LibC: Use our implementation of crti.o and crtn.o

We have had these for quite a while, but we didn't compile them, and
used GCC's version instead. Clang does not come with these, so we have
to provide our own implementation.

Our implementation follows what `musl` and `FreeBSD` do, so this should
work fine, even if documentation can hardly be found for them.

Userland/DynamicLoader/main.cpp

@@ -150,10 +150,4 @@ void _entry(int argc, char** argv, char** envp)
     ELF::DynamicLinker::linker_main(move(main_program_name), main_program_fd, is_secure, argc, argv, envp);
     VERIFY_NOT_REACHED();
 }
-
-void _fini();
-
-void _fini()
-{
-}
 }

Userland/Libraries/LibC/CMakeLists.txt

@@ -65,9 +65,13 @@ file(GLOB ELF_SOURCES CONFIGURE_DEPENDS "../LibELF/*.cpp")
 if ("${SERENITY_ARCH}" STREQUAL "i686")
     set(ASM_SOURCES "arch/i386/setjmp.S")
     set(ELF_SOURCES ${ELF_SOURCES} ../LibELF/Arch/i386/entry.S ../LibELF/Arch/i386/plt_trampoline.S)
+    set(CRTI_SOURCE "arch/i386/crti.S")
+    set(CRTN_SOURCE "arch/i386/crtn.S")
 elseif ("${SERENITY_ARCH}" STREQUAL "x86_64")
     set(ASM_SOURCES "arch/x86_64/setjmp.S")
     set(ELF_SOURCES ${ELF_SOURCES} ../LibELF/Arch/x86_64/entry.S ../LibELF/Arch/x86_64/plt_trampoline.S)
+    set(CRTI_SOURCE "arch/x86_64/crti.S")
+    set(CRTN_SOURCE "arch/x86_64/crtn.S")
 endif()
 
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-unknown-warning-option -DSERENITY_LIBC_BUILD")
@@ -83,6 +87,18 @@ add_custom_command(
     COMMAND ${CMAKE_COMMAND} -E copy $<TARGET_OBJECTS:crt0_shared> ${CMAKE_INSTALL_PREFIX}/usr/lib/crt0_shared.o
 )
 
+add_library(crti STATIC ${CRTI_SOURCE})
+add_custom_command(
+    TARGET crti
+    COMMAND ${CMAKE_COMMAND} -E copy $<TARGET_OBJECTS:crti> ${CMAKE_INSTALL_PREFIX}/usr/lib/crti.o
+)
+
+add_library(crtn STATIC ${CRTN_SOURCE})
+add_custom_command(
+    TARGET crtn
+    COMMAND ${CMAKE_COMMAND} -E copy $<TARGET_OBJECTS:crtn> ${CMAKE_INSTALL_PREFIX}/usr/lib/crtn.o
+)
+
 set_source_files_properties (ssp.cpp PROPERTIES COMPILE_FLAGS
     "-fno-stack-protector")
 add_library(ssp STATIC ssp.cpp)
@@ -118,7 +134,7 @@ set_property(
 
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -static-libstdc++")
 serenity_libc(LibC c)
-add_dependencies(LibC crt0 crt0_shared)
+add_dependencies(LibC crti crt0 crt0_shared crtn)
 target_link_libraries(LibC ssp system)
 
 # We mark LibCStatic as a dependency of LibC because this triggers the build of the LibCStatic target

Userland/Libraries/LibC/arch/i386/crti.S

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+.section .init, "ax", @progbits
+.align 4
+.global _init
+.type _init, @function
+_init:
+    pushl %ebp
+    movl %esp, %ebp
+    andl $-16, %esp
+
+.section .fini, "ax", @progbits
+.align 4
+.global _fini
+.type _fini, @function
+_fini:
+    pushl %ebp
+    movl %esp, %ebp
+    andl $-16, %esp

Userland/Libraries/LibC/arch/i386/crtn.S

@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+.section .init, "ax", @progbits
+    movl %ebp, %esp
+    popl %ebp
+    retl
+
+.section .fini, "ax", @progbits
+    movl %ebp, %esp
+    popl %ebp
+    retl

Userland/Libraries/LibC/arch/x86_64/crti.S

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2021, Daniel Bertalan <dani@danielbertalan.dev>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+.section .init, "ax", @progbits
+.align 4
+.global _init
+.type _init, @function
+_init:
+    pushq %rbp
+    movq %rsp, %rbp
+    andq $-16, %rsp
+
+.section .fini, "ax", @progbits
+.align 4
+.global _fini
+.type _fini, @function
+_fini:
+    pushq %rbp
+    movq %rsp, %rbp
+    andq $-16, %rsp

Userland/Libraries/LibC/arch/x86_64/crtn.S

@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2021, Daniel Bertalan <dani@danielbertalan.dev>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+.section .init, "ax", @progbits
+    movq %rbp, %rsp
+    popq %rbp
+    retq
+
+.section .fini, "ax", @progbits
+    movq %rbp, %rsp
+    popq %rbp
+    retq

Userland/Libraries/LibC/crti.S

@@ -1,15 +0,0 @@
-/*
- * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
- *
- * SPDX-License-Identifier: BSD-2-Clause
- */
-
-.global _init
-.section .init
-_init:
-    push %ebp
-
-.global _fini
-.section .fini
-_fini:
-    push %ebp

Userland/Libraries/LibC/crtn.S

@@ -1,13 +0,0 @@
-/*
- * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
- *
- * SPDX-License-Identifier: BSD-2-Clause
- */
-
-.section .init
-    pop %ebp
-    ret
-
-.section .fini
-    pop %ebp
-    ret