From eab39a9ef3979b44133d1e0ab3bb20327db87973 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Th=C3=A9ophile=20Bastian?= <contact@tobast.fr>
Date: Sat, 19 Oct 2019 09:31:34 +0200
Subject: [PATCH] Add lowlevellock DWARF

---
 slides.tex                 | 18 ++++++++++++------
 src/lowlevellock_dw.c      | 25 +++++++++++++++++++++++++
 src/lowlevellock_dw_extr.c | 24 ++++++++++++++++++++++++
 3 files changed, 61 insertions(+), 6 deletions(-)
 create mode 100644 src/lowlevellock_dw.c
 create mode 100644 src/lowlevellock_dw_extr.c

diff --git a/slides.tex b/slides.tex
index 2b9cedf..80a189b 100644
--- a/slides.tex
+++ b/slides.tex
@@ -328,14 +328,20 @@ Segmentation fault.
 \end{frame}
 
 \begin{frame}
-    \todo{Actually add lowlevellock code}
+    \lstinputlisting[language=bash,numbers=none,basicstyle=\tt\fontsize{8pt}{9pt}\selectfont]{src/lowlevellock_dw_extr.c}
 
-    In \prog{glibc}, \prog{lowlevellock.h}:
-    \alert{off by one error in unwinding data}.
+    \only<2>{
+        \begin{textblock*}{0.60\textwidth}[0.5,0.5](0.5\paperwidth,0.5\paperheight)%
+            \begin{tcolorbox}[halign=center, colframe=OliveGreen, colback=YellowGreen]
+                In \prog{glibc}, \prog{lowlevellock.h}:
+                \alert{off by one error in unwinding data}.
 
-    \lstinputlisting[language=gdb,numbers=none]{src/lowlevellock_backtrace}
+                \lstinputlisting[language=gdb,numbers=none]{src/lowlevellock_backtrace}
+            \end{tcolorbox}
+        \end{textblock*}
+    }
 
-    \only<2->{
+    \only<3->{
         \begin{textblock*}{0.90\textwidth}[0.5,0](0.5\paperwidth,0.10\paperheight)%
             \begin{tcolorbox}[halign=center, colframe=red, colback=Lavender]
                 \bf \LARGE
@@ -344,7 +350,7 @@ Segmentation fault.
         \end{textblock*}
     }
 
-    \only<3->{
+    \only<4->{
         \begin{textblock*}{0.90\textwidth}[0.5,0](0.5\paperwidth,0.30\paperheight)%
             \begin{tcolorbox}[halign=center, colframe=red, colback=Lavender]
                 \LARGE
diff --git a/src/lowlevellock_dw.c b/src/lowlevellock_dw.c
new file mode 100644
index 0000000..6916484
--- /dev/null
+++ b/src/lowlevellock_dw.c
@@ -0,0 +1,25 @@
+#define LLL_STUB_UNWIND_INFO_START
+    ".section    .eh_frame,\"a\",@progbits\n"
+"5:\t"    ".long    7f-6f            # Length of Common Information Entry\n"
+"6:\t"    ".long    0x0              # CIE Identifier Tag\n\t"
+    ".byte    0x1                    # CIE Version\n\t"
+    ".ascii \"zR\\0\"                # CIE Augmentation\n\t"
+    ".uleb128 0x1                    # CIE Code Alignment Factor\n\t"
+    ".sleb128 -4                     # CIE RA Column\n\t"
+    ".byte    0x8                    # Augmentation size\n\t"
+    ".uleb128 0x1                    # FDE Encoding (pcrel sdata4)\n\t"
+    ".byte    0x1b                   # DW_CFA_def_cfa\n\t"
+    ".byte    0xc\n\t"
+    ".uleb128 0x4\n\t"
+    ".uleb128 0x0\n\t"
+    ".align 4\n"
+"7:\t"    ".long    17f-8f           # FDE Length\n"
+"8:\t"    ".long    8b-5b            # FDE CIE offset\n\t"
+    ".long    1b-.                   # FDE initial location\n\t"
+    ".long    4b-1b                  # FDE address range\n\t"
+    ".uleb128 0x0                    # Augmentation size\n\t"
+    ".byte    0x16                   # DW_CFA_val_expression\n\t"
+    ".uleb128 0x8\n\t"
+    ".uleb128 10f-9f\n"
+"9:\t"    ".byte    0x78             # DW_OP_breg8\n\t"
+    ".sleb128 3b-1b\n"
diff --git a/src/lowlevellock_dw_extr.c b/src/lowlevellock_dw_extr.c
new file mode 100644
index 0000000..4147cea
--- /dev/null
+++ b/src/lowlevellock_dw_extr.c
@@ -0,0 +1,24 @@
+    .section    .eh_frame,"a",@progbits
+5:  .long    7f-6f       # Length of Common Information Entry
+6:  .long    0x0         # CIE Identifier Tag
+    .byte    0x1         # CIE Version
+    .ascii "zR\\0"       # CIE Augmentation
+    .uleb128 0x1         # CIE Code Alignment Factor
+    .sleb128 -4          # CIE RA Column
+    .byte    0x8         # Augmentation size
+    .uleb128 0x1         # FDE Encoding (pcrel sdata4)
+    .byte    0x1b        # DW_CFA_def_cfa
+    .byte    0xc
+    .uleb128 0x4
+    .uleb128 0x0
+    .align 4
+7:  .long    17f-8f      # FDE Length
+8:  .long    8b-5b       # FDE CIE offset
+    .long    1b-.        # FDE initial location
+    .long    4b-1b       # FDE address range
+    .uleb128 0x0         # Augmentation size
+    .byte    0x16        # DW_CFA_val_expression
+    .uleb128 0x8
+    .uleb128 10f-9f
+9:  .byte    0x78        # DW_OP_breg8
+    .sleb128 3b-1b