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Wed, 14 Aug 2019 17:07:28 -0700 (PDT) Received: from localhost ([49.205.218.176]) by smtp.gmail.com with ESMTPSA id n185sm762325pga.16.2019.08.14.17.07.26 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Wed, 14 Aug 2019 17:07:27 -0700 (PDT) From: Santosh Sivaraj To: Balbir Singh , linuxppc-dev , Linux Kernel Subject: Re: [PATCH v9 7/7] powerpc: add machine check safe copy_to_user In-Reply-To: <74d12529-d068-0210-e229-5cea68bcf9da@gmail.com> References: <20190812092236.16648-1-santosh@fossix.org> <20190812092236.16648-8-santosh@fossix.org> <74d12529-d068-0210-e229-5cea68bcf9da@gmail.com> Date: Thu, 15 Aug 2019 05:37:24 +0530 Message-ID: <874l2jqojn.fsf@santosiv.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Aneesh Kumar K.V" , Mahesh Salgaonkar , Nicholas Piggin , Chandan Rajendra , Reza Arbab Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Hi Balbir, Balbir Singh writes: > On 12/8/19 7:22 pm, Santosh Sivaraj wrote: >> Use memcpy_mcsafe() implementation to define copy_to_user_mcsafe() >> >> Signed-off-by: Santosh Sivaraj >> --- >> arch/powerpc/Kconfig | 1 + >> arch/powerpc/include/asm/uaccess.h | 14 ++++++++++++++ >> 2 files changed, 15 insertions(+) >> >> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig >> index 77f6ebf97113..4316e36095a2 100644 >> --- a/arch/powerpc/Kconfig >> +++ b/arch/powerpc/Kconfig >> @@ -137,6 +137,7 @@ config PPC >> select ARCH_HAS_STRICT_KERNEL_RWX if ((PPC_BOOK3S_64 || PPC32) && !RELOCATABLE && !HIBERNATION) >> select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST >> select ARCH_HAS_UACCESS_FLUSHCACHE if PPC64 >> + select ARCH_HAS_UACCESS_MCSAFE if PPC64 >> select ARCH_HAS_UBSAN_SANITIZE_ALL >> select ARCH_HAVE_NMI_SAFE_CMPXCHG >> select ARCH_KEEP_MEMBLOCK >> diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h >> index 8b03eb44e876..15002b51ff18 100644 >> --- a/arch/powerpc/include/asm/uaccess.h >> +++ b/arch/powerpc/include/asm/uaccess.h >> @@ -387,6 +387,20 @@ static inline unsigned long raw_copy_to_user(void __user *to, >> return ret; >> } >> >> +static __always_inline unsigned long __must_check >> +copy_to_user_mcsafe(void __user *to, const void *from, unsigned long n) >> +{ >> + if (likely(check_copy_size(from, n, true))) { >> + if (access_ok(to, n)) { >> + allow_write_to_user(to, n); >> + n = memcpy_mcsafe((void *)to, from, n); >> + prevent_write_to_user(to, n); >> + } >> + } >> + >> + return n; > > Do we always return n independent of the check_copy_size return value and > access_ok return values? Yes we always return the remaining bytes not copied even if check_copy_size or access_ok fails. Santosh > > Balbir Singh. > >> +} >> + >> extern unsigned long __clear_user(void __user *addr, unsigned long size); >> >> static inline unsigned long clear_user(void __user *addr, unsigned long size) >>