linux-kernel - [PATCH v2 4/5] arm64: Use the generic devmem_is

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Message-Id: <20200709211925.1926557-5-palmer@dabbelt.com>
Date:   Thu,  9 Jul 2020 14:19:24 -0700
From:   Palmer Dabbelt <palmer@...belt.com>
To:     zong.li@...ive.com, linux-riscv@...ts.infradead.org,
        rppt@...ux.ibm.com
Cc:     linux@...linux.org.uk, catalin.marinas@....com, will@...nel.org,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>, aou@...s.berkeley.edu,
        gxt@....edu.cn, Arnd Bergmann <arnd@...db.de>,
        linus.walleij@...aro.org, akpm@...ux-foundation.org,
        mchehab+samsung@...nel.org, gregory.0xf0@...il.com,
        masahiroy@...nel.org, Nick Desaulniers <ndesaulniers@...gle.com>,
        bgolaszewski@...libre.com, steve@....org, tglx@...utronix.de,
        keescook@...omium.org, alex@...ti.fr, mcgrof@...nel.org,
        mark.rutland@....com, james.morse@....com,
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        matti.vaittinen@...rohmeurope.com, uwe@...ine-koenig.org,
        clabbe@...libre.com, changbin.du@...el.com,
        Greg KH <gregkh@...uxfoundation.org>, paulmck@...nel.org,
        pmladek@...e.com, brendanhiggins@...gle.com, glider@...gle.com,
        elver@...gle.com, davidgow@...gle.com, ardb@...nel.org,
        takahiro.akashi@...aro.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org,
        linux-arch@...r.kernel.org, kernel-team@...roid.com,
        Palmer Dabbelt <palmerdabbelt@...gle.com>
Subject: [PATCH v2 4/5] arm64: Use the generic devmem_is_allowed()

From: Palmer Dabbelt <palmerdabbelt@...gle.com>

I recently copied this into lib/ for use by the RISC-V port.

[I haven't even build tested this.  The lib/ patch is on riscv/for-next,
which I'm targeting for 5.9, so this won't work alone.  See the cover
letter for more details.]

Signed-off-by: Palmer Dabbelt <palmerdabbelt@...gle.com>
---
 arch/arm64/Kconfig          |  2 +-
 arch/arm64/include/asm/io.h |  2 --
 arch/arm64/mm/mmap.c        | 21 ---------------------
 3 files changed, 1 insertion(+), 24 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 66dc41fd49f2..0682672cb244 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -13,7 +13,6 @@ config ARM64
 	select ARCH_BINFMT_ELF_STATE
 	select ARCH_HAS_DEBUG_VIRTUAL
 	select ARCH_HAS_DEBUG_VM_PGTABLE
-	select ARCH_HAS_DEVMEM_IS_ALLOWED
 	select ARCH_HAS_DMA_PREP_COHERENT
 	select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
 	select ARCH_HAS_FAST_MULTIPLIER
@@ -110,6 +109,7 @@ config ARM64
 	select GENERIC_IRQ_PROBE
 	select GENERIC_IRQ_SHOW
 	select GENERIC_IRQ_SHOW_LEVEL
+	select GENERIC_LIB_DEVMEM_IS_ALLOWED
 	select GENERIC_PCI_IOMAP
 	select GENERIC_PTDUMP
 	select GENERIC_SCHED_CLOCK
diff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h
index ff50dd731852..c53eba1a7fd2 100644
--- a/arch/arm64/include/asm/io.h
+++ b/arch/arm64/include/asm/io.h
@@ -200,6 +200,4 @@ extern void __iomem *ioremap_cache(phys_addr_t phys_addr, size_t size);
 extern int valid_phys_addr_range(phys_addr_t addr, size_t size);
 extern int valid_mmap_phys_addr_range(unsigned long pfn, size_t size);
 
-extern int devmem_is_allowed(unsigned long pfn);
-
 #endif	/* __ASM_IO_H */
diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c
index 3028bacbc4e9..07937b49cb88 100644
--- a/arch/arm64/mm/mmap.c
+++ b/arch/arm64/mm/mmap.c
@@ -47,24 +47,3 @@ int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
 {
 	return !(((pfn << PAGE_SHIFT) + size) & ~PHYS_MASK);
 }
-
-#ifdef CONFIG_STRICT_DEVMEM
-
-#include <linux/ioport.h>
-
-/*
- * 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;
-}
-
-#endif
-- 
2.27.0.383.g050319c2ae-goog