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[76.210.143.223]) by smtp.gmail.com with ESMTPSA id nl8sm3801559pjb.13.2020.07.09.14.20.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Jul 2020 14:20:20 -0700 (PDT) Subject: [PATCH v2 1/5] lib: Add a generic version of devmem_is_allowed() Date: Thu, 9 Jul 2020 14:19:21 -0700 Message-Id: <20200709211925.1926557-2-palmer@dabbelt.com> X-Mailer: git-send-email 2.27.0.383.g050319c2ae-goog In-Reply-To: <20200709211925.1926557-1-palmer@dabbelt.com> References: <20200709211925.1926557-1-palmer@dabbelt.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Cc: linux@armlinux.org.uk, catalin.marinas@arm.com, will@kernel.org, Paul Walmsley , Palmer Dabbelt , aou@eecs.berkeley.edu, gxt@pku.edu.cn, Arnd Bergmann , linus.walleij@linaro.org, akpm@linux-foundation.org, mchehab+samsung@kernel.org, gregory.0xf0@gmail.com, masahiroy@kernel.org, Nick Desaulniers , bgolaszewski@baylibre.com, steve@sk2.org, tglx@linutronix.de, keescook@chromium.org, alex@ghiti.fr, mcgrof@kernel.org, mark.rutland@arm.com, james.morse@arm.com, alex.shi@linux.alibaba.com, andriy.shevchenko@linux.intel.com, broonie@kernel.org, rdunlap@infradead.org, davem@davemloft.net, rostedt@goodmis.org, dan.j.williams@intel.com, mhiramat@kernel.org, krzk@kernel.org, zaslonko@linux.ibm.com, matti.vaittinen@fi.rohmeurope.com, uwe@kleine-koenig.org, clabbe@baylibre.com, changbin.du@intel.com, Greg KH , paulmck@kernel.org, pmladek@suse.com, brendanhiggins@google.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-riscv@lists.infradead.org, linux-arch@vger.kernel.org, kernel-team@android.com, Palmer Dabbelt From: Palmer Dabbelt To: zong.li@sifive.com, linux-riscv@lists.infradead.org, rppt@linux.ibm.com Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 | 3 +++ lib/Kconfig.debug | 2 +- lib/Makefile | 2 ++ lib/devmem_is_allowed.c | 27 +++++++++++++++++++++++++++ 5 files changed, 37 insertions(+), 1 deletion(-) 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..610c16ecbb7c 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -676,3 +676,6 @@ config GENERIC_LIB_CMPDI2 config GENERIC_LIB_UCMPDI2 bool + +config GENERIC_LIB_DEVMEM_IS_ALLOWED + bool diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 9ad9210d70a1..e095bd631ba1 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1577,7 +1577,7 @@ config ARCH_HAS_DEVMEM_IS_ALLOWED config STRICT_DEVMEM bool "Filter access to /dev/mem" depends on MMU && DEVMEM - depends on ARCH_HAS_DEVMEM_IS_ALLOWED + depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED default y if PPC || X86 || ARM64 help If this option is disabled, you allow userspace (root) access to all 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