From 5694289ce183bc3336407a78c8c722a0b9208f9b Mon Sep 17 00:00:00 2001 From: "peterz@infradead.org" Date: Thu, 21 Sep 2023 12:45:08 +0200 Subject: futex: Flag conversion MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Futex has 3 sets of flags: - legacy futex op bits - futex2 flags - internal flags Add a few helpers to convert from the API flags into the internal flags. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Thomas Gleixner Reviewed-by: André Almeida Link: https://lore.kernel.org/r/20230921105247.722140574@noisy.programming.kicks-ass.net --- kernel/futex/futex.h | 63 ++++++++++++++++++++++++++++++++++++++++++++++--- kernel/futex/syscalls.c | 24 +++++++------------ kernel/futex/waitwake.c | 4 ++-- 3 files changed, 71 insertions(+), 20 deletions(-) (limited to 'kernel') diff --git a/kernel/futex/futex.h b/kernel/futex/futex.h index b5379c0e6d6d..68fc052dc09b 100644 --- a/kernel/futex/futex.h +++ b/kernel/futex/futex.h @@ -5,6 +5,7 @@ #include #include #include +#include #ifdef CONFIG_PREEMPT_RT #include @@ -16,8 +17,15 @@ * Futex flags used to encode options to functions and preserve them across * restarts. */ +#define FLAGS_SIZE_8 0x00 +#define FLAGS_SIZE_16 0x01 +#define FLAGS_SIZE_32 0x02 +#define FLAGS_SIZE_64 0x03 + +#define FLAGS_SIZE_MASK 0x03 + #ifdef CONFIG_MMU -# define FLAGS_SHARED 0x01 +# define FLAGS_SHARED 0x10 #else /* * NOMMU does not have per process address space. Let the compiler optimize @@ -25,8 +33,57 @@ */ # define FLAGS_SHARED 0x00 #endif -#define FLAGS_CLOCKRT 0x02 -#define FLAGS_HAS_TIMEOUT 0x04 +#define FLAGS_CLOCKRT 0x20 +#define FLAGS_HAS_TIMEOUT 0x40 +#define FLAGS_NUMA 0x80 + +/* FUTEX_ to FLAGS_ */ +static inline unsigned int futex_to_flags(unsigned int op) +{ + unsigned int flags = FLAGS_SIZE_32; + + if (!(op & FUTEX_PRIVATE_FLAG)) + flags |= FLAGS_SHARED; + + if (op & FUTEX_CLOCK_REALTIME) + flags |= FLAGS_CLOCKRT; + + return flags; +} + +/* FUTEX2_ to FLAGS_ */ +static inline unsigned int futex2_to_flags(unsigned int flags2) +{ + unsigned int flags = flags2 & FUTEX2_SIZE_MASK; + + if (!(flags2 & FUTEX2_PRIVATE)) + flags |= FLAGS_SHARED; + + if (flags2 & FUTEX2_NUMA) + flags |= FLAGS_NUMA; + + return flags; +} + +static inline unsigned int futex_size(unsigned int flags) +{ + return 1 << (flags & FLAGS_SIZE_MASK); +} + +static inline bool futex_flags_valid(unsigned int flags) +{ + /* Only 64bit futexes for 64bit code */ + if (!IS_ENABLED(CONFIG_64BIT) || in_compat_syscall()) { + if ((flags & FLAGS_SIZE_MASK) == FLAGS_SIZE_64) + return false; + } + + /* Only 32bit futexes are implemented -- for now */ + if ((flags & FLAGS_SIZE_MASK) != FLAGS_SIZE_32) + return false; + + return true; +} #ifdef CONFIG_FAIL_FUTEX extern bool should_fail_futex(bool fshared); diff --git a/kernel/futex/syscalls.c b/kernel/futex/syscalls.c index 953f0a49de3a..948ac247c1c6 100644 --- a/kernel/futex/syscalls.c +++ b/kernel/futex/syscalls.c @@ -1,6 +1,5 @@ // SPDX-License-Identifier: GPL-2.0-or-later -#include #include #include @@ -85,15 +84,12 @@ err_unlock: long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout, u32 __user *uaddr2, u32 val2, u32 val3) { + unsigned int flags = futex_to_flags(op); int cmd = op & FUTEX_CMD_MASK; - unsigned int flags = 0; - if (!(op & FUTEX_PRIVATE_FLAG)) - flags |= FLAGS_SHARED; - - if (op & FUTEX_CLOCK_REALTIME) { - flags |= FLAGS_CLOCKRT; - if (cmd != FUTEX_WAIT_BITSET && cmd != FUTEX_WAIT_REQUEUE_PI && + if (flags & FLAGS_CLOCKRT) { + if (cmd != FUTEX_WAIT_BITSET && + cmd != FUTEX_WAIT_REQUEUE_PI && cmd != FUTEX_LOCK_PI2) return -ENOSYS; } @@ -201,21 +197,19 @@ static int futex_parse_waitv(struct futex_vector *futexv, unsigned int i; for (i = 0; i < nr_futexes; i++) { + unsigned int flags; + if (copy_from_user(&aux, &uwaitv[i], sizeof(aux))) return -EFAULT; if ((aux.flags & ~FUTEX2_VALID_MASK) || aux.__reserved) return -EINVAL; - if (!IS_ENABLED(CONFIG_64BIT) || in_compat_syscall()) { - if ((aux.flags & FUTEX2_SIZE_MASK) == FUTEX2_SIZE_U64) - return -EINVAL; - } - - if ((aux.flags & FUTEX2_SIZE_MASK) != FUTEX2_SIZE_U32) + flags = futex2_to_flags(aux.flags); + if (!futex_flags_valid(flags)) return -EINVAL; - futexv[i].w.flags = aux.flags; + futexv[i].w.flags = flags; futexv[i].w.val = aux.val; futexv[i].w.uaddr = aux.uaddr; futexv[i].q = futex_q_init; diff --git a/kernel/futex/waitwake.c b/kernel/futex/waitwake.c index ba01b9408203..fa9757766103 100644 --- a/kernel/futex/waitwake.c +++ b/kernel/futex/waitwake.c @@ -419,11 +419,11 @@ static int futex_wait_multiple_setup(struct futex_vector *vs, int count, int *wo */ retry: for (i = 0; i < count; i++) { - if ((vs[i].w.flags & FUTEX_PRIVATE_FLAG) && retry) + if (!(vs[i].w.flags & FLAGS_SHARED) && retry) continue; ret = get_futex_key(u64_to_user_ptr(vs[i].w.uaddr), - !(vs[i].w.flags & FUTEX_PRIVATE_FLAG), + vs[i].w.flags & FLAGS_SHARED, &vs[i].q.key, FUTEX_READ); if (unlikely(ret)) -- cgit v1.2.3