Revision d6bd8194e2867e85ac2de63486d3b83ccfae4e62 authored by Michael Ellerman on 26 June 2017, 01:30:57 UTC, committed by Michael Ellerman on 26 June 2017, 13:25:08 UTC
Larry Finger reported that his Powerbook G4 was no longer booting with v4.12-rc, userspace was up but giving weird errors such as: udevd[64]: starting version 175 udevd[64]: Unable to receive ctrl message: Bad address. modprobe: chdir(4.12-rc1): No such file or directory He bisected the problem to commit 3448890c32c3 ("powerpc: get rid of zeroing, switch to RAW_COPY_USER"). Al identified that the problem is actually a miscompilation by GCC 4.6.3, which is exposed by the above commit. Al also pointed out that inlining copy_to/from_user() is probably of little or no benefit, which is correct. Using Anton's copy_to_user benchmark, with a pathological single byte copy, we see a small increase in performance by *removing* inlining: Before (inlined): # time ./copy_to_user -w -l 1 -i 10000000 ( x 3 ) real 0m22.063s real 0m22.059s real 0m22.076s After: # time ./copy_to_user -w -l 1 -i 10000000 ( x 3 ) real 0m21.325s real 0m21.299s real 0m21.364s So as a small performance improvement and to avoid the miscompilation, drop inlining copy_to/from_user() on 32-bit. Fixes: 3448890c32c3 ("powerpc: get rid of zeroing, switch to RAW_COPY_USER") Reported-by: Larry Finger <Larry.Finger@lwfinger.net> Suggested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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File | Mode | Size |
---|---|---|
accessibility | ||
acpi | ||
amba | ||
android | ||
ata | ||
atm | ||
auxdisplay | ||
base | ||
bcma | ||
block | ||
bluetooth | ||
bus | ||
cdrom | ||
char | ||
clk | ||
clocksource | ||
connector | ||
cpufreq | ||
cpuidle | ||
crypto | ||
dax | ||
dca | ||
devfreq | ||
dio | ||
dma | ||
dma-buf | ||
edac | ||
eisa | ||
extcon | ||
firewire | ||
firmware | ||
fmc | ||
fpga | ||
fsi | ||
gpio | ||
gpu | ||
hid | ||
hsi | ||
hv | ||
hwmon | ||
hwspinlock | ||
hwtracing | ||
i2c | ||
ide | ||
idle | ||
iio | ||
infiniband | ||
input | ||
iommu | ||
ipack | ||
irqchip | ||
isdn | ||
leds | ||
lguest | ||
lightnvm | ||
macintosh | ||
mailbox | ||
mcb | ||
md | ||
media | ||
memory | ||
memstick | ||
message | ||
mfd | ||
misc | ||
mmc | ||
mtd | ||
net | ||
nfc | ||
ntb | ||
nubus | ||
nvdimm | ||
nvme | ||
nvmem | ||
of | ||
oprofile | ||
parisc | ||
parport | ||
pci | ||
pcmcia | ||
perf | ||
phy | ||
pinctrl | ||
platform | ||
pnp | ||
power | ||
powercap | ||
pps | ||
ps3 | ||
ptp | ||
pwm | ||
rapidio | ||
ras | ||
regulator | ||
remoteproc | ||
reset | ||
rpmsg | ||
rtc | ||
s390 | ||
sbus | ||
scsi | ||
sfi | ||
sh | ||
sn | ||
soc | ||
spi | ||
spmi | ||
ssb | ||
staging | ||
target | ||
tc | ||
tee | ||
thermal | ||
thunderbolt | ||
tty | ||
uio | ||
usb | ||
uwb | ||
vfio | ||
vhost | ||
video | ||
virt | ||
virtio | ||
vlynq | ||
vme | ||
w1 | ||
watchdog | ||
xen | ||
zorro | ||
Kconfig | -rw-r--r-- | 3.3 KB |
Makefile | -rw-r--r-- | 5.1 KB |
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