Linux: add a note to the ELF binary what minimum Linux is needed

Change-Id: Ia53158e207a94bf49489fffd14c8d2a1f173ff97
Reviewed-by: Lars Knoll <[email protected]>
Reviewed-by: Marc Mutz <[email protected]>
Reviewed-by: Thiago Macieira <[email protected]>

Author: thiagomacieira

src/corelib/global/global.pri

@@ -59,6 +59,22 @@ if(linux*|hurd*):!cross_compile:!static:!*-armcc* {
    DEFINES += ELF_INTERPRETER=\\\"$$system(LC_ALL=C readelf -l /bin/ls | perl -n -e \'$$prog\')\\\"
 }
 
+linux:!static {
+    precompile_header {
+        # we'll get an error if we just use SOURCES +=
+        no_pch_assembler.commands = $$QMAKE_CC -c $(CFLAGS) $(INCPATH) ${QMAKE_FILE_IN} -o ${QMAKE_FILE_OUT}
+        no_pch_assembler.dependency_type = TYPE_C
+        no_pch_assembler.output = ${QMAKE_VAR_OBJECTS_DIR}${QMAKE_FILE_BASE}$${first(QMAKE_EXT_OBJ)}
+        no_pch_assembler.input = NO_PCH_ASM
+        no_pch_assembler.name = compiling[no_pch] ${QMAKE_FILE_IN}
+        silent: no_pch_assembler.commands = @echo compiling[no_pch] ${QMAKE_FILE_IN} && $$no_pch_assembler.commands
+        QMAKE_EXTRA_COMPILERS += no_pch_assembler
+        NO_PCH_ASM += global/minimum-linux.S
+    } else {
+        SOURCES += global/minimum-linux.S
+    }
+}
+
 qtConfig(slog2): \
     LIBS_PRIVATE += -lslog2
 

src/corelib/global/minimum-linux.S

@@ -0,0 +1,92 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 Intel Corporation.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+/* Copied from #include <elf.h>:
+ */
+#define ELF_NOTE_GNU            "GNU"
+#define NT_GNU_ABI_TAG          1
+#define ELF_NOTE_OS_LINUX       0
+
+#ifdef __arm__
+#  define progbits              %progbits
+#  define note                  %note
+#else
+#  define progbits              @progbits
+#  define note                  @note
+#endif
+
+/* Add information for the ELF dynamic linker what the minimum Linux version
+ * required for Qt is.
+ *
+ * The .note.ABI-tag note section is defined at
+ *  https://refspecs.linuxfoundation.org/LSB_5.0.0/LSB-Core-generic/LSB-Core-generic/noteabitag.html
+ */
+
+    .section    ".note.GNU-stack", "", progbits
+    .section    ".note.ABI-tag", "a", note
+    .align      4       /* we have 32-bit data */
+
+/*  * For the format of the note section's contents, see Elf32_Nhdr / Elf64_Nhdr */
+    .long       .Lnameend-.Lname        /* n_namesz */
+    .long       16                      /* n_descsz(16 bytes, normative) */
+    .long       NT_GNU_ABI_TAG          /* n_type */
+
+.Lname:
+    .asciz      ELF_NOTE_GNU
+.Lnameend:
+
+/* Operating systems: */
+    .long       ELF_NOTE_OS_LINUX
+
+/* Minimum Linux kernel version:
+ * We require the following features in Qt (unconditional, no fallback):
+ *   Feature                    Added in version
+ * - inotify_init1              before 2.6.12-rc12
+ * - futex(2)                   before 2.6.12-rc12
+ * - FUTEX_PRIVATE_FLAG         2.6.22
+ * - O_CLOEXEC                  2.6.23
+ * - eventfd                    2.6.23
+ * - pipe2 & dup3               2.6.27
+ * - accept4                    2.6.28
+ */
+
+    .long       2
+    .long       6
+    .long       28
+