Recent probing at the Linux Kernel Memory Model uncovered a
'surprise'. Strongly ordered architectures where the atomic RmW
primitive implies full memory ordering and
smp_mb__{before,after}_atomic() are a simple barrier() (such as x86)
fail for:
*x = 1;
atomic_inc(u);
smp_mb__after_atomic();
r0 = *y;
Because, while the atomic_inc() implies memory order, it
(surprisingly) does not provide a compiler barrier. This then allows
the compiler to re-order like so:
atomic_inc(u);
*x = 1;
smp_mb__after_atomic();
r0 = *y;
Which the CPU is then allowed to re-order (under TSO rules) like:
atomic_inc(u);
r0 = *y;
*x = 1;
And this very much was not intended. Therefore strengthen the atomic
RmW ops to include a compiler barrier.
NOTE: atomic_{or,and,xor} and the bitops already had the compiler
barrier.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently the GEN_*_RMWcc() macros include a return statement, which
pretty much mandates we directly wrap them in a (inline) function.
Macros with return statements are tricky and, as per the above, limit
use, so remove the return statement and make them
statement-expressions. This allows them to be used more widely.
Also, shuffle the arguments a bit. Place the @cc argument as 3rd, this
makes it consistent between UNARY and BINARY, but more importantly, it
makes the @arg0 argument last.
Since the @arg0 argument is now last, we can do CPP trickery and make
it an optional argument, simplifying the users; 17 out of 18
occurences do not need this argument.
Finally, change to asm symbolic names, instead of the numeric ordering
of operands, which allows us to get rid of __BINARY_RMWcc_ARG and get
cleaner code overall.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: JBeulich@suse.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bp@alien8.de
Cc: hpa@linux.intel.com
Link: https://lkml.kernel.org/r/20181003130957.108960094@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Fix kernel-doc warnings in arch/x86/include/asm/atomic.h that are caused by
having a #define macro between the kernel-doc notation and the function
name. Fixed by moving the #define macro to after the function
implementation.
Make the same change for atomic64_{32,64}.h for consistency even though
there were no kernel-doc warnings found in these header files, but there
would be if they were used in generation of documentation.
Fixes these kernel-doc warnings:
../arch/x86/include/asm/atomic.h:84: warning: Excess function parameter 'i' description in 'arch_atomic_sub_and_test'
../arch/x86/include/asm/atomic.h:84: warning: Excess function parameter 'v' description in 'arch_atomic_sub_and_test'
../arch/x86/include/asm/atomic.h:96: warning: Excess function parameter 'v' description in 'arch_atomic_inc'
../arch/x86/include/asm/atomic.h:109: warning: Excess function parameter 'v' description in 'arch_atomic_dec'
../arch/x86/include/asm/atomic.h:124: warning: Excess function parameter 'v' description in 'arch_atomic_dec_and_test'
../arch/x86/include/asm/atomic.h:138: warning: Excess function parameter 'v' description in 'arch_atomic_inc_and_test'
../arch/x86/include/asm/atomic.h:153: warning: Excess function parameter 'i' description in 'arch_atomic_add_negative'
../arch/x86/include/asm/atomic.h:153: warning: Excess function parameter 'v' description in 'arch_atomic_add_negative'
Fixes: 18cc1814d4 ("atomics/treewide: Make test ops optional")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Mark Rutland <mark.rutland@arm.com>
Link: https://lkml.kernel.org/r/0a1e678d-c8c5-b32c-2640-ed4e94d399d2@infradead.org
Many of the inc/dec ops are mandatory, but for most architectures inc/dec are
simply trivial wrappers around their corresponding add/sub ops.
Let's make all the inc/dec ops optional, so that we can get rid of these
boilerplate wrappers.
The instrumented atomics are updated accordingly.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Palmer Dabbelt <palmer@sifive.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/lkml/20180621121321.4761-17-mark.rutland@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Some of the atomics return the result of a test applied after the atomic
operation, and almost all architectures implement these as trivial
wrappers around the underlying atomic. Specifically:
* <atomic>_inc_and_test(v) is (<atomic>_inc_return(v) == 0)
* <atomic>_dec_and_test(v) is (<atomic>_dec_return(v) == 0)
* <atomic>_sub_and_test(i, v) is (<atomic>_sub_return(i, v) == 0)
* <atomic>_add_negative(i, v) is (<atomic>_add_return(i, v) < 0)
Rather than have these definitions duplicated in all architectures, with
minor inconsistencies in formatting and documentation, let's make these
operations optional, with default fallbacks as above. Implementations
must now provide a preprocessor symbol.
The instrumented atomics are updated accordingly.
Both x86 and m68k have custom implementations, which are left as-is,
given preprocessor symbols to avoid being overridden.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Palmer Dabbelt <palmer@sifive.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/lkml/20180621121321.4761-16-mark.rutland@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Several architectures these have a near-identical implementation based
on atomic_read() and atomic_cmpxchg() which we can instead define in
<linux/atomic.h>, so let's do so, using something close to the existing
x86 implementation with try_cmpxchg().
Where an architecture provides its own atomic_fetch_add_unless(), it
must define a preprocessor symbol for it. The instrumented atomics are
updated accordingly.
Note that arch/arc's existing atomic_fetch_add_unless() had redundant
barriers, as these are already present in its atomic_cmpxchg()
implementation.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Palmer Dabbelt <palmer@sifive.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vineet Gupta <vgupta@synopsys.com>
Link: https://lore.kernel.org/lkml/20180621121321.4761-7-mark.rutland@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
While __atomic_add_unless() was originally intended as a building-block
for atomic_add_unless(), it's now used in a number of places around the
kernel. It's the only common atomic operation named __atomic*(), rather
than atomic_*(), and for consistency it would be better named
atomic_fetch_add_unless().
This lack of consistency is slightly confusing, and gets in the way of
scripting atomics. Given that, let's clean things up and promote it to
an official part of the atomics API, in the form of
atomic_fetch_add_unless().
This patch converts definitions and invocations over to the new name,
including the instrumented version, using the following script:
----
git grep -w __atomic_add_unless | while read line; do
sed -i '{s/\<__atomic_add_unless\>/atomic_fetch_add_unless/}' "${line%%:*}";
done
git grep -w __arch_atomic_add_unless | while read line; do
sed -i '{s/\<__arch_atomic_add_unless\>/arch_atomic_fetch_add_unless/}' "${line%%:*}";
done
----
Note that we do not have atomic{64,_long}_fetch_add_unless(), which will
be introduced by later patches.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Palmer Dabbelt <palmer@sifive.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/lkml/20180621121321.4761-2-mark.rutland@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The comments are factored out from the code changes to make them
easier to read. Add them separately to explain some non-obvious
aspects.
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: kasan-dev@googlegroups.com
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/cc595efc644bb905407012d82d3eb8bac3368e7a.1517246437.git.dvyukov@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Add arch_ prefix to all atomic operations and include
<asm-generic/atomic-instrumented.h>. This will allow
to add KASAN instrumentation to all atomic ops.
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: kasan-dev@googlegroups.com
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/54f0eb64260b84199e538652e079a89b5423ad41.1517246437.git.dvyukov@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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>
CPP turns perfectly readable code into a much harder to read syntactic soup.
Ingo suggested to write them out as-is in C and ignore the higher linecount.
Do this.
(As a side effect, plain C functions will be easier to KASAN-instrument as well.)
Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kasan-dev@googlegroups.com
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/a35b983dd3be937a3cf63c4e2db487de2cdc7b8f.1497690003.git.dvyukov@google.com
[ Beautified the C code some more and twiddled the changelog
to mention the linecount increase and the KASAN benefit. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
It is completely unused and implemented only on x86.
Remove it.
Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170526172900.91058-1-dvyukov@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Add a new cmpxchg interface:
bool try_cmpxchg(u{8,16,32,64} *ptr, u{8,16,32,64} *val, u{8,16,32,64} new);
Where the boolean returns the result of the compare; and thus if the
exchange happened; and in case of failure, the new value of *ptr is
returned in *val.
This allows simplification/improvement of loops like:
for (;;) {
new = val $op $imm;
old = cmpxchg(ptr, val, new);
if (old == val)
break;
val = old;
}
into:
do {
} while (!try_cmpxchg(ptr, &val, val $op $imm));
while also generating better code (GCC6 and onwards).
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull x86 mm updates from Ingo Molnar:
"Various x86 low level modifications:
- preparatory work to support virtually mapped kernel stacks (Andy
Lutomirski)
- support for 64-bit __get_user() on 32-bit kernels (Benjamin
LaHaise)
- (involved) workaround for Knights Landing CPU erratum (Dave Hansen)
- MPX enhancements (Dave Hansen)
- mremap() extension to allow remapping of the special VDSO vma, for
purposes of user level context save/restore (Dmitry Safonov)
- hweight and entry code cleanups (Borislav Petkov)
- bitops code generation optimizations and cleanups with modern GCC
(H. Peter Anvin)
- syscall entry code optimizations (Paolo Bonzini)"
* 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (43 commits)
x86/mm/cpa: Add missing comment in populate_pdg()
x86/mm/cpa: Fix populate_pgd(): Stop trying to deallocate failed PUDs
x86/syscalls: Add compat_sys_preadv64v2/compat_sys_pwritev64v2
x86/smp: Remove unnecessary initialization of thread_info::cpu
x86/smp: Remove stack_smp_processor_id()
x86/uaccess: Move thread_info::addr_limit to thread_struct
x86/dumpstack: Rename thread_struct::sig_on_uaccess_error to sig_on_uaccess_err
x86/uaccess: Move thread_info::uaccess_err and thread_info::sig_on_uaccess_err to thread_struct
x86/dumpstack: When OOPSing, rewind the stack before do_exit()
x86/mm/64: In vmalloc_fault(), use CR3 instead of current->active_mm
x86/dumpstack/64: Handle faults when printing the "Stack: " part of an OOPS
x86/dumpstack: Try harder to get a call trace on stack overflow
x86/mm: Remove kernel_unmap_pages_in_pgd() and efi_cleanup_page_tables()
x86/mm/cpa: In populate_pgd(), don't set the PGD entry until it's populated
x86/mm/hotplug: Don't remove PGD entries in remove_pagetable()
x86/mm: Use pte_none() to test for empty PTE
x86/mm: Disallow running with 32-bit PTEs to work around erratum
x86/mm: Ignore A/D bits in pte/pmd/pud_none()
x86/mm: Move swap offset/type up in PTE to work around erratum
x86/entry: Inline enter_from_user_mode()
...
Since all architectures have this implemented now natively, remove this
dead code.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Implement FETCH-OP atomic primitives, these are very similar to the
existing OP-RETURN primitives we already have, except they return the
value of the atomic variable _before_ modification.
This is especially useful for irreversible operations -- such as
bitops (because it becomes impossible to reconstruct the state prior
to modification).
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Change the lexical defintion of the GEN_*_RMWcc() macros to not take
the condition code as a quoted string. This will help support
changing them to use the new __GCC_ASM_FLAG_OUTPUTS__ feature in a
subsequent patch.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Link: http://lkml.kernel.org/r/1465414726-197858-4-git-send-email-hpa@linux.intel.com
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
The gcc people have confirmed that using "bool" when combined with
inline assembly always is treated as a byte-sized operand that can be
assumed to be 0 or 1, which is exactly what the SET instruction
emits. Change the output types and intermediate variables of as many
operations as practical to "bool".
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Link: http://lkml.kernel.org/r/1465414726-197858-3-git-send-email-hpa@linux.intel.com
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
asm/atomic.h doesn't really need asm/processor.h anymore. Everything
it uses has moved to other header files. So remove that include.
processor.h is a nasty header that includes lots of
other headers and makes it prone to include loops. Removing the
include here makes asm/atomic.h a "leaf" header that can
be safely included in most other headers.
The only fallout is in the lib/atomic tester which relied on
this implicit include. Give it an explicit include.
(the include is in ifdef because the user is also in ifdef)
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: rostedt@goodmis.org
Link: http://lkml.kernel.org/r/1449018060-1742-1-git-send-email-andi@firstfloor.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This patch makes sure that atomic_{read,set}() are at least
{READ,WRITE}_ONCE().
We already had the 'requirement' that atomic_read() should use
ACCESS_ONCE(), and most archs had this, but a few were lacking.
All are now converted to use READ_ONCE().
And, by a symmetry and general paranoia argument, upgrade atomic_set()
to use WRITE_ONCE().
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: james.hogan@imgtec.com
Cc: linux-kernel@vger.kernel.org
Cc: oleg@redhat.com
Cc: will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Move the now generic definitions of atomic_{set,clear}_mask() into
linux/atomic.h to avoid endless and pointless repetition.
Also, provide an atomic_andnot() wrapper for those few archs that can
implement that.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Implement atomic logic ops -- atomic_{or,xor,and}.
These will replace the atomic_{set,clear}_mask functions that are
available on some archs.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Implement atomic logic ops -- atomic_{or,xor,and}.
These will replace the atomic_{set,clear}_mask functions that are
available on some archs.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
With both gcc 4.7.2 and 4.9.2, sometimes gcc mysteriously
doesn't inline very small functions we expect to be inlined:
$ nm --size-sort vmlinux | grep -iF ' t ' | uniq -c | grep -v '^
*1 ' | sort -rn 473 000000000000000b t spin_unlock_irqrestore
449 000000000000005f t rcu_read_unlock
355 0000000000000009 t atomic_inc <== THIS
353 000000000000006e t rcu_read_lock
350 0000000000000075 t rcu_read_lock_sched_held
291 000000000000000b t spin_unlock
266 0000000000000019 t arch_local_irq_restore
215 000000000000000b t spin_lock
180 0000000000000011 t kzalloc
165 0000000000000012 t list_add_tail
161 0000000000000019 t arch_local_save_flags
153 0000000000000016 t test_and_set_bit
134 000000000000000b t spin_unlock_irq
134 0000000000000009 t atomic_dec <== THIS
130 000000000000000b t spin_unlock_bh
122 0000000000000010 t brelse
120 0000000000000016 t test_and_clear_bit
120 000000000000000b t spin_lock_irq
119 000000000000001e t get_dma_ops
117 0000000000000053 t cpumask_next
116 0000000000000036 t kref_get
114 000000000000001a t schedule_work
106 000000000000000b t spin_lock_bh
103 0000000000000019 t arch_local_irq_disable
...
Note sizes of marked functions. They are merely 9 bytes long!
Selecting function with 'atomic' in their names:
355 0000000000000009 t atomic_inc
134 0000000000000009 t atomic_dec
98 0000000000000014 t atomic_dec_and_test
31 000000000000000e t atomic_add_return
27 000000000000000a t atomic64_inc
26 000000000000002f t kmap_atomic
24 0000000000000009 t atomic_add
12 0000000000000009 t atomic_sub
10 0000000000000021 t __atomic_add_unless
10 000000000000000a t atomic64_add
5 000000000000001f t __atomic_add_unless.constprop.7
5 000000000000000a t atomic64_dec
4 000000000000001f t __atomic_add_unless.constprop.18
4 000000000000001f t __atomic_add_unless.constprop.12
4 000000000000001f t __atomic_add_unless.constprop.10
3 000000000000001f t __atomic_add_unless.constprop.13
3 0000000000000011 t atomic64_add_return
2 000000000000001f t __atomic_add_unless.constprop.9
2 000000000000001f t __atomic_add_unless.constprop.8
2 000000000000001f t __atomic_add_unless.constprop.6
2 000000000000001f t __atomic_add_unless.constprop.5
2 000000000000001f t __atomic_add_unless.constprop.3
2 000000000000001f t __atomic_add_unless.constprop.22
2 000000000000001f t __atomic_add_unless.constprop.14
2 000000000000001f t __atomic_add_unless.constprop.11
2 000000000000001e t atomic_dec_if_positive
2 0000000000000014 t atomic_inc_and_test
2 0000000000000011 t atomic_add_return.constprop.4
2 0000000000000011 t atomic_add_return.constprop.17
2 0000000000000011 t atomic_add_return.constprop.16
2 000000000000000d t atomic_inc.constprop.4
2 000000000000000c t atomic_cmpxchg
This patch fixes this for x86 atomic ops via
s/inline/__always_inline/. This decreases allyesconfig kernel by
about 25k:
text data bss dec hex filename
82399481 22255416 20627456 125282353 777a831 vmlinux.before
82375570 22255544 20627456 125258570 7774b4a vmlinux
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1431080762-17797-1-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
During some code analysis I realized that atomic_add(), atomic_sub()
and friends are not necessarily inlined AND that each function
is defined multiple times:
atomic_inc: 544 duplicates
atomic_dec: 215 duplicates
atomic_dec_and_test: 107 duplicates
atomic64_inc: 38 duplicates
[...]
Each definition is exact equally, e.g.:
ffffffff813171b8 <atomic_add>:
55 push %rbp
48 89 e5 mov %rsp,%rbp
f0 01 3e lock add %edi,(%rsi)
5d pop %rbp
c3 retq
In turn each definition has one or more callsites (sure):
ffffffff81317c78: e8 3b f5 ff ff callq ffffffff813171b8 <atomic_add> [...]
ffffffff8131a062: e8 51 d1 ff ff callq ffffffff813171b8 <atomic_add> [...]
ffffffff8131a190: e8 23 d0 ff ff callq ffffffff813171b8 <atomic_add> [...]
The other way around would be to remove the static linkage - but
I prefer an enforced inlining here.
Before:
text data bss dec hex filename
81467393 19874720 20168704 121510817 73e1ba1 vmlinux.orig
After:
text data bss dec hex filename
81461323 19874720 20168704 121504747 73e03eb vmlinux.inlined
Yes, the inlining here makes the kernel even smaller! ;)
Linus further observed:
"I have this memory of having seen that before - the size
heuristics for gcc getting confused by inlining.
[...]
It might be a good idea to mark things that are basically just
wrappers around a single (or a couple of) asm instruction to be
always_inline."
Signed-off-by: Hagen Paul Pfeifer <hagen@jauu.net>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1429565231-4609-1-git-send-email-hagen@jauu.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Use the much more reader friendly ACCESS_ONCE() instead of the cast to volatile.
This is purely a stylistic change.
Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
Acked-by: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Acked-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-arch@vger.kernel.org
Link: http://lkml.kernel.org/r/1411482607-20948-1-git-send-email-bobby.prani@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There are no users, kill it.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Jesse Brandeburg <jesse.brandeburg@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/20140508135851.768177189@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
x86 is strongly ordered and all its atomic ops imply a full barrier.
Implement the two new primitives as the old ones were.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/n/tip-knswsr5mldkr0w1lrdxvc81w@git.kernel.org
Cc: Dave Jones <davej@redhat.com>
Cc: Jesse Brandeburg <jesse.brandeburg@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michel Lespinasse <walken@google.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In checkin:
0c44c2d0f4 x86: Use asm goto to implement better modify_and_test() functions
the various functions which do modify and test were unified and
optimized using "asm goto". However, this change missed the detail
that the bitops require an "Ir" constraint rather than an "er"
constraint ("I" = integer constant from 0-31, "e" = signed 32-bit
integer constant). This would cause code to miscompile if these
functions were used on constant bit positions 32-255 and the build to
fail if used on constant bit positions above 255.
Add the constraints as a parameter to the GEN_BINARY_RMWcc() macro to
avoid this problem.
Reported-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/529E8719.4070202@zytor.com
Linus suggested using asm goto to get rid of the typical SETcc + TEST
instruction pair -- which also clobbers an extra register -- for our
typical modify_and_test() functions.
Because asm goto doesn't allow output fields it has to include an
unconditinal memory clobber when it changes a memory variable to force
a reload.
Luckily all atomic ops already imply a compiler barrier to go along
with their memory barrier semantics.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-0mtn9siwbeo1d33bap1422se@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The x86 implementation of atomic_dec_if_positive is quite generic, so make
it available to all architectures.
This is needed for "swap: add a simple detector for inappropriate swapin
readahead".
[akpm@linux-foundation.org: do the "#define foo foo" trick in the conventional manner]
Signed-off-by: Shaohua Li <shli@fusionio.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Rik van Riel <riel@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michal Simek <monstr@monstr.eu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Convert #include "..." to #include <path/...> in kernel system headers.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Dave Jones <davej@redhat.com>
This covers the trivial cases from open-coded xadd to the xadd macros.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Link: http://lkml.kernel.org/r/4E5BCC40.3030501@goop.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
After changing all consumers of atomics to include <linux/atomic.h>, we
ran into some compile time errors due to this dependency chain:
linux/atomic.h
-> asm/atomic.h
-> asm-generic/atomic-long.h
where atomic-long.h could use funcs defined later in linux/atomic.h
without a prototype. This patches moves the code that includes
asm-generic/atomic*.h to linux/atomic.h.
Archs that need <asm-generic/atomic64.h> need to select
CONFIG_GENERIC_ATOMIC64 from now on (some of them used to include it
unconditionally).
Compile tested on i386 and x86_64 with allnoconfig.
Signed-off-by: Arun Sharma <asharma@fb.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David Miller <davem@davemloft.net>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is in preparation for more generic atomic primitives based on
__atomic_add_unless.
Signed-off-by: Arun Sharma <asharma@fb.com>
Signed-off-by: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
Reviewed-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David Miller <davem@davemloft.net>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This allows us to move duplicated code in <asm/atomic.h>
(atomic_inc_not_zero() for now) to <linux/atomic.h>
Signed-off-by: Arun Sharma <asharma@fb.com>
Reviewed-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David Miller <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'x86-atomic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86: Fix LOCK_PREFIX_HERE for uniprocessor build
x86, atomic64: In selftest, distinguish x86-64 from 586+
x86-32: Fix atomic64_inc_not_zero return value convention
lib: Fix atomic64_inc_not_zero test
lib: Fix atomic64_add_unless return value convention
x86-32: Fix atomic64_add_unless return value convention
lib: Fix atomic64_add_unless test
x86: Implement atomic[64]_dec_if_positive()
lib: Only test atomic64_dec_if_positive on archs having it
x86-32: Rewrite 32-bit atomic64 functions in assembly
lib: Add self-test for atomic64_t
x86-32: Allow UP/SMP lock replacement in cmpxchg64
x86: Add support for lock prefix in alternatives
In preparation for removing volatile from the atomic_t definition, this
patch adds a volatile cast to all the atomic read functions.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add support for atomic_dec_if_positive(), and
atomic64_dec_if_positive() for x86-64.
atomic64_dec_if_positive() for x86-32 was already implemented in a previous patch.
Signed-off-by: Luca Barbieri <luca@luca-barbieri.com>
LKML-Reference: <1267183361-20775-2-git-send-email-luca@luca-barbieri.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
The atomic ops emulation for 32bit legacy CPUs floods the tracer with
irq off/on entries. The irq disabled regions are short and therefor
not interesting when chasing long irq disabled latencies. Mark them
raw and keep them out of the trace.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Merge the now identical code from asm/atomic_32.h and asm/atomic_64.h
into asm/atomic.h.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
LKML-Reference: <1262883215-4034-4-git-send-email-brgerst@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
