ARM: 9326/1: make <linux/uaccess.h> self-contained for ARM

When I compiled the following code for ARM, I encountered numerous
errors.

[Test Code]

#include <linux/compiler.h>
#include <linux/uaccess.h>

int foo(int *x, int __user *ptr)
{
return get_user(*x, ptr);
}

To fix the errors, make some asm headers self-contained:

1. In arch/arm/include/asm/domain.h, include <linux/thread_info.h>
for current_thread_info().

2. In arch/arm/include/asm/traps.h, remove unneeded __init, and
include <linux/linkage.h> for asmlinkage.

3. In arch/arm/include/asm/uaccess.h, include <linux/kernel.h> for
might_fault().

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

ARM: 9211/1: domain: drop modify_domain()

This function/macro isn't used anywhere in the kernel.
The only user was set_fs() and was deleted in the set_fs()
removal patch set.

Fixes: 8ac6f5d7f84b ("ARM: 9113/1: uaccess: remove set_fs() implementation")
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

ARM: 8908/1: add __always_inline to functions called from __get_user_check()

KernelCI reports that bcm2835_defconfig is no longer booting since
commit ac7c3e4ff401 ("compiler: enable CONFIG_OPTIMIZE_INLINING
forcibly") (https://lkml.org/lkml/2019/9/26/825).

I also received a regression report from Nicolas Saenz Julienne
(https://lkml.org/lkml/2019/9/27/263).

This problem has cropped up on bcm2835_defconfig because it enables
CONFIG_CC_OPTIMIZE_FOR_SIZE. The compiler tends to prefer not inlining
functions with -Os. I was able to reproduce it with other boards and
defconfig files by manually enabling CONFIG_CC_OPTIMIZE_FOR_SIZE.

The __get_user_check() specifically uses r0, r1, r2 registers.
So, uaccess_save_and_enable() and uaccess_restore() must be inlined.
Otherwise, those register assignments would be entirely dropped,
according to my analysis of the disassembly.

Prior to commit 9012d011660e ("compiler: allow all arches to enable
CONFIG_OPTIMIZE_INLINING"), the 'inline' marker was always enough for
inlining functions, except on x86.

Since that commit, all architectures can enable CONFIG_OPTIMIZE_INLINING.
So, __always_inline is now the only guaranteed way of forcible inlining.

I added __always_inline to 4 functions in the call-graph from the
__get_user_check() macro.

Fixes: 9012d011660e ("compiler: allow all arches to enable CONFIG_OPTIMIZE_INLINING")
Reported-by: "kernelci.org bot" <bot@kernelci.org>
Reported-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Tested-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500

Based on 2 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation #

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 4122 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

ARM: 8851/1: add TUSERCOND() macro for conditional postfix

Unified assembly syntax requires conditionals to be postfixes.
TUSER() currently only takes a single argument which then gets
appended t (with translation) on every instruction.

This fixes a build error when using LLVM's integrated assembler:
In file included from kernel/futex.c:72:
./arch/arm/include/asm/futex.h:116:3: error: invalid instruction, did you mean: strt?
"2: " TUSER(streq) " %3, [%4]n"
^
<inline asm>:5:4: note: instantiated into assembly here
2: streqt r2, [r4]
^~~~~~

Additionally, for GCC ".syntax unified" for inline assembly.
When compiling non-Thumb2 GCC always emits a ".syntax divided"
at the beginning of the inline assembly which makes the
assembler fail. Since GCC 5 there is the -masm-syntax-unified
GCC option which make GCC assume unified syntax asm and hence
emits ".syntax unified" even in ARM mode. However, the option
is broken since GCC version 6 (see GCC PR88648 [1]). Work
around by adding ".syntax unified" as part of the inline
assembly.

[0] https://gcc.gnu.org/onlinedocs/gcc/ARM-Options.html#index-masm-syntax-unified
[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88648

Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

ARM: 8573/1: domain: move {set,get}_domain under config guard

Recursive undefined instrcution falut is seen with R-class taking an
exception. The reson for that is __show_regs() tries to get domain
information, but domains is not available on !MMU cores, like R/M
class.

Fix it by puting {set,get}_domain functions under CONFIG_CPU_CP15_MMU
guard and providing stubs for the case where domains is not supported.

Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

ARM: domains: add memory dependencies to get_domain/set_domain

We need to have memory dependencies on get_domain/set_domain to avoid
the compiler over-optimising these inline assembly instructions.

Loads/stores must not be reordered across a set_domain(), so introduce
a compiler barrier for that assembly.

The value of get_domain() must not be cached across a set_domain(), but
we still want to allow the compiler to optimise it away. Introduce a
dependency on current_thread_info()->cpu_domain to avoid this; the new
memory clobber in set_domain() should therefore cause the compiler to
re-load this. The other advantage of using this is we should have its
address in the register set already, or very soon after at most call
sites.

Tested-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

ARM: software-based priviledged-no-access support

Provide a software-based implementation of the priviledged no access
support found in ARMv8.1.

Userspace pages are mapped using a different domain number from the
kernel and IO mappings. If we switch the user domain to "no access"
when we enter the kernel, we can prevent the kernel from touching
userspace.

However, the kernel needs to be able to access userspace via the
various user accessor functions. With the wrapping in the previous
patch, we can temporarily enable access when the kernel needs user
access, and re-disable it afterwards.

This allows us to trap non-intended accesses to userspace, eg, caused
by an inadvertent dereference of the LIST_POISON* values, which, with
appropriate user mappings setup, can be made to succeed. This in turn
can allow use-after-free bugs to be further exploited than would
otherwise be possible.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

ARM: domains: remove DOMAIN_TABLE

DOMAIN_TABLE is not used; in any case, it aliases to the kernel domain.
Remove this definition.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

ARM: domains: keep vectors in separate domain

Keep the machine vectors in its own domain to avoid software based
user access control from making the vector code inaccessible, and
thereby deadlocking the machine.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

ARM: domains: get rid of manager mode for user domain

Since we switched to early trap initialisation in 94e5a85b3be0
("ARM: earlier initialization of vectors page") we haven't been writing
directly to the vectors page, and so there's no need for this domain
to be in manager mode. Switch it to client mode.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

ARM: domains: move initial domain setting value to asm/domains.h

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

ARM: domains: provide domain_mask()

Provide a macro to generate the mask for a domain, rather than using
domain_val(, DOMAIN_MANAGER) which won't work when CPU_USE_DOMAINS
is turned off.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

ARM: domains: switch to keeping domain value in register

Rather than modifying both the domain access control register and our
per-thread copy, modify only the domain access control register, and
use the per-thread copy to save and restore the register over context
switches. We can also avoid the explicit initialisation of the
init thread_info structure.

This allows us to avoid needing to gain access to the thread information
at the uaccess control sites.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

ARM: fix set_domain() macro

Avoid polluting drivers with a set_domain() macro, which interferes with
structure member names:

drivers/net/wireless/ath/ath9k/dfs_pattern_detector.c:294:33: error: macro "set_domain" passed 2 arguments, but takes just 1

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Disintegrate asm/system.h for ARM

Disintegrate asm/system.h for ARM.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Russell King <linux@arm.linux.org.uk>
cc: linux-arm-kernel@lists.infradead.org

ARM: 7301/1: Rename the T() macro to TUSER() to avoid namespace conflicts

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>

ARM: 6384/1: Remove the domain switching on ARMv6k/v7 CPUs

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>

[ARM] move include/asm-arm to arch/arm/include/asm

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>