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: 966f4406d9 ("[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
Commit a94e4f24ec ("MIPS: init: Drop boot_mem_map") introduced a
reference to a non-existant "end" field in struct memblock_region.
Replace it with a sum of the base & size fields to fix builds with
CONFIG_PROC_VMCORE=y.
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Commit a5718fe8f7 ("MIPS: mm: Drop boot_mem_map") removed the
definition of a page variable for some reason, but that variable is
still used. Restore it to fix compilation with CONFIG_HIGHMEM enabled.
Signed-off-by: Paul Burton <paul.burton@mips.com>
boot_mem_map was introduced very early and cannot handle memory maps
with nid. Nowadays, memblock can exactly replace boot_mem_map.
Detect pfn info and setup resources with memblock maps.
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
[paul.burton@mips.com: Fix size calculation in check_kernel_sections_mem]
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: yasha.che3@gmail.com
Cc: aurelien@aurel32.net
Cc: sfr@canb.auug.org.au
Cc: fancer.lancer@gmail.com
Cc: matt.redfearn@mips.com
Cc: chenhc@lemote.com
Initialize maar by resource map and replace page_is_ram
by memblock_is_memory.
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
[paul.burton@mips.com:
- Fix bad MAAR address calculations.
- Use ALIGN() & define maar_align to make it clearer what's going on
with address manipulations.
- Drop the new used field from struct maar_config.
- Rework the RAM walk to avoid iterating over the cfg array needlessly
to find the first unused entry, then count used entries at the end.
Instead just keep the count as we go.]
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: yasha.che3@gmail.com
Cc: aurelien@aurel32.net
Cc: sfr@canb.auug.org.au
Cc: fancer.lancer@gmail.com
Cc: matt.redfearn@mips.com
Cc: chenhc@lemote.com
While do COMPILE_TEST building, if GENERIC_IRQ_CHIP is
not selected, it fails:
drivers/irqchip/irq-ingenic-tcu.o: In function `ingenic_tcu_intc_cascade':
irq-ingenic-tcu.c:(.text+0x13f): undefined reference to `irq_get_domain_generic_chip'
drivers/irqchip/irq-ingenic-tcu.o: In function `ingenic_tcu_irq_init':
irq-ingenic-tcu.c:(.init.text+0x97): undefined reference to `irq_generic_chip_ops'
irq-ingenic-tcu.c:(.init.text+0xdd): undefined reference to `__irq_alloc_domain_generic_chips'
irq-ingenic-tcu.c:(.init.text+0x10b): undefined reference to `irq_get_domain_generic_chip'
select GENERIC_IRQ_CHIP to fix this.
Reported-by: Hulk Robot <hulkci@huawei.com>
Fixes: 9536eba03e ("irqchip: Add irq-ingenic-tcu driver")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: <jason@lakedaemon.net>
Cc: <maz@kernel.org>
Cc: <paul@crapouillou.net>
Cc: <malat@debian.org>
Cc: <linux-kernel@vger.kernel.org>
Cc: <linux-mips@vger.kernel.org>
Cc: <linux-clk@vger.kernel.org>
clang warns:
arch/mips/mm/tlbex.c:634:19: error: use of logical '&&' with constant
operand [-Werror,-Wconstant-logical-operand]
if (cpu_has_rixi && _PAGE_NO_EXEC) {
^ ~~~~~~~~~~~~~
arch/mips/mm/tlbex.c:634:19: note: use '&' for a bitwise operation
if (cpu_has_rixi && _PAGE_NO_EXEC) {
^~
&
arch/mips/mm/tlbex.c:634:19: note: remove constant to silence this
warning
if (cpu_has_rixi && _PAGE_NO_EXEC) {
~^~~~~~~~~~~~~~~~
1 error generated.
Explicitly cast this value to a boolean so that clang understands we
intend for this to be a non-zero value.
Fixes: 00bf1c691d ("MIPS: tlbex: Avoid placing software PTE bits in Entry* PFN fields")
Link: https://github.com/ClangBuiltLinux/linux/issues/609
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: clang-built-linux@googlegroups.com
clang warns:
arch/mips/include/asm/syscall.h:136:3: error: variable 'ret' is
uninitialized when used here [-Werror,-Wuninitialized]
ret |= mips_get_syscall_arg(args++, task, regs, i++);
^~~
arch/mips/include/asm/syscall.h:129:9: note: initialize the variable
'ret' to silence this warning
int ret;
^
= 0
1 error generated.
It's not wrong; however, it's not an issue in practice because ret is
only assigned to, not read from. ret could just be initialized to zero
but looking into it further, ret has been unused since it was first
added in 2012 so just get rid of it and update mips_get_syscall_arg's
return type since none of the return values are ever checked. If it is
ever needed again, this commit can be reverted and ret can be properly
initialized.
Fixes: c0ff3c53d4 ("MIPS: Enable HAVE_ARCH_TRACEHOOK.")
Link: https://github.com/ClangBuiltLinux/linux/issues/604
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: clang-built-linux@googlegroups.com
Merge the Ingenic TCU patchset from the ingenic-tcu-v5.4 branch which
was created to enable follow-on changes in other subsystems.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Add documentation about the Timer/Counter Unit (TCU) present in the
Ingenic JZ47xx SoCs.
The Timer/Counter Unit (TCU) in Ingenic JZ47xx SoCs is a multi-function
hardware block. It features up to to eight channels, that can be used as
counters, timers, or PWM.
- JZ4725B, JZ4750, JZ4755 only have six TCU channels. The other SoCs all
have eight channels.
- JZ4725B introduced a separate channel, called Operating System Timer
(OST). It is a 32-bit programmable timer. On JZ4770 and above, it is
64-bit.
- Each one of the TCU channels has its own clock, which can be reparented
to three different clocks (pclk, ext, rtc), gated, and reclocked, through
their TCSR register.
* The watchdog and OST hardware blocks also feature a TCSR register with
the same format in their register space.
* The TCU registers used to gate/ungate can also gate/ungate the watchdog
and OST clocks.
- Each TCU channel works in one of two modes:
* mode TCU1: channels cannot work in sleep mode, but are easier to
operate.
* mode TCU2: channels can work in sleep mode, but the operation is a bit
more complicated than with TCU1 channels.
- The mode of each TCU channel depends on the SoC used:
* On the oldest SoCs (up to JZ4740), all of the eight channels operate in
TCU1 mode.
* On JZ4725B, channel 5 operates as TCU2, the others operate as TCU1.
* On newest SoCs (JZ4750 and above), channels 1-2 operate as TCU2, the
others operate as TCU1.
- Each channel can generate an interrupt. Some channels share an interrupt
line, some don't, and this changes between SoC versions:
* on older SoCs (JZ4740 and below), channel 0 and channel 1 have their
own interrupt line; channels 2-7 share the last interrupt line.
* On JZ4725B, channel 0 has its own interrupt; channels 1-5 share one
interrupt line; the OST uses the last interrupt line.
* on newer SoCs (JZ4750 and above), channel 5 has its own interrupt;
channels 0-4 and (if eight channels) 6-7 all share one interrupt line;
the OST uses the last interrupt line.
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Tested-by: Mathieu Malaterre <malat@debian.org>
Tested-by: Artur Rojek <contact@artur-rojek.eu>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Cc: linux-mips@vger.kernel.org
Cc: linux-clk@vger.kernel.org
Cc: od@zcrc.me
The cpu_has_saa feature macro was added along with Cavium Octeon CPU
support back in commit 5b3b16880f ("MIPS: Add Cavium OCTEON processor
support files to arch/mips/cavium-octeon.") but has never been used.
Remove the dead code.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Move all the platform data to devicetree.
The only bit dropped is the PWM beeper, which requires the PWM driver
to be updated. I figured it's okay to remove it here since it's really
a non-critical device, and it'll be re-introduced soon enough.
The other change is the CS line of the SPI is now set as active low. The
SPI core would have forced "active low" anyway, unless the 'spi-cs-high'
property is set.
In the process of moving to devicetree, we also switched to new drivers:
- We use the simple-audio-card and simple-amplifier drivers instead of
the custom ASoC code;
- We use the new Ingenic DRM driver coupled with the GiantPlus GPM940B0
DRM panel driver instead of the old framebuffer driver;
- We use the new jz4780-dma driver instead of the old jz4740-dma one;
- We use the ingenic-nand and jz4740-ecc drivers instead of the old
jz4740-nand driver;
- We use ingenic-battery instead of jz4740-battery;
- We use iio-hwmon instead of jz4740-hwmon;
- We use ingenic-iio instead of the old jz4740-adc MFD driver.
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Tested-by: Artur Rojek <contact@artur-rojek.eu>
[paul.burton@mips.com:
Drop the unused & undocumented ili8960 spi@0 node.]
Signed-off-by: Paul Burton <paul.burton@mips.com>
