mirror of
https://github.com/apache/nuttx.git
synced 2026-05-25 01:39:44 +08:00
arch/sim: replace macOS C++ constructor runtime hack with post-link patch
The sim architecture needs to defer C++ global constructors until after
NuttX kernel initialization completes. On macOS this was previously done
via a runtime hack (sim_macho_init.c): a __attribute__((constructor))
function intercepted constructors, saved them, and replayed them later.
That approach was fragile because it depended on constructor ordering
and required mprotect() to patch the read-only __mod_init_func section
at runtime.
This commit replaces the runtime hack with a post-link patching scheme:
1. Link with -Wl,-ld_classic,-no_fixup_chains to keep the classic
__mod_init_func pointer format (prevents ld64 from converting it
to __init_offsets).
2. Post-link, run patch_macho_initsection.py (python3 + lief) to
patch Mach-O section type flags from
MOD_INIT_FUNC_POINTERS/INIT_FUNC_OFFSETS to REGULAR, so dyld
skips them entirely.
3. Use the Mach-O auto-generated boundary symbols
section$start$__DATA_CONST$__mod_init_func /
section$end$__DATA_CONST$__mod_init_func, mapped via __asm()
labels in arch/sim/include/arch.h to the common _sinit[]/_einit[]
names used by lib_cxx_initialize().
Linux behavior is unchanged.
Changes:
- arch/sim/include/arch.h: add macOS __asm() declarations for
_sinit/_einit
- arch/sim/src/Makefile: drop sim_macho_init.c HEADSRC handling,
always pass -ld_classic,-no_fixup_chains on macOS, run
patch_macho_initsection.py after link when CONFIG_HAVE_CXXINITIALIZE
- arch/sim/src/sim/CMakeLists.txt: same for the CMake build
- arch/sim/src/patch_macho_initsection.py: new lief-based patcher
- arch/sim/src/sim/posix/sim_macho_init.c: deleted (135-line hack)
- libs/libc/misc/lib_cxx_initialize.c: remove
macho_call_saved_init_funcs special case; single unified loop
Testing:
- macOS (Ventura VM): verified lief patching with standalone test
(test_sinit7) confirming the constructor is deferred past main()
and only invoked when explicitly called via the _sinit/_einit loop.
Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
This commit is contained in:
Xiang Xiao
committed by
Alan C. Assis
Alan C. Assis
parent
306de5b04b
commit
754dfd980b
@@ -41,6 +41,7 @@ ignore-words-list =
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infor,
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inport,
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ist,
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lief,
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lod,
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mot,
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mis,
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@@ -27,4 +27,42 @@
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#ifndef __ARCH_SIM_INCLUDE_ARCH_H
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#define __ARCH_SIM_INCLUDE_ARCH_H
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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#ifdef __cplusplus
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#define EXTERN extern "C"
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extern "C"
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{
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#else
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#define EXTERN extern
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#endif
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/****************************************************************************
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* Public Data
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****************************************************************************/
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/* _sinit and _einit mark the beginning and end of the C++ constructor
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* array. They are mapped to platform-specific linker symbols:
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* macOS: section$start$__DATA_CONST$__mod_init_func /
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* section$end$__DATA_CONST$__mod_init_func (Mach-O auto)
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* On macOS, the section type flags are patched post-link to prevent
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* dyld from auto-running constructors before NuttX is initialized.
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*/
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#ifdef CONFIG_HAVE_CXXINITIALIZE
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# if defined(CONFIG_HOST_MACOS)
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extern void (*_sinit[])(void)
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__asm("section$start$__DATA_CONST$__mod_init_func");
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extern void (*_einit[])(void)
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__asm("section$end$__DATA_CONST$__mod_init_func");
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# endif
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#endif
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#undef EXTERN
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#ifdef __cplusplus
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}
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#endif
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#endif /* __ARCH_SIM_INCLUDE_ARCH_H */
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+8
-14
@@ -141,24 +141,15 @@ sim_hostfs.c: hostfs.h
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STDLIBS += -lpthread
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ifeq ($(CONFIG_HOST_MACOS),y)
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ifeq ($(CONFIG_HAVE_CXXINITIALIZE),y)
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# Note: sim_macho_init.c is not in CSRCS because it's picky about
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# the place in the object list for linking. Namely, its constructor
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# should be the first one in the executable.
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HEADSRC = sim_macho_init.c
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# sim_macho_init.c is not compatible with chained fixups.
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# cf. https://github.com/apache/nuttx/issues/15208
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ifeq ($(shell $(LD) -ld_classic -no_fixup_chains 2>&1 | grep "unknown option"),)
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ifeq ($(CONFIG_HAVE_CXXINITIALIZE),y)
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LDLINKFLAGS += -ld_classic -no_fixup_chains
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LDFLAGS += -Wl,-ld_classic,-no_fixup_chains
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endif
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endif
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# Keep the simulator executable from exporting NuttX symbols. Otherwise dyld
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# may resolve host libc references against NuttX's internal libc implementation
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# during process initialization, which can crash before main() runs.
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LDFLAGS += -Wl,-exported_symbol,__mh_execute_header
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# Keep the simulator executable from exporting NuttX symbols. Otherwise dyld
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# may resolve host libc references against NuttX's internal libc implementation
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# during process initialization, which can crash before main() runs.
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LDFLAGS += -Wl,-exported_symbol,__mh_execute_header
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else
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STDLIBS += -lrt
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endif
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@@ -521,6 +512,9 @@ else
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$(Q) $(call LINK_ALLSYMS_KASAN)
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$(Q) $(call LINK_ALLSYMS_KASAN)
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$(Q) $(call LINK_ALLSYMS_KASAN)
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endif
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ifeq ($(CONFIG_HOST_MACOS)$(CONFIG_HAVE_CXXINITIALIZE),yy)
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$(Q) python3 $(ARCH_SRCDIR)/patch_macho_initsection.py $(TOPDIR)/$@
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endif
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$(Q) $(NM) $(TOPDIR)/$@ | \
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grep -v '\(compiled\)\|\(\.o$$\)\|\( [aUw] \)\|\(\.\.ng$$\)\|\(LASH[RL]DI\)' | \
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Executable
+72
@@ -0,0 +1,72 @@
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#!/usr/bin/env python3
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############################################################################
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# arch/sim/src/patch_macho_initsection.py
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#
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# SPDX-License-Identifier: Apache-2.0
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#
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# Licensed to the Apache Software Foundation (ASF) under one or more
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# contributor license agreements. See the NOTICE file distributed with
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# this work for additional information regarding copyright ownership. The
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# ASF licenses this file to you under the Apache License, Version 2.0 (the
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# "License"); you may not use this file except in compliance with the
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# License. You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
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# implied. See the License for the specific language governing
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# permissions and limitations under the License.
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#
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############################################################################
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"""Patch Mach-O init section type flags to prevent dyld from
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auto-running C++ constructors.
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Changes MOD_INIT_FUNC_POINTERS (0x9) section types to REGULAR (0x0)
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so that dyld ignores them. NuttX will invoke the constructors
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explicitly from lib_cxx_initialize().
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Requires: pip install lief
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"""
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import argparse
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import sys
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try:
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import lief
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except ImportError:
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print(
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"Error: lief is required. Install with: pip install lief",
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file=sys.stderr,
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)
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sys.exit(1)
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def main():
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parser = argparse.ArgumentParser(description="Patch Mach-O init section type flags")
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parser.add_argument("binary", help="Path to the Mach-O binary")
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args = parser.parse_args()
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binary = lief.MachO.parse(args.binary)
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if binary is None:
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print(f"Error: failed to parse {args.binary}", file=sys.stderr)
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sys.exit(1)
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fat = binary.at(0)
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T = lief.MachO.Section.TYPE
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patched = 0
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for section in fat.sections:
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if section.type == T.MOD_INIT_FUNC_POINTERS:
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section.type = T.REGULAR
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patched += 1
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if patched:
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fat.write(args.binary)
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return 0
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if __name__ == "__main__":
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sys.exit(main())
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@@ -150,14 +150,17 @@ list(
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sim_hosttime.c
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sim_hostuart.c)
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# Note: sim_macho_init.c is picky about the place in the object list for
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# linking. Namely, its constructor should be the first one in the executable.
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# For now, we are just assuming no other files in HOSTSRCS provide constructors.
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if(CONFIG_HOST_MACOS)
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if(CONFIG_HAVE_CXXINITIALIZE)
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list(APPEND HOSTSRCS sim_macho_init.c)
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target_link_options(nuttx PRIVATE -Wl,-ld_classic,-no_fixup_chains)
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endif()
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if(CONFIG_HOST_MACOS AND CONFIG_HAVE_CXXINITIALIZE)
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# Keep classic __mod_init_func format so post-link lief patching works
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target_link_options(nuttx PRIVATE -Wl,-ld_classic,-no_fixup_chains)
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add_custom_command(
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TARGET nuttx
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POST_BUILD
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COMMAND
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${Python3_EXECUTABLE}
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${CMAKE_CURRENT_SOURCE_DIR}/../patch_macho_initsection.py
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$<TARGET_FILE:nuttx>
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COMMENT "Patching Mach-O init section type flags")
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endif()
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if(CONFIG_SIM_CAMERA_V4L2)
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@@ -1,135 +0,0 @@
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/****************************************************************************
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* arch/sim/src/sim/posix/sim_macho_init.c
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <sys/mman.h>
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#include <assert.h>
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#include <stdlib.h>
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#include <unistd.h>
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/****************************************************************************
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* Private Data
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****************************************************************************/
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typedef void (*init_func_t)(int argc, const char *argv[],
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const char *envp[], const char *apple[]);
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extern init_func_t mod_init_func_start \
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__asm("section$start$__DATA$__mod_init_func");
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extern init_func_t mod_init_func_end \
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__asm("section$end$__DATA$__mod_init_func");
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static void noop(int argc, const char *argv[], const char *envp[],
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const char *apple[])
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{
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/* nothing */
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}
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static init_func_t *g_saved_init_funcs;
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static unsigned int g_num_saved_init_funcs;
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static int g_saved_argc;
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static const char **g_saved_argv;
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static const char **g_saved_envp;
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static const char **g_saved_apple;
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static void
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allow_write(const void *start, const void *end)
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{
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const size_t page_size = sysconf(_SC_PAGE_SIZE);
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const size_t page_mask = ~(page_size - 1);
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void *p = (void *)((uintptr_t)start & page_mask);
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size_t sz = ((uintptr_t)end - (uintptr_t)p + page_size - 1) & ~page_mask;
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/* It seems that Monterey (12.1) maps the section read-only.
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* Make it writable as we want to patch it.
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* This was not necessary for Mojave.
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* Ignore failures as this might not be critical, depending on
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* the OS version.
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*/
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mprotect(p, sz, PROT_READ | PROT_WRITE);
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}
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__attribute__((constructor))
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static void save_and_replace_init_funcs(int argc, const char *argv[],
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const char *envp[],
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const char *apple[])
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{
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init_func_t *fp;
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unsigned int nfuncs = &mod_init_func_end - &mod_init_func_start;
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assert(nfuncs > 0);
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g_num_saved_init_funcs = nfuncs - 1;
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if (g_num_saved_init_funcs == 0)
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{
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/* This function is the only constructor in the binary.
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* no need to apply the following hack.
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*/
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return;
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}
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g_saved_argc = argc;
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g_saved_argv = argv;
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g_saved_envp = envp;
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g_saved_apple = apple;
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g_saved_init_funcs = malloc(g_num_saved_init_funcs *
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sizeof(*g_saved_init_funcs));
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allow_write(&mod_init_func_start, &mod_init_func_end);
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int i = 0;
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for (fp = &mod_init_func_start; fp < &mod_init_func_end; fp++)
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{
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if (*fp == save_and_replace_init_funcs)
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{
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assert(i == 0);
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}
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else
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{
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g_saved_init_funcs[i - 1] = *fp;
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*fp = noop;
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}
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i++;
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}
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: macho_call_saved_init_funcs
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****************************************************************************/
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void
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macho_call_saved_init_funcs(void)
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{
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unsigned int i;
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for (i = 0; i < g_num_saved_init_funcs; i++)
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{
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g_saved_init_funcs[i](g_saved_argc, g_saved_argv, g_saved_envp,
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g_saved_apple);
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}
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}
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@@ -38,10 +38,6 @@
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* External References
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****************************************************************************/
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#if defined(CONFIG_ARCH_SIM) && defined(CONFIG_HOST_MACOS)
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extern void macho_call_saved_init_funcs(void);
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#endif
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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@@ -69,9 +65,6 @@ void lib_cxx_initialize(void)
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if (inited == 0)
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{
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#if defined(CONFIG_ARCH_SIM) && defined(CONFIG_HOST_MACOS)
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macho_call_saved_init_funcs();
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#else
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initializer_t *initp;
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sinfo("_sinit: %p _einit: %p\n", _sinit, _einit);
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@@ -93,7 +86,6 @@ void lib_cxx_initialize(void)
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initializer();
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}
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}
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#endif
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inited = 1;
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}
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