#!/bin/bash
# udelay() test script
#
# Test is executed by writing and reading to /sys/kernel/debug/udelay_test
# and exercises a variety of delays to ensure that udelay() is delaying
# at least as long as requested (as compared to ktime).
#
# Copyright (C) 2014 Google, Inc.
#
# This software is licensed under the terms of the GNU General Public
# License version 2, as published by the Free Software Foundation, and
# may be copied, distributed, and modified under those terms.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
MODULE_NAME=udelay_test
UDELAY_PATH=/sys/kernel/debug/udelay_test
setup()
{
/sbin/modprobe -q $MODULE_NAME
tmp_file=`mktemp`
}
test_one()
{
delay=$1
echo $delay > $UDELAY_PATH
tee -a $tmp_file < $UDELAY_PATH
}
cleanup()
{
if [ -f $tmp_file ]; then
rm $tmp_file
fi
/sbin/modprobe -q -r $MODULE_NAME
}
trap cleanup EXIT
setup
# Delay for a variety of times.
# 1..200, 200..500 (by 10), 500..2000 (by 100)
for (( delay = 1; delay < 200; delay += 1 )); do
test_one $delay
done
for (( delay = 200; delay < 500; delay += 10 )); do
test_one $delay
done
for (( delay = 500; delay <= 2000; delay += 100 )); do
test_one $delay
done
# Search for failures
count=`grep -c FAIL $tmp_file`
if [ $? -eq "0" ]; then
echo "ERROR: $count delays failed to delay long enough"
retcode=1
fi
exit $retcode
cgit.cgi/linux/net-next.git/'>summaryrefslogtreecommitdiff
efi/fdt: Avoid FDT manipulation after ExitBootServices()
Some AArch64 UEFI implementations disable the MMU in ExitBootServices(),
after which unaligned accesses to RAM are no longer supported.
Commit:
abfb7b686a3e ("efi/libstub/arm*: Pass latest memory map to the kernel")
fixed an issue in the memory map handling of the stub FDT code, but
inadvertently created an issue with such firmware, by moving some
of the FDT manipulation to after the invocation of ExitBootServices().
Given that the stub's libfdt implementation uses the ordinary, accelerated
string functions, which rely on hardware handling of unaligned accesses,
manipulating the FDT with the MMU off may result in alignment faults.
So fix the situation by moving the update_fdt_memmap() call into the
callback function invoked by efi_exit_boot_services() right before it
calls the ExitBootServices() UEFI service (which is arguably a better
place for it anyway)
Note that disabling the MMU in ExitBootServices() is not compliant with
the UEFI spec, and carries great risk due to the fact that switching from
cached to uncached memory accesses halfway through compiler generated code
(i.e., involving a stack) can never be done in a way that is architecturally
safe.
Fixes: abfb7b686a3e ("efi/libstub/arm*: Pass latest memory map to the kernel")
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Riku Voipio <riku.voipio@linaro.org>
Cc: <stable@vger.kernel.org>
Cc: mark.rutland@arm.com
Cc: linux-efi@vger.kernel.org
Cc: matt@codeblueprint.co.uk
Cc: leif.lindholm@linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/1485971102-23330-2-git-send-email-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>