forked from M-Labs/libfringe
Explain how trampolines work.
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@ -28,6 +28,14 @@
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// after. A .cfi_def_* pseudoinstruction changes the CFA value similarly.
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// * Simulating return is as easy as restoring register values from the CFI table
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// and then setting stack pointer to CFA.
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//
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// A high-level overview of the function of the trampolines is:
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// * The 2nd init trampoline puts a controlled value (written in swap to `new_cfa`)
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// into %ebx.
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// * The 1st init trampoline tells the unwinder to set %esp to %ebx, thus continuing
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// unwinding at the swap call site instead of falling off the end of context stack.
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// * The 1st init trampoline together with the swap trampoline also restore %ebp
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// when unwinding as well as returning normally, because LLVM does not do it for us.
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use stack::Stack;
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#[derive(Debug)]
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@ -32,6 +32,14 @@
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// after. A .cfi_def_* pseudoinstruction changes the CFA value similarly.
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// * Simulating return is as easy as restoring register values from the CFI table
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// and then setting stack pointer to CFA.
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//
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// A high-level overview of the function of the trampolines is:
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// * The 2nd init trampoline puts a controlled value (written in swap to `new_cfa`)
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// into %rbx.
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// * The 1st init trampoline tells the unwinder to set %rsp to %rbx, thus continuing
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// unwinding at the swap call site instead of falling off the end of context stack.
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// * The 1st init trampoline together with the swap trampoline also restore %rbp
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// when unwinding as well as returning normally, because LLVM does not do it for us.
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use stack::Stack;
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#[derive(Debug)]
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