Minimalistic functionality for having the write rare version of atomic_long_t data.
Signed-off-by: Igor Stoppa <[email protected]> CC: Will Deacon <[email protected]> CC: Peter Zijlstra <[email protected]> CC: Boqun Feng <[email protected]> CC: Arnd Bergmann <[email protected]> CC: [email protected] CC: [email protected] --- MAINTAINERS | 1 + include/linux/pratomic-long.h | 73 +++++++++++++++++++++++++++++++++++ 2 files changed, 74 insertions(+) create mode 100644 include/linux/pratomic-long.h diff --git a/MAINTAINERS b/MAINTAINERS index e7f7cb1682a6..9d72688d00a3 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -9466,6 +9466,7 @@ F: mm/test_pmalloc.c F: Documentation/core-api/prmem.rst F: include/linux/prlist.h F: lib/test_prlist.c +F: include/linux/pratomic-long.h MEMORY MANAGEMENT L: [email protected] diff --git a/include/linux/pratomic-long.h b/include/linux/pratomic-long.h new file mode 100644 index 000000000000..8f1408593733 --- /dev/null +++ b/include/linux/pratomic-long.h @@ -0,0 +1,73 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Atomic operations for write rare memory */ +#ifndef _LINUX_PRATOMIC_LONG_H +#define _LINUX_PRATOMIC_LONG_H +#include <linux/prmem.h> +#include <linux/compiler.h> +#include <asm-generic/atomic-long.h> + +struct pratomic_long_t { + atomic_long_t l __aligned(sizeof(atomic_long_t)); +} __aligned(sizeof(atomic_long_t)); + +#define PRATOMIC_LONG_INIT(i) { \ + .l = ATOMIC_LONG_INIT((i)), \ +} + +static __always_inline +bool __pratomic_long_op(bool inc, struct pratomic_long_t *l) +{ + struct page *page; + uintptr_t base; + uintptr_t offset; + unsigned long flags; + size_t size = sizeof(*l); + bool is_virt = __is_wr_after_init(l, size); + + if (WARN(!(is_virt || likely(__is_wr_pool(l, size))), + WR_ERR_RANGE_MSG)) + return false; + local_irq_save(flags); + if (is_virt) + page = virt_to_page(l); + else + vmalloc_to_page(l); + offset = (~PAGE_MASK) & (uintptr_t)l; + base = (uintptr_t)vmap(&page, 1, VM_MAP, PAGE_KERNEL); + if (WARN(!base, WR_ERR_PAGE_MSG)) { + local_irq_restore(flags); + return false; + } + if (inc) + atomic_long_inc((atomic_long_t *)(base + offset)); + else + atomic_long_dec((atomic_long_t *)(base + offset)); + vunmap((void *)base); + local_irq_restore(flags); + return true; + +} + +/** + * pratomic_long_inc - atomic increment of rare write long + * @l: address of the variable of type struct pratomic_long_t + * + * Return: true on success, false otherwise + */ +static __always_inline bool pratomic_long_inc(struct pratomic_long_t *l) +{ + return __pratomic_long_op(true, l); +} + +/** + * pratomic_long_inc - atomic decrement of rare write long + * @l: address of the variable of type struct pratomic_long_t + * + * Return: true on success, false otherwise + */ +static __always_inline bool pratomic_long_dec(struct pratomic_long_t *l) +{ + return __pratomic_long_op(false, l); +} + +#endif -- 2.17.1
