Debugging aids

index 2a2d942..5d7506e 100644
@@ -22,7 +22,8 @@ cflatobjs := \
 	lib/printf.o \
 	lib/string.o \
 	lib/abort.o \
-	lib/report.o
+	lib/report.o \
+	lib/stack.o
 
 # libfdt paths
 LIBFDT_objdir = lib/libfdt

@@ -42,8 +43,8 @@ cc-option = $(shell if $(CC) $(1) -S -o /dev/null -xc /dev/null \
 
 CFLAGS += -g
 CFLAGS += $(autodepend-flags) -Wall -Werror
-
-fomit_frame_pointer := $(call cc-option, -fomit-frame-pointer, "")
+frame-pointer-flag=-f$(if $(KEEP_FRAME_POINTER),no-,)omit-frame-pointer
+fomit_frame_pointer := $(call cc-option, $(frame-pointer-flag), "")
 fnostack_protector := $(call cc-option, -fno-stack-protector, "")
 fnostack_protector_all := $(call cc-option, -fno-stack-protector-all, "")
 CFLAGS += $(fomit_frame_pointer)

index 3a14fea..ca80367 100644
@@ -12,6 +12,7 @@ cflatobjs += lib/x86/atomic.o
 cflatobjs += lib/x86/desc.o
 cflatobjs += lib/x86/isr.o
 cflatobjs += lib/x86/acpi.o
+cflatobjs += lib/x86/stack.o
 
 $(libcflat): LDFLAGS += -nostdlib
 $(libcflat): CFLAGS += -ffreestanding -I lib

@@ -19,6 +20,9 @@ $(libcflat): CFLAGS += -ffreestanding -I lib
 CFLAGS += -m$(bits)
 CFLAGS += -O1
 
+# dump_stack.o relies on frame pointers.
+KEEP_FRAME_POINTER := y
+
 libgcc := $(shell $(CC) -m$(bits) --print-libgcc-file-name)
 
 FLATLIBS = lib/libcflat.a $(libgcc)

new file mode 100755
index 0000000..ee5a52e
@@ -0,0 +1,89 @@
+#!/usr/bin/env python
+
+import re
+import subprocess
+import sys
+import traceback
+
+# Subvert output buffering.
+def puts(string):
+    sys.stdout.write(string)
+    sys.stdout.flush()
+
+def pretty_print_stack(binary, line):
+    addrs = line.split()[1:]
+    # Addresses are return addresses unless preceded by a '@'. We want the
+    # caller address so line numbers are more intuitive. Thus we subtract 1
+    # from the address to get the call code.
+    for i in range(len(addrs)):
+        addr = addrs[i]
+        if addr.startswith('@'):
+            addrs[i] = addr[1:]
+        else:
+            addrs[i] = '%lx' % (int(addrs[i], 16) - 1)
+
+    # Output like this:
+    #        0x004002be: start64 at path/to/kvm-unit-tests/x86/cstart64.S:208
+    #         (inlined by) test_ept_violation at path/to/kvm-unit-tests/x86/vmx_tests.c:1719 (discriminator 1)
+    cmd = ['addr2line', '-e', binary, '-i', '-f', '--pretty', '--address']
+    cmd.extend(addrs)
+
+    p = subprocess.Popen(cmd, stdout=subprocess.PIPE)
+    out, err = p.communicate()
+    if p.returncode != 0:
+        puts(line)
+        return
+
+    for line in out.splitlines():
+        m = re.match('(.*) at [^ ]*/kvm-unit-tests/([^ ]*):([0-9]+)(.*)', line)
+        if m is None:
+            puts('%s\n' % line)
+            return
+
+        head, path, line, tail = m.groups()
+        line = int(line)
+        puts('%s at %s:%d%s\n' % (head, path, line, tail))
+        try:
+            lines = open(path).readlines()
+        except IOError:
+            continue
+        if line > 1:
+            puts('        %s\n' % lines[line - 2].rstrip())
+        puts('      > %s\n' % lines[line - 1].rstrip())
+        if line < len(lines):
+            puts('        %s\n' % lines[line].rstrip())
+
+def main():
+    if len(sys.argv) != 2:
+        sys.stderr.write('usage: %s <kernel>\n' % sys.argv[0])
+        sys.exit(1)
+
+    binary = sys.argv[1]
+
+    try:
+        while True:
+            # Subvert input buffering.
+            line = sys.stdin.readline()
+            if line == '':
+                break
+
+            if not line.strip().startswith('STACK:'):
+                puts(line)
+                continue
+
+            try:
+                pretty_print_stack(binary, line)
+            except Exception:
+                puts('Error pretty printing stack:\n')
+                puts(traceback.format_exc())
+                puts('Continuing without pretty printing...\n')
+                while True:
+                    puts(line)
+                    line = sys.stdin.readline()
+                    if line == '':
+                        break
+    except:
+        sys.exit(1)
+
+if __name__ == '__main__':
+    main()

index 958321d..ba6c55b 100755
@@ -11,6 +11,7 @@ arch=`uname -m | sed -e 's/i.86/i386/;s/arm.*/arm/;s/ppc64.*/ppc64/'`
 host=$arch
 cross_prefix=
 endian=""
+pretty_print_stacks=yes
 
 usage() {
     cat <<-EOF

@@ -25,6 +26,8 @@ usage() {
 	    --prefix=PREFIX        where to install things ($prefix)
 	    --kerneldir=DIR        kernel build directory for kvm.h ($kerneldir)
 	    --endian=ENDIAN        endianness to compile for (little or big, ppc64 only)
+	    --[enable|disable]-pretty-print-stacks
+	                           enable or disable pretty stack printing (enabled by default)
 EOF
     exit 1
 }

@@ -61,6 +64,12 @@ while [[ "$1" = -* ]]; do
 	--ld)
 	    ld="$arg"
 	    ;;
+	--enable-pretty-print-stacks)
+	    pretty_print_stacks=yes
+	    ;;
+	--disable-pretty-print-stacks)
+	    pretty_print_stacks=no
+	    ;;
 	--help)
 	    usage
 	    ;;

@@ -149,4 +158,5 @@ API=$api
 TEST_DIR=$testdir
 FIRMWARE=$firmware
 ENDIAN=$endian
+PRETTY_PRINT_STACKS=$pretty_print_stacks
 EOF

index 89e8f84..7e0237f 100755
@@ -46,7 +46,13 @@ while getopts "g:hv" opt; do
     esac
 done
 
-RUNTIME_arch_run="./$TEST_DIR/run >> test.log"
+if [ "$PRETTY_PRINT_STACKS" = "yes" ]; then
+	log_redir="> >(./scripts/pretty_print_stacks.py \$kernel >> test.log)"
+else
+	log_redir=">> test.log"
+fi
+
+RUNTIME_arch_run="./$TEST_DIR/run $log_redir"
 config=$TEST_DIR/unittests.cfg
 rm -f test.log
 printf "BUILD_HEAD=$(cat build-head)\n\n" > test.log

index 1d3a20d..ef15bc8 100755
@@ -41,6 +41,8 @@ generate_test ()
 	echo "#!/bin/bash"
 	echo "export STANDALONE=yes"
 	echo "export HOST=\$(uname -m | sed -e s/i.86/i386/ | sed -e 's/arm.*/arm/')"
+	echo "export PRETTY_PRINT_STACKS=no"
+
 	config_export ARCH
 	config_export ARCH_NAME
 	config_export PROCESSOR