arm64 has a feature called Top Byte Ignore, which allows to embed pointer
tags into the top byte of each pointer. Userspace programs (such as
HWASan, a memory debugging tool [1]) might use this feature and pass
tagged user pointers to the kernel through syscalls or other interfaces.
Right now the kernel is already able to handle user faults with tagged
pointers, due to these patches:
1. 81cddd65 ("arm64: traps: fix userspace cache maintenance emulation on a
tagged pointer")
2. 7dcd9dd8 ("arm64: hw_breakpoint: fix watchpoint matching for tagged
pointers")
3. 276e9327 ("arm64: entry: improve data abort handling of tagged
pointers")
When passing tagged pointers to syscalls, there's a special case of such a
pointer being passed to one of the memory syscalls (mmap, mprotect, etc.).
These syscalls don't do memory accesses but rather deal with memory
ranges, hence an untagged pointer is better suited.
This patchset extends tagged pointer support to non-memory syscalls. This
is done by reusing the untagged_addr macro to untag user pointers when the
kernel performs pointer checking to find out whether the pointer comes
from userspace (most notably in access_ok). The untagging is done only
when the pointer is being checked, the tag is preserved as the pointer
makes its way through the kernel.
One of the alternative approaches to untagging that was considered is to
completely strip the pointer tag as the pointer enters the kernel with
some kind of a syscall wrapper, but that won't work with the countless
number of different ioctl calls. With this approach we would need a custom
wrapper for each ioctl variation, which doesn't seem practical.
The following testing approaches has been taken to find potential issues
with user pointer untagging:
1. Static testing (with sparse [2] and separately with a custom static
analyzer based on Clang) to track casts of __user pointers to integer
types to find places where untagging needs to be done.
2. Dynamic testing: adding BUG_ON(has_tag(addr)) to find_vma() and running
a modified syzkaller version that passes tagged pointers to the kernel.
Based on the results of the testing the requried patches have been added
to the patchset.
This patchset has been merged into the Pixel 2 kernel tree and is now
being used to enable testing of Pixel 2 phones with HWASan.
This patchset is a prerequisite for ARM's memory tagging hardware feature
support [3].
Thanks!
[1] http://clang.llvm.org/docs/HardwareAssistedAddressSanitizerDesign.html
[2] https://github.com/lucvoo/sparse-dev/commit/5f960cb10f56ec2017c128ef9d16060…
[3] https://community.arm.com/processors/b/blog/posts/arm-a-profile-architectur…
Changes in v9:
- Rebased onto 4.20-rc6.
- Used u64 instead of __u64 in type casts in the untagged_addr macro for
arm64.
- Added braces around (addr) in the untagged_addr macro for other arches.
Changes in v8:
- Rebased onto 65102238 (4.20-rc1).
- Added a note to the cover letter on why syscall wrappers/shims that untag
user pointers won't work.
- Added a note to the cover letter that this patchset has been merged into
the Pixel 2 kernel tree.
- Documentation fixes, in particular added a list of syscalls that don't
support tagged user pointers.
Changes in v7:
- Rebased onto 17b57b18 (4.19-rc6).
- Dropped the "arm64: untag user address in __do_user_fault" patch, since
the existing patches already handle user faults properly.
- Dropped the "usb, arm64: untag user addresses in devio" patch, since the
passed pointer must come from a vma and therefore be untagged.
- Dropped the "arm64: annotate user pointers casts detected by sparse"
patch (see the discussion to the replies of the v6 of this patchset).
- Added more context to the cover letter.
- Updated Documentation/arm64/tagged-pointers.txt.
Changes in v6:
1 From 502466b9652c57a23af3bd72124144319212f30b Mon Sep 17 00:00:00 2001
- Added annotations for user pointer casts found by sparse.
1 From 502466b9652c57a23af3bd72124144319212f30b Mon Sep 17 00:00:00 2001
- Rebased onto 050cdc6c (4.19-rc1+).
1 From 502466b9652c57a23af3bd72124144319212f30b Mon Sep 17 00:00:00 2001
Changes in v5:
- Added 3 new patches that add untagging to places found with static
analysis.
- Rebased onto 44c929e1 (4.18-rc8).
Changes in v4:
- Added a selftest for checking that passing tagged pointers to the
kernel succeeds.
- Rebased onto 81e97f013 (4.18-rc1+).
Changes in v3:
- Rebased onto e5c51f30 (4.17-rc6+).
- Added linux-arch@ to the list of recipients.
Changes in v2:
- Rebased onto 2d618bdf (4.17-rc3+).
- Removed excessive untagging in gup.c.
- Removed untagging pointers returned from __uaccess_mask_ptr.
Changes in v1:
- Rebased onto 4.17-rc1.
Changes in RFC v2:
- Added "#ifndef untagged_addr..." fallback in linux/uaccess.h instead of
defining it for each arch individually.
- Updated Documentation/arm64/tagged-pointers.txt.
- Dropped "mm, arm64: untag user addresses in memory syscalls".
- Rebased onto 3eb2ce82 (4.16-rc7).
Reviewed-by: Luc Van Oostenryck <luc.vanoostenryck(a)gmail.com>
Signed-off-by: Andrey Konovalov <andreyknvl(a)google.com>
Andrey Konovalov (8):
arm64: add type casts to untagged_addr macro
uaccess: add untagged_addr definition for other arches
arm64: untag user addresses in access_ok and __uaccess_mask_ptr
mm, arm64: untag user addresses in mm/gup.c
lib, arm64: untag addrs passed to strncpy_from_user and strnlen_user
fs, arm64: untag user address in copy_mount_options
arm64: update Documentation/arm64/tagged-pointers.txt
selftests, arm64: add a selftest for passing tagged pointers to kernel
Documentation/arm64/tagged-pointers.txt | 25 +++++++++++--------
arch/arm64/include/asm/uaccess.h | 14 +++++++----
fs/namespace.c | 2 +-
include/linux/uaccess.h | 4 +++
lib/strncpy_from_user.c | 2 ++
lib/strnlen_user.c | 2 ++
mm/gup.c | 4 +++
tools/testing/selftests/arm64/.gitignore | 1 +
tools/testing/selftests/arm64/Makefile | 11 ++++++++
.../testing/selftests/arm64/run_tags_test.sh | 12 +++++++++
tools/testing/selftests/arm64/tags_test.c | 19 ++++++++++++++
11 files changed, 80 insertions(+), 16 deletions(-)
create mode 100644 tools/testing/selftests/arm64/.gitignore
create mode 100644 tools/testing/selftests/arm64/Makefile
create mode 100755 tools/testing/selftests/arm64/run_tags_test.sh
create mode 100644 tools/testing/selftests/arm64/tags_test.c
--
2.20.0.rc2.403.gdbc3b29805-goog
In environments where tput is not available, we get the following
error
$ ./ftracetest: 163: [: Illegal number:
because ncolors is an empty string. Fix that by setting it to 0 if the
tput command fails.
Acked-by: Steven Rostedt (VMware) <rostedt(a)goodmis.org>
Acked-by: Masami Hiramatsu <mhiramat(a)kernel.org>
Signed-off-by: Juerg Haefliger <juergh(a)canonical.com>
---
tools/testing/selftests/ftrace/ftracetest | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/ftrace/ftracetest b/tools/testing/selftests/ftrace/ftracetest
index 75244db70331..fc755e1b50f1 100755
--- a/tools/testing/selftests/ftrace/ftracetest
+++ b/tools/testing/selftests/ftrace/ftracetest
@@ -154,13 +154,13 @@ fi
# Define text colors
# Check available colors on the terminal, if any
-ncolors=`tput colors 2>/dev/null`
+ncolors=`tput colors 2>/dev/null || echo 0`
color_reset=
color_red=
color_green=
color_blue=
# If stdout exists and number of colors is eight or more, use them
-if [ -t 1 -a "$ncolors" -a "$ncolors" -ge 8 ]; then
+if [ -t 1 -a "$ncolors" -ge 8 ]; then
color_reset="\e[0m"
color_red="\e[31m"
color_green="\e[32m"
--
2.19.1
Just like commit e2ba732a1681 ("selftests: fib_tests: sleep after
changing carrier"), wait one second to allow linkwatch to propagate the
carrier change to the stack.
There are two sets of carrier tests. The first slept after the carrier
was set to off, and when the second set ran, it was likely that the
linkwatch would be able to run again without much delay, reducing the
likelihood of a race. However, if you run 'fib_tests.sh -t carrier' on a
loop, you will quickly notice the failures.
Sleeping on the second set of tests make the failures go away.
Cc: David Ahern <dsahern(a)gmail.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo(a)canonical.com>
---
tools/testing/selftests/net/fib_tests.sh | 1 +
1 file changed, 1 insertion(+)
diff --git a/tools/testing/selftests/net/fib_tests.sh b/tools/testing/selftests/net/fib_tests.sh
index 802b4af18729..1080ff55a788 100755
--- a/tools/testing/selftests/net/fib_tests.sh
+++ b/tools/testing/selftests/net/fib_tests.sh
@@ -388,6 +388,7 @@ fib_carrier_unicast_test()
set -e
$IP link set dev dummy0 carrier off
+ sleep 1
set +e
echo " Carrier down"
--
2.20.1
From: Fathi Boudra <fathi.boudra(a)linaro.org>
[ Upstream commit 7d4e591bc051d3382c45caaa2530969fb42ed23d ]
posix_timers fails to build due to undefined reference errors:
aarch64-linaro-linux-gcc --sysroot=/build/tmp-rpb-glibc/sysroots/hikey
-O2 -pipe -g -feliminate-unused-debug-types -O3 -Wl,-no-as-needed -Wall
-DKTEST -Wl,-O1 -Wl,--hash-style=gnu -Wl,--as-needed -lrt -lpthread
posix_timers.c
-o /build/tmp-rpb-glibc/work/hikey-linaro-linux/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/timers/posix_timers
/tmp/cc1FTZzT.o: In function `check_timer_create':
/usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/timers/posix_timers.c:157:
undefined reference to `timer_create'
/usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/timers/posix_timers.c:170:
undefined reference to `timer_settime'
collect2: error: ld returned 1 exit status
It's GNU Make and linker specific.
The default Makefile rule looks like:
$(CC) $(CFLAGS) $(LDFLAGS) $@ $^ $(LDLIBS)
When linking is done by gcc itself, no issue, but when it needs to be passed
to proper ld, only LDLIBS follows and then ld cannot know what libs to link
with.
More detail:
https://www.gnu.org/software/make/manual/html_node/Implicit-Variables.html
LDFLAGS
Extra flags to give to compilers when they are supposed to invoke the linker,
‘ld’, such as -L. Libraries (-lfoo) should be added to the LDLIBS variable
instead.
LDLIBS
Library flags or names given to compilers when they are supposed to invoke the
linker, ‘ld’. LOADLIBES is a deprecated (but still supported) alternative to
LDLIBS. Non-library linker flags, such as -L, should go in the LDFLAGS
variable.
https://lkml.org/lkml/2010/2/10/362
tools/perf: libraries must come after objects
Link order matters, use LDLIBS instead of LDFLAGS to properly link against
libpthread.
Signed-off-by: Denys Dmytriyenko <denys(a)ti.com>
Signed-off-by: Fathi Boudra <fathi.boudra(a)linaro.org>
Signed-off-by: Shuah Khan <shuah(a)kernel.org>
Signed-off-by: Sasha Levin <sashal(a)kernel.org>
---
tools/testing/selftests/timers/Makefile | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/testing/selftests/timers/Makefile b/tools/testing/selftests/timers/Makefile
index 3496680981f20..d937e45532d83 100644
--- a/tools/testing/selftests/timers/Makefile
+++ b/tools/testing/selftests/timers/Makefile
@@ -1,6 +1,6 @@
# SPDX-License-Identifier: GPL-2.0
CFLAGS += -O3 -Wl,-no-as-needed -Wall
-LDFLAGS += -lrt -lpthread -lm
+LDLIBS += -lrt -lpthread -lm
# these are all "safe" tests that don't modify
# system time or require escalated privileges
--
2.19.1
From: Colin Ian King <colin.king(a)canonical.com>
[ Upstream commit 2b531b6137834a55857a337ac17510d6436b6fbb ]
The cpu-hotplug test assumes that we can offline the maximum CPU as
described by /sys/devices/system/cpu/offline. However, in the case
where the number of CPUs exceeds like kernel configuration then
the offline count can be greater than the present count and we end
up trying to test the offlining of a CPU that is not available to
offline. Fix this by testing the maximum present CPU instead.
Also, the test currently offlines the CPU and does not online it,
so fix this by onlining the CPU after the test.
Fixes: d89dffa976bc ("fault-injection: add selftests for cpu and memory hotplug")
Signed-off-by: Colin Ian King <colin.king(a)canonical.com>
Signed-off-by: Shuah Khan <shuah(a)kernel.org>
Signed-off-by: Sasha Levin <sashal(a)kernel.org>
---
.../selftests/cpu-hotplug/cpu-on-off-test.sh | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/tools/testing/selftests/cpu-hotplug/cpu-on-off-test.sh b/tools/testing/selftests/cpu-hotplug/cpu-on-off-test.sh
index f3a8933c12755..49ccd22933438 100755
--- a/tools/testing/selftests/cpu-hotplug/cpu-on-off-test.sh
+++ b/tools/testing/selftests/cpu-hotplug/cpu-on-off-test.sh
@@ -35,6 +35,10 @@ prerequisite()
exit 0
fi
+ present_cpus=`cat $SYSFS/devices/system/cpu/present`
+ present_max=${present_cpus##*-}
+ echo "present_cpus = $present_cpus present_max = $present_max"
+
echo -e "\t Cpus in online state: $online_cpus"
offline_cpus=`cat $SYSFS/devices/system/cpu/offline`
@@ -149,6 +153,8 @@ online_cpus=0
online_max=0
offline_cpus=0
offline_max=0
+present_cpus=0
+present_max=0
while getopts e:ahp: opt; do
case $opt in
@@ -188,9 +194,10 @@ if [ $allcpus -eq 0 ]; then
online_cpu_expect_success $online_max
if [[ $offline_cpus -gt 0 ]]; then
- echo -e "\t offline to online to offline: cpu $offline_max"
- online_cpu_expect_success $offline_max
- offline_cpu_expect_success $offline_max
+ echo -e "\t offline to online to offline: cpu $present_max"
+ online_cpu_expect_success $present_max
+ offline_cpu_expect_success $present_max
+ online_cpu $present_max
fi
exit 0
else
--
2.19.1