Fix ABI breakage in libc.so and libm.so between 1.6 and Eclair.

For a detailed description of the problem and why this fix is
needed, plrease read the comments in libgcc_compat.c

2 files changed, 153 insertions, 0 deletions

diff --git a/libc/Android.mk b/libc/Android.mk
index 12d5c92..5718d18 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -288,6 +288,7 @@ libc_common_src_files += \
 	arch-arm/bionic/clone.S \
 	arch-arm/bionic/ffs.S \
 	arch-arm/bionic/kill.S \
+	arch-arm/bionic/libgcc_compat.c \
 	arch-arm/bionic/tkill.S \
 	arch-arm/bionic/memcmp.S \
 	arch-arm/bionic/memcmp16.S \
diff --git a/libc/arch-arm/bionic/libgcc_compat.c b/libc/arch-arm/bionic/libgcc_compat.c
new file mode 100644
index 0000000..886d025
--- /dev/null
+++ b/libc/arch-arm/bionic/libgcc_compat.c
@@ -0,0 +1,152 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+/* This file contains dummy references to libgcc.a functions to force the
+ * dynamic linker to copy their definition into the final libc.so binary.
+ *
+ * They are required to ensure backwards binary compatibility with
+ * Android 1.5 and Android 1.6 system images. Some applications built
+ * using the NDK require them to be here.
+ *
+ * Now, for a more elaborate description of the issue:
+ *
+ * libgcc.a is a compiler-specific library containing various helper
+ * functions used to implement certain operations that are not necessarily
+ * supported by the target CPU. For example, integer division doesn't have a
+ * corresponding CPU instruction on ARMv5, and is instead implemented in the
+ * compiler-generated machine code as a call to an __idiv helper function.
+ *
+ * Normally, one has to place libgcc.a in the link command used to generate
+ * target binaries (shared libraries and executables) after all objects and
+ * static libraries, but before dependent shared libraries, i.e. something
+ * like:
+ *         gcc <options> -o libfoo.so  foo.a libgcc.a -lc -lm
+ *
+ * This ensures that any helper function needed by the code in foo.a is copied
+ * into the final libfoo.so. Unfortunately, the Android build system has been
+ * using this instead:
+ *
+ *         gcc <options> -o libfoo.so foo.a -lc -lm libgcc.a
+ *
+ * The problem with this is that if one helper function needed by foo.a has
+ * already been copied into libc.so or libm.so, then nothing will be copied
+ * into libfoo.so. Instead, a symbol import definition will be added to it
+ * so libfoo.so can directly call the one in libc.so at runtime.
+ *
+ * When changing toolchains for 2.0, the set of helper functions copied to
+ * libc.so changed, which resulted in some native shared libraries generated
+ * with the NDK to fail to load properly.
+ *
+ * The NDK has been fixed after 1.6_r1 to use the correct link command, so
+ * any native shared library generated with it should now be safe from that
+ * problem. On the other hand, existing shared libraries distributed with
+ * applications that were generated with a previous version of the NDK
+ * still need all 1.5/1.6 helper functions in libc.so and libn.so
+ *
+ * Final note: some of the functions below should really be in libm.so to
+ *             completely reflect the state of 1.5/1.6 system images. However,
+ *             since libm.so depends on libc.so, it's easier to put all of
+ *             these in libc.so instead, since the dynamic linker will always
+ *             search in libc.so before libm.so for dependencies.
+ */
+
+#define   COMPAT_FUNCTIONS_LIST \
+    XX(__adddf3)             \
+    XX(__addsf3)             \
+    XX(__aeabi_cdcmpeq)      \
+    XX(__aeabi_cdcmple)      \
+    XX(__aeabi_cdrcmple)     \
+    XX(__aeabi_d2f)          \
+    XX(__aeabi_d2iz)         \
+    XX(__aeabi_dadd)         \
+    XX(__aeabi_dcmpeq)       \
+    XX(__aeabi_dcmpge)       \
+    XX(__aeabi_dcmpgt)       \
+    XX(__aeabi_dcmple)       \
+    XX(__aeabi_dcmplt)       \
+    XX(__aeabi_dcmpun)       \
+    XX(__aeabi_ddiv)         \
+    XX(__aeabi_dmul)         \
+    XX(__aeabi_drsub)        \
+    XX(__aeabi_dsub)         \
+    XX(__aeabi_f2d)          \
+    XX(__aeabi_f2iz)         \
+    XX(__aeabi_fadd)         \
+    XX(__aeabi_fcmpun)       \
+    XX(__aeabi_fdiv)         \
+    XX(__aeabi_fmul)         \
+    XX(__aeabi_frsub)        \
+    XX(__aeabi_fsub)         \
+    XX(__aeabi_i2d)          \
+    XX(__aeabi_i2f)          \
+    XX(__aeabi_l2d)          \
+    XX(__aeabi_l2f)          \
+    XX(__aeabi_lmul)         \
+    XX(__aeabi_ui2d)         \
+    XX(__aeabi_ui2f)         \
+    XX(__aeabi_ul2d)         \
+    XX(__aeabi_ul2f)         \
+    XX(__cmpdf2)             \
+    XX(__divdf3)             \
+    XX(__divsf3)             \
+    XX(__eqdf2)             \
+    XX(__extendsfdf2)        \
+    XX(__fixdfsi)            \
+    XX(__fixsfsi)            \
+    XX(__floatdidf)          \
+    XX(__floatdisf)          \
+    XX(__floatsidf)          \
+    XX(__floatsisf)          \
+    XX(__floatundidf)        \
+    XX(__floatundisf)        \
+    XX(__floatunsidf)        \
+    XX(__floatunsisf)        \
+    XX(__gedf2)              \
+    XX(__gtdf2)              \
+    XX(__ledf2)              \
+    XX(__ltdf2)              \
+    XX(__muldf3)             \
+    XX(__muldi3)             \
+    XX(__mulsf3)             \
+    XX(__nedf2)              \
+    XX(__subdf3)             \
+    XX(__subsf3)             \
+    XX(__truncdfsf2)         \
+    XX(__unorddf2)           \
+    XX(__unordsf2)           \
+
+#define  XX(f)    extern void f(void);
+COMPAT_FUNCTIONS_LIST
+#undef XX
+
+void  __bionic_libgcc_compat_hooks(void)
+{
+#define XX(f)    f();
+COMPAT_FUNCTIONS_LIST
+#undef XX
+}