mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-08-27 22:13:55 -04:00
02475538be
While the GCC and Clang compilers already define __ASSEMBLER__ automatically when compiling assembly code, __ASSEMBLY__ is a macro that only gets defined by the Makefiles in the kernel. This can be very confusing when switching between userspace and kernelspace coding, or when dealing with uapi headers that rather should use __ASSEMBLER__ instead. So standardize now on the __ASSEMBLER__ macro that is provided by the compilers. Signed-off-by: Thomas Huth <thuth@redhat.com> Signed-off-by: Thomas Gleixner <tglx@kernel.org> Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Link: https://patch.msgid.link/20260619100600.121042-1-thuth@redhat.com
117 lines
3.0 KiB
C
117 lines
3.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
#ifndef __VDSO_HELPERS_H
|
|
#define __VDSO_HELPERS_H
|
|
|
|
#ifndef __ASSEMBLER__
|
|
|
|
#include <asm/barrier.h>
|
|
#include <vdso/datapage.h>
|
|
#include <vdso/processor.h>
|
|
#include <vdso/clocksource.h>
|
|
|
|
static __always_inline bool vdso_is_timens_clock(const struct vdso_clock *vc)
|
|
{
|
|
return IS_ENABLED(CONFIG_TIME_NS) && vc->clock_mode == VDSO_CLOCKMODE_TIMENS;
|
|
}
|
|
|
|
static __always_inline u32 vdso_read_begin(const struct vdso_clock *vc)
|
|
{
|
|
u32 seq;
|
|
|
|
while (unlikely((seq = READ_ONCE(vc->seq)) & 1))
|
|
cpu_relax();
|
|
|
|
smp_rmb();
|
|
return seq;
|
|
}
|
|
|
|
/*
|
|
* Variant of vdso_read_begin() to handle VDSO_CLOCKMODE_TIMENS.
|
|
*
|
|
* Time namespace enabled tasks have a special VVAR page installed which has
|
|
* vc->seq set to 1 and vc->clock_mode set to VDSO_CLOCKMODE_TIMENS. For non
|
|
* time namespace affected tasks this does not affect performance because if
|
|
* vc->seq is odd, i.e. a concurrent update is in progress the extra check for
|
|
* vc->clock_mode is just a few extra instructions while spin waiting for
|
|
* vc->seq to become even again.
|
|
*/
|
|
static __always_inline bool vdso_read_begin_timens(const struct vdso_clock *vc, u32 *seq)
|
|
{
|
|
while (unlikely((*seq = READ_ONCE(vc->seq)) & 1)) {
|
|
if (vdso_is_timens_clock(vc))
|
|
return true;
|
|
cpu_relax();
|
|
}
|
|
smp_rmb();
|
|
|
|
return false;
|
|
}
|
|
|
|
static __always_inline u32 vdso_read_retry(const struct vdso_clock *vc,
|
|
u32 start)
|
|
{
|
|
u32 seq;
|
|
|
|
smp_rmb();
|
|
seq = READ_ONCE(vc->seq);
|
|
return unlikely(seq != start);
|
|
}
|
|
|
|
static __always_inline void vdso_write_seq_begin(struct vdso_clock *vc)
|
|
{
|
|
/*
|
|
* WRITE_ONCE() is required otherwise the compiler can validly tear
|
|
* updates to vc->seq and it is possible that the value seen by the
|
|
* reader is inconsistent.
|
|
*/
|
|
WRITE_ONCE(vc->seq, vc->seq + 1);
|
|
}
|
|
|
|
static __always_inline void vdso_write_seq_end(struct vdso_clock *vc)
|
|
{
|
|
/*
|
|
* WRITE_ONCE() is required otherwise the compiler can validly tear
|
|
* updates to vc->seq and it is possible that the value seen by the
|
|
* reader is inconsistent.
|
|
*/
|
|
WRITE_ONCE(vc->seq, vc->seq + 1);
|
|
}
|
|
|
|
static __always_inline void vdso_write_begin_clock(struct vdso_clock *vc)
|
|
{
|
|
vdso_write_seq_begin(vc);
|
|
/* Ensure the sequence invalidation is visible before data is modified */
|
|
smp_wmb();
|
|
}
|
|
|
|
static __always_inline void vdso_write_end_clock(struct vdso_clock *vc)
|
|
{
|
|
/* Ensure the data update is visible before the sequence is set valid again */
|
|
smp_wmb();
|
|
vdso_write_seq_end(vc);
|
|
}
|
|
|
|
static __always_inline void vdso_write_begin(struct vdso_time_data *vd)
|
|
{
|
|
struct vdso_clock *vc = vd->clock_data;
|
|
|
|
vdso_write_seq_begin(&vc[CS_HRES_COARSE]);
|
|
vdso_write_seq_begin(&vc[CS_RAW]);
|
|
/* Ensure the sequence invalidation is visible before data is modified */
|
|
smp_wmb();
|
|
}
|
|
|
|
static __always_inline void vdso_write_end(struct vdso_time_data *vd)
|
|
{
|
|
struct vdso_clock *vc = vd->clock_data;
|
|
|
|
/* Ensure the data update is visible before the sequence is set valid again */
|
|
smp_wmb();
|
|
vdso_write_seq_end(&vc[CS_HRES_COARSE]);
|
|
vdso_write_seq_end(&vc[CS_RAW]);
|
|
}
|
|
|
|
#endif /* !__ASSEMBLER__ */
|
|
|
|
#endif /* __VDSO_HELPERS_H */
|