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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-27 10:05:51 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-27 10:05:51 +0000
commit5d1646d90e1f2cceb9f0828f4b28318cd0ec7744 (patch)
treea94efe259b9009378be6d90eb30d2b019d95c194 /arch/arm64/lib/clear_user.S
parentInitial commit. (diff)
downloadlinux-430c2fc249ea5c0536abd21c23382884005c9093.tar.xz
linux-430c2fc249ea5c0536abd21c23382884005c9093.zip
Adding upstream version 5.10.209.upstream/5.10.209upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/arm64/lib/clear_user.S')
-rw-r--r--arch/arm64/lib/clear_user.S50
1 files changed, 50 insertions, 0 deletions
diff --git a/arch/arm64/lib/clear_user.S b/arch/arm64/lib/clear_user.S
new file mode 100644
index 000000000..48a3a26ef
--- /dev/null
+++ b/arch/arm64/lib/clear_user.S
@@ -0,0 +1,50 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Based on arch/arm/lib/clear_user.S
+ *
+ * Copyright (C) 2012 ARM Ltd.
+ */
+#include <linux/linkage.h>
+
+#include <asm/asm-uaccess.h>
+#include <asm/assembler.h>
+
+ .text
+
+/* Prototype: int __arch_clear_user(void *addr, size_t sz)
+ * Purpose : clear some user memory
+ * Params : addr - user memory address to clear
+ * : sz - number of bytes to clear
+ * Returns : number of bytes NOT cleared
+ *
+ * Alignment fixed up by hardware.
+ */
+SYM_FUNC_START(__arch_clear_user)
+ mov x2, x1 // save the size for fixup return
+ subs x1, x1, #8
+ b.mi 2f
+1:
+uao_user_alternative 9f, str, sttr, xzr, x0, 8
+ subs x1, x1, #8
+ b.pl 1b
+2: adds x1, x1, #4
+ b.mi 3f
+uao_user_alternative 9f, str, sttr, wzr, x0, 4
+ sub x1, x1, #4
+3: adds x1, x1, #2
+ b.mi 4f
+uao_user_alternative 9f, strh, sttrh, wzr, x0, 2
+ sub x1, x1, #2
+4: adds x1, x1, #1
+ b.mi 5f
+uao_user_alternative 9f, strb, sttrb, wzr, x0, 0
+5: mov x0, #0
+ ret
+SYM_FUNC_END(__arch_clear_user)
+EXPORT_SYMBOL(__arch_clear_user)
+
+ .section .fixup,"ax"
+ .align 2
+9: mov x0, x2 // return the original size
+ ret
+ .previous