From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Rapoport Subject: Re: [PATCH 1/5] lib: Add a generic version of devmem_is_allowed() Date: Thu, 9 Jul 2020 23:49:21 +0300 Message-ID: <20200709204921.GJ781326@linux.ibm.com> References: <20200709200552.1910298-1-palmer@dabbelt.com> <20200709200552.1910298-2-palmer@dabbelt.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:42362 "EHLO mx0b-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726196AbgGIUum (ORCPT ); Thu, 9 Jul 2020 16:50:42 -0400 Content-Disposition: inline In-Reply-To: <20200709200552.1910298-2-palmer@dabbelt.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Palmer Dabbelt Cc: linux-riscv@lists.infradead.org, zong.li@sifive.com, linux@armlinux.org.uk, catalin.marinas@arm.com, will@kernel.org, Paul Walmsley , aou@eecs.berkeley.edu, gxt@pku.edu.cn, Arnd Bergmann , akpm@linux-foundation.org, linus.walleij@linaro.org, mchehab+samsung@kernel.org, gregory.0xf0@gmail.com, masahiroy@kernel.org, Nick Desaulniers , bgolaszewski@baylibre.com, tglx@linutronix.de, steve@sk2.org, keescook@chromium.org, mcgrof@kernel.org, alex@ghiti.fr, mark.rutland@arm.com, james.morse@arm.com, andriy.shevchenko@linux.intel.com, alex.shi@linux.alibaba.com, davem@davemloft.net, rdunlap@infradead.org, broonie@kernel.org, uwe@kleine-koenig.org, rostedt@goodmis.org, dan.j.williams@intel.com, mhiramat@kernel.org Hi Palmer, On Thu, Jul 09, 2020 at 01:05:48PM -0700, Palmer Dabbelt wrote: > From: Palmer Dabbelt > > As part of adding support for STRICT_DEVMEM to the RISC-V port, Zong > provided a devmem_is_allowed() implementation that's exactly the same as > all the others I checked. Instead I'm adding a generic version, which > will soon be used. > > Signed-off-by: Palmer Dabbelt > --- > include/asm-generic/io.h | 4 ++++ > lib/Kconfig | 4 ++++ > lib/Makefile | 2 ++ > lib/devmem_is_allowed.c | 27 +++++++++++++++++++++++++++ > 4 files changed, 37 insertions(+) > create mode 100644 lib/devmem_is_allowed.c > > diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h > index 8b1e020e9a03..69e3db65fba0 100644 > --- a/include/asm-generic/io.h > +++ b/include/asm-generic/io.h > @@ -1122,6 +1122,10 @@ static inline void memcpy_toio(volatile void __iomem *addr, const void *buffer, > } > #endif > > +#ifndef CONFIG_GENERIC_DEVMEM_IS_ALLOWED > +extern int devmem_is_allowed(unsigned long pfn); > +#endif > + > #endif /* __KERNEL__ */ > > #endif /* __ASM_GENERIC_IO_H */ > diff --git a/lib/Kconfig b/lib/Kconfig > index df3f3da95990..3b1b6481e073 100644 > --- a/lib/Kconfig > +++ b/lib/Kconfig > @@ -676,3 +676,7 @@ config GENERIC_LIB_CMPDI2 > > config GENERIC_LIB_UCMPDI2 > bool > + > +config GENERIC_LIB_DEVMEM_IS_ALLOWED > + bool > + select ARCH_HAS_DEVMEM_IS_ALLOWED This seems to work the other way around from the usual Kconfig chains. In the most cases ARCH_HAS_SOMETHING selects GENERIC_SOMETHING. I believe nicer way would be to make config STRICT_DEVMEM bool "Filter access to /dev/mem" depends on MMU && DEVMEM depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED config GENERIC_LIB_DEVMEM_IS_ALLOWED bool and then s/select ARCH_HAS_DEVMEM_IS_ALLOWED/select GENERIC_LIB_DEVMEM_IS_ALLOWED/ in the arch Kconfigs and drop ARCH_HAS_DEVMEM_IS_ALLOWED in the end. > diff --git a/lib/Makefile b/lib/Makefile > index b1c42c10073b..554ef14f9be5 100644 > --- a/lib/Makefile > +++ b/lib/Makefile > @@ -318,3 +318,5 @@ obj-$(CONFIG_OBJAGG) += objagg.o > # KUnit tests > obj-$(CONFIG_LIST_KUNIT_TEST) += list-test.o > obj-$(CONFIG_LINEAR_RANGES_TEST) += test_linear_ranges.o > + > +obj-$(CONFIG_GENERIC_LIB_DEVMEM_IS_ALLOWED) += devmem_is_allowed.o > diff --git a/lib/devmem_is_allowed.c b/lib/devmem_is_allowed.c > new file mode 100644 > index 000000000000..c0d67c541849 > --- /dev/null > +++ b/lib/devmem_is_allowed.c > @@ -0,0 +1,27 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * A generic version of devmem_is_allowed. > + * > + * Based on arch/arm64/mm/mmap.c > + * > + * Copyright (C) 2020 Google, Inc. > + * Copyright (C) 2012 ARM Ltd. > + */ > + > +#include > +#include > + > +/* > + * devmem_is_allowed() checks to see if /dev/mem access to a certain address > + * is valid. The argument is a physical page number. We mimic x86 here by > + * disallowing access to system RAM as well as device-exclusive MMIO regions. > + * This effectively disable read()/write() on /dev/mem. > + */ > +int devmem_is_allowed(unsigned long pfn) > +{ > + if (iomem_is_exclusive(pfn << PAGE_SHIFT)) > + return 0; > + if (!page_is_ram(pfn)) > + return 1; > + return 0; > +} > -- > 2.27.0.383.g050319c2ae-goog > -- Sincerely yours, Mike. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:42362 "EHLO mx0b-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726196AbgGIUum (ORCPT ); Thu, 9 Jul 2020 16:50:42 -0400 Date: Thu, 9 Jul 2020 23:49:21 +0300 From: Mike Rapoport Subject: Re: [PATCH 1/5] lib: Add a generic version of devmem_is_allowed() Message-ID: <20200709204921.GJ781326@linux.ibm.com> References: <20200709200552.1910298-1-palmer@dabbelt.com> <20200709200552.1910298-2-palmer@dabbelt.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200709200552.1910298-2-palmer@dabbelt.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Palmer Dabbelt Cc: linux-riscv@lists.infradead.org, zong.li@sifive.com, linux@armlinux.org.uk, catalin.marinas@arm.com, will@kernel.org, Paul Walmsley , aou@eecs.berkeley.edu, gxt@pku.edu.cn, Arnd Bergmann , akpm@linux-foundation.org, linus.walleij@linaro.org, mchehab+samsung@kernel.org, gregory.0xf0@gmail.com, masahiroy@kernel.org, Nick Desaulniers , bgolaszewski@baylibre.com, tglx@linutronix.de, steve@sk2.org, keescook@chromium.org, mcgrof@kernel.org, alex@ghiti.fr, mark.rutland@arm.com, james.morse@arm.com, andriy.shevchenko@linux.intel.com, alex.shi@linux.alibaba.com, davem@davemloft.net, rdunlap@infradead.org, broonie@kernel.org, uwe@kleine-koenig.org, rostedt@goodmis.org, dan.j.williams@intel.com, mhiramat@kernel.org, matti.vaittinen@fi.rohmeurope.com, zaslonko@linux.ibm.com, krzk@kernel.org, willy@infradead.org, paulmck@kernel.org, pmladek@suse.com, glider@google.com, elver@google.com, davidgow@google.com, ardb@kernel.org, takahiro.akashi@linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, kernel-team@android.com, Palmer Dabbelt Message-ID: <20200709204921.btthYCZZ7RZKil11XXaoOuM7uju5i_sPmaAXRLwxL-A@z> Hi Palmer, On Thu, Jul 09, 2020 at 01:05:48PM -0700, Palmer Dabbelt wrote: > From: Palmer Dabbelt > > As part of adding support for STRICT_DEVMEM to the RISC-V port, Zong > provided a devmem_is_allowed() implementation that's exactly the same as > all the others I checked. Instead I'm adding a generic version, which > will soon be used. > > Signed-off-by: Palmer Dabbelt > --- > include/asm-generic/io.h | 4 ++++ > lib/Kconfig | 4 ++++ > lib/Makefile | 2 ++ > lib/devmem_is_allowed.c | 27 +++++++++++++++++++++++++++ > 4 files changed, 37 insertions(+) > create mode 100644 lib/devmem_is_allowed.c > > diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h > index 8b1e020e9a03..69e3db65fba0 100644 > --- a/include/asm-generic/io.h > +++ b/include/asm-generic/io.h > @@ -1122,6 +1122,10 @@ static inline void memcpy_toio(volatile void __iomem *addr, const void *buffer, > } > #endif > > +#ifndef CONFIG_GENERIC_DEVMEM_IS_ALLOWED > +extern int devmem_is_allowed(unsigned long pfn); > +#endif > + > #endif /* __KERNEL__ */ > > #endif /* __ASM_GENERIC_IO_H */ > diff --git a/lib/Kconfig b/lib/Kconfig > index df3f3da95990..3b1b6481e073 100644 > --- a/lib/Kconfig > +++ b/lib/Kconfig > @@ -676,3 +676,7 @@ config GENERIC_LIB_CMPDI2 > > config GENERIC_LIB_UCMPDI2 > bool > + > +config GENERIC_LIB_DEVMEM_IS_ALLOWED > + bool > + select ARCH_HAS_DEVMEM_IS_ALLOWED This seems to work the other way around from the usual Kconfig chains. In the most cases ARCH_HAS_SOMETHING selects GENERIC_SOMETHING. I believe nicer way would be to make config STRICT_DEVMEM bool "Filter access to /dev/mem" depends on MMU && DEVMEM depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED config GENERIC_LIB_DEVMEM_IS_ALLOWED bool and then s/select ARCH_HAS_DEVMEM_IS_ALLOWED/select GENERIC_LIB_DEVMEM_IS_ALLOWED/ in the arch Kconfigs and drop ARCH_HAS_DEVMEM_IS_ALLOWED in the end. > diff --git a/lib/Makefile b/lib/Makefile > index b1c42c10073b..554ef14f9be5 100644 > --- a/lib/Makefile > +++ b/lib/Makefile > @@ -318,3 +318,5 @@ obj-$(CONFIG_OBJAGG) += objagg.o > # KUnit tests > obj-$(CONFIG_LIST_KUNIT_TEST) += list-test.o > obj-$(CONFIG_LINEAR_RANGES_TEST) += test_linear_ranges.o > + > +obj-$(CONFIG_GENERIC_LIB_DEVMEM_IS_ALLOWED) += devmem_is_allowed.o > diff --git a/lib/devmem_is_allowed.c b/lib/devmem_is_allowed.c > new file mode 100644 > index 000000000000..c0d67c541849 > --- /dev/null > +++ b/lib/devmem_is_allowed.c > @@ -0,0 +1,27 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * A generic version of devmem_is_allowed. > + * > + * Based on arch/arm64/mm/mmap.c > + * > + * Copyright (C) 2020 Google, Inc. > + * Copyright (C) 2012 ARM Ltd. > + */ > + > +#include > +#include > + > +/* > + * devmem_is_allowed() checks to see if /dev/mem access to a certain address > + * is valid. The argument is a physical page number. We mimic x86 here by > + * disallowing access to system RAM as well as device-exclusive MMIO regions. > + * This effectively disable read()/write() on /dev/mem. > + */ > +int devmem_is_allowed(unsigned long pfn) > +{ > + if (iomem_is_exclusive(pfn << PAGE_SHIFT)) > + return 0; > + if (!page_is_ram(pfn)) > + return 1; > + return 0; > +} > -- > 2.27.0.383.g050319c2ae-goog > -- Sincerely yours, Mike.