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[60.241.117.97]) by smtp.gmail.com with ESMTPSA id o15sm4808718pgj.60.2020.04.03.02.00.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 03 Apr 2020 02:00:03 -0700 (PDT) Date: Fri, 03 Apr 2020 18:59:58 +1000 From: Nicholas Piggin Subject: Re: [PATCH 1/4] powerpc/64s: implement probe_kernel_read/write without touching AMR To: Christophe Leroy , linuxppc-dev@lists.ozlabs.org References: <20200327070240.427074-1-npiggin@gmail.com> In-Reply-To: MIME-Version: 1.0 User-Agent: astroid/0.15.0 (https://github.com/astroidmail/astroid) Message-Id: <1585904337.b41amzn27o.astroid@bobo.none> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable 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: , Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Christophe Leroy's on March 27, 2020 5:13 pm: >=20 >=20 > Le 27/03/2020 =C3=A0 08:02, Nicholas Piggin a =C3=A9crit=C2=A0: >> There is no need to allow user accesses when probing kernel addresses. >>=20 >> Signed-off-by: Nicholas Piggin >> --- >> arch/powerpc/include/asm/uaccess.h | 25 ++++++++++----- >> arch/powerpc/lib/Makefile | 2 +- >> arch/powerpc/lib/uaccess.c | 50 ++++++++++++++++++++++++++++++ >> 3 files changed, 68 insertions(+), 9 deletions(-) >> create mode 100644 arch/powerpc/lib/uaccess.c >>=20 >=20 > [...] >=20 >> diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile >> index b8de3be10eb4..a15060b5008e 100644 >> --- a/arch/powerpc/lib/Makefile >> +++ b/arch/powerpc/lib/Makefile >> @@ -36,7 +36,7 @@ extra-$(CONFIG_PPC64) +=3D crtsavres.o >> endif >> =20 >> obj-$(CONFIG_PPC_BOOK3S_64) +=3D copyuser_power7.o copypage_power7.o \ >> - memcpy_power7.o >> + memcpy_power7.o uaccess.o >=20 > Why only book3s/64 ? It applies to the 8xx and book3s/32 as well, I=20 > think it should just be for all powerpc. Okay I can do that. >> =20 >> obj64-y +=3D copypage_64.o copyuser_64.o mem_64.o hweight_64.o \ >> memcpy_64.o memcpy_mcsafe_64.o >> diff --git a/arch/powerpc/lib/uaccess.c b/arch/powerpc/lib/uaccess.c >> new file mode 100644 >> index 000000000000..0057ab52d6fe >> --- /dev/null >> +++ b/arch/powerpc/lib/uaccess.c >> @@ -0,0 +1,50 @@ >> +#include >> +#include >> + >> +static __always_inline long >> +probe_read_common(void *dst, const void __user *src, size_t size) >> +{ >> + long ret; >> + >> + pagefault_disable(); >> + ret =3D raw_copy_from_user_allowed(dst, src, size); >> + pagefault_enable(); >> + >> + return ret ? -EFAULT : 0; >> +} >> + >> +static __always_inline long >> +probe_write_common(void __user *dst, const void *src, size_t size) >> +{ >> + long ret; >> + >> + pagefault_disable(); >> + ret =3D raw_copy_to_user_allowed(dst, src, size); >> + pagefault_enable(); >> + >> + return ret ? -EFAULT : 0; >> +} >> + >> +long probe_kernel_read(void *dst, const void *src, size_t size) >> +{ >> + long ret; >> + mm_segment_t old_fs =3D get_fs(); >> + >> + set_fs(KERNEL_DS); >> + ret =3D probe_read_common(dst, (__force const void __user *)src, size)= ; >=20 > I think you should squash probe_read_common() here, having it separated=20 > is a lot of lines for no added value. It also may make people believe it=20 > overwrites the generic probe_read_common() Yeah I'll see how that looks. Thanks, Nick =