[PATCH v4 3/7] um: "borrow" atomics from x86 architecture

anton.ivanov
2020-12-11T17:46:23Z

From: Anton Ivanov <anton.ivanov@cambridgegreys.com>

This moves UML on 64 bit from generic atomics to their x86
equivalents.

Generic atomics bracket most operations by interrupts off/interrupts
on. This is quite expensive on UML - it translates to changing
the signal mask and rerunning the signal loop every time.

Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
---
arch/um/include/asm/atomic-x86.h | 1 +
arch/um/include/asm/atomic.h | 7 +++++++
arch/um/include/asm/atomic64_64.h | 1 +
3 files changed, 9 insertions(+)
create mode 120000 arch/um/include/asm/atomic-x86.h
create mode 100644 arch/um/include/asm/atomic.h
create mode 120000 arch/um/include/asm/atomic64_64.h

diff --git a/arch/um/include/asm/atomic-x86.h b/arch/um/include/asm/atomic-x86.h
new file mode 120000
index 000000000000..e71a389e112d
--- /dev/null
+++ b/arch/um/include/asm/atomic-x86.h
@@ -0,0 +1 @@
+../../../x86/include/asm/atomic.h
\ No newline at end of file
diff --git a/arch/um/include/asm/atomic.h b/arch/um/include/asm/atomic.h
new file mode 100644
index 000000000000..6ff22c587c10
--- /dev/null
+++ b/arch/um/include/asm/atomic.h
@@ -0,0 +1,7 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_ATOMIC_XOR_H
+#define _ASM_ATOMIC_XOR_H
+
+#include <asm/atomic-x86.h>
+
+#endif
diff --git a/arch/um/include/asm/atomic64_64.h b/arch/um/include/asm/atomic64_64.h
new file mode 120000
index 000000000000..f817a1478603
--- /dev/null
+++ b/arch/um/include/asm/atomic64_64.h
@@ -0,0 +1 @@
+../../../x86/include/asm/atomic64_64.h
\ No newline at end of file
--
2.20.1