Fix colon spaces, reorganize fib7 listing flow
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@ -273,23 +273,20 @@ them.
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caption={Original C},label={lst:ex1_c}]
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{src/fib7/fib7.c}
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\end{minipage} \hfill \begin{minipage}{0.45\textwidth}
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\lstinputlisting[language=C,caption={Processed DWARF},
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label={lst:ex1_dw}]
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{src/fib7/fib7.fde}
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\lstinputlisting[language=C,caption={Raw DWARF},label={lst:ex1_dwraw}]
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{src/fib7/fib7.raw_fde}
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\lstinputlisting[language={[x86masm]Assembler},
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caption={Generated assembly},label={lst:ex1_asm}]
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{src/fib7/fib7.s}
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\end{minipage}
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\end{figure}
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\begin{figure}[h]
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\begin{minipage}{0.45\textwidth}
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\lstinputlisting[language={[x86masm]Assembler},lastline=11,
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caption={Generated assembly},label={lst:ex1_asm}]
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{src/fib7/fib7.s}
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\lstinputlisting[language=C,caption={Raw DWARF},label={lst:ex1_dwraw}]
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{src/fib7/fib7.raw_fde}
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\end{minipage} \hfill \begin{minipage}{0.45\textwidth}
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\lstinputlisting[language={[x86masm]Assembler},firstline=12,
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firstnumber=last]
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{src/fib7/fib7.s}
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\lstinputlisting[language=C,caption={Processed DWARF},
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label={lst:ex1_dw}]
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{src/fib7/fib7.fde}
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\end{minipage}
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\end{figure}
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@ -413,7 +410,7 @@ pointer. The C function representing it will thus take as parameters an array
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of the registers' values as well as an IP, and will return another array of
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registers values, which will represent the evaluated DWARF row.
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\subsection{Original language~: DWARF instructions}
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\subsection{Original language: DWARF instructions}
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These are the DWARF instructions used for CFI description, that is, the
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instructions that contain the stack unwinding table informations. The following
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@ -427,50 +424,50 @@ here, those variations between eg. \dwcfa{advance\_loc1} and
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operand~-- are irrelevant and will be eluded.
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\begin{itemize}
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\item{} \dwcfa{set\_loc(loc)}~:
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\item{} \dwcfa{set\_loc(loc)}:
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start a new table row from address $loc$
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\item{} \dwcfa{advance\_loc(delta)}~:
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\item{} \dwcfa{advance\_loc(delta)}:
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start a new table row at address $prev\_loc + delta$
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\item{} \dwcfa{def\_cfa(reg, offset)}~:
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\item{} \dwcfa{def\_cfa(reg, offset)}:
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sets this row's CFA at $(\reg{reg} + \textit{offset})$
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\item{} \dwcfa{def\_cfa\_register(reg)}~:
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\item{} \dwcfa{def\_cfa\_register(reg)}:
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sets CFA at $(\reg{reg} + \textit{prev\_offset})$
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\item{} \dwcfa{def\_cfa\_offset(offset)}~:
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\item{} \dwcfa{def\_cfa\_offset(offset)}:
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sets CFA at $(\reg{prev\_reg} + \textit{offset})$
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\item{} \dwcfa{def\_cfa\_expression(expr)}~:
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\item{} \dwcfa{def\_cfa\_expression(expr)}:
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sets CFA as the result of $expr$
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\item{} \dwcfa{undefined(reg)}~:
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\item{} \dwcfa{undefined(reg)}:
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sets the register \reg{reg} as undefined in this row
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\item{} \dwcfa{same\_value(reg)}~:
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\item{} \dwcfa{same\_value(reg)}:
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declares that the register \reg{reg} hasn't been touched, or was
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restored to its previous value, in this row. An unwinding procedure can
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leave it as-is.
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\item{} \dwcfa{offset(reg, offset)}~:
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\item{} \dwcfa{offset(reg, offset)}:
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the value of the register \reg{reg} is stored in memory at the address
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$CFA + \textit{offset}$.
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\item{} \dwcfa{val\_offset(reg, offset)}~:
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\item{} \dwcfa{val\_offset(reg, offset)}:
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the value of the register \reg{reg} is the value $CFA + \textit{offset}$
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\item{} \dwcfa{register(reg, model)}~:
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\item{} \dwcfa{register(reg, model)}:
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the register \reg{reg} has, in this row, the value that $\reg{model}$
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had in the previous row
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\item{} \dwcfa{expression(reg, expr)}~:
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\item{} \dwcfa{expression(reg, expr)}:
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the value of \reg{reg} is stored in memory at the address defined by
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$expr$
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\item{} \dwcfa{val\_expression(reg, expr)}~:
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\item{} \dwcfa{val\_expression(reg, expr)}:
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\reg{reg} has the value of $expr$
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\item{} \dwcfa{restore(reg)}~:
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\item{} \dwcfa{restore(reg)}:
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\reg{reg} has the same value as in this FDE's preamble (CIE) in this
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row. This is \emph{not implemented in this semantics} for simplicity
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and brevity (we would have to introduce CIE (preamble) and FDE (body)
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independently). This is also not much used in actual ELF
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files: the analysis in Section~\ref{ssec:instr_cov} found no such
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instruction, on a random uniform sample of 4000 ELF files.
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\item{} \dwcfa{remember\_state()}~:
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\item{} \dwcfa{remember\_state()}:
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push the state of all the registers of this row on an implicit stack
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\item{} \dwcfa{restore\_state()}~:
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\item{} \dwcfa{restore\_state()}:
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pop an entry of the implicit stack, and restore all registers in this
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row to the value held in the stack record.
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\item{} \dwcfa{nop()}~:
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\item{} \dwcfa{nop()}:
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do nothing (padding)
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\end{itemize}
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@ -516,7 +513,7 @@ to define $\reg{rax}$ to the value contained in memory 16 bytes below the CFA,
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we would have $\reg{rax} \mapsto \valaddr{\reg{CFA}, -16}$, since the stack
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grows downwards.
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\subsection{Target language~: a C function body}
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\subsection{Target language: a C function body}
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The target language of these semantics is a C function, to be interpreted with
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respect to the C11 standard~\cite{c11std}. The function is supposed to be run
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@ -532,7 +529,7 @@ unless the IP obtained after the first unwinding comes from another shared
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object file, for instance a call to \prog{libc}. In this case, unwinding the
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second frame will require loading the corresponding DWARF information.
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The function is the following~:
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The function is the following:
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\lstinputlisting[language=C]{src/dw_semantics/c_context.c}
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@ -553,7 +550,7 @@ kept in subscript.
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\medskip
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Thus, we define $\semI{\bullet}{s}(\bullet) : \DWARF \times \FDE \to \FDE$, for
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Thus, we define $\semI{\bullet}{s}(\bullet): \DWARF \times \FDE \to \FDE$, for
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$s$ a stack of $\dwrow$, that is,
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\[
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s \in \rowstack := \dwrow^\ast
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@ -642,7 +639,7 @@ this way.}
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\medskip
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We now define $\semC{\bullet} : \DWARF \to C$, in the context presented
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We now define $\semC{\bullet}: \DWARF \to C$, in the context presented
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earlier. The translation from $\intermedlang$ to C is defined as follows:
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\begin{itemize}
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@ -2,17 +2,14 @@
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615: sub $0x28,%rsp ; Alloc stack
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619: movl $0x1,(%rsp) ; fibo[0]
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620: movl $0x1,0x4(%rsp) ; fibo[1]
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627:
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; Begin for loop
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628: mov %rsp,%rax
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628: mov %rsp,%rax ; BEGIN FOR
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62b: lea 0x18(%rax),%rcx
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62f: mov (%rax),%edx
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631: add 0x4(%rax),%edx
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634: mov %edx,0x8(%rax)
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637: add $0x4,%rax
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63b: cmp %rcx,%rax
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63e: jne 62f <fib7+0x1a>
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; End for loop
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63e: jne 62f <fib7+0x1a> ; END FOR
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640: mov 0x1c(%rsp),%esi
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644: lea 0xb9(%rip),%rdi
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64b: mov $0x0,%eax
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