| Message ID | 20240424191740.3088894-1-keescook@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Annotate atomics for signed integer wrap-around | expand |
On Wed, Apr 24, 2024 at 12:17:34PM -0700, Kees Cook wrote: > @@ -82,7 +83,7 @@ static __always_inline bool arch_atomic_add_negative(int i, atomic_t *v) > > static __always_inline int arch_atomic_add_return(int i, atomic_t *v) > { > - return i + xadd(&v->counter, i); > + return wrapping_add(int, i, xadd(&v->counter, i)); > } > #define arch_atomic_add_return arch_atomic_add_return this is going to get old *real* quick :-/ This must be the ugliest possible way to annotate all this, and then litter the kernel with all this... urgh.
On Thu, Apr 25, 2024 at 12:41:41AM +0200, Peter Zijlstra wrote: > On Wed, Apr 24, 2024 at 12:17:34PM -0700, Kees Cook wrote: > > > @@ -82,7 +83,7 @@ static __always_inline bool arch_atomic_add_negative(int i, atomic_t *v) > > > > static __always_inline int arch_atomic_add_return(int i, atomic_t *v) > > { > > - return i + xadd(&v->counter, i); > > + return wrapping_add(int, i, xadd(&v->counter, i)); > > } > > #define arch_atomic_add_return arch_atomic_add_return > > this is going to get old *real* quick :-/ > > This must be the ugliest possible way to annotate all this, and then > litter the kernel with all this... urgh. I'm expecting to have explicit wrapping type annotations soon[1], but for the atomics, it's kind of a wash on how intrusive the annotations get. I had originally wanted to mark the function (as I did in other cases) rather than using the helper, but Mark preferred it this way. I'm happy to do whatever! :) -Kees [1] https://github.com/llvm/llvm-project/pull/86618
On Thu, Apr 25, 2024 at 12:41:41AM +0200, Peter Zijlstra wrote: > On Wed, Apr 24, 2024 at 12:17:34PM -0700, Kees Cook wrote: > > > @@ -82,7 +83,7 @@ static __always_inline bool arch_atomic_add_negative(int i, atomic_t *v) > > > > static __always_inline int arch_atomic_add_return(int i, atomic_t *v) > > { > > - return i + xadd(&v->counter, i); > > + return wrapping_add(int, i, xadd(&v->counter, i)); > > } > > #define arch_atomic_add_return arch_atomic_add_return > > this is going to get old *real* quick :-/ > > This must be the ugliest possible way to annotate all this, and then > litter the kernel with all this... urgh. Also, what drugs is involved with __builtin_add_overflow() ? Per -fno-strict-overflow everything is 2s complement and you can just do the unsigned add. Over the years we've been writing code with the express knowledge that everything wraps properly, this annotation is going to be utter pain. As I've said before, add an explicit non-wrapping type and use that for the cases you care about actually not wrapping. NAK
On Wed, Apr 24, 2024 at 03:45:07PM -0700, Kees Cook wrote: > On Thu, Apr 25, 2024 at 12:41:41AM +0200, Peter Zijlstra wrote: > > On Wed, Apr 24, 2024 at 12:17:34PM -0700, Kees Cook wrote: > > > > > @@ -82,7 +83,7 @@ static __always_inline bool arch_atomic_add_negative(int i, atomic_t *v) > > > > > > static __always_inline int arch_atomic_add_return(int i, atomic_t *v) > > > { > > > - return i + xadd(&v->counter, i); > > > + return wrapping_add(int, i, xadd(&v->counter, i)); > > > } > > > #define arch_atomic_add_return arch_atomic_add_return > > > > this is going to get old *real* quick :-/ > > > > This must be the ugliest possible way to annotate all this, and then > > litter the kernel with all this... urgh. > > I'm expecting to have explicit wrapping type annotations soon[1], but for > the atomics, it's kind of a wash on how intrusive the annotations get. I > had originally wanted to mark the function (as I did in other cases) > rather than using the helper, but Mark preferred it this way. I'm happy > to do whatever! :) > > -Kees > > [1] https://github.com/llvm/llvm-project/pull/86618 This is arse-about-face. Signed stuff wraps per -fno-strict-overflow. We've been writing code for years under that assumption. You want to mark the non-wrapping case.
On Thu, Apr 25, 2024 at 12:54:36AM +0200, Peter Zijlstra wrote: > On Wed, Apr 24, 2024 at 03:45:07PM -0700, Kees Cook wrote: > > On Thu, Apr 25, 2024 at 12:41:41AM +0200, Peter Zijlstra wrote: > > > On Wed, Apr 24, 2024 at 12:17:34PM -0700, Kees Cook wrote: > > > > > > > @@ -82,7 +83,7 @@ static __always_inline bool arch_atomic_add_negative(int i, atomic_t *v) > > > > > > > > static __always_inline int arch_atomic_add_return(int i, atomic_t *v) > > > > { > > > > - return i + xadd(&v->counter, i); > > > > + return wrapping_add(int, i, xadd(&v->counter, i)); > > > > } > > > > #define arch_atomic_add_return arch_atomic_add_return > > > > > > this is going to get old *real* quick :-/ > > > > > > This must be the ugliest possible way to annotate all this, and then > > > litter the kernel with all this... urgh. > > > > I'm expecting to have explicit wrapping type annotations soon[1], but for > > the atomics, it's kind of a wash on how intrusive the annotations get. I > > had originally wanted to mark the function (as I did in other cases) > > rather than using the helper, but Mark preferred it this way. I'm happy > > to do whatever! :) > > > > -Kees > > > > [1] https://github.com/llvm/llvm-project/pull/86618 > > This is arse-about-face. Signed stuff wraps per -fno-strict-overflow. > We've been writing code for years under that assumption. > > You want to mark the non-wrapping case. That is, anything that actively warns about signed overflow when build with -fno-strict-overflow is a bug. If you want this warning you have to explicitly mark things. Signed overflow is not UB, is not a bug. Now, it might be unexpected in some places, but fundamentally we run on 2s complement and expect 2s complement. If you want more, mark it so.
On Thu, Apr 25, 2024 at 12:54:36AM +0200, Peter Zijlstra wrote: > On Wed, Apr 24, 2024 at 03:45:07PM -0700, Kees Cook wrote: > > On Thu, Apr 25, 2024 at 12:41:41AM +0200, Peter Zijlstra wrote: > > > On Wed, Apr 24, 2024 at 12:17:34PM -0700, Kees Cook wrote: > > > > > > > @@ -82,7 +83,7 @@ static __always_inline bool arch_atomic_add_negative(int i, atomic_t *v) > > > > > > > > static __always_inline int arch_atomic_add_return(int i, atomic_t *v) > > > > { > > > > - return i + xadd(&v->counter, i); > > > > + return wrapping_add(int, i, xadd(&v->counter, i)); > > > > } > > > > #define arch_atomic_add_return arch_atomic_add_return > > > > > > this is going to get old *real* quick :-/ > > > > > > This must be the ugliest possible way to annotate all this, and then > > > litter the kernel with all this... urgh. > > > > I'm expecting to have explicit wrapping type annotations soon[1], but for > > the atomics, it's kind of a wash on how intrusive the annotations get. I > > had originally wanted to mark the function (as I did in other cases) > > rather than using the helper, but Mark preferred it this way. I'm happy > > to do whatever! :) > > > > -Kees > > > > [1] https://github.com/llvm/llvm-project/pull/86618 > > This is arse-about-face. Signed stuff wraps per -fno-strict-overflow. > We've been writing code for years under that assumption. Right, which is why this is going to take time to roll out. :) What we were really doing with -fno-strict-overflow was getting rid of undefined behavior. That was really really horrible; we don't need the compiler hallucinating. > You want to mark the non-wrapping case. What we want is lack of ambiguity. Having done these kinds of things in the kernel for a while now, I have strong evidence that we get much better results with the "fail safe" approach, but start by making it non-fatal. That way we get full coverage, but we don't melt the world for anyone that doesn't want it, and we can shake things out over a few years. For example, it has worked well for CONFIG_FORTIFY, CONFIG_UBSAN_BOUNDS, KCFI, etc. The riskier condition is having something wrap when it wasn't expected (e.g. allocations, pointer offsets, etc), so we start by defining our regular types as non-wrapping, and annotate the wrapping types (or specific calculations or functions). For signed types in particular, wrapping is overwhelmingly the uncommon case, so from a purely "how much annotations is needed" perspective, marking wrapping is also easiest. Yes, there are cases of expected wrapping, but we'll track them all down and get them marked unambiguously. One thing on the short list is atomics, so here we are. :) -Kees
On Thu, Apr 25, 2024 at 01:05:00AM +0200, Peter Zijlstra wrote: > On Thu, Apr 25, 2024 at 12:54:36AM +0200, Peter Zijlstra wrote: > > On Wed, Apr 24, 2024 at 03:45:07PM -0700, Kees Cook wrote: > > > On Thu, Apr 25, 2024 at 12:41:41AM +0200, Peter Zijlstra wrote: > > > > On Wed, Apr 24, 2024 at 12:17:34PM -0700, Kees Cook wrote: > > > > > > > > > @@ -82,7 +83,7 @@ static __always_inline bool arch_atomic_add_negative(int i, atomic_t *v) > > > > > > > > > > static __always_inline int arch_atomic_add_return(int i, atomic_t *v) > > > > > { > > > > > - return i + xadd(&v->counter, i); > > > > > + return wrapping_add(int, i, xadd(&v->counter, i)); > > > > > } > > > > > #define arch_atomic_add_return arch_atomic_add_return > > > > > > > > this is going to get old *real* quick :-/ > > > > > > > > This must be the ugliest possible way to annotate all this, and then > > > > litter the kernel with all this... urgh. > > > > > > I'm expecting to have explicit wrapping type annotations soon[1], but for > > > the atomics, it's kind of a wash on how intrusive the annotations get. I > > > had originally wanted to mark the function (as I did in other cases) > > > rather than using the helper, but Mark preferred it this way. I'm happy > > > to do whatever! :) > > > > > > -Kees > > > > > > [1] https://github.com/llvm/llvm-project/pull/86618 > > > > This is arse-about-face. Signed stuff wraps per -fno-strict-overflow. > > We've been writing code for years under that assumption. > > > > You want to mark the non-wrapping case. > > That is, anything that actively warns about signed overflow when build > with -fno-strict-overflow is a bug. If you want this warning you have to > explicitly mark things. This is confusing UB with "overflow detection". We're doing the latter. > Signed overflow is not UB, is not a bug. > > Now, it might be unexpected in some places, but fundamentally we run on > 2s complement and expect 2s complement. If you want more, mark it so. Regular C never provided us with enough choice in types to be able to select the overflow resolution strategy. :( So we're stuck mixing expectations into our types. (One early defense you were involved in touched on this too: refcount_t uses a saturating overflow strategy, as that works best for how it gets used.) Regardless, yes, someone intent on wrapping gets their expected 2s complement results, but in the cases were a few values started collecting in some dark corner of protocol handling, having a calculation wrap around is at best a behavioral bug and at worst a total system compromise. Wrapping is the uncommon case here, so we mark those.
On Wed, Apr 24, 2024 at 04:20:20PM -0700, Kees Cook wrote: > > This is arse-about-face. Signed stuff wraps per -fno-strict-overflow. > > We've been writing code for years under that assumption. > > Right, which is why this is going to take time to roll out. :) What we > were really doing with -fno-strict-overflow was getting rid of undefined > behavior. That was really really horrible; we don't need the compiler > hallucinating. Right, but that then got us well defined semantics for signed overflow. > > You want to mark the non-wrapping case. > > What we want is lack of ambiguity. Having done these kinds of things in > the kernel for a while now, I have strong evidence that we get much better > results with the "fail safe" approach, but start by making it non-fatal. > That way we get full coverage, but we don't melt the world for anyone > that doesn't want it, and we can shake things out over a few years. For > example, it has worked well for CONFIG_FORTIFY, CONFIG_UBSAN_BOUNDS, > KCFI, etc. The non-fatal argument doesn't have bearing on the mark warp or mark non-wrap argument though. > The riskier condition is having something wrap when it wasn't expected > (e.g. allocations, pointer offsets, etc), so we start by defining our > regular types as non-wrapping, and annotate the wrapping types (or > specific calculations or functions). But but most of those you mention are unsigned. Are you saying you're making all unsigned variables non-wrap by default too? That's bloody insane. > For signed types in particular, wrapping is overwhelmingly the > uncommon case, so from a purely "how much annotations is needed" > perspective, marking wrapping is also easiest. Yes, there are cases of > expected wrapping, but we'll track them all down and get them marked > unambiguously. But I am confused now, because above you seem to imply you're making unsigned non-wrap too, and there wrapping is *far* more common, and I must say I hate this wrapping_add() thing with a passion. > One thing on the short list is atomics, so here we are. :) Well, there are wrapping and non-wrapping users of atomic. If only C had generics etc.. (and yeah, _Generic doesn't really count).
On Wed, Apr 24, 2024 at 04:30:50PM -0700, Kees Cook wrote: > > That is, anything that actively warns about signed overflow when build > > with -fno-strict-overflow is a bug. If you want this warning you have to > > explicitly mark things. > > This is confusing UB with "overflow detection". We're doing the latter. Well, all of this is confusing to me because it is not presented coherently. The traditional 'must not let signed overflow' is because of the UB nonsense, which we fixed. > > Signed overflow is not UB, is not a bug. > > > > Now, it might be unexpected in some places, but fundamentally we run on > > 2s complement and expect 2s complement. If you want more, mark it so. > > Regular C never provided us with enough choice in types to be able to > select the overflow resolution strategy. :( So we're stuck mixing > expectations into our types. Traditionally C has explicit wrapping for unsigned and UB on signed. We fixed the UB, so now expect wrapping for everything. You want to add overflow, so you should make that a special and preserve semantics for existing code. Also I would very strongly suggest you add an overflow qualifier to the type system and please provide sane means of qualifier manipulation -- stripping qualifiers is painful :/ > Regardless, yes, someone intent on wrapping gets their expected 2s > complement results, but in the cases were a few values started collecting > in some dark corner of protocol handling, having a calculation wrap around > is at best a behavioral bug and at worst a total system compromise. > Wrapping is the uncommon case here, so we mark those. Then feel free to sprinkle copious amounts of 'overflow' qualifiers in the protocol handling code.
On Wed, Apr 24, 2024 at 03:45:07PM -0700, Kees Cook wrote: > On Thu, Apr 25, 2024 at 12:41:41AM +0200, Peter Zijlstra wrote: > > On Wed, Apr 24, 2024 at 12:17:34PM -0700, Kees Cook wrote: > > > > > @@ -82,7 +83,7 @@ static __always_inline bool arch_atomic_add_negative(int i, atomic_t *v) > > > > > > static __always_inline int arch_atomic_add_return(int i, atomic_t *v) > > > { > > > - return i + xadd(&v->counter, i); > > > + return wrapping_add(int, i, xadd(&v->counter, i)); > > > } > > > #define arch_atomic_add_return arch_atomic_add_return > > > > this is going to get old *real* quick :-/ > > > > This must be the ugliest possible way to annotate all this, and then > > litter the kernel with all this... urgh. > > I'm expecting to have explicit wrapping type annotations soon[1], but for > the atomics, it's kind of a wash on how intrusive the annotations get. I > had originally wanted to mark the function (as I did in other cases) > rather than using the helper, but Mark preferred it this way. I'm happy > to do whatever! :) To be clear, I dislike the function annotation because then it applies to *everything* within the function, which is overly broad and the intent becomes unclear. That makes it painful to refactor the code (since e.g. if we want to add another operation to the function which *should not* wrap, that gets silenced too). I'm happy with something that applies to specific types/variables or specific operations (which is what these patches do). As to whether or not we do this at all I'll have to defer to Peter. Mark.
On Thu, Apr 25, 2024 at 11:28:12AM +0200, Peter Zijlstra wrote: > On Wed, Apr 24, 2024 at 04:30:50PM -0700, Kees Cook wrote: > > > > That is, anything that actively warns about signed overflow when build > > > with -fno-strict-overflow is a bug. If you want this warning you have to > > > explicitly mark things. > > > > This is confusing UB with "overflow detection". We're doing the latter. > > Well, all of this is confusing to me because it is not presented > coherently. > > The traditional 'must not let signed overflow' is because of the UB > nonsense, which we fixed. > > > > Signed overflow is not UB, is not a bug. > > > > > > Now, it might be unexpected in some places, but fundamentally we run on > > > 2s complement and expect 2s complement. If you want more, mark it so. > > > > Regular C never provided us with enough choice in types to be able to > > select the overflow resolution strategy. :( So we're stuck mixing > > expectations into our types. > > Traditionally C has explicit wrapping for unsigned and UB on signed. We > fixed the UB, so now expect wrapping for everything. > > You want to add overflow, so you should make that a special and preserve > semantics for existing code. > > Also I would very strongly suggest you add an overflow qualifier to the > type system and please provide sane means of qualifier manipulation -- > stripping qualifiers is painful :/ I agree that having an overflow/nooverflow qualifier that's separate from signed/unsigned would make more sense than inferring that from signed vs unsigned. Mark.
On Thu, Apr 25, 2024 at 11:15:17AM +0100, Mark Rutland wrote: > To be clear, I dislike the function annotation because then it applies to > *everything* within the function, which is overly broad and the intent becomes > unclear. That makes it painful to refactor the code (since e.g. if we want to > add another operation to the function which *should not* wrap, that gets > silenced too). Yeah, I find that a convincing argument for larger functions, but it seemed to me that for these 1-line implementations it was okay. But regardless, yup, no function-level annotation here. > I'm happy with something that applies to specific types/variables or specific > operations (which is what these patches do). Thanks!
On Thu, Apr 25, 2024 at 11:17:52AM +0200, Peter Zijlstra wrote: > On Wed, Apr 24, 2024 at 04:20:20PM -0700, Kees Cook wrote: > > > > This is arse-about-face. Signed stuff wraps per -fno-strict-overflow. > > > We've been writing code for years under that assumption. > > > > Right, which is why this is going to take time to roll out. :) What we > > were really doing with -fno-strict-overflow was getting rid of undefined > > behavior. That was really really horrible; we don't need the compiler > > hallucinating. > > Right, but that then got us well defined semantics for signed overflow. Yes, and this gets us to the next step: disambiguation for general users. It's good that we have a well-defined overflow resolution strategy, but our decades of persistent wrap-around flaws in the kernel show that many devs (even experienced ones) produce code with unexpected and unwanted (to the logic of the code) wrap-around. So we have to find a way to distinguish wrapping and non-wrapping operations or types up front and in a clear way. > > > > You want to mark the non-wrapping case. > > > > What we want is lack of ambiguity. Having done these kinds of things in > > the kernel for a while now, I have strong evidence that we get much better > > results with the "fail safe" approach, but start by making it non-fatal. > > That way we get full coverage, but we don't melt the world for anyone > > that doesn't want it, and we can shake things out over a few years. For > > example, it has worked well for CONFIG_FORTIFY, CONFIG_UBSAN_BOUNDS, > > KCFI, etc. > > The non-fatal argument doesn't have bearing on the mark warp or mark > non-wrap argument though. This gets at the strategy of refactoring our code to gain our unambiguous coverage. Since we can't sanely have a flag-day, we have to go piecemeal, and there will continue to be places where the coverage was missed, and so we want to progress through marking wrapping cases without BUGing the kernel. (We don't care about catching non-wrapping -- the exceptional condition is hitting an overflow.) > > The riskier condition is having something wrap when it wasn't expected > > (e.g. allocations, pointer offsets, etc), so we start by defining our > > regular types as non-wrapping, and annotate the wrapping types (or > > specific calculations or functions). > > But but most of those you mention are unsigned. Are you saying you're > making all unsigned variables non-wrap by default too? That's bloody > insane. We have a mix (and a regular confusion even in core code) where "int" gets passed around even though at one end or another of a call chain it's actually u32 or u16 or whatever. Regardless, yes, the next step after signed overflow mitigation would be unsigned overflow mitigation, and as you suggest, it's much more tricky. > > For signed types in particular, wrapping is overwhelmingly the > > uncommon case, so from a purely "how much annotations is needed" > > perspective, marking wrapping is also easiest. Yes, there are cases of > > expected wrapping, but we'll track them all down and get them marked > > unambiguously. > > But I am confused now, because above you seem to imply you're making > unsigned non-wrap too, and there wrapping is *far* more common, and I > must say I hate this wrapping_add() thing with a passion. Yes, most people are not a fan of the wrapping_*() helpers, which is why I'm trying to get a typedef attribute created. But again, to gain the "fail safe by default" coverage, we have to start with the assumption that the default is non-wrapping, and mark those that aren't. (Otherwise we're not actually catching unexpected cases.) And no, it's not going to be over-night. It's taken almost 5 years to disambiguate array bounds and we're still not done. :) > > One thing on the short list is atomics, so here we are. :) > > Well, there are wrapping and non-wrapping users of atomic. If only C had > generics etc.. (and yeah, _Generic doesn't really count). Non-wrapping users of atomics should be using refcount_t, which is our non-wrapping atomic type. But regardless, atomics are internally wrapping, yes? Anyway, I suspect this whole plan needs wider discussion. I will write up a more complete RFC that covers my plans, including the rationale for why we should adopt this in a certain way. (These kinds of strategic RFCs don't usually get much traction since our development style is much more "show the patches", so that's why I have been just sending patches. But since it's a pretty big topic, I'll give it a shot...)
Kees Cook <keescook@chromium.org> wrote: > - return i + xadd(&v->counter, i); > + return wrapping_add(int, i, xadd(&v->counter, i)); Ewww. Can't you just mark the variable as wrapping in some way, either by: unsigned int __cyclic counter; or, to use rxrpc packet sequence numbers as an example: typedef unsigned int __cyclic rxrpc_seq_t; rxrpc_seq_t tx_top; Then you can get the compiler to spit out a warning if you use <, <=, > or >= on the numbers as an added bonus. (You should use before() and after() instead). David
On Fri, Apr 26, 2024 at 08:40:50AM +0100, David Howells wrote: > Kees Cook <keescook@chromium.org> wrote: > > > - return i + xadd(&v->counter, i); > > + return wrapping_add(int, i, xadd(&v->counter, i)); > > Ewww. Can't you just mark the variable as wrapping in some way, either by: > > unsigned int __cyclic counter; Yeah, that's the plan now. Justin is currently working on the "wraps" attribute for Clang: https://github.com/llvm/llvm-project/pull/86618
diff --git a/arch/x86/include/asm/atomic.h b/arch/x86/include/asm/atomic.h index 55a55ec04350..a5862a258760 100644 --- a/arch/x86/include/asm/atomic.h +++ b/arch/x86/include/asm/atomic.h @@ -3,6 +3,7 @@ #define _ASM_X86_ATOMIC_H #include <linux/compiler.h> +#include <linux/overflow.h> #include <linux/types.h> #include <asm/alternative.h> #include <asm/cmpxchg.h> @@ -82,7 +83,7 @@ static __always_inline bool arch_atomic_add_negative(int i, atomic_t *v) static __always_inline int arch_atomic_add_return(int i, atomic_t *v) { - return i + xadd(&v->counter, i); + return wrapping_add(int, i, xadd(&v->counter, i)); } #define arch_atomic_add_return arch_atomic_add_return diff --git a/arch/x86/include/asm/atomic64_32.h b/arch/x86/include/asm/atomic64_32.h index 3486d91b8595..608b100e8ffe 100644 --- a/arch/x86/include/asm/atomic64_32.h +++ b/arch/x86/include/asm/atomic64_32.h @@ -254,7 +254,7 @@ static __always_inline s64 arch_atomic64_fetch_add(s64 i, atomic64_t *v) { s64 old, c = 0; - while ((old = arch_atomic64_cmpxchg(v, c, c + i)) != c) + while ((old = arch_atomic64_cmpxchg(v, c, wrapping_add(s64, c, i))) != c) c = old; return old; diff --git a/arch/x86/include/asm/atomic64_64.h b/arch/x86/include/asm/atomic64_64.h index 3165c0feedf7..f1dc8aa54b52 100644 --- a/arch/x86/include/asm/atomic64_64.h +++ b/arch/x86/include/asm/atomic64_64.h @@ -76,7 +76,7 @@ static __always_inline bool arch_atomic64_add_negative(s64 i, atomic64_t *v) static __always_inline s64 arch_atomic64_add_return(s64 i, atomic64_t *v) { - return i + xadd(&v->counter, i); + return wrapping_add(s64, i, xadd(&v->counter, i)); } #define arch_atomic64_add_return arch_atomic64_add_return
Use add_wrap() to annotate the addition in atomic_add_return() as expecting to wrap around. Signed-off-by: Kees Cook <keescook@chromium.org> --- Cc: Will Deacon <will@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: x86@kernel.org Cc: "H. Peter Anvin" <hpa@zytor.com> --- arch/x86/include/asm/atomic.h | 3 ++- arch/x86/include/asm/atomic64_32.h | 2 +- arch/x86/include/asm/atomic64_64.h | 2 +- 3 files changed, 4 insertions(+), 3 deletions(-)