iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

futex: Remove futex_cmpxchg detection

Browse Source 
Now that all architectures have a working futex implementation in any
configuration, remove the runtime detection code.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Acked-by: Vineet Gupta <vgupta@kernel.org>
Acked-by: Max Filippov <jcmvbkbc@gmail.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Link: https://lore.kernel.org/r/20211026100432.1730393-2-arnd@kernel.org
This commit is contained in:
Arnd Bergmann 2021-10-26 12:03:48 +02:00 committed by Thomas Gleixner
parent 3f2bedabb6
commit 3297481d68
15 changed files with 0 additions and 82 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/arc/Kconfig
View File

@ -32,7 +32,6 @@ config ARC
select HAVE_ARCH_TRANSPARENT_HUGEPAGE if ARC_MMU_V4 select HAVE_ARCH_TRANSPARENT_HUGEPAGE if ARC_MMU_V4
select HAVE_DEBUG_STACKOVERFLOW select HAVE_DEBUG_STACKOVERFLOW
select HAVE_DEBUG_KMEMLEAK select HAVE_DEBUG_KMEMLEAK
select HAVE_FUTEX_CMPXCHG if FUTEX
select HAVE_IOREMAP_PROT select HAVE_IOREMAP_PROT
select HAVE_KERNEL_GZIP select HAVE_KERNEL_GZIP
select HAVE_KERNEL_LZMA select HAVE_KERNEL_LZMA

1
arch/arm/Kconfig
View File

@ -92,7 +92,6 @@ config ARM
select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
select HAVE_FUNCTION_GRAPH_TRACER if !THUMB2_KERNEL && !CC_IS_CLANG select HAVE_FUNCTION_GRAPH_TRACER if !THUMB2_KERNEL && !CC_IS_CLANG
select HAVE_FUNCTION_TRACER if !XIP_KERNEL && !(THUMB2_KERNEL && CC_IS_CLANG) select HAVE_FUNCTION_TRACER if !XIP_KERNEL && !(THUMB2_KERNEL && CC_IS_CLANG)
select HAVE_FUTEX_CMPXCHG if FUTEX
select HAVE_GCC_PLUGINS select HAVE_GCC_PLUGINS
select HAVE_HW_BREAKPOINT if PERF_EVENTS && (CPU_V6 || CPU_V6K || CPU_V7) select HAVE_HW_BREAKPOINT if PERF_EVENTS && (CPU_V6 || CPU_V6K || CPU_V7)
select HAVE_IRQ_TIME_ACCOUNTING select HAVE_IRQ_TIME_ACCOUNTING

1
arch/arm64/Kconfig
View File

@ -194,7 +194,6 @@ config ARM64
select HAVE_REGS_AND_STACK_ACCESS_API select HAVE_REGS_AND_STACK_ACCESS_API
select HAVE_POSIX_CPU_TIMERS_TASK_WORK select HAVE_POSIX_CPU_TIMERS_TASK_WORK
select HAVE_FUNCTION_ARG_ACCESS_API select HAVE_FUNCTION_ARG_ACCESS_API
select HAVE_FUTEX_CMPXCHG if FUTEX
select MMU_GATHER_RCU_TABLE_FREE select MMU_GATHER_RCU_TABLE_FREE
select HAVE_RSEQ select HAVE_RSEQ
select HAVE_STACKPROTECTOR select HAVE_STACKPROTECTOR

1
arch/csky/Kconfig
View File

@ -52,7 +52,6 @@ config CSKY
select HAVE_FUNCTION_TRACER select HAVE_FUNCTION_TRACER
select HAVE_FUNCTION_GRAPH_TRACER select HAVE_FUNCTION_GRAPH_TRACER
select HAVE_FUNCTION_ERROR_INJECTION select HAVE_FUNCTION_ERROR_INJECTION
select HAVE_FUTEX_CMPXCHG if FUTEX && SMP
select HAVE_FTRACE_MCOUNT_RECORD select HAVE_FTRACE_MCOUNT_RECORD
select HAVE_KERNEL_GZIP select HAVE_KERNEL_GZIP
select HAVE_KERNEL_LZO select HAVE_KERNEL_LZO

1
arch/m68k/Kconfig
View File

@ -20,7 +20,6 @@ config M68K
select HAVE_ASM_MODVERSIONS select HAVE_ASM_MODVERSIONS
select HAVE_DEBUG_BUGVERBOSE select HAVE_DEBUG_BUGVERBOSE
select HAVE_EFFICIENT_UNALIGNED_ACCESS if !CPU_HAS_NO_UNALIGNED select HAVE_EFFICIENT_UNALIGNED_ACCESS if !CPU_HAS_NO_UNALIGNED
select HAVE_FUTEX_CMPXCHG if MMU && FUTEX
select HAVE_MOD_ARCH_SPECIFIC select HAVE_MOD_ARCH_SPECIFIC
select HAVE_UID16 select HAVE_UID16
select MMU_GATHER_NO_RANGE if MMU select MMU_GATHER_NO_RANGE if MMU

1
arch/riscv/Kconfig
View File

@ -83,7 +83,6 @@ config RISCV
select HAVE_DMA_CONTIGUOUS if MMU select HAVE_DMA_CONTIGUOUS if MMU
select HAVE_EBPF_JIT if MMU select HAVE_EBPF_JIT if MMU
select HAVE_FUNCTION_ERROR_INJECTION select HAVE_FUNCTION_ERROR_INJECTION
select HAVE_FUTEX_CMPXCHG if FUTEX
select HAVE_GCC_PLUGINS select HAVE_GCC_PLUGINS
select HAVE_GENERIC_VDSO if MMU && 64BIT select HAVE_GENERIC_VDSO if MMU && 64BIT
select HAVE_IRQ_TIME_ACCOUNTING select HAVE_IRQ_TIME_ACCOUNTING

1
arch/s390/Kconfig
View File

@ -165,7 +165,6 @@ config S390
select HAVE_FUNCTION_ERROR_INJECTION select HAVE_FUNCTION_ERROR_INJECTION
select HAVE_FUNCTION_GRAPH_TRACER select HAVE_FUNCTION_GRAPH_TRACER
select HAVE_FUNCTION_TRACER select HAVE_FUNCTION_TRACER
select HAVE_FUTEX_CMPXCHG if FUTEX
select HAVE_GCC_PLUGINS select HAVE_GCC_PLUGINS
select HAVE_GENERIC_VDSO select HAVE_GENERIC_VDSO
select HAVE_IOREMAP_PROT if PCI select HAVE_IOREMAP_PROT if PCI

1
arch/sh/Kconfig
View File

@ -34,7 +34,6 @@ config SUPERH
select HAVE_FAST_GUP if MMU select HAVE_FAST_GUP if MMU
select HAVE_FUNCTION_GRAPH_TRACER select HAVE_FUNCTION_GRAPH_TRACER
select HAVE_FUNCTION_TRACER select HAVE_FUNCTION_TRACER
select HAVE_FUTEX_CMPXCHG if FUTEX
select HAVE_FTRACE_MCOUNT_RECORD select HAVE_FTRACE_MCOUNT_RECORD
select HAVE_HW_BREAKPOINT select HAVE_HW_BREAKPOINT
select HAVE_IOREMAP_PROT if MMU && !X2TLB select HAVE_IOREMAP_PROT if MMU && !X2TLB

1
arch/um/Kconfig
View File

@ -14,7 +14,6 @@ config UML
select HAVE_ARCH_SECCOMP_FILTER select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ASM_MODVERSIONS select HAVE_ASM_MODVERSIONS
select HAVE_UID16 select HAVE_UID16
select HAVE_FUTEX_CMPXCHG if FUTEX
select HAVE_DEBUG_KMEMLEAK select HAVE_DEBUG_KMEMLEAK
select HAVE_DEBUG_BUGVERBOSE select HAVE_DEBUG_BUGVERBOSE
select NO_DMA if !UML_DMA_EMULATION select NO_DMA if !UML_DMA_EMULATION

1
arch/um/kernel/skas/uaccess.c
View File

@ -348,7 +348,6 @@ EXPORT_SYMBOL(arch_futex_atomic_op_inuser);
* 0 - On success * 0 - On success
* -EFAULT - User access resulted in a page fault * -EFAULT - User access resulted in a page fault
* -EAGAIN - Atomic operation was unable to complete due to contention * -EAGAIN - Atomic operation was unable to complete due to contention
* -ENOSYS - Function not implemented (only if !HAVE_FUTEX_CMPXCHG)
*/ */
int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,

1
arch/xtensa/Kconfig
View File

@ -31,7 +31,6 @@ config XTENSA
select HAVE_DMA_CONTIGUOUS select HAVE_DMA_CONTIGUOUS
select HAVE_EXIT_THREAD select HAVE_EXIT_THREAD
select HAVE_FUNCTION_TRACER select HAVE_FUNCTION_TRACER
select HAVE_FUTEX_CMPXCHG if !MMU && FUTEX
select HAVE_HW_BREAKPOINT if PERF_EVENTS select HAVE_HW_BREAKPOINT if PERF_EVENTS
select HAVE_IRQ_TIME_ACCOUNTING select HAVE_IRQ_TIME_ACCOUNTING
select HAVE_PCI select HAVE_PCI

8
init/Kconfig
View File

@ -1592,14 +1592,6 @@ config FUTEX_PI
depends on FUTEX && RT_MUTEXES depends on FUTEX && RT_MUTEXES
default y default y
config HAVE_FUTEX_CMPXCHG
bool
depends on FUTEX
help
Architectures should select this if futex_atomic_cmpxchg_inatomic()
is implemented and always working. This removes a couple of runtime
checks.
config EPOLL config EPOLL
bool "Enable eventpoll support" if EXPERT bool "Enable eventpoll support" if EXPERT
default y default y

35
kernel/futex/core.c
View File

@ -41,11 +41,6 @@
#include "futex.h" #include "futex.h"
#include "../locking/rtmutex_common.h" #include "../locking/rtmutex_common.h"
#ifndef CONFIG_HAVE_FUTEX_CMPXCHG
int __read_mostly futex_cmpxchg_enabled;
#endif
/* /*
* The base of the bucket array and its size are always used together * The base of the bucket array and its size are always used together
* (after initialization only in futex_hash()), so ensure that they * (after initialization only in futex_hash()), so ensure that they
@ -776,9 +771,6 @@ static void exit_robust_list(struct task_struct *curr)
unsigned long futex_offset; unsigned long futex_offset;
int rc; int rc;
if (!futex_cmpxchg_enabled)
return;
/* /*
* Fetch the list head (which was registered earlier, via * Fetch the list head (which was registered earlier, via
* sys_set_robust_list()): * sys_set_robust_list()):
@ -874,9 +866,6 @@ static void compat_exit_robust_list(struct task_struct *curr)
compat_long_t futex_offset; compat_long_t futex_offset;
int rc; int rc;
if (!futex_cmpxchg_enabled)
return;
/* /*
* Fetch the list head (which was registered earlier, via * Fetch the list head (which was registered earlier, via
* sys_set_robust_list()): * sys_set_robust_list()):
@ -950,8 +939,6 @@ static void exit_pi_state_list(struct task_struct *curr)
struct futex_hash_bucket *hb; struct futex_hash_bucket *hb;
union futex_key key = FUTEX_KEY_INIT; union futex_key key = FUTEX_KEY_INIT;
if (!futex_cmpxchg_enabled)
return;
/* /*
* We are a ZOMBIE and nobody can enqueue itself on * We are a ZOMBIE and nobody can enqueue itself on
* pi_state_list anymore, but we have to be careful * pi_state_list anymore, but we have to be careful
@ -1125,26 +1112,6 @@ void futex_exit_release(struct task_struct *tsk)
futex_cleanup_end(tsk, FUTEX_STATE_DEAD); futex_cleanup_end(tsk, FUTEX_STATE_DEAD);
} }
static void __init futex_detect_cmpxchg(void)
{
#ifndef CONFIG_HAVE_FUTEX_CMPXCHG
u32 curval;
/*
* This will fail and we want it. Some arch implementations do
* runtime detection of the futex_atomic_cmpxchg_inatomic()
* functionality. We want to know that before we call in any
* of the complex code paths. Also we want to prevent
* registration of robust lists in that case. NULL is
* guaranteed to fault and we get -EFAULT on functional
* implementation, the non-functional ones will return
* -ENOSYS.
*/
if (futex_cmpxchg_value_locked(&curval, NULL, 0, 0) == -EFAULT)
futex_cmpxchg_enabled = 1;
#endif
}
static int __init futex_init(void) static int __init futex_init(void)
{ {
unsigned int futex_shift; unsigned int futex_shift;
@ -1163,8 +1130,6 @@ static int __init futex_init(void)
futex_hashsize, futex_hashsize); futex_hashsize, futex_hashsize);
futex_hashsize = 1UL << futex_shift; futex_hashsize = 1UL << futex_shift;
futex_detect_cmpxchg();
for (i = 0; i < futex_hashsize; i++) { for (i = 0; i < futex_hashsize; i++) {
atomic_set(&futex_queues[i].waiters, 0); atomic_set(&futex_queues[i].waiters, 0);
plist_head_init(&futex_queues[i].chain); plist_head_init(&futex_queues[i].chain);

6
kernel/futex/futex.h
View File

@ -27,12 +27,6 @@
#define FLAGS_CLOCKRT 0x02 #define FLAGS_CLOCKRT 0x02
#define FLAGS_HAS_TIMEOUT 0x04 #define FLAGS_HAS_TIMEOUT 0x04
#ifdef CONFIG_HAVE_FUTEX_CMPXCHG
#define futex_cmpxchg_enabled 1
#else
extern int __read_mostly futex_cmpxchg_enabled;
#endif
#ifdef CONFIG_FAIL_FUTEX #ifdef CONFIG_FAIL_FUTEX
extern bool should_fail_futex(bool fshared); extern bool should_fail_futex(bool fshared);
#else #else

22
kernel/futex/syscalls.c
View File

@ -29,8 +29,6 @@
SYSCALL_DEFINE2(set_robust_list, struct robust_list_head __user *, head, SYSCALL_DEFINE2(set_robust_list, struct robust_list_head __user *, head,
size_t, len) size_t, len)
{ {
if (!futex_cmpxchg_enabled)
return -ENOSYS;
/* /*
* The kernel knows only one size for now: * The kernel knows only one size for now:
*/ */
@ -56,9 +54,6 @@ SYSCALL_DEFINE3(get_robust_list, int, pid,
unsigned long ret; unsigned long ret;
struct task_struct *p; struct task_struct *p;
if (!futex_cmpxchg_enabled)
return -ENOSYS;
rcu_read_lock(); rcu_read_lock();
ret = -ESRCH; ret = -ESRCH;
@ -103,17 +98,6 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
return -ENOSYS; return -ENOSYS;
} }
switch (cmd) {
case FUTEX_LOCK_PI:
case FUTEX_LOCK_PI2:
case FUTEX_UNLOCK_PI:
case FUTEX_TRYLOCK_PI:
case FUTEX_WAIT_REQUEUE_PI:
case FUTEX_CMP_REQUEUE_PI:
if (!futex_cmpxchg_enabled)
return -ENOSYS;
}
switch (cmd) { switch (cmd) {
case FUTEX_WAIT: case FUTEX_WAIT:
val3 = FUTEX_BITSET_MATCH_ANY; val3 = FUTEX_BITSET_MATCH_ANY;
@ -323,9 +307,6 @@ COMPAT_SYSCALL_DEFINE2(set_robust_list,
struct compat_robust_list_head __user *, head, struct compat_robust_list_head __user *, head,
compat_size_t, len) compat_size_t, len)
{ {
if (!futex_cmpxchg_enabled)
return -ENOSYS;
if (unlikely(len != sizeof(*head))) if (unlikely(len != sizeof(*head)))
return -EINVAL; return -EINVAL;
@ -342,9 +323,6 @@ COMPAT_SYSCALL_DEFINE3(get_robust_list, int, pid,
unsigned long ret; unsigned long ret;
struct task_struct *p; struct task_struct *p;
if (!futex_cmpxchg_enabled)
return -ENOSYS;
rcu_read_lock(); rcu_read_lock();
ret = -ESRCH; ret = -ESRCH;