Revert "Fix the C library initialization to avoid calling static C++ constructors twice."
This reverts commit 03eabfe65e.
This commit is contained in:
David 'Digit' Turner
parent
03eabfe65e
commit
3a654b1e04
@ -30,35 +30,25 @@
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.type _start,#function
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.globl _start
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# This is the small startup code that is called from
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# the dynamic linker to execute an executable once all
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# dependent shared libraries have been loaded and
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# initialized.
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# this is the small startup code that is first run when
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# any executable that is statically-linked with Bionic
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# runs.
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#
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# It's purpose is to call __libc_init as defined in
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# bionic/libc_init_dynamic.c with appropriate
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# it's purpose is to call __libc_init with appropriate
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# arguments, which are:
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#
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# - the address of the raw data block setup by the Linux
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# kernel ELF loader
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#
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# - address of an "onexit" function (not used on any
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# platform supported by Bionic)
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# - address of an "onexit" function, not used on any
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# platform supported by Bionic
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#
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# - address of the "main" function of the program. We
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# can't hard-code it in the adr pseudo instruction
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# so we use a tiny trampoline that will get relocated
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# by the dynamic linker before this code runs
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#
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# - address of the constructors table, i.e. a table
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# that points to various initialization and
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# finalization sections for the program.
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#
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# NOTE: This code is currently placed in shared libraries
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# by the build system, but will be ignored.
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#
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# On the other hand, the arrays defined below are
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# required and will be parsed by the dynamic linker.
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# - address of the constructor list
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#
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_start:
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mov r0, sp
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@ -30,27 +30,25 @@
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.type _start,#function
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.globl _start
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# This is the small startup code that is first run when
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# any static executable runs. A static executable is one
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# that is started directly by the Linux kernel, not from
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# the dynamic linker, it thus cannot depend on any shared
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# library.
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# this is the small startup code that is first run when
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# any executable that is statically-linked with Bionic
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# runs.
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#
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# It's purpose is to call __libc_init as defined in
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# bionic/libc_init_static.c with appropriate
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# it's purpose is to call __libc_init with appropriate
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# arguments, which are:
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#
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# - the address of the raw data block setup by the Linux
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# kernel ELF loader
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#
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# - address of an "onexit" function (not used on any
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# platform supported by Bionic).
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# - address of an "onexit" function, not used on any
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# platform supported by Bionic
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#
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# - address of the "main" function of the program.
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# - address of the "main" function of the program. We
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# can't hard-code it in the adr pseudo instruction
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# so we use a tiny trampoline that will get relocated
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# by the dynamic linker before this code runs
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#
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# - address of the constructors table, i.e. a table
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# that points to various initialization and
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# finalization sections for the program.
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# - address of the constructor list
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#
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_start:
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mov r0, sp
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@ -61,13 +59,6 @@ _start:
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0: b main
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# The "C++ ABI for ARM" document that static C++ constructors
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# shall only be called from the .init_array section.
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#
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# Do we really need a .ctors section on ARM platforms ?
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# It looks like it will always be empty.
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#
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1: .long __PREINIT_ARRAY__
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.long __INIT_ARRAY__
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.long __FINI_ARRAY__
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@ -29,35 +29,25 @@
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.type _start, @function
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.globl _start
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# This is the small startup code that is called from
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# the dynamic linker to execute an executable once all
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# dependent shared libraries have been loaded and
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# initialized.
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# this is the small startup code that is first run when
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# any executable that is statically-linked with Bionic
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# runs.
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#
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# It's purpose is to call __libc_init as defined in
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# bionic/libc_init_dynamic.c with appropriate
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# it's purpose is to call __libc_init with appropriate
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# arguments, which are:
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#
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# - the address of the raw data block setup by the Linux
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# kernel ELF loader
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#
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# - address of an "onexit" function (not used on any
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# platform supported by Bionic)
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# - address of an "onexit" function, not used on any
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# platform supported by Bionic
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#
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# - address of the "main" function of the program. We
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# can't hard-code it in the adr pseudo instruction
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# so we use a tiny trampoline that will get relocated
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# by the dynamic linker before this code runs
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#
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# - address of the constructors table, i.e. a table
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# that points to various initialization and
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# finalization sections for the program.
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#
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# NOTE: This code is currently placed in shared libraries
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# by the build system, but will be ignored.
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#
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# On the other hand, the arrays defined below are
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# required and will be parsed by the dynamic linker.
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# - address of the constructor list
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#
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_start:
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mov %esp, %eax
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@ -29,27 +29,25 @@
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.type _start, @function
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.globl _start
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# This is the small startup code that is first run when
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# any static executable runs. A static executable is one
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# that is started directly by the Linux kernel, not from
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# the dynamic linker, it thus cannot depend on any shared
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# library.
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# this is the small startup code that is first run when
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# any executable that is statically-linked with Bionic
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# runs.
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#
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# It's purpose is to call __libc_init as defined in
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# bionic/libc_init_static.c with appropriate
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# it's purpose is to call __libc_init with appropriate
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# arguments, which are:
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#
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# - the address of the raw data block setup by the Linux
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# kernel ELF loader
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#
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# - address of an "onexit" function (not used on any
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# platform supported by Bionic).
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# - address of an "onexit" function, not used on any
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# platform supported by Bionic
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#
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# - address of the "main" function of the program.
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# - address of the "main" function of the program. We
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# can't hard-code it in the adr pseudo instruction
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# so we use a tiny trampoline that will get relocated
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# by the dynamic linker before this code runs
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#
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# - address of the constructors table, i.e. a table
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# that points to various initialization and
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# finalization sections for the program.
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# - address of the constructor list
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#
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_start:
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mov %esp, %eax
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@ -39,11 +39,8 @@
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#include <bionic_tls.h>
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#include <errno.h>
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/* This contains the common C library initialization code.
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* To understand what happens here, you should read the
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* "Initialization and Finalization" section of the file
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* named bionic/linker/README.TXT
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*/
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extern void _init(void);
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extern void _fini(void);
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static void call_array(void(**list)())
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{
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@ -53,6 +50,15 @@ static void call_array(void(**list)())
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}
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}
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static void __bionic_do_global_dtors(structors_array_t const * const p)
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{
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call_array(p->fini_array);
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//_fini();
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}
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extern unsigned __get_sp(void);
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extern pid_t gettid(void);
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char* __progname;
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char **environ;
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@ -63,28 +69,30 @@ unsigned int __page_shift = PAGE_SHIFT;
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int __system_properties_init(void);
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/* This function can be run under two different contexts:
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*
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* - for statically linked executables (i.e. those who do
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* not depend on shared libraries at all), it will be
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* called from the __libc_init() function defined in
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* bionic/libc_init_static.c
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*
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* - for dynamic executables, it will be called from the
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* __libc_init() function defined in bionic/libc_init_dynamic.c
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*
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*/
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void __libc_init_common(uintptr_t *elfdata,
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void (*onexit)(void),
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int (*slingshot)(int, char**, char**),
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structors_array_t const * const structors,
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void (*pre_ctor_hook)())
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{
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pthread_internal_t thread;
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pthread_attr_t thread_attr;
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void *tls_area[BIONIC_TLS_SLOTS];
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int argc;
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char **argv, **envp, **envend;
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struct auxentry *auxentry;
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unsigned int page_size = 0, page_shift = 0;
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/* The main thread's stack has empirically shown to be 84k */
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unsigned stacktop = (__get_sp() & ~(PAGE_SIZE - 1)) + PAGE_SIZE;
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unsigned stacksize = 128 * 1024; //84 * 1024;
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unsigned stackbottom = stacktop - stacksize;
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pthread_attr_init(&thread_attr);
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pthread_attr_setstack(&thread_attr, (void*)stackbottom, stacksize);
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_init_thread(&thread, gettid(), &thread_attr, (void*)stackbottom);
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__init_tls(tls_area, &thread);
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argc = (int) *elfdata++;
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argv = (char**) elfdata;
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envp = argv+(argc+1);
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@ -98,17 +106,17 @@ void __libc_init_common(uintptr_t *elfdata,
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if (pre_ctor_hook) pre_ctor_hook();
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if (structors != NULL) {
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// XXX: we should execute the .fini_array upon exit
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// pre-init array.
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// XXX: I'm not sure what's the different with the init array.
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call_array(structors->preinit_array);
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// for compatibility with non-eabi binary, call the .ctors section
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// this is only useful for static non-ARM (e.g. x86) executables.
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call_array(structors->ctors_array);
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// call static constructors
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call_array(structors->init_array);
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}
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exit(slingshot(argc, argv, envp));
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}
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@ -25,29 +25,18 @@
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* libc_init_static.c
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*
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* This function is called for dynamic executables after the dynamic
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* linker has loaded and initialized all dependent shared libraries.
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*
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* It takes the raw data block set up by the ELF loader
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* in the kernel and parses it.
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* This function takes the raw data block set up by the ELF loader
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* in the kernel and parses it. It is invoked by crt0.S which makes
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* any necessary adjustments and passes calls this function using
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* the standard C calling convention.
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*
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* The arguments are:
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* elfdata -- The ELF loader data block; usually from the stack.
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* uintptr_t *elfdata -- The ELF loader data block; usually from the stack.
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* Basically a pointer to argc.
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*
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* onexit -- Function to call on exit, can be NULL.
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*
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* slingshot -- Address of the program's main function
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*
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* structors -- Table of constructor functions arrays that must
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* be called before the slingshot.
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*
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* It is called from the assembly fragment found in
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* arch-$ARCH/bionic/crtbegin_dynamic.S
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* void (*onexit)(void) -- Function to install into onexit
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*/
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/*
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@ -73,18 +62,5 @@ __noreturn void __libc_init(uintptr_t *elfdata,
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int (*slingshot)(int, char**, char**),
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structors_array_t const * const structors)
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{
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/* NOTE: At this point, the dynamic linker has *already* called
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* all initializers properly, so we ignore 'structors' to
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* avoid calling them twice.
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*/
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/* NOTE2: Is it worthwhile to use malloc_debug_init() in the case of
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* of the non-debug shared C library ?
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*
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* The implementation in bionic/malloc_leak.c contains a lot
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* of code which will turn to be unused, and we add a dispatch
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* overhead to malloc() et al. that proved to be significant
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* in the past (e.g. making boot sequence 5% slower)
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*/
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__libc_init_common(elfdata, onexit, slingshot, NULL, malloc_debug_init);
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__libc_init_common(elfdata, onexit, slingshot, structors, malloc_debug_init);
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}
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@ -25,30 +25,18 @@
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* libc_init_static.c
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*
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* This function is called for static executables, i.e. those that
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* dont depend on shared libraries and are directly started by the
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* Linux kernel.
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*
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* It takes the raw data block set up by the ELF loader
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* in the kernel and parses it.
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* This function takes the raw data block set up by the ELF loader
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* in the kernel and parses it. It is invoked by crt0.S which makes
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* any necessary adjustments and passes calls this function using
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* the standard C calling convention.
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*
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* The arguments are:
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* elfdata -- The ELF loader data block; usually from the stack.
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* uintptr_t *elfdata -- The ELF loader data block; usually from the stack.
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* Basically a pointer to argc.
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*
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* onexit -- Function to call on exit, can be NULL.
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*
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* slingshot -- Address of the program's main function
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*
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* structors -- Table of constructor functions arrays that must
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* be called before the slingshot.
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*
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* It is called from the assembly fragment found in
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* arch-$ARCH/bionic/crtbegin_static.S
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* void (*onexit)(void) -- Function to install into onexit
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*/
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/*
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@ -63,19 +51,18 @@
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#include <stdlib.h>
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#include <stdint.h>
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#include <elf.h>
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#include "bionic_preinit.h"
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#include "pthread_internal.h"
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#include "atexit.h"
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#include "libc_init_common.h"
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#include <bionic_tls.h>
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#include <errno.h>
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__noreturn void __libc_init(uintptr_t *elfdata,
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void (*onexit)(void),
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int (*slingshot)(int, char**, char**),
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structors_array_t const * const structors)
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{
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pthread_internal_t thread;
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void *tls_area[BIONIC_TLS_SLOTS];
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__libc_preinit( &thread, tls_area );
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/*
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* To enable malloc checks for statically linked programs, add
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* "WITH_MALLOC_CHECK_LIBC_A := true" in device/buildspec.mk
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@ -1,76 +0,0 @@
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/*
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* Copyright (C) 2009 The Android Open Source Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
|
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* modification, are permitted provided that the following conditions
|
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* are met:
|
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* * 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
|
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* distribution.
|
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*
|
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
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* "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.
|
||||
*/
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#ifndef _BIONIC_PREINIT_H
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#define _BIONIC_PREINIT_H
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#include "pthread_internal.h"
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#include "bionic_tls.h"
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#include <asm/page.h>
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|
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/* this function is used to perform a minimal initialization of the
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* the C library. This must be performed before any other call to
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* other functions, in either the dynamic linker's startup code
|
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* or libc_init_static.c
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*
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* 'main_thread' and 'tls_area' must be persistent variables,
|
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* which means they must be either global, or allocated in the
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* main thread's stack frame and never, ever, freed before
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* program exit.
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*
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* VERY IMPORTANT NOTE:
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*
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* THIS IMPLEMENTATION SHOULD NOT USE GLOBAL VARIABLES.
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*
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* The reason is the dynamic linker's tricky usage of C library
|
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* functions and later renaming of their symbols. See the
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* "C Library Usage Restriction" section in bionic/linker/README.TXT
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* for details.
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*/
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extern unsigned __get_sp(void);
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extern pid_t gettid(void);
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static __inline__ void
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__libc_preinit( pthread_internal_t* main_thread,
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void* tls_area[BIONIC_TLS_SLOTS] )
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{
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pthread_attr_t thread_attr;
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/* Setup the main thread's information */
|
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unsigned stacktop = (__get_sp() & ~(PAGE_SIZE - 1)) + PAGE_SIZE;
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unsigned stacksize = 128 * 1024;
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unsigned stackbottom = stacktop - stacksize;
|
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pthread_attr_init(&thread_attr);
|
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pthread_attr_setstack(&thread_attr, (void*)stackbottom, stacksize);
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_init_thread(main_thread, gettid(), &thread_attr, (void*)stackbottom);
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__init_tls(tls_area, main_thread);
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}
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#endif /* _BIONIC_INIT_H */
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@ -112,46 +112,3 @@ On x86, the lists of constructors and destructors are placed in special
|
||||
sections named ".ctors" and ".dtors", and the DT_INIT / DT_FINI functions
|
||||
are in charge of calling them explicitely.
|
||||
|
||||
|
||||
C Library Usage Restrictions:
|
||||
-----------------------------
|
||||
|
||||
The dynamic linker executable (/system/bin/linker) is built using the
|
||||
static version of the C library (libc.a), in order to use various functions
|
||||
and system calls provided by it.
|
||||
|
||||
However, it will normally, at runtime, map the shared library version
|
||||
of the C library (/system/lib/libc.so) as well in the process' address
|
||||
space. This means that:
|
||||
|
||||
- any global variable defined by the C library will appear twice in
|
||||
the process address space, at different addresses.
|
||||
|
||||
- some functions will be duplicated too, though those that refer to
|
||||
global variables will refer to distinct addresses.
|
||||
|
||||
This can lead to subtle conflicts, typically for process-specific data that
|
||||
is managed through the kernel. A good example is the handling of the
|
||||
end of the data segment, which is normally done through the 'sbrk' or
|
||||
'brk' system call by the malloc implementation.
|
||||
|
||||
If two similar, but distinct, malloc implementations run at the same time,
|
||||
and if each one thinks it exclusively manages some process settings, hideous
|
||||
corruption or crashes may occur.
|
||||
|
||||
For this very reason, THE DYNAMIC LINKER CANNOT USE malloc()/free() !
|
||||
That's why it is linked to a special version of the C library that will
|
||||
abort when any of these functions (or calloc()/realloc()) is called.
|
||||
|
||||
Moreover, it cannot use any C library feature that could use these
|
||||
indirectly. Experience as shown that this meant:
|
||||
|
||||
- avoiding any FILE* - related stdio function (fopen, fread, fprintf, etc...)
|
||||
- avoiding snprintf() with any floating-point formatter ("%f", "%g")
|
||||
|
||||
There are probably other cases that haven't been discovered yet, so the
|
||||
code needs to be very frugal in its use of the C library.
|
||||
|
||||
This also explains why the linker's tracing macros are all disabled by
|
||||
default. Enabling them sometimes creates problems, depending on the process
|
||||
being loaded, so they should be considered an experimental feature for now.
|
||||
|
||||
@ -44,7 +44,7 @@
|
||||
#include <sys/atomics.h>
|
||||
|
||||
/* special private C library header - see Android.mk */
|
||||
#include <bionic_preinit.h>
|
||||
#include <bionic_tls.h>
|
||||
|
||||
#include "linker.h"
|
||||
#include "linker_debug.h"
|
||||
@ -1691,7 +1691,6 @@ int main(int argc, char **argv)
|
||||
#define ANDROID_TLS_SLOTS BIONIC_TLS_SLOTS
|
||||
|
||||
static void * __tls_area[ANDROID_TLS_SLOTS];
|
||||
static pthread_internal_t __main_thread;
|
||||
|
||||
unsigned __linker_init(unsigned **elfdata)
|
||||
{
|
||||
@ -1710,7 +1709,8 @@ unsigned __linker_init(unsigned **elfdata)
|
||||
gettimeofday(&t0, 0);
|
||||
#endif
|
||||
|
||||
__libc_preinit(&__main_thread, __tls_area);
|
||||
__set_tls(__tls_area);
|
||||
((unsigned *)__get_tls())[TLS_SLOT_THREAD_ID] = gettid();
|
||||
|
||||
debugger_init();
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user