From mboxrd@z Thu Jan 1 00:00:00 1970 From: lauraa@codeaurora.org (Laura Abbott) Date: Wed, 11 Dec 2013 09:35:18 -0800 Subject: [PATCH] arm64: Correct virt_addr_valid In-Reply-To: <20131211104429.GE26730@mudshark.cambridge.arm.com> References: <1386724982-16997-1-git-send-email-lauraa@codeaurora.org> <1386724982-16997-2-git-send-email-lauraa@codeaurora.org> <20131211104429.GE26730@mudshark.cambridge.arm.com> Message-ID: <52A8A256.3080801@codeaurora.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 12/11/2013 2:44 AM, Will Deacon wrote: > On Wed, Dec 11, 2013 at 01:23:02AM +0000, Laura Abbott wrote: >> The definition of virt_addr_valid is that virt_addr_valid should >> return true if and only if virt_to_page returns a valid pointer. >> The current definition of virt_addr_valid only checks against the >> virtual address range. There's no guarantee that just because a >> virtual address falls bewteen PAGE_OFFSET and high_memory the >> associated physical memory has a valid backing struct page. Follow >> the example of other architectures and convert to pfn_valid to >> verify that the virtual address is actually valid. >> >> Cc: Catalin Marinas >> Cc: Will Deacon >> Cc: Nicolas Pitre >> Signed-off-by: Laura Abbott >> --- >> arch/arm64/include/asm/memory.h | 3 +-- >> 1 files changed, 1 insertions(+), 2 deletions(-) >> >> diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h >> index 3776217..9dc5dc3 100644 >> --- a/arch/arm64/include/asm/memory.h >> +++ b/arch/arm64/include/asm/memory.h >> @@ -146,8 +146,7 @@ static inline void *phys_to_virt(phys_addr_t x) >> #define ARCH_PFN_OFFSET PHYS_PFN_OFFSET >> >> #define virt_to_page(kaddr) pfn_to_page(__pa(kaddr) >> PAGE_SHIFT) >> -#define virt_addr_valid(kaddr) (((void *)(kaddr) >= (void *)PAGE_OFFSET) && \ >> - ((void *)(kaddr) < (void *)high_memory)) >> +#define virt_addr_valid(kaddr) pfn_valid(__pa(kaddr) >> PAGE_SHIFT) > > Hmm, this is pretty expensive on both arm and arm64, since we end up doing a > binary search through all of the memblocks. > > Are you seeing real problems with the current code? > No, thankfully I'm not seeing actual problems at the moment. I found this while looking at other code. It's also worth noting that almost all other architectures use this same code as well so I don't see this as something that would be uniquely bad on ARM. > Will > Laura -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation