mm/Makefile b/arch/arm64/mm/Makefile > index 9b0ba191e48e..22e5cab543d8 100644 > --- a/arch/arm64/mm/Makefile > +++ b/arch/arm64/mm/Makefile > @@ -11,3 +11,5 @@ KASAN_SANITIZE_physaddr.o += n > > obj-$(CONFIG_KASAN) += kasan_init.o > KASAN_SANITIZE_kasan_init.o := n > + > +obj-$(CONFIG_XPFO) += xpfo.o > diff --git a/arch/arm64/mm/xpfo.c b/arch/arm64/mm/xpfo.c > new file mode 100644 > index 000000000000..678e2be848eb > --- /dev/null > +++ b/arch/arm64/mm/xpfo.c > @@ -0,0 +1,58 @@ > +/* > + * Copyright (C) 2017 Hewlett Packard Enterprise Development, L.P. > + * Copyright (C) 2016 Brown University. All rights reserved. > + * > + * Authors: > + * Juerg Haefliger <juerg.haefliger@hpe.com> > + * Vasileios P. Kemerlis <vpk@cs.brown.edu> > + * > + * This program is free software; you can redistribute it and/or modify it > + * under the terms of the GNU General Public License version 2 as published by > + * the Free Software Foundation. > + */ > + > +#include <linux/mm.h> > +#include <linux/module.h> > + > +#include <asm/tlbflush.h> > + > +/* > + * Lookup the page table entry for a virtual address and return a pointer to > + * the entry. Based on x86 tree. > + */ Is this intended for kernel VAs, user VAs, or both? There are different constraints for fiddling with either (e.g. holding mmap_sem), so we should be clear regarding the intended use-case. > +static pte_t *lookup_address(unsigned long addr) > +{ > + pgd_t *pgd; > + pud_t *pud; > + pmd_t *pmd; > + > + pgd = pgd_offset_k(addr); > + if (pgd_none(*pgd)) > + return NULL; > + > + pud = pud_offset(pgd, addr); > + if (pud_none(*pud)) > + return NULL; What if it's not none, but not a table? I think we chould check pud_sect() here, and/or pud_bad(). > + > + pmd = pmd_offset(pud, addr); > + if (pmd_none(*pmd)) > + return NULL; Likewise. > + > + return pte_offset_kernel(pmd, addr); > +} Given this expects a pte, it might make more sense to call this lookup_address_pte() to make that clear. > + > +/* Update a single kernel page table entry */ > +inline void set_kpte(void *kaddr, struct page *page, pgprot_t prot) > +{ > + pte_t *pte = lookup_address((unsigned long)kaddr); > + > + set_pte(pte, pfn_pte(page_to_pfn(page), prot)); We can get NULL from lookup_address(), so this doesn't look right. If NULL implies an error, drop a BUG_ON(!pte) before the set_pte. > +} > + > +inline void xpfo_flush_kernel_tlb(struct page *page, int order) > +{ > + unsigned long kaddr = (unsigned long)page_address(page); > + unsigned long size = PAGE_SIZE; unsigned long size = PAGE_SIZE << order; > + > + flush_tlb_kernel_range(kaddr, kaddr + (1 << order) * size); ... and this can be simpler. I haven't brought myself back up to speed, so it might not be possible, but I still think it would be preferable for XPFO to call flush_tlb_kernel_range() directly. Thanks, Mark.
Hi Mark, On Thu, Sep 14, 2017 at 07:22:08PM +0100, Mark Rutland wrote: > Hi, > > On Thu, Sep 07, 2017 at 11:36:03AM -0600, Tycho Andersen wrote: > > From: Juerg Haefliger <juerg.haefliger@canonical.com> > > > > Enable support for eXclusive Page Frame Ownership (XPFO) for arm64 and > > provide a hook for updating a single kernel page table entry (which is > > required by the generic XPFO code). > > > > v6: use flush_tlb_kernel_range() instead of __flush_tlb_one() > > > > CC: linux-arm-kernel@lists.infradead.org > > Signed-off-by: Juerg Haefliger <juerg.haefliger@canonical.com> > > Signed-off-by: Tycho Andersen <tycho@docker.com> > > --- > > arch/arm64/Kconfig | 1 + > > arch/arm64/mm/Makefile | 2 ++ > > arch/arm64/mm/xpfo.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++ > > 3 files changed, 61 insertions(+) > > > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > > index dfd908630631..44fa44ef02ec 100644 > > --- a/arch/arm64/Kconfig > > +++ b/arch/arm64/Kconfig > > @@ -121,6 +121,7 @@ config ARM64 > > select SPARSE_IRQ > > select SYSCTL_EXCEPTION_TRACE > > select THREAD_INFO_IN_TASK > > + select ARCH_SUPPORTS_XPFO > > A bit of a nit, but this list is (intended to be) organised alphabetically. > Could you please try to retain that? > > i.e. place this between ARCH_SUPPORTS_NUMA_BALANCING and > ARCH_WANT_COMPAT_IPC_PARSE_VERSION. Will do. > > help > > ARM 64-bit (AArch64) Linux support. > > > > diff --git a/arch/arm64/mm/Makefile b/arch/arm64/mm/Makefile > > index 9b0ba191e48e..22e5cab543d8 100644 > > --- a/arch/arm64/mm/Makefile > > +++ b/arch/arm64/mm/Makefile > > @@ -11,3 +11,5 @@ KASAN_SANITIZE_physaddr.o += n > > > > obj-$(CONFIG_KASAN) += kasan_init.o > > KASAN_SANITIZE_kasan_init.o := n > > + > > +obj-$(CONFIG_XPFO) += xpfo.o > > diff --git a/arch/arm64/mm/xpfo.c b/arch/arm64/mm/xpfo.c > > new file mode 100644 > > index 000000000000..678e2be848eb > > --- /dev/null > > +++ b/arch/arm64/mm/xpfo.c > > @@ -0,0 +1,58 @@ > > +/* > > + * Copyright (C) 2017 Hewlett Packard Enterprise Development, L.P. > > + * Copyright (C) 2016 Brown University. All rights reserved. > > + * > > + * Authors: > > + * Juerg Haefliger <juerg.haefliger@hpe.com> > > + * Vasileios P. Kemerlis <vpk@cs.brown.edu> > > + * > > + * This program is free software; you can redistribute it and/or modify it > > + * under the terms of the GNU General Public License version 2 as published by > > + * the Free Software Foundation. > > + */ > > + > > +#include <linux/mm.h> > > +#include <linux/module.h> > > + > > +#include <asm/tlbflush.h> > > + > > +/* > > + * Lookup the page table entry for a virtual address and return a pointer to > > + * the entry. Based on x86 tree. > > + */ > > Is this intended for kernel VAs, user VAs, or both? > > There are different constraints for fiddling with either (e.g. holding > mmap_sem), so we should be clear regarding the intended use-case. kernel only; I can add a comment noting this. > > +static pte_t *lookup_address(unsigned long addr) > > +{ > > + pgd_t *pgd; > > + pud_t *pud; > > + pmd_t *pmd; > > + > > + pgd = pgd_offset_k(addr); > > + if (pgd_none(*pgd)) > > + return NULL; > > + > > + pud = pud_offset(pgd, addr); > > + if (pud_none(*pud)) > > + return NULL; > > What if it's not none, but not a table? > > I think we chould check pud_sect() here, and/or pud_bad(). > > > + > > + pmd = pmd_offset(pud, addr); > > + if (pmd_none(*pmd)) > > + return NULL; > > Likewise. In principle pud_sect() should be okay, because we say that XPFO doesn't support section mappings yet. I'll add a check for pud_bad(). However, Christoph suggested that we move this to common code and there it won't be okay. > > + > > + return pte_offset_kernel(pmd, addr); > > +} > > Given this expects a pte, it might make more sense to call this > lookup_address_pte() to make that clear. > > > + > > +/* Update a single kernel page table entry */ > > +inline void set_kpte(void *kaddr, struct page *page, pgprot_t prot) > > +{ > > + pte_t *pte = lookup_address((unsigned long)kaddr); > > + > > + set_pte(pte, pfn_pte(page_to_pfn(page), prot)); > > We can get NULL from lookup_address(), so this doesn't look right. > > If NULL implies an error, drop a BUG_ON(!pte) before the set_pte. It does, I'll add this (as a WARN() and then no-op), thanks. > > +} > > + > > +inline void xpfo_flush_kernel_tlb(struct page *page, int order) > > +{ > > + unsigned long kaddr = (unsigned long)page_address(page); > > + unsigned long size = PAGE_SIZE; > > unsigned long size = PAGE_SIZE << order; > > > + > > + flush_tlb_kernel_range(kaddr, kaddr + (1 << order) * size); > > ... and this can be simpler. > > I haven't brought myself back up to speed, so it might not be possible, but I > still think it would be preferable for XPFO to call flush_tlb_kernel_range() > directly. I don't think we can, since on x86 it uses smp functions, and in some cases those aren't safe. Cheers, Tycho
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index dfd908630631..44fa44ef02ec 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -121,6 +121,7 @@ config ARM64 select SPARSE_IRQ select SYSCTL_EXCEPTION_TRACE select THREAD_INFO_IN_TASK + select ARCH_SUPPORTS_XPFO help ARM 64-bit (AArch64) Linux support. diff --git a/arch/arm64/mm/Makefile b/arch/arm64/mm/Makefile index 9b0ba191e48e..22e5cab543d8 100644 --- a/arch/arm64/mm/Makefile +++ b/arch/arm64/mm/Makefile @@ -11,3 +11,5 @@ KASAN_SANITIZE_physaddr.o += n obj-$(CONFIG_KASAN) += kasan_init.o KASAN_SANITIZE_kasan_init.o := n + +obj-$(CONFIG_XPFO) += xpfo.o diff --git a/arch/arm64/mm/xpfo.c b/arch/arm64/mm/xpfo.c new file mode 100644 index 000000000000..678e2be848eb --- /dev/null +++ b/arch/arm64/mm/xpfo.c @@ -0,0 +1,58 @@ +/* + * Copyright (C) 2017 Hewlett Packard Enterprise Development, L.P. + * Copyright (C) 2016 Brown University. All rights reserved. + * + * Authors: + * Juerg Haefliger <juerg.haefliger@hpe.com> + * Vasileios P. Kemerlis <vpk@cs.brown.edu> + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published by + * the Free Software Foundation. + */ + +#include <linux/mm.h> +#include <linux/module.h> + +#include <asm/tlbflush.h> + +/* + * Lookup the page table entry for a virtual address and return a pointer to + * the entry. Based on x86 tree. + */ +static pte_t *lookup_address(unsigned long addr) +{ + pgd_t *pgd; + pud_t *pud; + pmd_t *pmd; + + pgd = pgd_offset_k(addr); + if (pgd_none(*pgd)) + return NULL; + + pud = pud_offset(pgd, addr); + if (pud_none(*pud)) + return NULL; + + pmd = pmd_offset(pud, addr); + if (pmd_none(*pmd)) + return NULL; + + return pte_offset_kernel(pmd, addr); +} + +/* Update a single kernel page table entry */ +inline void set_kpte(void *kaddr, struct page *page, pgprot_t prot) +{ + pte_t *pte = lookup_address((unsigned long)kaddr); + + set_pte(pte, pfn_pte(page_to_pfn(page), prot)); +} + +inline void xpfo_flush_kernel_tlb(struct page *page, int order) +{ + unsigned long kaddr = (unsigned long)page_address(page); + unsigned long size = PAGE_SIZE; + + flush_tlb_kernel_range(kaddr, kaddr + (1 << order) * size); +}