linux-toradex.git/arch/x86/lib/usercopy_32.c, branch v4.4.7

mm/uaccess, mm/fault: Clarify that uaccess may only sleep if pagefaults are enabled

2015-05-19T06:39:14+00:00

In general, non-atomic variants of user access functions must not sleep
if pagefaults are disabled.

Let's update all relevant comments in uaccess code. This also reflects
the might_sleep() checks in might_fault().

Reviewed-and-tested-by: Thomas Gleixner 
Signed-off-by: David Hildenbrand 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: David.Laight@ACULAB.COM
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: airlied@linux.ie
Cc: akpm@linux-foundation.org
Cc: benh@kernel.crashing.org
Cc: bigeasy@linutronix.de
Cc: borntraeger@de.ibm.com
Cc: daniel.vetter@intel.com
Cc: heiko.carstens@de.ibm.com
Cc: herbert@gondor.apana.org.au
Cc: hocko@suse.cz
Cc: hughd@google.com
Cc: mst@redhat.com
Cc: paulus@samba.org
Cc: ralf@linux-mips.org
Cc: schwidefsky@de.ibm.com
Cc: yang.shi@windriver.com
Link: http://lkml.kernel.org/r/1431359540-32227-4-git-send-email-dahi@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar

x86: Unify copy_to_user() and add size checking to it

2013-10-26T10:27:37+00:00

Similarly to copy_from_user(), where the range check is to
protect against kernel memory corruption, copy_to_user() can
benefit from such checking too: Here it protects against kernel
information leaks.

Signed-off-by: Jan Beulich 
Cc: 
Cc: Linus Torvalds 
Cc: Andrew Morton 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/5265059502000078000FC4F6@nat28.tlf.novell.com
Signed-off-by: Ingo Molnar 
Cc: Arjan van de Ven

x86: Unify copy_from_user() size checking

2013-10-26T10:27:36+00:00

Commits 4a3127693001c61a21d1ce680db6340623f52e93 ("x86: Turn the
copy_from_user check into an (optional) compile time warning")
and 63312b6a6faae3f2e5577f2b001e3b504f10a2aa ("x86: Add a
Kconfig option to turn the copy_from_user warnings into errors")
touched only the 32-bit variant of copy_from_user(), whereas the
original commit 9f0cf4adb6aa0bfccf675c938124e68f7f06349d ("x86:
Use __builtin_object_size() to validate the buffer size for
copy_from_user()") also added the same code to the 64-bit one.

Further the earlier conversion from an inline WARN() to the call
to copy_from_user_overflow() went a little too far: When the
number of bytes to be copied is not a constant (e.g. [looking at
3.11] in drivers/net/tun.c:__tun_chr_ioctl() or
drivers/pci/pcie/aer/aer_inject.c:aer_inject_write()), the
compiler will always have to keep the funtion call, and hence
there will always be a warning. By using __builtin_constant_p()
we can avoid this.

And then this slightly extends the effect of
CONFIG_DEBUG_STRICT_USER_COPY_CHECKS in that apart from
converting warnings to errors in the constant size case, it
retains the (possibly wrong) warnings in the non-constant size
case, such that if someone is prepared to get a few false
positives, (s)he'll be able to recover the current behavior
(except that these diagnostics now will never be converted to
errors).

Since the 32-bit variant (intentionally) didn't call
might_fault(), the unification results in this being called
twice now. Adding a suitable #ifdef would be the alternative if
that's a problem.

I'd like to point out though that with
__compiletime_object_size() being restricted to gcc before 4.6,
the whole construct is going to become more and more pointless
going forward. I would question however that commit
2fb0815c9ee6b9ac50e15dd8360ec76d9fa46a2 ("gcc4: disable
__compiletime_object_size for GCC 4.6+") was really necessary,
and instead this should have been dealt with as is done here
from the beginning.

Signed-off-by: Jan Beulich 
Cc: Arjan van de Ven 
Cc: Guenter Roeck 
Cc: Linus Torvalds 
Cc: Andrew Morton 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/5265056D02000078000FC4F3@nat28.tlf.novell.com
Signed-off-by: Ingo Molnar

Kconfig: consolidate CONFIG_DEBUG_STRICT_USER_COPY_CHECKS

2013-05-01T00:04:09+00:00

The help text for this config is duplicated across the x86, parisc, and
s390 Kconfig.debug files.  Arnd Bergman noted that the help text was
slightly misleading and should be fixed to state that enabling this
option isn't a problem when using pre 4.4 gcc.

To simplify the rewording, consolidate the text into lib/Kconfig.debug
and modify it there to be more explicit about when you should say N to
this config.

Also, make the text a bit more generic by stating that this option
enables compile time checks so we can cover architectures which emit
warnings vs.  ones which emit errors.  The details of how an
architecture decided to implement the checks isn't as important as the
concept of compile time checking of copy_from_user() calls.

While we're doing this, remove all the copy_from_user_overflow() code
that's duplicated many times and place it into lib/ so that any
architecture supporting this option can get the function for free.

Signed-off-by: Stephen Boyd 
Acked-by: Arnd Bergmann 
Acked-by: Ingo Molnar 
Acked-by: H. Peter Anvin 
Cc: Arjan van de Ven 
Acked-by: Helge Deller 
Cc: Heiko Carstens 
Cc: Stephen Rothwell 
Cc: Chris Metcalf 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

x86, 386 removal: Remove CONFIG_X86_WP_WORKS_OK

2012-11-29T21:23:03+00:00

All 486+ CPUs support WP in supervisor mode, so remove the fallback
386 support code.

Signed-off-by: H. Peter Anvin 
Link: http://lkml.kernel.org/r/1354132230-21854-7-git-send-email-hpa@linux.intel.com

x86, smap: Add STAC and CLAC instructions to control user space access

2012-09-21T19:45:27+00:00

When Supervisor Mode Access Prevention (SMAP) is enabled, access to
userspace from the kernel is controlled by the AC flag.  To make the
performance of manipulating that flag acceptable, there are two new
instructions, STAC and CLAC, to set and clear it.

This patch adds those instructions, via alternative(), when the SMAP
feature is enabled.  It also adds X86_EFLAGS_AC unconditionally to the
SYSCALL entry mask; there is simply no reason to make that one
conditional.

Signed-off-by: H. Peter Anvin 
Link: http://lkml.kernel.org/r/1348256595-29119-9-git-send-email-hpa@linux.intel.com

x86: use the new generic strnlen_user() function

2012-05-26T18:33:54+00:00

This throws away the old x86-specific functions in favor of the generic
optimized version.

Signed-off-by: Linus Torvalds

x86, extable: Remove open-coded exception table entries in arch/x86/lib/usercopy_32.c

2012-04-20T20:51:39+00:00

Remove open-coded exception table entries in arch/x86/lib/usercopy_32.c,
and replace them with _ASM_EXTABLE() macros; this will allow us to
change the format and type of the exception table entries.

Signed-off-by: H. Peter Anvin 
Cc: David Daney 
Link: http://lkml.kernel.org/r/CA%2B55aFyijf43qSu3N9nWHEBwaGbb7T2Oq9A=9EyR=Jtyqfq_cQ@mail.gmail.com

x86: merge 32/64-bit versions of 'strncpy_from_user()' and speed it up

2012-04-11T16:41:28+00:00

This merges the 32- and 64-bit versions of the x86 strncpy_from_user()
by just rewriting it in C rather than the ancient inline asm versions
that used lodsb/stosb and had been duplicated for (trivial) differences
between the 32-bit and 64-bit versions.

While doing that, it also speeds them up by doing the accesses a word at
a time.  Finally, the new routines also properly handle the case of
hitting the end of the address space, which we have never done correctly
before (fs/namei.c has a hack around it for that reason).

Despite all these improvements, it actually removes more lines than it
adds, due to the de-duplication.  Also, we no longer export (or define)
the legacy __strncpy_from_user() function (that was defined to not do
the user permission checks), since it's not actually used anywhere, and
the user address space checks are built in to the new code.

Other architecture maintainers have been notified that the old hack in
fs/namei.c will be going away in the 3.5 merge window, in case they
copied the x86 approach of being a bit cavalier about the end of the
address space.

Cc: linux-arch@vger.kernel.org
Cc: Ingo Molnar 
Cc: Peter Anvin" 
Signed-off-by: Linus Torvalds

x86: remove the second argument of k[un]map_atomic()

2012-03-20T13:48:15+00:00

Acked-by: Avi Kivity 
Acked-by: Herbert Xu 
Signed-off-by: Cong Wang