csky: uaccess.h: Coding convention with asm generic
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Message ID 1618995255-91499-1-git-send-email-guoren@kernel.org
State In Next
Commit d3900e8d918f8fbd1366b9c2998e2830e66a0081
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  • csky: uaccess.h: Coding convention with asm generic
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Commit Message

Guo Ren April 21, 2021, 8:54 a.m. UTC
From: Guo Ren <guoren@linux.alibaba.com>

Using asm-generic/uaccess.h to prevent duplicated code:
 - Add user_addr_max which mentioned in generic uaccess.h
 - Remove custom definitions of KERNEL/USER_DS, get/set_fs,
   uaccess_kerenl
 - Using generic extable.h instead of custom definitions in
   uaccess.h

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Cc: Arnd Bergmann <arnd@arndb.de>
---
 arch/csky/include/asm/Kbuild    |   1 +
 arch/csky/include/asm/segment.h |   7 -
 arch/csky/include/asm/uaccess.h | 362 ++++++++-------------------------------
 arch/csky/lib/usercopy.c        | 364 +++++++++++++++++++++++-----------------
 arch/csky/mm/fault.c            |   2 +-
 5 files changed, 287 insertions(+), 449 deletions(-)

Comments

Christoph Hellwig April 21, 2021, 2:48 p.m. UTC | #1
On Wed, Apr 21, 2021 at 08:54:15AM +0000, guoren@kernel.org wrote:
> From: Guo Ren <guoren@linux.alibaba.com>
> 
> Using asm-generic/uaccess.h to prevent duplicated code:
>  - Add user_addr_max which mentioned in generic uaccess.h
>  - Remove custom definitions of KERNEL/USER_DS, get/set_fs,
>    uaccess_kerenl

Instead of using the generic definitions removing support for set_fs
entirely would be much preferred.  The series in linux-next for mips,
or the riscv version that landed in 5.10 might be good examples.
Guenter Roeck April 28, 2021, 3:18 a.m. UTC | #2
On Wed, Apr 21, 2021 at 08:54:15AM +0000, guoren@kernel.org wrote:
> From: Guo Ren <guoren@linux.alibaba.com>
> 
> Using asm-generic/uaccess.h to prevent duplicated code:
>  - Add user_addr_max which mentioned in generic uaccess.h
>  - Remove custom definitions of KERNEL/USER_DS, get/set_fs,
>    uaccess_kerenl
>  - Using generic extable.h instead of custom definitions in
>    uaccess.h
> 
> Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
> Cc: Arnd Bergmann <arnd@arndb.de>

Building csky:tinyconfig ... failed
--------------
Error log:
csky-linux-ld: fs/readdir.o: in function `__put_user_fn':
readdir.c:(.text+0x7c): undefined reference to `__put_user_bad'
csky-linux-ld: fs/readdir.o: in function `$d':
readdir.c:(.text+0x1bc): undefined reference to `__put_user_bad'
make[1]: *** [Makefile:1277: vmlinux] Error 1
make: *** [Makefile:222: __sub-make] Error 2

Bisect log attached.

Guenter

---
# bad: [3f1fee3e7237347f09a2c7fa538119e6d9ea4b84] Add linux-next specific files for 20210426
# good: [9f4ad9e425a1d3b6a34617b8ea226d56a119a717] Linux 5.12
git bisect start 'HEAD' 'v5.12'
# bad: [bb8f486776983897309645c98705670c3d2a16e5] Merge remote-tracking branch 'crypto/master'
git bisect bad bb8f486776983897309645c98705670c3d2a16e5
# bad: [6ab4f4364c450991a476eef5bc57bef3586354ed] Merge remote-tracking branch 'jc_docs/docs-next'
git bisect bad 6ab4f4364c450991a476eef5bc57bef3586354ed
# bad: [fd73cab0b2a046136842b23f027dae3686588ba5] Merge remote-tracking branch 'parisc-hd/for-next'
git bisect bad fd73cab0b2a046136842b23f027dae3686588ba5
# good: [f0e6103e023e0ede67848ddcd6b07044574f4fd3] soc: document merges
git bisect good f0e6103e023e0ede67848ddcd6b07044574f4fd3
# good: [70361dc0add47d3818acf9c33718ce7395f8aaa5] Merge remote-tracking branch 'arm-soc/for-next'
git bisect good 70361dc0add47d3818acf9c33718ce7395f8aaa5
# good: [f62ad9f6e1100e3a1b6ca7a004fd5a972ff768df] Merge remote-tracking branch 'ti-k3/ti-k3-next'
git bisect good f62ad9f6e1100e3a1b6ca7a004fd5a972ff768df
# bad: [b3b33dda4fd25e201c77f0ce9277dd34f31e86ce] Merge remote-tracking branch 'h8300/h8300-next'
git bisect bad b3b33dda4fd25e201c77f0ce9277dd34f31e86ce
# good: [6a861bd8cf3c96f5825d031732e365b7721a84a5] Merge branch 'clk-qcom' into clk-next
git bisect good 6a861bd8cf3c96f5825d031732e365b7721a84a5
# good: [1dd129f1deec0606fb70992521a7e5bcd2f85c69] Merge branch 'clk-qcom' into clk-next
git bisect good 1dd129f1deec0606fb70992521a7e5bcd2f85c69
# good: [8808515be0ed4e33de9bfdc65f4c1b547ee11065] h8300: Replace <linux/clk-provider.h> by <linux/of_clk.h>
git bisect good 8808515be0ed4e33de9bfdc65f4c1b547ee11065
# good: [e27d3ecdeb8923f35cb856fd20be14256aaa7575] Merge remote-tracking branch 'clk/clk-next'
git bisect good e27d3ecdeb8923f35cb856fd20be14256aaa7575
# bad: [d3900e8d918f8fbd1366b9c2998e2830e66a0081] csky: uaccess.h: Coding convention with asm generic
git bisect bad d3900e8d918f8fbd1366b9c2998e2830e66a0081
# good: [0b1f557a1fa02174a982f557581e348d91987ec6] csky: Fixup typos
git bisect good 0b1f557a1fa02174a982f557581e348d91987ec6
# good: [8bfe70e696584deeed1de1bcbfcde405aa1a1344] csky: fix syscache.c fallthrough warning
git bisect good 8bfe70e696584deeed1de1bcbfcde405aa1a1344
# first bad commit: [d3900e8d918f8fbd1366b9c2998e2830e66a0081] csky: uaccess.h: Coding convention with asm generic
Guo Ren April 28, 2021, 8:29 a.m. UTC | #3
Thx, Guenter

On Wed, Apr 28, 2021 at 11:18 AM Guenter Roeck <linux@roeck-us.net> wrote:
>
> On Wed, Apr 21, 2021 at 08:54:15AM +0000, guoren@kernel.org wrote:
> > From: Guo Ren <guoren@linux.alibaba.com>
> >
> > Using asm-generic/uaccess.h to prevent duplicated code:
> >  - Add user_addr_max which mentioned in generic uaccess.h
> >  - Remove custom definitions of KERNEL/USER_DS, get/set_fs,
> >    uaccess_kerenl
> >  - Using generic extable.h instead of custom definitions in
> >    uaccess.h
> >
> > Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
> > Cc: Arnd Bergmann <arnd@arndb.de>
>
> Building csky:tinyconfig ... failed
> --------------
> Error log:
> csky-linux-ld: fs/readdir.o: in function `__put_user_fn':
> readdir.c:(.text+0x7c): undefined reference to `__put_user_bad'
> csky-linux-ld: fs/readdir.o: in function `$d':
> readdir.c:(.text+0x1bc): undefined reference to `__put_user_bad'
> make[1]: *** [Makefile:1277: vmlinux] Error 1
> make: *** [Makefile:222: __sub-make] Error 2
It's a bug, I can't put __put_user_bad in __put_user_fn, and
__put_user has done that:

/*
 * These are the main single-value transfer routines.  They automatically
 * use the right size if we just have the right pointer type.
 * This version just falls back to copy_{from,to}_user, which should
 * provide a fast-path for small values.
 */
#define __put_user(x, ptr) \
({                                                              \
        __typeof__(*(ptr)) __x = (x);                           \
        int __pu_err = -EFAULT;                                 \
        __chk_user_ptr(ptr);                                    \
        switch (sizeof (*(ptr))) {                              \
        case 1:                                                 \
        case 2:                                                 \
        case 4:                                                 \
        case 8:                                                 \
                __pu_err = __put_user_fn(sizeof (*(ptr)),       \
                                         ptr, &__x);            \
                break;                                          \
        default:                                                \
                __put_user_bad();                               \
                break;                                          \
         }                                                      \
        __pu_err;                                               \
})

Also, the same problem in __get_user, and I didn't implement "case 8:".

I'll fix up it in another patch and implement __get_user_case_8
(similar with arch/arc.)

>
> Bisect log attached.
>
> Guenter
>
> ---
> # bad: [3f1fee3e7237347f09a2c7fa538119e6d9ea4b84] Add linux-next specific files for 20210426
> # good: [9f4ad9e425a1d3b6a34617b8ea226d56a119a717] Linux 5.12
> git bisect start 'HEAD' 'v5.12'
> # bad: [bb8f486776983897309645c98705670c3d2a16e5] Merge remote-tracking branch 'crypto/master'
> git bisect bad bb8f486776983897309645c98705670c3d2a16e5
> # bad: [6ab4f4364c450991a476eef5bc57bef3586354ed] Merge remote-tracking branch 'jc_docs/docs-next'
> git bisect bad 6ab4f4364c450991a476eef5bc57bef3586354ed
> # bad: [fd73cab0b2a046136842b23f027dae3686588ba5] Merge remote-tracking branch 'parisc-hd/for-next'
> git bisect bad fd73cab0b2a046136842b23f027dae3686588ba5
> # good: [f0e6103e023e0ede67848ddcd6b07044574f4fd3] soc: document merges
> git bisect good f0e6103e023e0ede67848ddcd6b07044574f4fd3
> # good: [70361dc0add47d3818acf9c33718ce7395f8aaa5] Merge remote-tracking branch 'arm-soc/for-next'
> git bisect good 70361dc0add47d3818acf9c33718ce7395f8aaa5
> # good: [f62ad9f6e1100e3a1b6ca7a004fd5a972ff768df] Merge remote-tracking branch 'ti-k3/ti-k3-next'
> git bisect good f62ad9f6e1100e3a1b6ca7a004fd5a972ff768df
> # bad: [b3b33dda4fd25e201c77f0ce9277dd34f31e86ce] Merge remote-tracking branch 'h8300/h8300-next'
> git bisect bad b3b33dda4fd25e201c77f0ce9277dd34f31e86ce
> # good: [6a861bd8cf3c96f5825d031732e365b7721a84a5] Merge branch 'clk-qcom' into clk-next
> git bisect good 6a861bd8cf3c96f5825d031732e365b7721a84a5
> # good: [1dd129f1deec0606fb70992521a7e5bcd2f85c69] Merge branch 'clk-qcom' into clk-next
> git bisect good 1dd129f1deec0606fb70992521a7e5bcd2f85c69
> # good: [8808515be0ed4e33de9bfdc65f4c1b547ee11065] h8300: Replace <linux/clk-provider.h> by <linux/of_clk.h>
> git bisect good 8808515be0ed4e33de9bfdc65f4c1b547ee11065
> # good: [e27d3ecdeb8923f35cb856fd20be14256aaa7575] Merge remote-tracking branch 'clk/clk-next'
> git bisect good e27d3ecdeb8923f35cb856fd20be14256aaa7575
> # bad: [d3900e8d918f8fbd1366b9c2998e2830e66a0081] csky: uaccess.h: Coding convention with asm generic
> git bisect bad d3900e8d918f8fbd1366b9c2998e2830e66a0081
> # good: [0b1f557a1fa02174a982f557581e348d91987ec6] csky: Fixup typos
> git bisect good 0b1f557a1fa02174a982f557581e348d91987ec6
> # good: [8bfe70e696584deeed1de1bcbfcde405aa1a1344] csky: fix syscache.c fallthrough warning
> git bisect good 8bfe70e696584deeed1de1bcbfcde405aa1a1344
> # first bad commit: [d3900e8d918f8fbd1366b9c2998e2830e66a0081] csky: uaccess.h: Coding convention with asm generic
Arnd Bergmann April 28, 2021, 9:25 a.m. UTC | #4
On Wed, Apr 28, 2021 at 10:30 AM Guo Ren <guoren@kernel.org> wrote:
> On Wed, Apr 28, 2021 at 11:18 AM Guenter Roeck <linux@roeck-us.net> wrote:
> >
> > On Wed, Apr 21, 2021 at 08:54:15AM +0000, guoren@kernel.org wrote:
> > > From: Guo Ren <guoren@linux.alibaba.com>
> > >
> > > Using asm-generic/uaccess.h to prevent duplicated code:
> > >  - Add user_addr_max which mentioned in generic uaccess.h
> > >  - Remove custom definitions of KERNEL/USER_DS, get/set_fs,
> > >    uaccess_kerenl
> > >  - Using generic extable.h instead of custom definitions in
> > >    uaccess.h
> > >
> > > Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
> > > Cc: Arnd Bergmann <arnd@arndb.de>
> >
> > Building csky:tinyconfig ... failed
> > --------------
> > Error log:
> > csky-linux-ld: fs/readdir.o: in function `__put_user_fn':
> > readdir.c:(.text+0x7c): undefined reference to `__put_user_bad'
> > csky-linux-ld: fs/readdir.o: in function `$d':
> > readdir.c:(.text+0x1bc): undefined reference to `__put_user_bad'
> > make[1]: *** [Makefile:1277: vmlinux] Error 1
> > make: *** [Makefile:222: __sub-make] Error 2
> It's a bug, I can't put __put_user_bad in __put_user_fn, and
> __put_user has done that:
>
> /*
>  * These are the main single-value transfer routines.  They automatically
>  * use the right size if we just have the right pointer type.
>  * This version just falls back to copy_{from,to}_user, which should
>  * provide a fast-path for small values.
>  */
> #define __put_user(x, ptr) \
> ({                                                              \
>         __typeof__(*(ptr)) __x = (x);                           \
>         int __pu_err = -EFAULT;                                 \
>         __chk_user_ptr(ptr);                                    \
>         switch (sizeof (*(ptr))) {                              \
>         case 1:                                                 \
>         case 2:                                                 \
>         case 4:                                                 \
>         case 8:                                                 \
>                 __pu_err = __put_user_fn(sizeof (*(ptr)),       \
>                                          ptr, &__x);            \
>                 break;                                          \
>         default:                                                \
>                 __put_user_bad();                               \
>                 break;                                          \
>          }                                                      \
>         __pu_err;                                               \
> })

Actually, please don't use the asm-generic __put_user version based
on copy_to_user, we probably have killed it off long ago.

We might want to come up with a new version of asm-generic/uaccess.h
that actually makes it easier to have a sane per-architecture
implementation of the low-level accessors without set_fs().

I've added Christoph to Cc here, he probably has some ideas
on where we should be heading.

One noteworthy aspect is that almost nothing users the low-level
__get_user()/__put_user() helpers any more outside of architecture
specific code, so we may not need to have separate versions
for much longer.

      Arnd
Christoph Hellwig April 28, 2021, 12:49 p.m. UTC | #5
On Wed, Apr 28, 2021 at 11:25:29AM +0200, Arnd Bergmann wrote:
> Actually, please don't use the asm-generic __put_user version based
> on copy_to_user, we probably have killed it off long ago.

Yes, they are horrible.  

> We might want to come up with a new version of asm-generic/uaccess.h
> that actually makes it easier to have a sane per-architecture
> implementation of the low-level accessors without set_fs().
> 
> I've added Christoph to Cc here, he probably has some ideas
> on where we should be heading.

I think asm-generic/uaccess.h pretty much only makes sense for
nommu.  For that case we can just kill the __{get,put}_user_fn
indirection.  I actually have work for that in an old branch.

Trying to use any of asm-generic/uaccess.h for MMU based kernel is
just asking for trouble.

> One noteworthy aspect is that almost nothing users the low-level
> __get_user()/__put_user() helpers any more outside of architecture
> specific code, so we may not need to have separate versions
> for much longer.

Al has been trying to kill them off entirely for a while, and I hope
he'll eventually succeed.  That being said the difference should be
that the __ versions just skip the access_ok, so having both is
fairly trivial to implement.
Guo Ren April 28, 2021, 1:03 p.m. UTC | #6
On Wed, Apr 28, 2021 at 5:26 PM Arnd Bergmann <arnd@arndb.de> wrote:
>
> On Wed, Apr 28, 2021 at 10:30 AM Guo Ren <guoren@kernel.org> wrote:
> > On Wed, Apr 28, 2021 at 11:18 AM Guenter Roeck <linux@roeck-us.net> wrote:
> > >
> > > On Wed, Apr 21, 2021 at 08:54:15AM +0000, guoren@kernel.org wrote:
> > > > From: Guo Ren <guoren@linux.alibaba.com>
> > > >
> > > > Using asm-generic/uaccess.h to prevent duplicated code:
> > > >  - Add user_addr_max which mentioned in generic uaccess.h
> > > >  - Remove custom definitions of KERNEL/USER_DS, get/set_fs,
> > > >    uaccess_kerenl
> > > >  - Using generic extable.h instead of custom definitions in
> > > >    uaccess.h
> > > >
> > > > Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
> > > > Cc: Arnd Bergmann <arnd@arndb.de>
> > >
> > > Building csky:tinyconfig ... failed
> > > --------------
> > > Error log:
> > > csky-linux-ld: fs/readdir.o: in function `__put_user_fn':
> > > readdir.c:(.text+0x7c): undefined reference to `__put_user_bad'
> > > csky-linux-ld: fs/readdir.o: in function `$d':
> > > readdir.c:(.text+0x1bc): undefined reference to `__put_user_bad'
> > > make[1]: *** [Makefile:1277: vmlinux] Error 1
> > > make: *** [Makefile:222: __sub-make] Error 2
> > It's a bug, I can't put __put_user_bad in __put_user_fn, and
> > __put_user has done that:
> >
> > /*
> >  * These are the main single-value transfer routines.  They automatically
> >  * use the right size if we just have the right pointer type.
> >  * This version just falls back to copy_{from,to}_user, which should
> >  * provide a fast-path for small values.
> >  */
> > #define __put_user(x, ptr) \
> > ({                                                              \
> >         __typeof__(*(ptr)) __x = (x);                           \
> >         int __pu_err = -EFAULT;                                 \
> >         __chk_user_ptr(ptr);                                    \
> >         switch (sizeof (*(ptr))) {                              \
> >         case 1:                                                 \
> >         case 2:                                                 \
> >         case 4:                                                 \
> >         case 8:                                                 \
> >                 __pu_err = __put_user_fn(sizeof (*(ptr)),       \
> >                                          ptr, &__x);            \
> >                 break;                                          \
> >         default:                                                \
> >                 __put_user_bad();                               \
> >                 break;                                          \
> >          }                                                      \
> >         __pu_err;                                               \
> > })
>
> Actually, please don't use the asm-generic __put_user version based
> on copy_to_user, we probably have killed it off long ago.
>
> We might want to come up with a new version of asm-generic/uaccess.h
> that actually makes it easier to have a sane per-architecture
> implementation of the low-level accessors without set_fs().
>
> I've added Christoph to Cc here, he probably has some ideas
> on where we should be heading.
>
> One noteworthy aspect is that almost nothing users the low-level
> __get_user()/__put_user() helpers any more outside of architecture
> specific code, so we may not need to have separate versions
> for much longer.

Thx Arnd, here is my implementation:

#define __put_user_asm_64(x, ptr, err)                  \
do {                                                    \
        int tmp;                                        \
        int errcode;                                    \
                                                        \
        __asm__ __volatile__(                           \
        "     ldw     %3, (%1, 0)     \n"               \
        "1:   stw     %3, (%2, 0)     \n"               \
        "     ldw     %3, (%1, 4)     \n"               \
        "2:   stw     %3, (%2, 4)     \n"               \
        "     br      4f              \n"               \
        "3:   mov     %0, %4          \n"               \
        "     br      4f              \n"               \
        ".section __ex_table, \"a\"   \n"               \
        ".align   2                   \n"               \
        ".long    1b, 3b              \n"               \
        ".long    2b, 3b              \n"               \
        ".previous                    \n"               \
        "4:                           \n"               \
        : "=r"(err), "=r"(x), "=r"(ptr),                \
          "=r"(tmp), "=r"(errcode)                      \
        : "0"(err), "1"(x), "2"(ptr), "3"(0),           \
          "4"(-EFAULT)                                  \
        : "memory");                                    \
} while (0)

static inline int __put_user_fn(size_t size, void __user *ptr, void *x)
{
        int retval = 0;
        u32 tmp;
...
        case 8:
                __put_user_asm_64(x, (u64 *)ptr, retval);
                break;
        }

        return retval;
}
#define __put_user_fn __put_user_fn

#define __get_user_asm_64(x, ptr, err)                  \
do {                                                    \
        int tmp;                                        \
        int errcode;                                    \
                                                        \
        __asm__ __volatile__(                           \
        "1:   ldw     %3, (%2, 0)     \n"               \
        "     stw     %3, (%1, 0)     \n"               \
        "2:   ldw     %3, (%2, 4)     \n"               \
        "     stw     %3, (%1, 4)     \n"               \
        "     br      4f              \n"               \
        "3:   mov     %0, %4          \n"               \
        "     br      4f              \n"               \
        ".section __ex_table, \"a\"   \n"               \
        ".align   2                   \n"               \
        ".long    1b, 3b              \n"               \
        ".long    2b, 3b              \n"               \
        ".previous                    \n"               \
        "4:                           \n"               \
        : "=r"(err), "=r"(x), "=r"(ptr),                \
          "=r"(tmp), "=r"(errcode)                      \
        : "0"(err), "1"(x), "2"(ptr), "3"(0),           \
          "4"(-EFAULT)                                  \
        : "memory");                                    \
} while (0)

static inline int __get_user_fn(size_t size, const void __user *ptr, void *x)
{
        int retval;
        u32 tmp;

...
        case 8:
                __get_user_asm_64(x, ptr, retval);
                break;
        }

        return retval;
}
#define __get_user_fn __get_user_fn
Guo Ren April 28, 2021, 1:07 p.m. UTC | #7
On Wed, Apr 28, 2021 at 8:50 PM Christoph Hellwig <hch@infradead.org> wrote:
>
> On Wed, Apr 28, 2021 at 11:25:29AM +0200, Arnd Bergmann wrote:
> > Actually, please don't use the asm-generic __put_user version based
> > on copy_to_user, we probably have killed it off long ago.
>
> Yes, they are horrible.
>
> > We might want to come up with a new version of asm-generic/uaccess.h
> > that actually makes it easier to have a sane per-architecture
> > implementation of the low-level accessors without set_fs().
> >
> > I've added Christoph to Cc here, he probably has some ideas
> > on where we should be heading.
>
> I think asm-generic/uaccess.h pretty much only makes sense for
> nommu.  For that case we can just kill the __{get,put}_user_fn
> indirection.  I actually have work for that in an old branch.
>
> Trying to use any of asm-generic/uaccess.h for MMU based kernel is
> just asking for trouble.
I still think the arch should base on asm-generic/uaccess.h, not abandon it.

Thx for reviewing.

>
> > One noteworthy aspect is that almost nothing users the low-level
> > __get_user()/__put_user() helpers any more outside of architecture
> > specific code, so we may not need to have separate versions
> > for much longer.
>
> Al has been trying to kill them off entirely for a while, and I hope
> he'll eventually succeed.  That being said the difference should be
> that the __ versions just skip the access_ok, so having both is
> fairly trivial to implement.
Arnd Bergmann April 28, 2021, 1:48 p.m. UTC | #8
On Wed, Apr 28, 2021 at 2:49 PM Christoph Hellwig <hch@infradead.org> wrote:
> On Wed, Apr 28, 2021 at 11:25:29AM +0200, Arnd Bergmann wrote:
> > We might want to come up with a new version of asm-generic/uaccess.h
> > that actually makes it easier to have a sane per-architecture
> > implementation of the low-level accessors without set_fs().
> >
> > I've added Christoph to Cc here, he probably has some ideas
> > on where we should be heading.
>
> I think asm-generic/uaccess.h pretty much only makes sense for
> nommu.  For that case we can just kill the __{get,put}_user_fn
> indirection.  I actually have work for that in an old branch.
>
> Trying to use any of asm-generic/uaccess.h for MMU based kernel is
> just asking for trouble.

The one thing I'd like to see is a generic implementation of the outer
bit that implements handling the variable-length arguments, there are
so many ways that people have gotten that wrong in the past, and
it would be nice if architectures only had to implement a set of fixed-size
accessors that contain the architecture specific inline asm.

There is now a new version for x86 that based on asm-goto with
output, which should in theory provide a better implementation
for any architecture when using gcc-11/clang-11 or higher.

> > One noteworthy aspect is that almost nothing users the low-level
> > __get_user()/__put_user() helpers any more outside of architecture
> > specific code, so we may not need to have separate versions
> > for much longer.
>
> Al has been trying to kill them off entirely for a while, and I hope
> he'll eventually succeed.  That being said the difference should be
> that the __ versions just skip the access_ok, so having both is
> fairly trivial to implement.

That is the difference in the interface, but in some of architectures
there is another difference in that the __ version is completely
inlined while the normal version calls an external function.
I could never quite figure out the reason for this difference.

      Arnd

Patch
diff mbox series

diff --git a/arch/csky/include/asm/Kbuild b/arch/csky/include/asm/Kbuild
index cc24bb8..904a18a 100644
--- a/arch/csky/include/asm/Kbuild
+++ b/arch/csky/include/asm/Kbuild
@@ -1,5 +1,6 @@ 
 # SPDX-License-Identifier: GPL-2.0
 generic-y += asm-offsets.h
+generic-y += extable.h
 generic-y += gpio.h
 generic-y += kvm_para.h
 generic-y += qrwlock.h
diff --git a/arch/csky/include/asm/segment.h b/arch/csky/include/asm/segment.h
index 589e832..5bc1cc62 100644
--- a/arch/csky/include/asm/segment.h
+++ b/arch/csky/include/asm/segment.h
@@ -7,11 +7,4 @@  typedef struct {
 	unsigned long seg;
 } mm_segment_t;
 
-#define KERNEL_DS		((mm_segment_t) { 0xFFFFFFFF })
-
-#define USER_DS			((mm_segment_t) { PAGE_OFFSET })
-#define get_fs()		(current_thread_info()->addr_limit)
-#define set_fs(x)		(current_thread_info()->addr_limit = (x))
-#define uaccess_kernel()	(get_fs().seg == KERNEL_DS.seg)
-
 #endif /* __ASM_CSKY_SEGMENT_H */
diff --git a/arch/csky/include/asm/uaccess.h b/arch/csky/include/asm/uaccess.h
index 3dec272..c33077e 100644
--- a/arch/csky/include/asm/uaccess.h
+++ b/arch/csky/include/asm/uaccess.h
@@ -3,118 +3,22 @@ 
 #ifndef __ASM_CSKY_UACCESS_H
 #define __ASM_CSKY_UACCESS_H
 
-/*
- * User space memory access functions
- */
-#include <linux/compiler.h>
-#include <linux/errno.h>
-#include <linux/types.h>
-#include <linux/sched.h>
-#include <linux/string.h>
-#include <linux/version.h>
-#include <asm/segment.h>
+#define user_addr_max() \
+	(uaccess_kernel() ? KERNEL_DS.seg : get_fs().seg)
 
-static inline int access_ok(const void *addr, unsigned long size)
+static inline int __access_ok(unsigned long addr, unsigned long size)
 {
 	unsigned long limit = current_thread_info()->addr_limit.seg;
 
-	return (((unsigned long)addr < limit) &&
-		((unsigned long)(addr + size) < limit));
+	return ((addr < limit) && ((addr + size) < limit));
 }
-
-#define __addr_ok(addr) (access_ok(addr, 0))
-
-extern int __put_user_bad(void);
+#define __access_ok __access_ok
 
 /*
- * Tell gcc we read from memory instead of writing: this is because
- * we do not write to any memory gcc knows about, so there are no
- * aliasing issues.
+ * __put_user_fn
  */
+extern int __put_user_bad(void);
 
-/*
- * These are the main single-value transfer routines.  They automatically
- * use the right size if we just have the right pointer type.
- *
- * This gets kind of ugly. We want to return _two_ values in "get_user()"
- * and yet we don't want to do any pointers, because that is too much
- * of a performance impact. Thus we have a few rather ugly macros here,
- * and hide all the ugliness from the user.
- *
- * The "__xxx" versions of the user access functions are versions that
- * do not verify the address space, that must have been done previously
- * with a separate "access_ok()" call (this is used when we do multiple
- * accesses to the same area of user memory).
- *
- * As we use the same address space for kernel and user data on
- * Ckcore, we can just do these as direct assignments.  (Of course, the
- * exception handling means that it's no longer "just"...)
- */
-
-#define put_user(x, ptr) \
-	__put_user_check((x), (ptr), sizeof(*(ptr)))
-
-#define __put_user(x, ptr) \
-	__put_user_nocheck((x), (ptr), sizeof(*(ptr)))
-
-#define __ptr(x) ((unsigned long *)(x))
-
-#define get_user(x, ptr) \
-	__get_user_check((x), (ptr), sizeof(*(ptr)))
-
-#define __get_user(x, ptr) \
-	__get_user_nocheck((x), (ptr), sizeof(*(ptr)))
-
-#define __put_user_nocheck(x, ptr, size)				\
-({									\
-	long __pu_err = 0;						\
-	typeof(*(ptr)) *__pu_addr = (ptr);				\
-	typeof(*(ptr)) __pu_val = (typeof(*(ptr)))(x);			\
-	if (__pu_addr)							\
-		__put_user_size(__pu_val, (__pu_addr), (size),		\
-				__pu_err);				\
-	__pu_err;							\
-})
-
-#define __put_user_check(x, ptr, size)					\
-({									\
-	long __pu_err = -EFAULT;					\
-	typeof(*(ptr)) *__pu_addr = (ptr);				\
-	typeof(*(ptr)) __pu_val = (typeof(*(ptr)))(x);			\
-	if (access_ok(__pu_addr, size) && __pu_addr)	\
-		__put_user_size(__pu_val, __pu_addr, (size), __pu_err);	\
-	__pu_err;							\
-})
-
-#define __put_user_size(x, ptr, size, retval)		\
-do {							\
-	retval = 0;					\
-	switch (size) {                                 \
-	case 1:						\
-		__put_user_asm_b(x, ptr, retval);	\
-		break;					\
-	case 2:						\
-		__put_user_asm_h(x, ptr, retval);	\
-		break;					\
-	case 4:						\
-		__put_user_asm_w(x, ptr, retval);	\
-		break;					\
-	case 8:						\
-		__put_user_asm_64(x, ptr, retval);	\
-		break;					\
-	default:					\
-		__put_user_bad();			\
-	}	                                        \
-} while (0)
-
-/*
- * We don't tell gcc that we are accessing memory, but this is OK
- * because we do not write to any memory gcc knows about, so there
- * are no aliasing issues.
- *
- * Note that PC at a fault is the address *after* the faulting
- * instruction.
- */
 #define __put_user_asm_b(x, ptr, err)			\
 do {							\
 	int errcode;					\
@@ -173,8 +77,6 @@  do {							\
 do {								\
 	int tmp;						\
 	int errcode;						\
-	typeof(*(ptr))src = (typeof(*(ptr)))x;			\
-	typeof(*(ptr))*psrc = &src;				\
 								\
 	asm volatile(						\
 	"     ldw     %3, (%1, 0)     \n"			\
@@ -190,53 +92,52 @@  do {								\
 	".long    2b, 3b              \n"			\
 	".previous                    \n"			\
 	"4:                           \n"			\
-	: "=r"(err), "=r"(psrc), "=r"(ptr),			\
+	: "=r"(err), "=r"(x), "=r"(ptr),			\
 	  "=r"(tmp), "=r"(errcode)				\
-	: "0"(err), "1"(psrc), "2"(ptr), "3"(0), "4"(-EFAULT)	\
+	: "0"(err), "1"(x), "2"(ptr), "3"(0), "4"(-EFAULT)	\
 	: "memory");						\
 } while (0)
 
-#define __get_user_nocheck(x, ptr, size)			\
-({								\
-	long  __gu_err;						\
-	__get_user_size(x, (ptr), (size), __gu_err);		\
-	__gu_err;						\
-})
-
-#define __get_user_check(x, ptr, size)				\
-({								\
-	int __gu_err = -EFAULT;					\
-	const __typeof__(*(ptr)) __user *__gu_ptr = (ptr);	\
-	if (access_ok(__gu_ptr, size) && __gu_ptr)	\
-		__get_user_size(x, __gu_ptr, size, __gu_err);	\
-	__gu_err;						\
-})
+static inline int __put_user_fn(size_t size, void __user *ptr, void *x)
+{
+	int retval = 0;
+	u32 tmp;
+
+	switch (size) {
+	case 1:
+		tmp = *(u8 *)x;
+		__put_user_asm_b(tmp, ptr, retval);
+		break;
+	case 2:
+		tmp = *(u16 *)x;
+		__put_user_asm_h(tmp, ptr, retval);
+		break;
+	case 4:
+		tmp = *(u32 *)x;
+		__put_user_asm_w(tmp, ptr, retval);
+		break;
+	case 8:
+		__put_user_asm_64(x, (u64 *)ptr, retval);
+		break;
+	default:
+		__put_user_bad();
+	}
+
+	return retval;
+}
+#define __put_user_fn __put_user_fn
 
-#define __get_user_size(x, ptr, size, retval)			\
-do {								\
-	switch (size) {						\
-	case 1:							\
-		__get_user_asm_common((x), ptr, "ldb", retval);	\
-		break;						\
-	case 2:							\
-		__get_user_asm_common((x), ptr, "ldh", retval);	\
-		break;						\
-	case 4:							\
-		__get_user_asm_common((x), ptr, "ldw", retval);	\
-		break;						\
-	default:						\
-		x = 0;						\
-		(retval) = __get_user_bad();			\
-	}							\
-} while (0)
+/*
+ * __get_user_fn
+ */
+extern int __get_user_bad(void);
 
 #define __get_user_asm_common(x, ptr, ins, err)			\
 do {								\
 	int errcode;						\
-	asm volatile(						\
-	"1:   " ins " %1, (%4,0)	\n"			\
+	__asm__ __volatile__(					\
+	"1:   " ins " %1, (%4, 0)	\n"			\
 	"       br    3f		\n"			\
-	/* Fix up codes */					\
 	"2:     mov   %0, %2		\n"			\
 	"       movi  %1, 0		\n"			\
 	"       br    3f		\n"			\
@@ -250,160 +151,45 @@  do {								\
 	: "memory");						\
 } while (0)
 
-extern int __get_user_bad(void);
-
-#define ___copy_to_user(to, from, n)			\
-do {							\
-	int w0, w1, w2, w3;				\
-	asm volatile(					\
-	"0:     cmpnei  %1, 0           \n"		\
-	"       bf      8f              \n"		\
-	"       mov     %3, %1          \n"		\
-	"       or      %3, %2          \n"		\
-	"       andi    %3, 3           \n"		\
-	"       cmpnei  %3, 0           \n"		\
-	"       bf      1f              \n"		\
-	"       br      5f              \n"		\
-	"1:     cmplti  %0, 16          \n" /* 4W */	\
-	"       bt      3f              \n"		\
-	"       ldw     %3, (%2, 0)     \n"		\
-	"       ldw     %4, (%2, 4)     \n"		\
-	"       ldw     %5, (%2, 8)     \n"		\
-	"       ldw     %6, (%2, 12)    \n"		\
-	"2:     stw     %3, (%1, 0)     \n"		\
-	"9:     stw     %4, (%1, 4)     \n"		\
-	"10:    stw     %5, (%1, 8)     \n"		\
-	"11:    stw     %6, (%1, 12)    \n"		\
-	"       addi    %2, 16          \n"		\
-	"       addi    %1, 16          \n"		\
-	"       subi    %0, 16          \n"		\
-	"       br      1b              \n"		\
-	"3:     cmplti  %0, 4           \n" /* 1W */	\
-	"       bt      5f              \n"		\
-	"       ldw     %3, (%2, 0)     \n"		\
-	"4:     stw     %3, (%1, 0)     \n"		\
-	"       addi    %2, 4           \n"		\
-	"       addi    %1, 4           \n"		\
-	"       subi    %0, 4           \n"		\
-	"       br      3b              \n"		\
-	"5:     cmpnei  %0, 0           \n"  /* 1B */   \
-	"       bf      13f             \n"		\
-	"       ldb     %3, (%2, 0)     \n"		\
-	"6:     stb     %3, (%1, 0)     \n"		\
-	"       addi    %2,  1          \n"		\
-	"       addi    %1,  1          \n"		\
-	"       subi    %0,  1          \n"		\
-	"       br      5b              \n"		\
-	"7:     subi	%0,  4          \n"		\
-	"8:     subi	%0,  4          \n"		\
-	"12:    subi	%0,  4          \n"		\
-	"       br      13f             \n"		\
-	".section __ex_table, \"a\"     \n"		\
-	".align   2                     \n"		\
-	".long    2b, 13f               \n"		\
-	".long    4b, 13f               \n"		\
-	".long    6b, 13f               \n"		\
-	".long    9b, 12b               \n"		\
-	".long   10b, 8b                \n"		\
-	".long   11b, 7b                \n"		\
-	".previous                      \n"		\
-	"13:                            \n"		\
-	: "=r"(n), "=r"(to), "=r"(from), "=r"(w0),	\
-	  "=r"(w1), "=r"(w2), "=r"(w3)			\
-	: "0"(n), "1"(to), "2"(from)			\
-	: "memory");					\
-} while (0)
-
-#define ___copy_from_user(to, from, n)			\
-do {							\
-	int tmp;					\
-	int nsave;					\
-	asm volatile(					\
-	"0:     cmpnei  %1, 0           \n"		\
-	"       bf      7f              \n"		\
-	"       mov     %3, %1          \n"		\
-	"       or      %3, %2          \n"		\
-	"       andi    %3, 3           \n"		\
-	"       cmpnei  %3, 0           \n"		\
-	"       bf      1f              \n"		\
-	"       br      5f              \n"		\
-	"1:     cmplti  %0, 16          \n"		\
-	"       bt      3f              \n"		\
-	"2:     ldw     %3, (%2, 0)     \n"		\
-	"10:    ldw     %4, (%2, 4)     \n"		\
-	"       stw     %3, (%1, 0)     \n"		\
-	"       stw     %4, (%1, 4)     \n"		\
-	"11:    ldw     %3, (%2, 8)     \n"		\
-	"12:    ldw     %4, (%2, 12)    \n"		\
-	"       stw     %3, (%1, 8)     \n"		\
-	"       stw     %4, (%1, 12)    \n"		\
-	"       addi    %2, 16          \n"		\
-	"       addi    %1, 16          \n"		\
-	"       subi    %0, 16          \n"		\
-	"       br      1b              \n"		\
-	"3:     cmplti  %0, 4           \n"		\
-	"       bt      5f              \n"		\
-	"4:     ldw     %3, (%2, 0)     \n"		\
-	"       stw     %3, (%1, 0)     \n"		\
-	"       addi    %2, 4           \n"		\
-	"       addi    %1, 4           \n"		\
-	"       subi    %0, 4           \n"		\
-	"       br      3b              \n"		\
-	"5:     cmpnei  %0, 0           \n"		\
-	"       bf      7f              \n"		\
-	"6:     ldb     %3, (%2, 0)     \n"		\
-	"       stb     %3, (%1, 0)     \n"		\
-	"       addi    %2,  1          \n"		\
-	"       addi    %1,  1          \n"		\
-	"       subi    %0,  1          \n"		\
-	"       br      5b              \n"		\
-	"8:     stw     %3, (%1, 0)     \n"		\
-	"       subi    %0, 4           \n"		\
-	"       bf      7f              \n"		\
-	"9:     subi    %0, 8           \n"		\
-	"       bf      7f              \n"		\
-	"13:    stw     %3, (%1, 8)     \n"		\
-	"       subi    %0, 12          \n"		\
-	"       bf      7f              \n"		\
-	".section __ex_table, \"a\"     \n"		\
-	".align   2                     \n"		\
-	".long    2b, 7f                \n"		\
-	".long    4b, 7f                \n"		\
-	".long    6b, 7f                \n"		\
-	".long   10b, 8b                \n"		\
-	".long   11b, 9b                \n"		\
-	".long   12b,13b                \n"		\
-	".previous                      \n"		\
-	"7:                             \n"		\
-	: "=r"(n), "=r"(to), "=r"(from), "=r"(nsave),	\
-	  "=r"(tmp)					\
-	: "0"(n), "1"(to), "2"(from)			\
-	: "memory");					\
-} while (0)
+static inline int __get_user_fn(size_t size, const void __user *ptr, void *x)
+{
+	int retval;
+	u32 tmp;
+
+	switch (size) {
+	case 1:
+		__get_user_asm_common(tmp, ptr, "ldb", retval);
+		*(u8 *)x = (u8)tmp;
+		break;
+	case 2:
+		__get_user_asm_common(tmp, ptr, "ldh", retval);
+		*(u16 *)x = (u16)tmp;
+		break;
+	case 4:
+		__get_user_asm_common(tmp, ptr, "ldw", retval);
+		*(u32 *)x = (u32)tmp;
+		break;
+	default:
+		retval = __get_user_bad();
+	}
+
+	return retval;
+}
+#define __get_user_fn __get_user_fn
 
 unsigned long raw_copy_from_user(void *to, const void *from, unsigned long n);
 unsigned long raw_copy_to_user(void *to, const void *from, unsigned long n);
 
-unsigned long clear_user(void *to, unsigned long n);
 unsigned long __clear_user(void __user *to, unsigned long n);
+#define __clear_user __clear_user
 
-long strncpy_from_user(char *dst, const char *src, long count);
 long __strncpy_from_user(char *dst, const char *src, long count);
+#define __strncpy_from_user __strncpy_from_user
 
-/*
- * Return the size of a string (including the ending 0)
- *
- * Return 0 on exception, a value greater than N if too long
- */
-long strnlen_user(const char *src, long n);
-
-#define strlen_user(str) strnlen_user(str, 32767)
-
-struct exception_table_entry {
-	unsigned long insn;
-	unsigned long nextinsn;
-};
+long __strnlen_user(const char *s, long n);
+#define __strnlen_user __strnlen_user
 
-extern int fixup_exception(struct pt_regs *regs);
+#include <asm/segment.h>
+#include <asm-generic/uaccess.h>
 
 #endif /* __ASM_CSKY_UACCESS_H */
diff --git a/arch/csky/lib/usercopy.c b/arch/csky/lib/usercopy.c
index 3c9bd64..a718360 100644
--- a/arch/csky/lib/usercopy.c
+++ b/arch/csky/lib/usercopy.c
@@ -7,7 +7,70 @@ 
 unsigned long raw_copy_from_user(void *to, const void *from,
 			unsigned long n)
 {
-	___copy_from_user(to, from, n);
+	int tmp, nsave;
+
+	__asm__ __volatile__(
+	"0:     cmpnei  %1, 0           \n"
+	"       bf      7f              \n"
+	"       mov     %3, %1          \n"
+	"       or      %3, %2          \n"
+	"       andi    %3, 3           \n"
+	"       cmpnei  %3, 0           \n"
+	"       bf      1f              \n"
+	"       br      5f              \n"
+	"1:     cmplti  %0, 16          \n"
+	"       bt      3f              \n"
+	"2:     ldw     %3, (%2, 0)     \n"
+	"10:    ldw     %4, (%2, 4)     \n"
+	"       stw     %3, (%1, 0)     \n"
+	"       stw     %4, (%1, 4)     \n"
+	"11:    ldw     %3, (%2, 8)     \n"
+	"12:    ldw     %4, (%2, 12)    \n"
+	"       stw     %3, (%1, 8)     \n"
+	"       stw     %4, (%1, 12)    \n"
+	"       addi    %2, 16          \n"
+	"       addi    %1, 16          \n"
+	"       subi    %0, 16          \n"
+	"       br      1b              \n"
+	"3:     cmplti  %0, 4           \n"
+	"       bt      5f              \n"
+	"4:     ldw     %3, (%2, 0)     \n"
+	"       stw     %3, (%1, 0)     \n"
+	"       addi    %2, 4           \n"
+	"       addi    %1, 4           \n"
+	"       subi    %0, 4           \n"
+	"       br      3b              \n"
+	"5:     cmpnei  %0, 0           \n"
+	"       bf      7f              \n"
+	"6:     ldb     %3, (%2, 0)     \n"
+	"       stb     %3, (%1, 0)     \n"
+	"       addi    %2,  1          \n"
+	"       addi    %1,  1          \n"
+	"       subi    %0,  1          \n"
+	"       br      5b              \n"
+	"8:     stw     %3, (%1, 0)     \n"
+	"       subi    %0, 4           \n"
+	"       bf      7f              \n"
+	"9:     subi    %0, 8           \n"
+	"       bf      7f              \n"
+	"13:    stw     %3, (%1, 8)     \n"
+	"       subi    %0, 12          \n"
+	"       bf      7f              \n"
+	".section __ex_table, \"a\"     \n"
+	".align   2                     \n"
+	".long    2b, 7f                \n"
+	".long    4b, 7f                \n"
+	".long    6b, 7f                \n"
+	".long   10b, 8b                \n"
+	".long   11b, 9b                \n"
+	".long   12b,13b                \n"
+	".previous                      \n"
+	"7:                             \n"
+	: "=r"(n), "=r"(to), "=r"(from), "=r"(nsave),
+	  "=r"(tmp)
+	: "0"(n), "1"(to), "2"(from)
+	: "memory");
+
 	return n;
 }
 EXPORT_SYMBOL(raw_copy_from_user);
@@ -15,48 +78,70 @@  EXPORT_SYMBOL(raw_copy_from_user);
 unsigned long raw_copy_to_user(void *to, const void *from,
 			unsigned long n)
 {
-	___copy_to_user(to, from, n);
+	int w0, w1, w2, w3;
+
+	__asm__ __volatile__(
+	"0:     cmpnei  %1, 0           \n"
+	"       bf      8f              \n"
+	"       mov     %3, %1          \n"
+	"       or      %3, %2          \n"
+	"       andi    %3, 3           \n"
+	"       cmpnei  %3, 0           \n"
+	"       bf      1f              \n"
+	"       br      5f              \n"
+	"1:     cmplti  %0, 16          \n" /* 4W */
+	"       bt      3f              \n"
+	"       ldw     %3, (%2, 0)     \n"
+	"       ldw     %4, (%2, 4)     \n"
+	"       ldw     %5, (%2, 8)     \n"
+	"       ldw     %6, (%2, 12)    \n"
+	"2:     stw     %3, (%1, 0)     \n"
+	"9:     stw     %4, (%1, 4)     \n"
+	"10:    stw     %5, (%1, 8)     \n"
+	"11:    stw     %6, (%1, 12)    \n"
+	"       addi    %2, 16          \n"
+	"       addi    %1, 16          \n"
+	"       subi    %0, 16          \n"
+	"       br      1b              \n"
+	"3:     cmplti  %0, 4           \n" /* 1W */
+	"       bt      5f              \n"
+	"       ldw     %3, (%2, 0)     \n"
+	"4:     stw     %3, (%1, 0)     \n"
+	"       addi    %2, 4           \n"
+	"       addi    %1, 4           \n"
+	"       subi    %0, 4           \n"
+	"       br      3b              \n"
+	"5:     cmpnei  %0, 0           \n"  /* 1B */
+	"       bf      13f             \n"
+	"       ldb     %3, (%2, 0)     \n"
+	"6:     stb     %3, (%1, 0)     \n"
+	"       addi    %2,  1          \n"
+	"       addi    %1,  1          \n"
+	"       subi    %0,  1          \n"
+	"       br      5b              \n"
+	"7:     subi	%0,  4          \n"
+	"8:     subi	%0,  4          \n"
+	"12:    subi	%0,  4          \n"
+	"       br      13f             \n"
+	".section __ex_table, \"a\"     \n"
+	".align   2                     \n"
+	".long    2b, 13f               \n"
+	".long    4b, 13f               \n"
+	".long    6b, 13f               \n"
+	".long    9b, 12b               \n"
+	".long   10b, 8b                \n"
+	".long   11b, 7b                \n"
+	".previous                      \n"
+	"13:                            \n"
+	: "=r"(n), "=r"(to), "=r"(from), "=r"(w0),
+	  "=r"(w1), "=r"(w2), "=r"(w3)
+	: "0"(n), "1"(to), "2"(from)
+	: "memory");
+
 	return n;
 }
 EXPORT_SYMBOL(raw_copy_to_user);
 
-
-/*
- * copy a null terminated string from userspace.
- */
-#define __do_strncpy_from_user(dst, src, count, res)	\
-do {							\
-	int tmp;					\
-	long faultres;					\
-	asm volatile(					\
-	"       cmpnei  %3, 0           \n"		\
-	"       bf      4f              \n"		\
-	"1:     cmpnei  %1, 0          	\n"		\
-	"       bf      5f              \n"		\
-	"2:     ldb     %4, (%3, 0)     \n"		\
-	"       stb     %4, (%2, 0)     \n"		\
-	"       cmpnei  %4, 0           \n"		\
-	"       bf      3f              \n"		\
-	"       addi    %3,  1          \n"		\
-	"       addi    %2,  1          \n"		\
-	"       subi    %1,  1          \n"		\
-	"       br      1b              \n"		\
-	"3:     subu	%0, %1          \n"		\
-	"       br      5f              \n"		\
-	"4:     mov     %0, %5          \n"		\
-	"       br      5f              \n"		\
-	".section __ex_table, \"a\"     \n"		\
-	".align   2                     \n"		\
-	".long    2b, 4b                \n"		\
-	".previous                      \n"		\
-	"5:                             \n"		\
-	: "=r"(res), "=r"(count), "=r"(dst),		\
-	  "=r"(src), "=r"(tmp),   "=r"(faultres)	\
-	: "5"(-EFAULT), "0"(count), "1"(count),		\
-	  "2"(dst), "3"(src)				\
-	: "memory", "cc");				\
-} while (0)
-
 /*
  * __strncpy_from_user: - Copy a NUL terminated string from userspace,
  * with less checking.
@@ -80,40 +165,40 @@  do {							\
  */
 long __strncpy_from_user(char *dst, const char *src, long count)
 {
-	long res;
+	long res, faultres;
+	int tmp;
 
-	__do_strncpy_from_user(dst, src, count, res);
-	return res;
-}
-EXPORT_SYMBOL(__strncpy_from_user);
-
-/*
- * strncpy_from_user: - Copy a NUL terminated string from userspace.
- * @dst:   Destination address, in kernel space.  This buffer must be at
- *         least @count bytes long.
- * @src:   Source address, in user space.
- * @count: Maximum number of bytes to copy, including the trailing NUL.
- *
- * Copies a NUL-terminated string from userspace to kernel space.
- *
- * On success, returns the length of the string (not including the trailing
- * NUL).
- *
- * If access to userspace fails, returns -EFAULT (some data may have been
- * copied).
- *
- * If @count is smaller than the length of the string, copies @count bytes
- * and returns @count.
- */
-long strncpy_from_user(char *dst, const char *src, long count)
-{
-	long res = -EFAULT;
+	__asm__ __volatile__(
+	"       cmpnei  %3, 0           \n"
+	"       bf      4f              \n"
+	"1:     cmpnei  %1, 0          	\n"
+	"       bf      5f              \n"
+	"2:     ldb     %4, (%3, 0)     \n"
+	"       stb     %4, (%2, 0)     \n"
+	"       cmpnei  %4, 0           \n"
+	"       bf      3f              \n"
+	"       addi    %3,  1          \n"
+	"       addi    %2,  1          \n"
+	"       subi    %1,  1          \n"
+	"       br      1b              \n"
+	"3:     subu	%0, %1          \n"
+	"       br      5f              \n"
+	"4:     mov     %0, %5          \n"
+	"       br      5f              \n"
+	".section __ex_table, \"a\"     \n"
+	".align   2                     \n"
+	".long    2b, 4b                \n"
+	".previous                      \n"
+	"5:                             \n"
+	: "=r"(res), "=r"(count), "=r"(dst),
+	  "=r"(src), "=r"(tmp), "=r"(faultres)
+	: "5"(-EFAULT), "0"(count), "1"(count),
+	  "2"(dst), "3"(src)
+	: "memory");
 
-	if (access_ok(src, 1))
-		__do_strncpy_from_user(dst, src, count, res);
 	return res;
 }
-EXPORT_SYMBOL(strncpy_from_user);
+EXPORT_SYMBOL(__strncpy_from_user);
 
 /*
  * strlen_user: - Get the size of a string in user space.
@@ -126,14 +211,11 @@  EXPORT_SYMBOL(strncpy_from_user);
  * On exception, returns 0.
  * If the string is too long, returns a value greater than @n.
  */
-long strnlen_user(const char *s, long n)
+long __strnlen_user(const char *s, long n)
 {
 	unsigned long res, tmp;
 
-	if (s == NULL)
-		return 0;
-
-	asm volatile(
+	__asm__ __volatile__(
 	"       cmpnei  %1, 0           \n"
 	"       bf      3f              \n"
 	"1:     cmpnei  %0, 0           \n"
@@ -156,87 +238,11 @@  long strnlen_user(const char *s, long n)
 	"5:                             \n"
 	: "=r"(n), "=r"(s), "=r"(res), "=r"(tmp)
 	: "0"(n), "1"(s), "2"(n)
-	: "memory", "cc");
+	: "memory");
 
 	return res;
 }
-EXPORT_SYMBOL(strnlen_user);
-
-#define __do_clear_user(addr, size)			\
-do {							\
-	int __d0, zvalue, tmp;				\
-							\
-	asm volatile(					\
-	"0:     cmpnei  %1, 0           \n"		\
-	"       bf      7f              \n"		\
-	"       mov     %3, %1          \n"		\
-	"       andi    %3, 3           \n"		\
-	"       cmpnei  %3, 0           \n"		\
-	"       bf      1f              \n"		\
-	"       br      5f              \n"		\
-	"1:     cmplti  %0, 32          \n" /* 4W */	\
-	"       bt      3f              \n"		\
-	"8:     stw     %2, (%1, 0)     \n"		\
-	"10:    stw     %2, (%1, 4)     \n"		\
-	"11:    stw     %2, (%1, 8)     \n"		\
-	"12:    stw     %2, (%1, 12)    \n"		\
-	"13:    stw     %2, (%1, 16)    \n"		\
-	"14:    stw     %2, (%1, 20)    \n"		\
-	"15:    stw     %2, (%1, 24)    \n"		\
-	"16:    stw     %2, (%1, 28)    \n"		\
-	"       addi    %1, 32          \n"		\
-	"       subi    %0, 32          \n"		\
-	"       br      1b              \n"		\
-	"3:     cmplti  %0, 4           \n" /* 1W */	\
-	"       bt      5f              \n"		\
-	"4:     stw     %2, (%1, 0)     \n"		\
-	"       addi    %1, 4           \n"		\
-	"       subi    %0, 4           \n"		\
-	"       br      3b              \n"		\
-	"5:     cmpnei  %0, 0           \n" /* 1B */	\
-	"9:     bf      7f              \n"		\
-	"6:     stb     %2, (%1, 0)     \n"		\
-	"       addi    %1,  1          \n"		\
-	"       subi    %0,  1          \n"		\
-	"       br      5b              \n"		\
-	".section __ex_table,\"a\"      \n"		\
-	".align   2                     \n"		\
-	".long    8b, 9b                \n"		\
-	".long    10b, 9b               \n"		\
-	".long    11b, 9b               \n"		\
-	".long    12b, 9b               \n"		\
-	".long    13b, 9b               \n"		\
-	".long    14b, 9b               \n"		\
-	".long    15b, 9b               \n"		\
-	".long    16b, 9b               \n"		\
-	".long    4b, 9b                \n"		\
-	".long    6b, 9b                \n"		\
-	".previous                      \n"		\
-	"7:                             \n"		\
-	: "=r"(size), "=r" (__d0),			\
-	  "=r"(zvalue), "=r"(tmp)			\
-	: "0"(size), "1"(addr), "2"(0)			\
-	: "memory", "cc");				\
-} while (0)
-
-/*
- * clear_user: - Zero a block of memory in user space.
- * @to:   Destination address, in user space.
- * @n:    Number of bytes to zero.
- *
- * Zero a block of memory in user space.
- *
- * Returns number of bytes that could not be cleared.
- * On success, this will be zero.
- */
-unsigned long
-clear_user(void __user *to, unsigned long n)
-{
-	if (access_ok(to, n))
-		__do_clear_user(to, n);
-	return n;
-}
-EXPORT_SYMBOL(clear_user);
+EXPORT_SYMBOL(__strnlen_user);
 
 /*
  * __clear_user: - Zero a block of memory in user space, with less checking.
@@ -252,7 +258,59 @@  EXPORT_SYMBOL(clear_user);
 unsigned long
 __clear_user(void __user *to, unsigned long n)
 {
-	__do_clear_user(to, n);
+	int data, value, tmp;
+
+	__asm__ __volatile__(
+	"0:     cmpnei  %1, 0           \n"
+	"       bf      7f              \n"
+	"       mov     %3, %1          \n"
+	"       andi    %3, 3           \n"
+	"       cmpnei  %3, 0           \n"
+	"       bf      1f              \n"
+	"       br      5f              \n"
+	"1:     cmplti  %0, 32          \n" /* 4W */
+	"       bt      3f              \n"
+	"8:     stw     %2, (%1, 0)     \n"
+	"10:    stw     %2, (%1, 4)     \n"
+	"11:    stw     %2, (%1, 8)     \n"
+	"12:    stw     %2, (%1, 12)    \n"
+	"13:    stw     %2, (%1, 16)    \n"
+	"14:    stw     %2, (%1, 20)    \n"
+	"15:    stw     %2, (%1, 24)    \n"
+	"16:    stw     %2, (%1, 28)    \n"
+	"       addi    %1, 32          \n"
+	"       subi    %0, 32          \n"
+	"       br      1b              \n"
+	"3:     cmplti  %0, 4           \n" /* 1W */
+	"       bt      5f              \n"
+	"4:     stw     %2, (%1, 0)     \n"
+	"       addi    %1, 4           \n"
+	"       subi    %0, 4           \n"
+	"       br      3b              \n"
+	"5:     cmpnei  %0, 0           \n" /* 1B */
+	"9:     bf      7f              \n"
+	"6:     stb     %2, (%1, 0)     \n"
+	"       addi    %1,  1          \n"
+	"       subi    %0,  1          \n"
+	"       br      5b              \n"
+	".section __ex_table,\"a\"      \n"
+	".align   2                     \n"
+	".long    8b, 9b                \n"
+	".long    10b, 9b               \n"
+	".long    11b, 9b               \n"
+	".long    12b, 9b               \n"
+	".long    13b, 9b               \n"
+	".long    14b, 9b               \n"
+	".long    15b, 9b               \n"
+	".long    16b, 9b               \n"
+	".long    4b, 9b                \n"
+	".long    6b, 9b                \n"
+	".previous                      \n"
+	"7:                             \n"
+	: "=r"(n), "=r" (data), "=r"(value), "=r"(tmp)
+	: "0"(n), "1"(to), "2"(0)
+	: "memory");
+
 	return n;
 }
 EXPORT_SYMBOL(__clear_user);
diff --git a/arch/csky/mm/fault.c b/arch/csky/mm/fault.c
index 1482de5..466ad94 100644
--- a/arch/csky/mm/fault.c
+++ b/arch/csky/mm/fault.c
@@ -12,7 +12,7 @@  int fixup_exception(struct pt_regs *regs)
 
 	fixup = search_exception_tables(instruction_pointer(regs));
 	if (fixup) {
-		regs->pc = fixup->nextinsn;
+		regs->pc = fixup->fixup;
 
 		return 1;
 	}