Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 55 insertions, 0 deletions

diff --git a/tools/testing/selftests/x86/thunks_32.S b/tools/testing/selftests/x86/thunks_32.S
new file mode 100644
index 000000000..29b644bb9
--- /dev/null
+++ b/tools/testing/selftests/x86/thunks_32.S
@@ -0,0 +1,55 @@
+/*
+ * thunks_32.S - assembly helpers for mixed-bitness code
+ * Copyright (c) 2015 Denys Vlasenko
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * These are little helpers that make it easier to switch bitness on
+ * the fly.
+ */
+
+	.text
+	.code32
+
+	.global call64_from_32
+	.type call32_from_64, @function
+
+	// 4(%esp): function to call
+call64_from_32:
+	// Fetch function address
+	mov	4(%esp), %eax
+
+	// Save registers which are callee-clobbered by 64-bit ABI
+	push	%ecx
+	push	%edx
+	push	%esi
+	push	%edi
+
+	// Switch to long mode
+	jmp	$0x33,$1f
+1:	.code64
+
+	// Call the function
+	call	*%rax
+
+	// Switch to compatibility mode
+	push	$0x23  /* USER32_CS */
+	.code32; push $1f; .code64 /* hack: can't have X86_64_32S relocation in 32-bit ELF */
+	lretq
+1:	.code32
+
+	pop	%edi
+	pop	%esi
+	pop	%edx
+	pop	%ecx
+
+	ret
+
+.size call64_from_32, .-call64_from_32