[PATCH] Make _Unwind_GetIPInfo part of the ABI

[Florian Weimer <fweimer@redhat.com>]

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Without _Unwind_GetIPInfo, it is not possible to unwind correctly 
through signal handlers.  glibc needs this, otherwise cancellation does 
not work.

The attached patch documents this function and makes it part of the ABI. 
  I tried to explain as best as I could why this function is needed, 
without talking about exception handler regions.

The 32-bit ABI will need a similar change.

The second patch is for the Makefile, so that it doesn't ask for input 
on an error.

Thanks,
Florian

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diff --git a/libraries.tex b/libraries.tex
index 7c5d214..a539e6d 100644
--- a/libraries.tex
+++ b/libraries.tex
@@ -42,6 +42,7 @@ The unwind library interface consists of at least the following routines:\\
 \codeindex{\_Unwind\_GetGR},\\
 \codeindex{\_Unwind\_SetGR},\\
 \codeindex{\_Unwind\_GetIP},\\
+\codeindex{\_Unwind\_GetIPInfo},\\
 \codeindex{\_Unwind\_SetIP},\\
 \codeindex{\_Unwind\_GetRegionStart},\\
 \codeindex{\_Unwind\_GetLanguageSpecificData},\\
@@ -524,6 +525,41 @@ identified by the unwind context. This value may be outside of the
 procedure fragment for a function call that is known to not return
 (such as \code{\_Unwind\_Resume}).
 
+Applications which unwind through asynchronous signals and other
+non-call locations should use \code{\_Unwind\_GetIPInfo} below, and
+the additional flag that function provides.
+
+\subsubsection{\code{\_Unwind\_GetIPInfo}}
+
+\code{
+\begin{tabular}{l}
+    uint64 \_Unwind\_GetIPInfo\\
+    \ \ (struct \_Unwind\_Context *context, int *not\_nested);\\
+\end{tabular}
+}
+
+This function returns the same value as \code{\_Unwind\_GetIP}.  In
+addition, the argument \code{not\_nested} must not be not null, and
+\code{*not\_nested} is updated with a flag which indicates whether
+this unwind context refers to a call site which was reached through
+stack unwinding.
+
+If \code{*not\_nested} is false, the application calling
+\code{\_Unwind\_GetIPInfo} should assume that the instruction pointer
+provided points after a call instruction which has not yet returned.
+In general, this means that the application should use the preceding
+call instruction as the instruction pointer location of the unwind
+context.  Typically, this can be approximated by subtracting one from
+the returned instruction pointer.
+
+If \code{*not\_nested} is true, then the instruction pointer does not
+refer to an active call site.  Usually, this means that the
+instruction pointer refers to the point at which an asynchronous
+signal arrived.  In this case, the application should use the
+instruction pointer returned from \code{\_Unwind\_GetIPInfo} as the
+instruction pointer location of the unwind context, without
+adjustment.
+
 \subsubsection{\code{\_Unwind\_SetIP}}
 \code{
 \begin{tabular}{l}

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diff --git a/Makefile b/Makefile
index 89dfd18..3fc1d65 100644
--- a/Makefile
+++ b/Makefile
@@ -5,6 +5,8 @@ INCLUDES  := execution.tex low-level-sys-info.tex development.tex      \
 
 ALL_FILES := abi.tex $(INCLUDES)
 
+TEXFLAGS = -interaction=nonstopmode -file-line-error
+
 .PHONY: all abi clean ps pdf update
 
 # default
@@ -14,14 +16,14 @@ all: abi.ps abi.pdf
 
 
 abi.dvi: $(ALL_FILES)
-	latex abi
+	latex $(TEXFLAGS) abi
 	makeindex abi
-	latex abi
-	latex abi
+	latex $(TEXFLAGS) abi
+	latex $(TEXFLAGS) abi
 
 # Depend on abi.dvi to get index.
 pdf abi.pdf: abi.dvi
-	pdflatex abi
+	pdflatex $(TEXFLAGS) abi
 
 ps abi.ps: abi.dvi
 	dvips abi.dvi -o abi.ps