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118 lines
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118 lines
6.0 KiB
HTML
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<title>Stack Smashing Protection (GNU Compiler Collection (GCC) Internals)</title>
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<link href="Option-Index.html#Option-Index" rel="index" title="Option Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Miscellaneous-Register-Hooks.html#Miscellaneous-Register-Hooks" rel="next" title="Miscellaneous Register Hooks">
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<a name="Stack-Smashing-Protection"></a>
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<p>
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Next: <a href="Miscellaneous-Register-Hooks.html#Miscellaneous-Register-Hooks" accesskey="n" rel="next">Miscellaneous Register Hooks</a>, Previous: <a href="Shrink_002dwrapping-separate-components.html#Shrink_002dwrapping-separate-components" accesskey="p" rel="prev">Shrink-wrapping separate components</a>, Up: <a href="Stack-and-Calling.html#Stack-and-Calling" accesskey="u" rel="up">Stack and Calling</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
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<hr>
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<a name="Stack-smashing-protection"></a>
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<h4 class="subsection">18.9.15 Stack smashing protection</h4>
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<a name="index-stack-smashing-protection"></a>
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<dl>
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<dt><a name="index-TARGET_005fSTACK_005fPROTECT_005fGUARD"></a>Target Hook: <em>tree</em> <strong>TARGET_STACK_PROTECT_GUARD</strong> <em>(void)</em></dt>
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<dd><p>This hook returns a <code>DECL</code> node for the external variable to use
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for the stack protection guard. This variable is initialized by the
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runtime to some random value and is used to initialize the guard value
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that is placed at the top of the local stack frame. The type of this
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variable must be <code>ptr_type_node</code>.
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</p>
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<p>The default version of this hook creates a variable called
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‘<samp>__stack_chk_guard</samp>’, which is normally defined in <samp>libgcc2.c</samp>.
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</p></dd></dl>
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<dl>
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<dt><a name="index-TARGET_005fSTACK_005fPROTECT_005fFAIL"></a>Target Hook: <em>tree</em> <strong>TARGET_STACK_PROTECT_FAIL</strong> <em>(void)</em></dt>
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<dd><p>This hook returns a <code>CALL_EXPR</code> that alerts the runtime that the
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stack protect guard variable has been modified. This expression should
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involve a call to a <code>noreturn</code> function.
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</p>
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<p>The default version of this hook invokes a function called
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‘<samp>__stack_chk_fail</samp>’, taking no arguments. This function is
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normally defined in <samp>libgcc2.c</samp>.
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</p></dd></dl>
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<dl>
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<dt><a name="index-TARGET_005fSTACK_005fPROTECT_005fRUNTIME_005fENABLED_005fP"></a>Target Hook: <em>bool</em> <strong>TARGET_STACK_PROTECT_RUNTIME_ENABLED_P</strong> <em>(void)</em></dt>
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<dd><p>Returns true if the target wants GCC’s default stack protect runtime support, otherwise return false. The default implementation always returns true.
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</p></dd></dl>
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<dl>
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<dt><a name="index-TARGET_005fSUPPORTS_005fSPLIT_005fSTACK"></a>Common Target Hook: <em>bool</em> <strong>TARGET_SUPPORTS_SPLIT_STACK</strong> <em>(bool <var>report</var>, struct gcc_options *<var>opts</var>)</em></dt>
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<dd><p>Whether this target supports splitting the stack when the options described in <var>opts</var> have been passed. This is called after options have been parsed, so the target may reject splitting the stack in some configurations. The default version of this hook returns false. If <var>report</var> is true, this function may issue a warning or error; if <var>report</var> is false, it must simply return a value
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</p></dd></dl>
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