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Thomas Gleixner 2023963916 ARM: futex: Address build warning 
[ Upstream commit 8101b5a153 ]

Stephen reported the following build warning on a ARM multi_v7_defconfig
build with GCC 9.2.1:

kernel/futex.c: In function 'do_futex':
kernel/futex.c:1676:17: warning: 'oldval' may be used uninitialized in this function [-Wmaybe-uninitialized]
 1676 |   return oldval == cmparg;
      |          ~~~~~~~^~~~~~~~~
kernel/futex.c:1652:6: note: 'oldval' was declared here
 1652 |  int oldval, ret;
      |      ^~~~~~

introduced by commit a08971e948 ("futex: arch_futex_atomic_op_inuser()
calling conventions change").

While that change should not make any difference it confuses GCC which
fails to work out that oldval is not referenced when the return value is
not zero.

GCC fails to properly analyze arch_futex_atomic_op_inuser(). It's not the
early return, the issue is with the assembly macros. GCC fails to detect
that those either set 'ret' to 0 and set oldval or set 'ret' to -EFAULT
which makes oldval uninteresting. The store to the callsite supplied oldval
pointer is conditional on ret == 0.

The straight forward way to solve this is to make the store unconditional.

Aside of addressing the build warning this makes sense anyway because it
removes the conditional from the fastpath. In the error case the stored
value is uninteresting and the extra store does not matter at all.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/87pncao2ph.fsf@nanos.tec.linutronix.de
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-05-27 17:37:35 +02:00
..
hardware Merge branches 'fixes', 'misc', 'sa1111' and 'sa1100-for-next' into for-next 2018-01-21 15:38:10 +00:00
mach Merge branch 'x86-timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-08-13 18:28:19 -07:00
xen License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
arch_gicv3.h irqchip/gic-v3: Probe for SCR_EL3 being clear before resetting AP0Rn 2018-03-22 13:46:18 +00:00
arch_timer.h arm64 updates for 4.15 2017-11-15 10:56:56 -08:00
arm-cci.h arm-cci: Get rid of secure transactions for PMU driver 2015-03-27 13:44:35 +00:00
asm-offsets.h
assembler.h ARM: 8796/1: spectre-v1,v1.1: provide helpers for address sanitization 2019-02-20 10:25:37 +01:00
atomic.h atomics/treewide: Clean up '*_andnot()' ifdeffery 2018-06-21 14:25:24 +02:00
auxvec.h ARM: 8329/1: miscellaneous vdso infrastructure, preparation 2015-03-27 22:20:45 +00:00
barrier.h ARM: avoid Cortex-A9 livelock on tight dmb loops 2019-04-05 22:33:12 +02:00
bitops.h ARM: 8785/1: use compiler built-ins for ffs and fls 2018-07-30 11:45:53 +01:00
bitrev.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
bL_switcher.h
bug.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
bugs.h ARM: bugs: hook processor bug checking into SMP and suspend paths 2018-05-31 10:39:29 +01:00
cache.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
cacheflush.h docs: Fix some broken references 2018-06-15 18:10:01 -03:00
cachetype.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
checksum.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
clocksource.h arm/arm64: arch_timer: Use archdata to indicate vdso suitability 2016-09-23 17:19:25 +01:00
cmpxchg.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
compiler.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
cp15.h ARM: vdso: Remove dependency with the arch_timer driver internals 2019-05-31 06:46:11 -07:00
cpu.h
cpufeature.h ARM: 8663/1: wire up HWCAP/HWCAP2 feature bits to the CPU modalias 2017-03-30 19:45:52 +01:00
cpuidle.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
cputype.h ARM: split out processor lookup 2019-02-20 10:25:38 +01:00
cti.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
dcc.h ARM: tty: Move HVC DCC assembly to arch/arm 2014-05-28 13:33:18 -07:00
delay.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
device.h ARM: dma-mapping: Don't tear down third-party mappings 2017-05-30 11:31:33 +02:00
div64.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
dma-contiguous.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
dma-direct.h dma/direct: Handle the memory encryption bit in common code 2018-03-20 10:01:59 +01:00
dma-iommu.h kmemcheck: remove annotations 2017-11-15 18:21:04 -08:00
dma-mapping.h dma-direct: rename dma_noop to dma_direct 2018-01-15 09:35:06 +01:00
dma.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
dmi.h efi/arm: Enable DMI/SMBIOS 2017-06-05 17:50:44 +02:00
domain.h ARM: 8573/1: domain: move {set,get}_domain under config guard 2016-05-05 19:03:02 +01:00
ecard.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
edac.h EDAC: Cleanup atomic_scrub mess 2015-05-28 15:31:53 +02:00
efi.h efi: Deduplicate efi_open_volume() 2018-07-22 14:13:43 +02:00
elf.h Merge branch 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm 2017-11-16 12:50:35 -08:00
entry-macro-multi.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
exception.h ARM: probes: avoid adding kprobes to sensitive kernel-entry/exit code 2017-12-17 22:14:21 +00:00
fb.h
fiq.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
firmware.h ARM: EXYNOS: add exynos_get_boot_addr() helper 2015-06-06 02:17:56 +09:00
fixmap.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
flat.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
floppy.h ARM: 8584/1: floppy: avoid gcc-6 warning 2016-07-02 11:02:13 +01:00
fncpy.h
fpstate.h
ftrace.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
futex.h ARM: futex: Address build warning 2020-05-27 17:37:35 +02:00
glue-cache.h ARM: 8725/1: Add Broadcom Brahma-B15 readahead cache support 2017-12-17 22:15:35 +00:00
glue-df.h ARM: 8065/1: remove last use of CONFIG_CPU_ARM710 2014-05-30 01:12:30 +01:00
glue-pf.h
glue-proc.h ARM: 8103/1: save/restore Cortex-A9 CP15 registers on suspend/resume 2014-07-18 12:29:37 +01:00
glue.h
gpio.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
hardirq.h ARM: prevent tracing IPI_CPU_BACKTRACE 2019-06-15 11:54:00 +02:00
highmem.h Merge branch 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm 2017-11-16 12:50:35 -08:00
hugetlb-3level.h
hugetlb.h mm/hugetlb: remove arch_prepare/release_hugepage from arch headers 2015-06-25 17:00:35 -07:00
hw_breakpoint.h perf/hw_breakpoint: Remove default hw_breakpoint_arch_parse() 2018-06-26 09:07:58 +02:00
hw_irq.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
hwcap.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
hypervisor.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ide.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
idmap.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
insn.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
io.h ARM: Implement pci_remap_cfgspace() interface 2017-04-24 13:53:13 -05:00
irq_work.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
irq.h ARM: 8824/1: fix a migrating irq bug when hotplug cpu 2019-03-23 20:09:48 +01:00
irqflags.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
jump_label.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kbuild time: Add an asm-generic/compat.h file 2018-04-19 13:28:51 +02:00
kexec.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
kgdb.h ARM: 8764/1: kgdb: fix NUMREGBYTES so that gdb_regs[] is the correct size 2018-05-19 11:53:46 +01:00
kmap_types.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
kprobes.h ARM/kprobes: Remove jprobe arm implementation 2018-06-21 12:33:07 +02:00
kvm_arm.h arm: KVM: Fix VTTBR_BADDR_MASK BUG_ON off-by-one 2017-11-29 16:46:18 +01:00
kvm_asm.h Merge branches 'fixes', 'misc' and 'spectre' into for-linus 2018-06-05 10:03:27 +01:00
kvm_coproc.h KVM: arm: plug potential guest hardware debug leakage 2017-05-15 14:29:19 +02:00
kvm_emulate.h KVM: arm64: Only sign-extend MMIO up to register width 2020-02-11 04:33:58 -08:00
kvm_host.h arm/arm64: KVM: Allow a VCPU to fully reset itself 2019-03-23 20:09:43 +01:00
kvm_hyp.h KVM: arm/arm64: Avoid VGICv3 save/restore on VHE with no IRQs 2018-03-19 10:53:21 +00:00
kvm_mmio.h KVM: arm64: Only sign-extend MMIO up to register width 2020-02-11 04:33:58 -08:00
kvm_mmu.h KVM: arm/arm64: vgic-its: Take the srcu lock when writing to guest memory 2019-05-04 09:20:13 +02:00
limits.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
linkage.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mc146818rtc.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mcpm.h ARM: MCPM: remove residency argument from mcpm_cpu_suspend() 2015-05-06 11:47:10 -04:00
mcs_spinlock.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
memblock.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
memory.h linux/const.h: move UL() macro to include/linux/const.h 2018-04-11 10:28:38 -07:00
mmu_context.h sched/headers: Prepare to remove the <linux/mm_types.h> dependency from <linux/sched.h> 2017-03-02 08:42:37 +01:00
mmu.h Merge branch 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm 2017-11-16 12:50:35 -08:00
module.h ARM: module: fix modsign build error 2018-07-09 20:29:49 +02:00
mpu.h ARM: 8757/1: NOMMU: Support PMSAv8 MPU 2018-05-19 11:53:46 +01:00
mtd-xip.h
neon.h
nwflash.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
opcodes-sec.h
opcodes-virt.h
opcodes.h
outercache.h ARM: move heavy barrier support out of line 2015-07-25 15:28:05 +01:00
page-nommu.h ARM: 8684/1: NOMMU: Remove unused KTHREAD_SIZE definition 2017-06-27 14:58:10 +01:00
page.h
paravirt.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
patch.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
pci.h PCI: remove PCI_DMA_BUS_IS_PHYS 2018-05-07 07:15:41 +02:00
percpu.h ARM: 8174/1: Use global stack register variable for percpu 2014-11-13 23:58:06 +00:00
perf_event.h arm: perf: Fix callchain parse error with kernel tracepoint events 2015-05-27 16:12:05 +01:00
pgalloc.h kmemcheck: stop using GFP_NOTRACK and SLAB_NOTRACK 2017-11-15 18:21:04 -08:00
pgtable-2level-hwdef.h ARM: 8612/1: LPAE: initialize cache policy correctly 2016-09-12 12:12:30 +01:00
pgtable-2level-types.h
pgtable-2level.h mm: make the __PAGETABLE_PxD_FOLDED defines non-empty 2018-12-29 13:37:57 +01:00
pgtable-3level-hwdef.h ARM: 8612/1: LPAE: initialize cache policy correctly 2016-09-12 12:12:30 +01:00
pgtable-3level-types.h
pgtable-3level.h mm: introduce ARCH_HAS_PTE_SPECIAL 2018-06-07 17:34:35 -07:00
pgtable-hwdef.h
pgtable-nommu.h ARM: 8676/1: NOMMU: provide pgprot_device() macro 2017-06-05 10:29:40 +01:00
pgtable.h KVM: arm/arm64: Limit icache invalidation to prefetch aborts 2018-01-08 15:20:45 +01:00
probes.h ARM/kprobes: Remove jprobe arm implementation 2018-06-21 12:33:07 +02:00
proc-fns.h ARM: spectre-v2: per-CPU vtables to work around big.Little systems 2019-02-20 10:25:38 +01:00
processor.h ARM: avoid Cortex-A9 livelock on tight dmb loops 2019-04-05 22:33:12 +02:00
procinfo.h
prom.h of/fdt: move memreserve and dtb memory reservations into core 2014-04-30 00:59:17 -05:00
psci.h ARM: SoC cleanups for v4.5 2016-01-20 17:55:20 -08:00
ptdump.h ARM: 8737/1: mm: dump: add checking for writable and executable 2018-01-21 15:32:20 +00:00
ptrace.h linux/compiler.h: Split into compiler.h and compiler_types.h 2017-10-24 13:17:32 +02:00
sections.h ARM: probes: avoid adding kprobes to sensitive kernel-entry/exit code 2017-12-17 22:14:21 +00:00
secure_cntvoff.h ARM: smp: Add initialization of CNTVOFF 2018-05-08 14:50:42 +02:00
set_memory.h treewide: move set_memory_* functions away from cacheflush.h 2017-05-08 17:15:13 -07:00
setup.h ARM: 8495/1: ATAGS: move save_atags() to arch/arm/include/asm/setup.h 2016-01-04 11:26:00 +00:00
shmparam.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
signal.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
smp_plat.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
smp_scu.h ARM: SoC platform updates for 4.15 2017-11-16 14:05:12 -08:00
smp_twd.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
smp.h ARM: 8708/1: NOMMU: Rework MPU to be mostly done in C 2017-10-23 16:58:59 +01:00
sparsemem.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
spinlock_types.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
spinlock.h Merge branch 'linus' into locking/core, to resolve conflicts 2017-11-07 10:32:44 +01:00
stackprotector.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
stacktrace.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
stage2_pgtable.h kvm-arm: arm32: Introduce stage2 page table helpers 2016-04-21 14:57:26 +02:00
string.h ARM: 8745/1: get rid of __memzero() 2018-01-21 15:37:56 +00:00
suspend.h ARM: 8847/1: pm: fix HYP/SVC mode mismatch when MCPM is used 2020-01-27 14:50:28 +01:00
swab.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
switch_to.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
sync_bitops.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
syscall.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
system_info.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
system_misc.h ARM: spectre-v2: harden user aborts in kernel space 2018-05-31 10:40:32 +01:00
tcm.h
therm.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
thread_info.h ARM: 8791/1: vfp: use __copy_to_user() when saving VFP state 2019-02-20 10:25:36 +01:00
thread_notify.h
timex.h
tlb.h arm/asm/tlb.h: Fix build error implicit func declaration 2018-07-25 12:09:09 +02:00
tlbflush.h sched/headers: Prepare to remove the <linux/mm_types.h> dependency from <linux/sched.h> 2017-03-02 08:42:37 +01:00
tls.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
topology.h Merge branch 'pm-cpufreq' 2017-11-13 01:34:49 +01:00
traps.h ARM: probes: avoid adding kprobes to sensitive kernel-entry/exit code 2017-12-17 22:14:21 +00:00
trusted_foundations.h treewide: remove redundant #include <linux/kconfig.h> 2016-10-11 15:06:33 -07:00
uaccess.h ARM: 8813/1: Make aligned 2-byte getuser()/putuser() atomic on ARMv6+ 2019-12-13 08:51:10 +01:00
ucontext.h Merge branch 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm 2017-11-16 12:50:35 -08:00
unaligned.h ARM: 8715/1: add a private asm/unaligned.h 2017-10-24 10:33:23 +01:00
unified.h ARM: 8723/2: always assume the "unified" syntax for assembly code 2017-12-17 22:14:21 +00:00
unistd.h ARM: wire up new pkey syscalls 2016-10-19 10:18:47 +01:00
unwind.h
uprobes.h ARM: add uprobes support 2014-03-18 16:39:40 -04:00
user.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
v7m.h ARM: 8830/1: NOMMU: Toggle only bits in EXC_RETURN we are really care of 2019-04-05 22:33:12 +02:00
vdso_datapage.h ARM: 8329/1: miscellaneous vdso infrastructure, preparation 2015-03-27 22:20:45 +00:00
vdso.h ARM: 8748/1: mm: Define vdso_start, vdso_end as array 2018-03-24 14:27:49 +00:00
vfp.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
vfpmacros.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
vga.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
virt.h ARM: hyp-stub/KVM: Kill __hyp_get_vectors 2017-04-09 07:49:34 -07:00
word-at-a-time.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
xor.h