| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <YsC7qlQba4+VJ3W1@yury-laptop>
Date: Sat, 2 Jul 2022 14:42:02 -0700
From: Yury Norov <yury.norov@...il.com>
To: Sander Vanheule <sander@...nheule.net>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org,
Andrew Morton <akpm@...ux-foundation.org>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
elver@...gle.com, gregkh@...uxfoundation.org,
Peter Zijlstra <peterz@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>, vschneid@...hat.com,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
"H . Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH v4 2/5] cpumask: Fix invalid uniprocessor mask assumption
On Sat, Jul 02, 2022 at 06:08:25PM +0200, Sander Vanheule wrote:
> On uniprocessor builds, any CPU mask is assumed to contain exactly one
> CPU (cpu0). This assumption ignores the existence of empty masks,
> resulting in incorrect behaviour.
> cpumask_first_zero(), cpumask_next_zero(), and for_each_cpu_not() don't
> provide behaviour matching the assumption that a UP mask is always "1",
> and instead provide behaviour matching the empty mask.
>
> Drop the incorrectly optimised code and use the generic implementations
> in all cases.
>
> Signed-off-by: Sander Vanheule <sander@...nheule.net>
Suggested-by: Yury Norov <yury.norov@...il.com>
> ---
>
> Notes:
> Changes since v3:
> - Add back UP-optimised cpumask_local_spread, cpumask_any_distribute,
> cpumask_any_and_distribute
>
> Changes since v1:
> - Drop UP implementations instead of trying to fix them
>
> include/linux/cpumask.h | 99 ++++++++---------------------------------
> lib/Makefile | 3 +-
> lib/cpumask.c | 2 +
> 3 files changed, 22 insertions(+), 82 deletions(-)
>
> diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
> index fe29ac7cc469..7fbef41b3093 100644
> --- a/include/linux/cpumask.h
> +++ b/include/linux/cpumask.h
> @@ -116,85 +116,6 @@ static __always_inline unsigned int cpumask_check(unsigned int cpu)
> return cpu;
> }
>
> -#if NR_CPUS == 1
> -/* Uniprocessor. Assume all masks are "1". */
> -static inline unsigned int cpumask_first(const struct cpumask *srcp)
> -{
> - return 0;
> -}
> -
> -static inline unsigned int cpumask_first_zero(const struct cpumask *srcp)
> -{
> - return 0;
> -}
> -
> -static inline unsigned int cpumask_first_and(const struct cpumask *srcp1,
> - const struct cpumask *srcp2)
> -{
> - return 0;
> -}
> -
> -static inline unsigned int cpumask_last(const struct cpumask *srcp)
> -{
> - return 0;
> -}
> -
> -/* Valid inputs for n are -1 and 0. */
> -static inline unsigned int cpumask_next(int n, const struct cpumask *srcp)
> -{
> - return n+1;
> -}
> -
> -static inline unsigned int cpumask_next_zero(int n, const struct cpumask *srcp)
> -{
> - return n+1;
> -}
> -
> -static inline unsigned int cpumask_next_and(int n,
> - const struct cpumask *srcp,
> - const struct cpumask *andp)
> -{
> - return n+1;
> -}
> -
> -static inline unsigned int cpumask_next_wrap(int n, const struct cpumask *mask,
> - int start, bool wrap)
> -{
> - /* cpu0 unless stop condition, wrap and at cpu0, then nr_cpumask_bits */
> - return (wrap && n == 0);
> -}
> -
> -/* cpu must be a valid cpu, ie 0, so there's no other choice. */
> -static inline unsigned int cpumask_any_but(const struct cpumask *mask,
> - unsigned int cpu)
> -{
> - return 1;
> -}
> -
> -static inline unsigned int cpumask_local_spread(unsigned int i, int node)
> -{
> - return 0;
> -}
> -
> -static inline int cpumask_any_and_distribute(const struct cpumask *src1p,
> - const struct cpumask *src2p) {
> - return cpumask_first_and(src1p, src2p);
> -}
> -
> -static inline int cpumask_any_distribute(const struct cpumask *srcp)
> -{
> - return cpumask_first(srcp);
> -}
> -
> -#define for_each_cpu(cpu, mask) \
> - for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask)
> -#define for_each_cpu_not(cpu, mask) \
> - for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask)
> -#define for_each_cpu_wrap(cpu, mask, start) \
> - for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask, (void)(start))
> -#define for_each_cpu_and(cpu, mask1, mask2) \
> - for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask1, (void)mask2)
> -#else
> /**
> * cpumask_first - get the first cpu in a cpumask
> * @srcp: the cpumask pointer
> @@ -260,10 +181,29 @@ static inline unsigned int cpumask_next_zero(int n, const struct cpumask *srcp)
>
> int __pure cpumask_next_and(int n, const struct cpumask *, const struct cpumask *);
> int __pure cpumask_any_but(const struct cpumask *mask, unsigned int cpu);
> +
> +#if NR_CPUS == 1
> +/* Uniprocessor: there is only one valid CPU */
> +static inline unsigned int cpumask_local_spread(unsigned int i, int node)
> +{
> + return 0;
> +}
> +
> +static inline int cpumask_any_and_distribute(const struct cpumask *src1p,
> + const struct cpumask *src2p) {
> + return cpumask_first_and(src1p, src2p);
> +}
> +
> +static inline int cpumask_any_distribute(const struct cpumask *srcp)
> +{
> + return cpumask_first(srcp);
> +}
> +#else
> unsigned int cpumask_local_spread(unsigned int i, int node);
> int cpumask_any_and_distribute(const struct cpumask *src1p,
> const struct cpumask *src2p);
> int cpumask_any_distribute(const struct cpumask *srcp);
> +#endif /* NR_CPUS */
>
> /**
> * for_each_cpu - iterate over every cpu in a mask
> @@ -324,7 +264,6 @@ extern int cpumask_next_wrap(int n, const struct cpumask *mask, int start, bool
> for ((cpu) = -1; \
> (cpu) = cpumask_next_and((cpu), (mask1), (mask2)), \
> (cpu) < nr_cpu_ids;)
> -#endif /* SMP */
>
> #define CPU_BITS_NONE \
> { \
> diff --git a/lib/Makefile b/lib/Makefile
> index f99bf61f8bbc..bcc7e8ea0cde 100644
> --- a/lib/Makefile
> +++ b/lib/Makefile
> @@ -34,10 +34,9 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
> is_single_threaded.o plist.o decompress.o kobject_uevent.o \
> earlycpio.o seq_buf.o siphash.o dec_and_lock.o \
> nmi_backtrace.o nodemask.o win_minmax.o memcat_p.o \
> - buildid.o
> + buildid.o cpumask.o
>
> lib-$(CONFIG_PRINTK) += dump_stack.o
> -lib-$(CONFIG_SMP) += cpumask.o
>
> lib-y += kobject.o klist.o
> obj-y += lockref.o
> diff --git a/lib/cpumask.c b/lib/cpumask.c
> index a971a82d2f43..b9728513a4d4 100644
> --- a/lib/cpumask.c
> +++ b/lib/cpumask.c
> @@ -192,6 +192,7 @@ void __init free_bootmem_cpumask_var(cpumask_var_t mask)
> }
> #endif
>
> +#if NR_CPUS > 1
> /**
> * cpumask_local_spread - select the i'th cpu with local numa cpu's first
> * @i: index number
> @@ -279,3 +280,4 @@ int cpumask_any_distribute(const struct cpumask *srcp)
> return next;
> }
> EXPORT_SYMBOL(cpumask_any_distribute);
> +#endif /* NR_CPUS */
> --
> 2.36.1
Powered by blists - more mailing lists