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Currently, on x86-64, perf uses LFENCE and MFENCE (rmb() and mb(),
respectively) when processing events from the perf ring buffer which
is unnecessarily expensive as we can do more lightweight in particular
given this is critical fast-path in perf.
According to Peter rmb()/mb() were added back then via a94d342b9cb0
("tools/perf: Add required memory barriers") at a time where kernel
still supported chips that needed it, but nowadays support for these
has been ditched completely, therefore we can fix them up as well.
While for x86-64, replacing rmb() and mb() with smp_*() variants would
result in just a compiler barrier for the former and LOCK + ADD for
the latter (__sync_synchronize() uses slower MFENCE by the way), Peter
suggested we can use smp_{load_acquire,store_release}() instead for
architectures where its implementation doesn't resolve in slower smp_mb().
Thus, e.g. in x86-64 we would be able to avoid CPU barrier entirely due
to TSO. For architectures where the latter needs to use smp_mb() e.g.
on arm, we stick to cheaper smp_rmb() variant for fetching the head.
This work adds helpers ring_buffer_read_head() and ring_buffer_write_tail()
for tools infrastructure that either switches to smp_load_acquire() for
architectures where it is cheaper or uses READ_ONCE() + smp_rmb() barrier
for those where it's not in order to fetch the data_head from the perf
control page, and it uses smp_store_release() to write the data_tail.
Latter is smp_mb() + WRITE_ONCE() combination or a cheaper variant if
architecture allows for it. Those that rely on smp_rmb() and smp_mb() can
further improve performance in a follow up step by implementing the two
under tools/arch/*/include/asm/barrier.h such that they don't have to
fallback to rmb() and mb() in tools/include/asm/barrier.h.
Switch perf to use ring_buffer_read_head() and ring_buffer_write_tail()
so it can make use of the optimizations. Later, we convert libbpf as
well to use the same helpers.
Side note [0]: the topic has been raised of whether one could simply use
the C11 gcc builtins [1] for the smp_load_acquire() and smp_store_release()
instead:
__atomic_load_n(ptr, __ATOMIC_ACQUIRE);
__atomic_store_n(ptr, val, __ATOMIC_RELEASE);
Kernel and (presumably) tooling shipped along with the kernel has a
minimum requirement of being able to build with gcc-4.6 and the latter
does not have C11 builtins. While generally the C11 memory models don't
align with the kernel's, the C11 load-acquire and store-release alone
/could/ suffice, however. Issue is that this is implementation dependent
on how the load-acquire and store-release is done by the compiler and
the mapping of supported compilers must align to be compatible with the
kernel's implementation, and thus needs to be verified/tracked on a
case by case basis whether they match (unless an architecture uses them
also from kernel side). The implementations for smp_load_acquire() and
smp_store_release() in this patch have been adapted from the kernel side
ones to have a concrete and compatible mapping in place.
[0] http://patchwork.ozlabs.org/patch/985422/
[1] https://gcc.gnu.org/onlinedocs/gcc/_005f_005fatomic-Builtins.html
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Many user space API headers are missing licensing information, which
makes it hard for compliance tools to determine the correct license.
By default are files without license information under the default
license of the kernel, which is GPLV2. Marking them GPLV2 would exclude
them from being included in non GPLV2 code, which is obviously not
intended. The user space API headers fall under the syscall exception
which is in the kernels COPYING file:
NOTE! This copyright does *not* cover user programs that use kernel
services by normal system calls - this is merely considered normal use
of the kernel, and does *not* fall under the heading of "derived work".
otherwise syscall usage would not be possible.
Update the files which contain no license information with an SPDX
license identifier. The chosen identifier is 'GPL-2.0 WITH
Linux-syscall-note' which is the officially assigned identifier for the
Linux syscall exception. SPDX license identifiers are a legally binding
shorthand, which can be used instead of the full boiler plate text.
This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne. See the previous patch in this series for the
methodology of how this patch was researched.
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.
By default all files without license information are under the default
license of the kernel, which is GPL version 2.
Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.
This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.
How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,
Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.
The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.
The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.
Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).
All documentation files were explicitly excluded.
The following heuristics were used to determine which SPDX license
identifiers to apply.
- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.
For non */uapi/* files that summary was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139
and resulted in the first patch in this series.
If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930
and resulted in the second patch in this series.
- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:
SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1
and that resulted in the third patch in this series.
- when the two scanners agreed on the detected license(s), that became
the concluded license(s).
- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.
- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).
- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.
- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.
In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.
Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.
Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.
In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.
Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct
This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.
These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Some macros required by tools/perf/trace/beauty/mmap.c is not support
for all architectures. For example, MAP_32BIT is defined on x86 only,
alpha doesn't define MADV_HWPOISON and MADV_SOFT_OFFLINE.
This patch regenerates mman.h for each arch, defines these missing
macros for perf. For missing MADV_*, fall back to asm-generic/mman-common
because they are in a 'case ...' statement. For flags, define it to 0.
Following is the script to generate this patch:
macros=`cat $0 | awk 'V==1 {print}; /^# start macro list/ {V=1}'`
rm `find ./tools/arch/ -name mman.h`
for arch in `ls tools/arch`
do
[ -d tools/arch/$arch/include/uapi/asm ] || mkdir -p tools/arch/$arch/include/uapi/asm
src=arch/$arch/include/uapi/asm/mman.h
target=tools/arch/$arch/include/uapi/asm/mman.h.tmp
real_target=tools/arch/$arch/include/uapi/asm/mman.h
guard="TOOLS_ARCH_"`echo $arch | awk '{print toupper($0)}'`_UAPI_ASM_MMAN_FIX_H
rm -f $target
[ -f $src ] &&
for m in $macros
do
if grep '#define[ \t]*'$m $src > /dev/null 2>&1
then
grep -h '#define[ \t]*'$m $src | sed 's/[ \t]*\/\*.*$//g' >> $target
fi
done
if [ -f $src ]
then
grep '#include <asm-generic' $src >> $target
else
echo "#include <asm-generic/mman.h>" >> $target
fi
touch $real_target
for m in $macros
do
if cat << EOF | gcc -Itools/arch/$arch/include -Itools/arch/$arch/include/uapi -Iinclude/ -Iinclude/uapi -E - | grep $m > /dev/null 2>&1
#include <uapi/asm/mman.h.tmp>
#include <uapi/linux/mman.h>
$m
EOF
then
echo "Fixing $m for $arch"
echo "/* $m is undefined on $arch, fix it for perf */" >> $target
if echo $m | grep '^MADV_' > /dev/null 2>&1
then
grep -h '#define[ \t]*'$m include/uapi/asm-generic/mman-common.h | sed 's/[ \t]*\/\*.*$//g' >> $target
else
echo "#define $m 0" >> $target
fi
fi
done
real_target=tools/arch/$arch/include/uapi/asm/mman.h
echo '#ifndef '$guard > $real_target
echo '#define '$guard >> $real_target
cat $target | sed 's|asm-generic|uapi/asm-generic|g' >> $real_target
echo '#endif' >> $real_target
rm $target
echo "$real_target"
done
exit 0
# Following macros are extracted from:
# tools/perf/trace/beauty/mmap.c
#
# start macro list
MADV_DODUMP
MADV_DOFORK
MADV_DONTDUMP
MADV_DONTFORK
MADV_DONTNEED
MADV_FREE
MADV_HUGEPAGE
MADV_HWPOISON
MADV_MERGEABLE
MADV_NOHUGEPAGE
MADV_NORMAL
MADV_RANDOM
MADV_REMOVE
MADV_SEQUENTIAL
MADV_SOFT_OFFLINE
MADV_UNMERGEABLE
MADV_WILLNEED
MAP_32BIT
MAP_ANONYMOUS
MAP_DENYWRITE
MAP_EXECUTABLE
MAP_FILE
MAP_FIXED
MAP_GROWSDOWN
MAP_HUGETLB
MAP_LOCKED
MAP_NONBLOCK
MAP_NORESERVE
MAP_POPULATE
MAP_PRIVATE
MAP_SHARED
MAP_STACK
MAP_UNINITIALIZED
MREMAP_FIXED
MREMAP_MAYMOVE
PROT_EXEC
PROT_GROWSDOWN
PROT_GROWSUP
PROT_NONE
PROT_READ
PROT_SEM
PROT_WRITE
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Tested-by: Kim Phillips <kim.phillips@arm.com>
Tested-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Fixes: 277cf08f3feb ("perf trace beauty mmap: Fix defines for non !x86_64")
Link: http://lkml.kernel.org/r/1473850649-83389-3-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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Some mmap related macros have different values for different
architectures. This patch introduces uapi mman.h for each
architectures.
Three headers are cloned from kernel include to tools/include:
tools/include/uapi/asm-generic/mman-common.h
tools/include/uapi/asm-generic/mman.h
tools/include/uapi/linux/mman.h
The main part of this patch is generated by following script:
macros=`cat $0 | awk 'V==1 {print}; /^# start macro list/ {V=1}'`
for arch in `ls tools/arch`
do
[ -d tools/arch/$arch/include/uapi/asm ] || mkdir -p tools/arch/$arch/include/uapi/asm
src=arch/$arch/include/uapi/asm/mman.h
target=tools/arch/$arch/include/uapi/asm/mman.h
guard="TOOLS_ARCH_"`echo $arch | awk '{print toupper($0)}'`_UAPI_ASM_MMAN_FIX_H
echo '#ifndef '$guard > $target
echo '#define '$guard >> $target
[ -f $src ] &&
for m in $macros
do
if grep '#define[ \t]*'$m $src > /dev/null 2>&1
then
grep -h '#define[ \t]*'$m $src | sed 's/[ \t]*\/\*.*$//g' >> $target
fi
done
if [ -f $src ]
then
grep '#include <asm-generic' $src >> $target
else
echo "#include <asm-generic/mman.h>" >> $target
fi
echo '#endif' >> $target
echo "$target"
done
exit 0
# Following macros are extracted from:
# tools/perf/trace/beauty/mmap.c
#
# start macro list
MADV_DODUMP
MADV_DOFORK
MADV_DONTDUMP
MADV_DONTFORK
MADV_DONTNEED
MADV_HUGEPAGE
MADV_HWPOISON
MADV_MERGEABLE
MADV_NOHUGEPAGE
MADV_NORMAL
MADV_RANDOM
MADV_REMOVE
MADV_SEQUENTIAL
MADV_SOFT_OFFLINE
MADV_UNMERGEABLE
MADV_WILLNEED
MAP_32BIT
MAP_ANONYMOUS
MAP_DENYWRITE
MAP_EXECUTABLE
MAP_FILE
MAP_FIXED
MAP_GROWSDOWN
MAP_HUGETLB
MAP_LOCKED
MAP_NONBLOCK
MAP_NORESERVE
MAP_POPULATE
MAP_PRIVATE
MAP_SHARED
MAP_STACK
MAP_UNINITIALIZED
MREMAP_FIXED
MREMAP_MAYMOVE
PROT_EXEC
PROT_GROWSDOWN
PROT_GROWSUP
PROT_NONE
PROT_READ
PROT_SEM
PROT_WRITE
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1473684871-209320-2-git-send-email-wangnan0@huawei.com
[ Added new files to tools/perf/MANIFEST to fix the detached tarball build, add mman.h for ARC ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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We use it in bitops/__ffs.h and bitops/atomic.h, that we also got from
the kernel, but were getting it from either newer systems that carry it
in /usr/include, or from the kernel sources, that we decided not to
touch from tools/ code. Fix it.
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-lwqvgbuitjmrdpjmjp6zqnyx@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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We will need it for atomic.h, so move it from the ad-hoc tools/perf/
place to a tools/ subset of the kernel arch/ hierarchy.
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-4op0qdukegrdumyefz4icxk0@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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Daniel Borkmann
Greg Kroah-Hartman
Wang Nan
Arnaldo Carvalho de Melo