getuser() and putuser() (and there underscored variants) use two
strb[t]/ldrb[t] instructions when they are asked to get/put 16-bits.
This means that the read/write is not atomic even when performed to a
16-bit-aligned address.
This leads to problems with vhost: vhost uses __getuser() to read the
vring's 16-bit avail.index field, and if it happens to observe a partial
update of the index, wrong descriptors will be used which will lead to a
breakdown of the virtio communication. A similar problem exists for
__putuser() which is used to write to the vring's used.index field.
The reason these functions use strb[t]/ldrb[t] is because strht/ldrht
instructions did not exist until ARMv6T2/ARMv7. So we should be easily
able to fix this on ARMv7. Also, since all ARMv6 processors also don't
actually use the unprivileged instructions anymore for uaccess (since
CONFIG_CPU_USE_DOMAINS is not used) we can easily fix them too.
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Since do_undefinstr() uses get_user to get the undefined
instruction, it can be called before kprobes processes
recursive check. This can cause an infinit recursive
exception.
Prohibit probing on get_user functions.
Fixes: 24ba613c9d ("ARM kprobes: core code")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
The 64-bit get_user() wasn't clearing the high word due to a typo in the
error handler. The exception handler entry was already correct, though.
Noticed during recent usercopy test additions in lib/test_user_copy.c.
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: stable@vger.kernel.org
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
This reverts commit 4dd1837d75.
Moving the exports for assembly code into the assembly files breaks
KSYM trimming, but also breaks modversions.
While fixing the KSYM trimming is trivial, fixing modversions brings
us to a technically worse position that we had prior to the above
change:
- We end up with the prototype definitions divorsed from everything
else, which means that adding or removing assembly level ksyms
become more fragile:
* if adding a new assembly ksyms export, a missed prototype in
asm-prototypes.h results in a successful build if no module in
the selected configuration makes use of the symbol.
* when removing a ksyms export, asm-prototypes.h will get forgotten,
with armksyms.c, you'll get a build error if you forget to touch
the file.
- We end up with the same amount of include files and prototypes,
they're just in a header file instead of a .c file with their
exports.
As for lines of code, we don't get much of a size reduction:
(original commit)
47 files changed, 131 insertions(+), 208 deletions(-)
(fix for ksyms trimming)
7 files changed, 18 insertions(+), 5 deletions(-)
(two fixes for modversions)
1 file changed, 34 insertions(+)
3 files changed, 7 insertions(+), 2 deletions(-)
which results in a net total of only 25 lines deleted.
As there does not seem to be much benefit from this change of approach,
revert the change.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
e38361d 'ARM: 8091/2: add get_user() support for 8 byte types' commit
broke V7 BE get_user call when target var size is 64 bit, but '*ptr' size
is 32 bit or smaller. e38361d changed type of __r2 from 'register
unsigned long' to 'register typeof(x) __r2 asm("r2")' i.e before the change
even when target variable size was 64 bit, __r2 was still 32 bit.
But after e38361d commit, for target var of 64 bit size, __r2 became 64
bit and now it should occupy 2 registers r2, and r3. The issue in BE case
that r3 register is least significant word of __r2 and r2 register is most
significant word of __r2. But __get_user_4 still copies result into r2 (most
significant word of __r2). Subsequent code copies from __r2 into x, but
for situation described it will pick up only garbage from r3 register.
Special __get_user_64t_(124) functions are introduced. They are similar to
corresponding __get_user_(124) function but result stored in r3 register
(lsw in case of 64 bit __r2 in BE image). Those function are used by
get_user macro in case of BE and target var size is 64bit.
Also changed __get_user_lo8 name into __get_user_32t_8 to get consistent
naming accross all cases.
Signed-off-by: Victor Kamensky <victor.kamensky@linaro.org>
Suggested-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Recent contributions, including to DRM and binder, introduce 64-bit
values in their interfaces. A common motivation for this is to allow
the same ABI for 32- and 64-bit userspaces (and therefore also a shared
ABI for 32/64 hybrid userspaces). Anyhow, the developers would like to
avoid gotchas like having to use copy_from_user().
This feature is already implemented on x86-32 and the majority of other
32-bit architectures. The current list of get_user_8 hold out
architectures are: arm, avr32, blackfin, m32r, metag, microblaze,
mn10300, sh.
Credit:
My name sits rather uneasily at the top of this patch. The v1 and
v2 versions of the patch were written by Rob Clark and to produce v4
I mostly copied code from Russell King and H. Peter Anvin. However I
have mangled the patch sufficiently that *blame* is rightfully mine
even if credit should more widely shared.
Changelog:
v5: updated to use the ret macro (requested by Russell King)
v4: remove an inlined add on big endian systems (spotted by Russell King),
used __ARMEB__ rather than BIG_ENDIAN (to match rest of file),
cleared r3 on EFAULT during __get_user_8.
v3: fix a couple of checkpatch issues
v2: pass correct size to check_uaccess, and better handling of narrowing
double word read with __get_user_xb() (Russell King's suggestion)
v1: original
Signed-off-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
ARMv6 and greater introduced a new instruction ("bx") which can be used
to return from function calls. Recent CPUs perform better when the
"bx lr" instruction is used rather than the "mov pc, lr" instruction,
and this sequence is strongly recommended to be used by the ARM
architecture manual (section A.4.1.1).
We provide a new macro "ret" with all its variants for the condition
code which will resolve to the appropriate instruction.
Rather than doing this piecemeal, and miss some instances, change all
the "mov pc" instances to use the new macro, with the exception of
the "movs" instruction and the kprobes code. This allows us to detect
the "mov pc, lr" case and fix it up - and also gives us the possibility
of deploying this for other registers depending on the CPU selection.
Reported-by: Will Deacon <will.deacon@arm.com>
Tested-by: Stephen Warren <swarren@nvidia.com> # Tegra Jetson TK1
Tested-by: Robert Jarzmik <robert.jarzmik@free.fr> # mioa701_bootresume.S
Tested-by: Andrew Lunn <andrew@lunn.ch> # Kirkwood
Tested-by: Shawn Guo <shawn.guo@freescale.com>
Tested-by: Tony Lindgren <tony@atomide.com> # OMAPs
Tested-by: Gregory CLEMENT <gregory.clement@free-electrons.com> # Armada XP, 375, 385
Acked-by: Sekhar Nori <nsekhar@ti.com> # DaVinci
Acked-by: Christoffer Dall <christoffer.dall@linaro.org> # kvm/hyp
Acked-by: Haojian Zhuang <haojian.zhuang@gmail.com> # PXA3xx
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> # Xen
Tested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> # ARMv7M
Tested-by: Simon Horman <horms+renesas@verge.net.au> # Shmobile
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The {get,put}_user macros don't perform range checking on the provided
__user address when !CPU_HAS_DOMAINS.
This patch reworks the out-of-line assembly accessors to check the user
address against a specified limit, returning -EFAULT if is is out of
range.
[will: changed get_user register allocation to match put_user]
[rmk: fixed building on older ARM architectures]
Reported-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: stable@vger.kernel.org
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This macro is used to generate unprivileged accesses (LDRT/STRT) to user
space.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This patch removes the domain switching functionality via the set_fs and
__switch_to functions on cores that have a TLS register.
Currently, the ioremap and vmalloc areas share the same level 1 page
tables and therefore have the same domain (DOMAIN_KERNEL). When the
kernel domain is modified from Client to Manager (via the __set_fs or in
the __switch_to function), the XN (eXecute Never) bit is overridden and
newer CPUs can speculatively prefetch the ioremap'ed memory.
Linux performs the kernel domain switching to allow user-specific
functions (copy_to/from_user, get/put_user etc.) to access kernel
memory. In order for these functions to work with the kernel domain set
to Client, the patch modifies the LDRT/STRT and related instructions to
the LDR/STR ones.
The user pages access rights are also modified for kernel read-only
access rather than read/write so that the copy-on-write mechanism still
works. CPU_USE_DOMAINS gets disabled only if the hardware has a TLS register
(CPU_32v6K is defined) since writing the TLS value to the high vectors page
isn't possible.
The user addresses passed to the kernel are checked by the access_ok()
function so that they do not point to the kernel space.
Tested-by: Anton Vorontsov <cbouatmailru@gmail.com>
Cc: Tony Lindgren <tony@atomide.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
/tmp/ccJ3ssZW.s: Assembler messages:
/tmp/ccJ3ssZW.s:1952: Error: can't resolve `.text' {.text section} - `.LFB1077'
This is caused because:
.section .data
.section .text
.section .text
.previous
does not return us to the .text section, but the .data section; this
makes use of .previous dangerous if the ordering of previous sections
is not known.
Fix up the other users of .previous; .pushsection and .popsection are
a safer pairing to use than .section and .previous.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This declaration specifies the "function" type and size for various
assembly functions, mainly needed for generating the correct branch
instructions in Thumb-2.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Move platform independent header files to arch/arm/include/asm, leaving
those in asm/arch* and asm/plat* alone.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Unfortunately, later gcc versions error out when our get_user is passed
a const pointer, since we write to a temporary variable declared as
typeof(*(p)) which propagates the const-ness.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
