[ Upstream commit 12051b318bc3ce5b42d6d786191008284b067d83 ]
The code in question is modifying a variable declared const through
pointer manipulation. Such code is explicitly undefined behavior, and
is the lone issue preventing malta_defconfig from booting when built
with Clang:
If an attempt is made to modify an object defined with a const-qualified
type through use of an lvalue with non-const-qualified type, the
behavior is undefined.
LLVM is removing such assignments. A simple fix is to not declare
variables const that you plan on modifying. Limiting the scope would be
a better method of preventing unwanted writes to such a variable.
Further, the code in question mentions "compiler bugs" without any links
to bug reports, so it is difficult to know if the issue is resolved in
GCC. The patch was authored in 2006, which would have been GCC 4.0.3 or
4.1.1. The minimal supported version of GCC in the Linux kernel is
currently 4.6.
For what its worth, there was UB before the commit in question, it just
added a barrier and got lucky IRT codegen. I don't think there's any
actual compiler bugs related, just runtime bugs due to UB.
Link: https://github.com/ClangBuiltLinux/linux/issues/610
Fixes: 966f4406d903 ("[MIPS] Work around bad code generation for <asm/io.h>.")
Reported-by: Nathan Chancellor <natechancellor@gmail.com>
Debugged-by: Nathan Chancellor <natechancellor@gmail.com>
Suggested-by: Eli Friedman <efriedma@quicinc.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: ralf@linux-mips.org
Cc: jhogan@kernel.org
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Cc: Hassan Naveed <hnaveed@wavecomp.com>
Cc: Stephen Kitt <steve@sk2.org>
Cc: Serge Semin <fancer.lancer@gmail.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: clang-built-linux@googlegroups.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit bbcc5672b0063b0e9d65dc8787a4f09c3b5bb5cc upstream.
Declaring __current_thread_info as a global register variable has the
effect of preventing GCC from saving & restoring its value in cases
where the ABI would typically do so.
To quote GCC documentation:
> If the register is a call-saved register, call ABI is affected: the
> register will not be restored in function epilogue sequences after the
> variable has been assigned. Therefore, functions cannot safely return
> to callers that assume standard ABI.
When our position independent VDSO is built for the n32 or n64 ABIs all
functions it exposes should be preserving the value of $gp/$28 for their
caller, but in the presence of the __current_thread_info global register
variable GCC stops doing so & simply clobbers $gp/$28 when calculating
the address of the GOT.
In cases where the VDSO returns success this problem will typically be
masked by the caller in libc returning & restoring $gp/$28 itself, but
that is by no means guaranteed. In cases where the VDSO returns an error
libc will typically contain a fallback path which will now fail
(typically with a bad memory access) if it attempts anything which
relies upon the value of $gp/$28 - eg. accessing anything via the GOT.
One fix for this would be to move the declaration of
__current_thread_info inside the current_thread_info() function,
demoting it from global register variable to local register variable &
avoiding inadvertently creating a non-standard calling ABI for the VDSO.
Unfortunately this causes issues for clang, which doesn't support local
register variables as pointed out by commit fe92da0f355e ("MIPS: Changed
current_thread_info() to an equivalent supported by both clang and GCC")
which introduced the global register variable before we had a VDSO to
worry about.
Instead, fix this by continuing to use the global register variable for
the kernel proper but declare __current_thread_info as a simple extern
variable when building the VDSO. It should never be referenced, and will
cause a link error if it is. This resolves the calling convention issue
for the VDSO without having any impact upon the build of the kernel
itself for either clang or gcc.
Signed-off-by: Paul Burton <paulburton@kernel.org>
Fixes: ebb5e78cc634 ("MIPS: Initial implementation of a VDSO")
Reported-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com>
Tested-by: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christian Brauner <christian.brauner@canonical.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: <stable@vger.kernel.org> # v4.4+
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 1c6121c39677175bd372076020948e184bad4b6b ]
cn58xx is compatible with cn50xx, so use the latter.
Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
[paul.burton@mips.com: s/cn52xx/cn50xx/ in commit message.]
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@vger.kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit a6da4d6fdf8bd512c98d3ac7f1d16bc4bb282919 ]
We can rely on the system kernel and the dump capture kernel themselves in
memory usage.
Being restrictive with 512MB limit may cause kexec tool failure on some
platforms.
Tested-by: Rachel Mozes <rachel.mozes@intel.com>
Reported-by: Rachel Mozes <rachel.mozes@intel.com>
Signed-off-by: Dengcheng Zhu <dzhu@wavecomp.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/20568/
Cc: pburton@wavecomp.com
Cc: ralf@linux-mips.org
Cc: linux-mips@linux-mips.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit e4f5cb1a9b27c0f94ef4f5a0178a3fde2d3d0e9e ]
The vectors span more than one byte, so mark them as arrays.
Fixes the following build error when building when using GCC 8.3:
In file included from ./include/linux/string.h:19,
from ./include/linux/bitmap.h:9,
from ./include/linux/cpumask.h:12,
from ./arch/mips/include/asm/processor.h:15,
from ./arch/mips/include/asm/thread_info.h:16,
from ./include/linux/thread_info.h:38,
from ./include/asm-generic/preempt.h:5,
from ./arch/mips/include/generated/asm/preempt.h:1,
from ./include/linux/preempt.h:81,
from ./include/linux/spinlock.h:51,
from ./include/linux/mmzone.h:8,
from ./include/linux/bootmem.h:8,
from arch/mips/bcm63xx/prom.c:10:
arch/mips/bcm63xx/prom.c: In function 'prom_init':
./arch/mips/include/asm/string.h:162:11: error: '__builtin_memcpy' forming offset [2, 32] is out of the bounds [0, 1] of object 'bmips_smp_movevec' with type 'char' [-Werror=array-bounds]
__ret = __builtin_memcpy((dst), (src), __len); \
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
arch/mips/bcm63xx/prom.c:97:3: note: in expansion of macro 'memcpy'
memcpy((void *)0xa0000200, &bmips_smp_movevec, 0x20);
^~~~~~
In file included from arch/mips/bcm63xx/prom.c:14:
./arch/mips/include/asm/bmips.h:80:13: note: 'bmips_smp_movevec' declared here
extern char bmips_smp_movevec;
Fixes: 18a1eef92dcd ("MIPS: BMIPS: Introduce bmips.h")
Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Paul Burton <paulburton@kernel.org>
Cc: linux-mips@vger.kernel.org
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 02eec6c9fc0cb13169cc97a6139771768791f92b upstream.
In nlm_fmn_send() we have a loop which attempts to send a message
multiple times in order to handle the transient failure condition of a
lack of available credit. When examining the status register to detect
the failure we check for a condition that can never be true, which falls
foul of gcc 8's -Wtautological-compare:
In file included from arch/mips/netlogic/common/irq.c:65:
./arch/mips/include/asm/netlogic/xlr/fmn.h: In function 'nlm_fmn_send':
./arch/mips/include/asm/netlogic/xlr/fmn.h:304:22: error: bitwise
comparison always evaluates to false [-Werror=tautological-compare]
if ((status & 0x2) == 1)
^~
If the path taken if this condition were true all we do is print a
message to the kernel console. Since failures seem somewhat expected
here (making the console message questionable anyway) and the condition
has clearly never evaluated true we simply remove it, rather than
attempting to fix it to check status correctly.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/20174/
Cc: Ganesan Ramalingam <ganesanr@broadcom.com>
Cc: James Hogan <jhogan@kernel.org>
Cc: Jayachandran C <jnair@caviumnetworks.com>
Cc: John Crispin <john@phrozen.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 351fdddd366245c0fb4636f32edfb4198c8d6b8c upstream.
VDSO code should not be using smp_processor_id(), since it is executed
in user mode.
Introduce a VDSO-specific path which will cause a compile-time
or link-time error (depending upon support for __compiletime_error) if
the VDSO ever incorrectly attempts to use smp_processor_id().
[Matt Redfearn <matt.redfearn@imgtec.com>: Move before change to
smp_processor_id in series]
Signed-off-by: Paul Burton <paul.burton@mips.com>
Signed-off-by: Matt Redfearn <matt.redfearn@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/17932/
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@linux-mips.org
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit db13a5ba2732755cf13320f3987b77cf2a71e790 ]
While trying to get the uart with parity working I found setting even
parity enabled odd parity insted. Fix the register settings to match
the datasheet of AR9331.
A similar patch was created by 8devices, but not sent upstream.
77c5586ade
Signed-off-by: Stefan Hellermann <stefan@the2masters.de>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 1287533d3d95d5ad8b02773733044500b1be06bc upstream.
When building BPF code using "clang -target bpf -c", clang does not
define __linux__.
To build BPF IR decoders the include linux/lirc.h is needed which
includes linux/types.h. Currently this workaround is needed:
https://git.linuxtv.org/v4l-utils.git/commit/?id=dd3ff81f58c4e1e6f33765dc61ad33c48ae6bb07
This check might otherwise be useful to stop users from using a non-linux
compiler, but if you're doing that you are going to have a lot more
trouble anyway.
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/21149/
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Cc: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 906d441febc0de974b2a6ef848a8f058f3bfada3 ]
Some versions of GCC for the MIPS architecture suffer from a bug which
can lead to instructions from beyond an unreachable statement being
incorrectly reordered into earlier branch delay slots if the unreachable
statement is the only content of a case in a switch statement. This can
lead to seemingly random behaviour, such as invalid memory accesses from
incorrectly reordered loads or stores, and link failures on microMIPS
builds.
See this potential GCC fix for details:
https://gcc.gnu.org/ml/gcc-patches/2015-09/msg00360.html
Runtime problems resulting from this bug were initially observed using a
maltasmvp_defconfig v4.4 kernel built using GCC 4.9.2 (from a Codescape
SDK 2015.06-05 toolchain), with the result being an address exception
taken after log messages about the L1 caches (during probe of the L2
cache):
Initmem setup node 0 [mem 0x0000000080000000-0x000000009fffffff]
VPE topology {2,2} total 4
Primary instruction cache 64kB, VIPT, 4-way, linesize 32 bytes.
Primary data cache 64kB, 4-way, PIPT, no aliases, linesize 32 bytes
<AdEL exception here>
This is early enough that the kernel exception vectors are not in use,
so any further output depends upon the bootloader. This is reproducible
in QEMU where no further output occurs - ie. the system hangs here.
Given the nature of the bug it may potentially be hit with differing
symptoms. The bug is known to affect GCC versions as recent as 7.3, and
it is unclear whether GCC 8 fixed it or just happens not to encounter
the bug in the testcase found at the link above due to differing
optimizations.
This bug can be worked around by placing a volatile asm statement, which
GCC is prevented from reordering past, prior to the
__builtin_unreachable call.
That was actually done already for other reasons by commit 173a3efd3edb
("bug.h: work around GCC PR82365 in BUG()"), but creates problems for
microMIPS builds due to the lack of a .insn directive. The microMIPS ISA
allows for interlinking with regular MIPS32 code by repurposing bit 0 of
the program counter as an ISA mode bit. To switch modes one changes the
value of this bit in the PC. However typical branch instructions encode
their offsets as multiples of 2-byte instruction halfwords, which means
they cannot change ISA mode - this must be done using either an indirect
branch (a jump-register in MIPS terminology) or a dedicated jalx
instruction. In order to ensure that regular branches don't attempt to
target code in a different ISA which they can't actually switch to, the
linker will check that branch targets are code in the same ISA as the
branch.
Unfortunately our empty asm volatile statements don't qualify as code,
and the link for microMIPS builds fails with errors such as:
arch/mips/mm/dma-default.s:3265: Error: branch to a symbol in another ISA mode
arch/mips/mm/dma-default.s:5027: Error: branch to a symbol in another ISA mode
Resolve this by adding a .insn directive within the asm statement which
declares that what comes next is code. This may or may not be true,
since we don't really know what comes next, but as this code is in an
unreachable path anyway that doesn't matter since we won't execute it.
We do this in asm/compiler.h & select CONFIG_HAVE_ARCH_COMPILER_H in
order to have this included by linux/compiler_types.h after
linux/compiler-gcc.h. This will result in asm/compiler.h being included
in all C compilations via the -include linux/compiler_types.h argument
in c_flags, which should be harmless.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Fixes: 173a3efd3edb ("bug.h: work around GCC PR82365 in BUG()")
Patchwork: https://patchwork.linux-mips.org/patch/20270/
Cc: James Hogan <jhogan@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: linux-mips@linux-mips.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 47c25036b60f27b86ab44b66a8861bcf81cde39b upstream.
Insert Branch instruction instead of NOP to make sure assembler don't
patch code in forbidden slot. In jump label function, it might
be possible to patch Control Transfer Instructions(CTIs) into
forbidden slot, which will generate Reserved Instruction exception
in MIPS release 6.
Signed-off-by: Archer Yan <ayan@wavecomp.com>
Reviewed-by: Paul Burton <paul.burton@mips.com>
[paul.burton@mips.com:
- Add MIPS prefix to subject.
- Mark for stable from v4.0, which introduced r6 support, onwards.]
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: stable@vger.kernel.org # v4.0+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
