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authorJosé Pekkarinen <jose.pekkarinen@nokia.com>2016-04-11 10:41:07 +0300
committerJosé Pekkarinen <jose.pekkarinen@nokia.com>2016-04-13 08:17:18 +0300
commite09b41010ba33a20a87472ee821fa407a5b8da36 (patch)
treed10dc367189862e7ca5c592f033dc3726e1df4e3 /kernel/tools/testing/selftests/x86/thunks_32.S
parentf93b97fd65072de626c074dbe099a1fff05ce060 (diff)
These changes are the raw update to linux-4.4.6-rt14. Kernel sources
are taken from kernel.org, and rt patch from the rt wiki download page. During the rebasing, the following patch collided: Force tick interrupt and get rid of softirq magic(I70131fb85). Collisions have been removed because its logic was found on the source already. Change-Id: I7f57a4081d9deaa0d9ccfc41a6c8daccdee3b769 Signed-off-by: José Pekkarinen <jose.pekkarinen@nokia.com>
Diffstat (limited to 'kernel/tools/testing/selftests/x86/thunks_32.S')
-rw-r--r--kernel/tools/testing/selftests/x86/thunks_32.S55
1 files changed, 55 insertions, 0 deletions
diff --git a/kernel/tools/testing/selftests/x86/thunks_32.S b/kernel/tools/testing/selftests/x86/thunks_32.S
new file mode 100644
index 000000000..29b644bb9
--- /dev/null
+++ b/kernel/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