linux-stable.git/include/asm-generic/uaccess.h, branch linux-5.14.y

asm-generic: uaccess: 1-byte access is always aligned

2021-05-17T11:30:29+00:00

With the cleaned up version of asm-generic/unaligned.h,
there is a warning about the get_user/put_user helpers using
unaligned access for single-byte variables:

include/asm-generic/uaccess.h: In function ‘__get_user_fn’:
include/asm-generic/unaligned.h:13:15: warning: ‘packed’ attribute ignored for field of type ‘u8’ {aka ‘unsigned char’} [-Wattributes]
  const struct { type x __packed; } *__pptr = (typeof(__pptr))(ptr); \

Change these to use a direct pointer dereference to avoid the
warnings.

Signed-off-by: Arnd Bergmann

asm-generic: mark __{get,put}_user_fn as __always_inline

2020-10-27T15:13:09+00:00

Without the explicit __always_inline, some RISC-V configs place the
functions out of line, triggering the BUILD_BUG_ON checks in the
function.

Fixes: 11129e8ed4d9 ("riscv: use memcpy based uaccess for nommu again")
Reported-by: kernel test robot 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Arnd Bergmann

asm-generic: make the set_fs implementation optional

2020-10-04T17:27:02+00:00

Put all the set_fs related code under CONFIG_SET_FS so that
asm-generic/uaccess.h can be used for set_fs-less builds.

Signed-off-by: Christoph Hellwig 
Acked-by: Arnd Bergmann 
Signed-off-by: Palmer Dabbelt

asm-generic: add nommu implementations of __{get,put}_kernel_nofault

2020-10-04T17:26:57+00:00

Add native implementations of __{get,put}_kernel_nofault using
{get,put}_unaligned, just like the {get,put}_user implementations.

Signed-off-by: Christoph Hellwig 
Acked-by: Arnd Bergmann 
Signed-off-by: Palmer Dabbelt

asm-generic: improve the nommu {get,put}_user handling

2020-10-04T17:26:43+00:00

Instead of reusing raw_{copy,to}_from_user implement separate handlers
using {get,put}_unaligned.  This ensures unaligned access is handled
correctly, and avoid the need for the small constant size optimization
in raw_{copy,to}_from_user.

Signed-off-by: Christoph Hellwig 
Acked-by: Arnd Bergmann 
Signed-off-by: Palmer Dabbelt

uaccess: remove segment_eq

2020-08-12T17:57:58+00:00

segment_eq is only used to implement uaccess_kernel.  Just open code
uaccess_kernel in the arch uaccess headers and remove one layer of
indirection.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Andrew Morton 
Acked-by: Linus Torvalds 
Acked-by: Greentime Hu 
Acked-by: Geert Uytterhoeven 
Cc: Nick Hu 
Cc: Vincent Chen 
Cc: Paul Walmsley 
Cc: Palmer Dabbelt 
Link: http://lkml.kernel.org/r/20200710135706.537715-5-hch@lst.de
Signed-off-by: Linus Torvalds

asm-generic: optimize generic uaccess for 8-byte loads and stores

2019-04-23T19:51:41+00:00

On 64-bit architectures we can also use the direct load/store trick for
8-byte values.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Arnd Bergmann

asm-generic: provide entirely generic nommu uaccess

2019-04-23T19:51:40+00:00

Move the code to implement uaccess using memcpy or direct loads and
stores to asm-generic/uaccess.h and make it selectable kconfig option.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Arnd Bergmann

asm-generic: don't include from

2019-04-23T19:51:39+00:00

 is an odd x86 legacy that we shouldn't force on other
architectures.  arc used it to bring in mm_context_t, but we can do
that inside the arc code easily.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Arnd Bergmann

get rid of legacy 'get_ds()' function

2019-03-04T18:50:14+00:00

Every in-kernel use of this function defined it to KERNEL_DS (either as
an actual define, or as an inline function).  It's an entirely
historical artifact, and long long long ago used to actually read the
segment selector valueof '%ds' on x86.

Which in the kernel is always KERNEL_DS.

Inspired by a patch from Jann Horn that just did this for a very small
subset of users (the ones in fs/), along with Al who suggested a script.
I then just took it to the logical extreme and removed all the remaining
gunk.

Roughly scripted with

   git grep -l '(get_ds())' -- :^tools/ | xargs sed -i 's/(get_ds())/(KERNEL_DS)/'
   git grep -lw 'get_ds' -- :^tools/ | xargs sed -i '/^#define get_ds()/d'

plus manual fixups to remove a few unusual usage patterns, the couple of
inline function cases and to fix up a comment that had become stale.

The 'get_ds()' function remains in an x86 kvm selftest, since in user
space it actually does something relevant.

Inspired-by: Jann Horn 
Inspired-by: Al Viro 
Signed-off-by: Linus Torvalds