Minimalistic functionality for having the write rare version of
atomic_long_t data.
Signed-off-by: Igor Stoppa <igor.stoppa@xxxxxxxxxx>
CC: Will Deacon <will.deacon@xxxxxxx>
CC: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CC: Boqun Feng <boqun.feng@xxxxxxxxx>
CC: Arnd Bergmann <arnd@xxxxxxxx>
CC: linux-arch@xxxxxxxxxxxxxxx
CC: linux-kernel@xxxxxxxxxxxxxxx
---
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: linux-mm@xxxxxxxxx
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
