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| author |   Christophe Leroy <christophe.leroy@c-s.fr> | 2020-04-17 17:08:52 +0000 |
|---|---|---|
| committer |   Michael Ellerman <mpe@ellerman.id.au> | 2020-04-30 20:30:40 +1000 |
| commit | 17bc43367fc2a720400d21c745db641c654c1e6b (patch) | |
| tree | d3d03d7c6321de33147c211881dd76d9060c42dd | |
| parent | powerpc/uaccess: Implement unsafe_put_user() using 'asm goto' (diff) | |
| download | wireguard-linux-17bc43367fc2a720400d21c745db641c654c1e6b.tar.xz wireguard-linux-17bc43367fc2a720400d21c745db641c654c1e6b.zip | |
powerpc/uaccess: Implement unsafe_copy_to_user() as a simple loop
At the time being, unsafe_copy_to_user() is based on
raw_copy_to_user() which calls __copy_tofrom_user().
__copy_tofrom_user() is a big optimised function to copy big amount
of data. It aligns destinations to cache line in order to use
dcbz instruction.
Today unsafe_copy_to_user() is called only from filldir().
It is used to mainly copy small amount of data like filenames,
so __copy_tofrom_user() is not fit.
Also, unsafe_copy_to_user() is used within user_access_begin/end
sections. In those section, it is preferable to not call functions.
Rewrite unsafe_copy_to_user() as a macro that uses __put_user_goto().
We first perform a loop of long, then we finish with necessary
complements.
unsafe_copy_to_user() might be used in the near future to copy
fixed-size data, like pt_regs structs during signal processing.
Having it as a macro allows GCC to optimise it for instead when
it knows the size in advance, it can unloop loops, drop complements
when the size is a multiple of longs, etc ...
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/fe952112c29bf6a0a2778c9e6bbb4f4afd2c4258.1587143308.git.christophe.leroy@c-s.fr
| -rw-r--r-- | arch/powerpc/include/asm/uaccess.h | 21 |
1 files changed, 20 insertions, 1 deletions
diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h index 3f30a1dbc198..42b6c44e36a7 100644 --- a/arch/powerpc/include/asm/uaccess.h +++ b/arch/powerpc/include/asm/uaccess.h @@ -535,7 +535,26 @@ static __must_check inline bool user_access_begin(const void __user *ptr, size_t #define unsafe_op_wrap(op, err) do { if (unlikely(op)) goto err; } while (0) #define unsafe_get_user(x, p, e) unsafe_op_wrap(__get_user_allowed(x, p), e) #define unsafe_put_user(x, p, e) __put_user_goto(x, p, e) + #define unsafe_copy_to_user(d, s, l, e) \ - unsafe_op_wrap(raw_copy_to_user_allowed(d, s, l), e) +do { \ + u8 __user *_dst = (u8 __user *)(d); \ + const u8 *_src = (const u8 *)(s); \ + size_t _len = (l); \ + int _i; \ + \ + for (_i = 0; _i < (_len & ~(sizeof(long) - 1)); _i += sizeof(long)) \ + __put_user_goto(*(long*)(_src + _i), (long __user *)(_dst + _i), e);\ + if (IS_ENABLED(CONFIG_PPC64) && (_len & 4)) { \ + __put_user_goto(*(u32*)(_src + _i), (u32 __user *)(_dst + _i), e); \ + _i += 4; \ + } \ + if (_len & 2) { \ + __put_user_goto(*(u16*)(_src + _i), (u16 __user *)(_dst + _i), e); \ + _i += 2; \ + } \ + if (_len & 1) \ + __put_user_goto(*(u8*)(_src + _i), (u8 __user *)(_dst + _i), e);\ +} while (0) #endif /* _ARCH_POWERPC_UACCESS_H */ |