From: Guo Ren <ren_guo@c-sky.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
David Miller <davem@davemloft.net>,
gregkh <gregkh@linuxfoundation.org>,
Christoph Hellwig <hch@infradead.org>,
Marc Zyngier <marc.zyngier@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Peter Zijlstra <peterz@infradead.org>,
Rob Herring <robh@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-arch <linux-arch@vger.kernel.org>,
DTML <devicetree@vger.kernel.org>,
Rob Herring <robh+dt@kernel.org>,
c-sky_gcc_upstream@c-sky.com
Subject: Re: [PATCH V9 21/21] csky: support dword access for get_user_size()
Date: Thu, 18 Oct 2018 16:57:52 +0800 [thread overview]
Message-ID: <20181018085751.GA21934@guoren-Inspiron-7460> (raw)
In-Reply-To: <CAK8P3a0cFhBE1tX0xisP__MYiBfaAUQHsW6ZhkmTPocRf1Zb6w@mail.gmail.com>
On Thu, Oct 18, 2018 at 10:34:00AM +0200, Arnd Bergmann wrote:
> On Thu, Oct 18, 2018 at 5:41 AM Guo Ren <ren_guo@c-sky.com> wrote:
> >
> > On Wed, Oct 17, 2018 at 05:44:17PM +0200, Arnd Bergmann wrote:
> > > On Tue, Oct 16, 2018 at 5:33 AM Guo Ren <ren_guo@c-sky.com> wrote:
> > > >
> > > > Support dword access for get_user_size and redesign put_user_size with
> > > > the same style of get_user_size. It's Ok to use xxx_user_asm_common for
> > > > all size of variable with ldb, ldh, ldw, ld.d
> > > >
> > > > ld.d rx, (addr, 0) could "rx <= addr" "and r(x+1) <= addr+4" and this also
> > > > follow abiv2 gcc ABI for dword access.
> > >
> > > Are you sure this is correct for this?
> > >
> > > static inline u32 get_64_to_32(__u64 __user *p)
> > > {
> > > u32 ret;
> > > get_user(ret, p);
> > > return ret;
> > > }
> > >
> > > If I read __get_user_asm_common() right, the ld.d would overwrite
> > > two registers, but the caller only expects one, so it clobbers one
> > > that might be in use.
> > Ah... BUG! I only consider the get_user(u64, u64 *) :P
> >
> > Change to:
> > case 8: \
> > __get_user_asm_dword((x), ptr, "ld.d", retval); \
> > break;
> >
> > #define __get_user_asm_dword(x, ptr, err) \
> > do { \
> > u64 tmp; \
> > __get_user_asm_common(tmp, ptr, "ld.d", err); \
> > x = typeof(x) tmp; \
> > } while(0)
> >
> > #define __put_user_asm_dword(x, ptr, err) \
> > do { \
> > u64 tmp = (u64) x; \
> > __put_user_asm_common(tmp, ptr, "st.d", err); \
> > } while(0)
> >
>
> I think this will cause warnings for code that passes a pointer.
>
> The 64-bit __get_user() is really hard, and most 32-bit architectures don't
> implement it at all. If you really want to add it, have a look at what
> x86 and arm do. IIRC they both use __builtin_choose_expr(),
Thx for the tips and I'll drop the patch first for the upstream.
I want to implement it because of make allmodconfig and
drivers/android/binder.c need it. I'll learn __builtin_choose_expr()
and prepare patch next.
Best Regards
Guo Ren
next prev parent reply other threads:[~2018-10-18 8:58 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-16 2:58 [PATCH V9 00/21] C-SKY(csky) Linux Kernel Port Guo Ren
2018-10-16 2:58 ` [PATCH V9 01/21] csky: Build infrastructure Guo Ren
2018-10-23 0:08 ` Guo Ren
2018-10-24 22:53 ` Arnd Bergmann
2018-10-25 17:04 ` Guo Ren
2018-10-16 2:58 ` [PATCH V9 02/21] csky: defconfig Guo Ren
2018-10-17 14:56 ` Arnd Bergmann
2018-10-16 2:58 ` [PATCH V9 03/21] csky: Kernel booting Guo Ren
2018-10-17 14:58 ` Arnd Bergmann
2018-10-16 2:58 ` [PATCH V9 04/21] csky: Exception handling and mm-fault Guo Ren
2018-10-17 14:59 ` Arnd Bergmann
2018-10-16 2:58 ` [PATCH V9 05/21] csky: System Call Guo Ren
2018-10-17 15:02 ` Arnd Bergmann
2018-10-18 2:02 ` Guo Ren
2018-10-16 2:58 ` [PATCH V9 06/21] csky: Cache and TLB routines Guo Ren
2018-10-17 15:08 ` Arnd Bergmann
2018-10-16 2:58 ` [PATCH V9 07/21] csky: MMU and page table management Guo Ren
2018-10-17 15:06 ` Arnd Bergmann
2018-10-18 2:05 ` Guo Ren
2018-10-16 2:58 ` [PATCH V9 08/21] csky: Process management and Signal Guo Ren
2018-10-17 15:11 ` Arnd Bergmann
2018-10-18 2:37 ` Guo Ren
2018-10-16 2:58 ` [PATCH V9 09/21] csky: VDSO and rt_sigreturn Guo Ren
2018-10-17 15:13 ` Arnd Bergmann
2018-10-16 2:58 ` [PATCH V9 10/21] csky: IRQ handling Guo Ren
2018-10-17 15:14 ` Arnd Bergmann
2018-10-18 2:39 ` Guo Ren
2018-10-16 2:58 ` [PATCH V9 11/21] csky: Atomic operations Guo Ren
2018-10-17 15:17 ` Arnd Bergmann
2018-10-18 2:40 ` Guo Ren
2018-10-21 20:55 ` Peter Zijlstra
2018-10-22 1:52 ` Guo Ren
2018-10-16 2:58 ` [PATCH V9 12/21] csky: ELF and module probe Guo Ren
2018-10-17 15:18 ` Arnd Bergmann
2018-10-18 2:49 ` Guo Ren
2018-10-18 8:31 ` Arnd Bergmann
2018-10-16 2:58 ` [PATCH V9 13/21] csky: Library functions Guo Ren
2018-10-17 15:24 ` Arnd Bergmann
2018-10-18 3:10 ` Guo Ren
2018-10-16 2:58 ` [PATCH V9 14/21] csky: User access Guo Ren
2018-10-17 15:37 ` Arnd Bergmann
2018-10-16 2:58 ` [PATCH V9 15/21] csky: Debug and Ptrace GDB Guo Ren
2018-10-17 15:46 ` Arnd Bergmann
2018-10-18 3:17 ` Guo Ren
2018-10-16 2:58 ` [PATCH V9 16/21] csky: SMP support Guo Ren
2018-10-17 15:47 ` Arnd Bergmann
2018-10-16 2:58 ` [PATCH V9 17/21] csky: Misc headers Guo Ren
2018-10-17 15:49 ` Arnd Bergmann
2018-10-16 2:58 ` [PATCH V9 18/21] dt-bindings: csky CPU Bindings Guo Ren
2018-10-17 15:50 ` Arnd Bergmann
2018-10-18 3:21 ` Guo Ren
2018-10-18 3:45 ` Guo Ren
2018-10-18 14:31 ` Rob Herring
2018-10-19 2:19 ` Guo Ren
2018-10-16 2:58 ` [PATCH V9 19/21] dt-bindings: Add vendor prefix for csky Guo Ren
2018-10-16 2:58 ` [PATCH V9 20/21] MAINTAINERS: Add csky Guo Ren
2018-10-17 15:51 ` Arnd Bergmann
2018-10-16 5:48 ` [PATCH V9 21/21] csky: support dword access for get_user_size() Guo Ren
2018-10-17 15:44 ` Arnd Bergmann
2018-10-18 3:41 ` Guo Ren
2018-10-18 8:34 ` Arnd Bergmann
2018-10-18 8:57 ` Guo Ren [this message]
2018-10-24 7:17 ` Arnd Bergmann
2018-10-25 17:08 ` Guo Ren
2018-10-17 15:58 ` [PATCH V9 00/21] C-SKY(csky) Linux Kernel Port Arnd Bergmann
2018-10-18 4:10 ` Guo Ren
2018-10-18 8:36 ` Arnd Bergmann
2018-10-18 9:03 ` Guo Ren
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