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Calling Global Constructors: Difference between revisions
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This wiki has no AT&T assembly syntax high-lighting
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It is very simple to implement this under x86. You simply have to define the header of two functions in <tt>crti.o</tt> and the footer in <tt>crtn.o</tt> and use these objects in your C library or kernel. You can then simply call <tt>_init</tt> to perform the initialization tasks and call <tt>_fini</tt> to perform the termination tasks (normally done from a <tt>crt0.o</tt> or <tt>my-kernel-boot-object.o</tt>).
<pre>
/* x86 crti.s */
.section .init
Line 96:
movl %esp, %ebp
/* gcc will nicely put the contents of crtbegin.o's .fini section here. */
</
<pre>
/* x86 crtn.s */
.section .init
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popl %ebp
ret
</
== x86_64 (64-bit) ==
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The system ABI on x86_64 is similar to its 32-bit counterpart and we also just need to provide function headers and function footers and the compiler will insert the rest of the <tt>_init</tt> and <tt>_fini</tt> functions through <tt>crtbegin.o</tt> and <tt>crtend.o</tt>.
<pre>
/* x86_64 crti.s */
.section .init
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movq %rsp, %rbp
/* gcc will nicely put the contents of crtbegin.o's .fini section here. */
</
<pre>
/* x86_64 crtn.s */
.section .init
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popq %rbp
ret
</
== ARM (BPABI) ==
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