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068df05363
Previous to the change to distinguish read-write accesses, when CONFIG_KCSAN_ASSUME_PLAIN_WRITES_ATOMIC=y is set, KCSAN would consider the non-atomic bitops as atomic. We want to partially revert to this behaviour, but with one important distinction: report racing modifications, since lost bits due to non-atomicity are certainly possible. Given the operations here only modify a single bit, assuming non-atomicity of the writer is sufficient may be reasonable for certain usage (and follows the permissible nature of the "assume plain writes atomic" rule). In other words: 1. We want non-atomic read-modify-write races to be reported; this is accomplished by kcsan_check_read(), where any concurrent write (atomic or not) will generate a report. 2. We do not want to report races with marked readers, but -do- want to report races with unmarked readers; this is accomplished by the instrument_write() ("assume atomic write" with Kconfig option set). With the above rules, when KCSAN_ASSUME_PLAIN_WRITES_ATOMIC is selected, it is hoped that KCSAN's reporting behaviour is better aligned with current expected permissible usage for non-atomic bitops. Note that, a side-effect of not telling KCSAN that the accesses are read-writes, is that this information is not displayed in the access summary in the report. It is, however, visible in inline-expanded stack traces. For now, it does not make sense to introduce yet another special case to KCSAN's runtime, only to cater to the case here. Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Will Deacon <will@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Daniel Axtens <dja@axtens.net> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: <linux-arch@vger.kernel.org> Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> |
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.. | ||
bitops | ||
vdso | ||
asm-offsets.h | ||
asm-prototypes.h | ||
atomic-instrumented.h | ||
atomic-long.h | ||
atomic.h | ||
atomic64.h | ||
audit_change_attr.h | ||
audit_dir_write.h | ||
audit_read.h | ||
audit_signal.h | ||
audit_write.h | ||
barrier.h | ||
bitops.h | ||
bitsperlong.h | ||
bug.h | ||
bugs.h | ||
cache.h | ||
cacheflush.h | ||
checksum.h | ||
cmpxchg-local.h | ||
cmpxchg.h | ||
compat.h | ||
current.h | ||
delay.h | ||
device.h | ||
div64.h | ||
dma-contiguous.h | ||
dma-mapping.h | ||
dma.h | ||
early_ioremap.h | ||
emergency-restart.h | ||
error-injection.h | ||
exec.h | ||
export.h | ||
extable.h | ||
fb.h | ||
fixmap.h | ||
flat.h | ||
ftrace.h | ||
futex.h | ||
getorder.h | ||
gpio.h | ||
hardirq.h | ||
hugetlb.h | ||
hw_irq.h | ||
hyperv-tlfs.h | ||
ide_iops.h | ||
int-ll64.h | ||
io.h | ||
ioctl.h | ||
iomap.h | ||
irq.h | ||
irq_regs.h | ||
irq_work.h | ||
irqflags.h | ||
Kbuild | ||
kdebug.h | ||
kmap_types.h | ||
kprobes.h | ||
kvm_para.h | ||
kvm_types.h | ||
linkage.h | ||
local.h | ||
local64.h | ||
mcs_spinlock.h | ||
memory_model.h | ||
mm-arch-hooks.h | ||
mm_hooks.h | ||
mmiowb.h | ||
mmiowb_types.h | ||
mmu.h | ||
mmu_context.h | ||
module.h | ||
mshyperv.h | ||
msi.h | ||
page.h | ||
param.h | ||
parport.h | ||
pci.h | ||
pci_iomap.h | ||
percpu.h | ||
pgalloc.h | ||
pgtable-nop4d.h | ||
pgtable-nopmd.h | ||
pgtable-nopud.h | ||
pgtable_uffd.h | ||
preempt.h | ||
qrwlock.h | ||
qrwlock_types.h | ||
qspinlock.h | ||
qspinlock_types.h | ||
resource.h | ||
rwonce.h | ||
seccomp.h | ||
sections.h | ||
serial.h | ||
set_memory.h | ||
shmparam.h | ||
signal.h | ||
simd.h | ||
spinlock.h | ||
statfs.h | ||
string.h | ||
switch_to.h | ||
syscall.h | ||
syscalls.h | ||
termios-base.h | ||
termios.h | ||
timex.h | ||
tlb.h | ||
tlbflush.h | ||
topology.h | ||
trace_clock.h | ||
uaccess.h | ||
unaligned.h | ||
user.h | ||
vermagic.h | ||
vga.h | ||
vmlinux.lds.h | ||
vtime.h | ||
word-at-a-time.h | ||
xor.h |