[PATCH v2 2/3] x86/boot: Uses nm command instead of map file to get symbols

[Frediano Ziglio <frediano.ziglio@cloud.com>]

Map file format is not standard making it code readind it
not portable and potentially hard to maintain.
Use nm command instead to get list of symbols; specifically
BSD format as it does not truncate symbols names like sysv one.

Fixes: aa9045e77130 ('x86/boot: Rework how 32bit C is linked/included for early boot')

Signed-off-by: Frediano Ziglio <frediano.ziglio@cloud.com>
---
 xen/arch/x86/boot/Makefile        |  5 +++--
 xen/tools/combine_two_binaries.py | 28 ++++++++++++++++++----------
 2 files changed, 21 insertions(+), 12 deletions(-)

diff --git a/xen/arch/x86/boot/Makefile b/xen/arch/x86/boot/Makefile
index 777b4befeb..01100a4b72 100644
--- a/xen/arch/x86/boot/Makefile
+++ b/xen/arch/x86/boot/Makefile
@@ -67,7 +67,8 @@ $(obj)/built-in-32.tmp.o: $(obj32)
 # If possible we use --orphan-handling=error option to make sure we account
 # for all possible sections from C code.
 $(obj)/built-in-32.%.bin: $(obj)/build32.%.lds $(obj)/built-in-32.tmp.o
-	$(LD32) $(orphan-handling-y) -N -T $< -Map $(@:bin=map) -o $(@:bin=o) $(filter %.o,$^)
+	$(LD32) $(orphan-handling-y) -N -T $< -o $(@:bin=o) $(filter %.o,$^)
+	$(NM) -p --format=bsd $(@:bin=o) > $(@:bin=nm)
 	$(OBJCOPY) -j .text -O binary $(@:bin=o) $@
 	rm -f $(@:bin=o)
 
@@ -79,7 +80,7 @@ cmd_combine = \
               --script    $(obj)/build32.base.lds \
               --bin1      $(obj)/built-in-32.base.bin \
               --bin2      $(obj)/built-in-32.offset.bin \
-              --map       $(obj)/built-in-32.base.map \
+              --symbols   $(obj)/built-in-32.base.nm \
               --exports   cmdline_parse_early,reloc,reloc_trampoline32 \
               --output    $@
 
diff --git a/xen/tools/combine_two_binaries.py b/xen/tools/combine_two_binaries.py
index 447c0d3bdb..db02494b28 100755
--- a/xen/tools/combine_two_binaries.py
+++ b/xen/tools/combine_two_binaries.py
@@ -28,8 +28,8 @@ parser.add_argument('--text-diff', dest='text_diff',
                     help='Difference between code section start')
 parser.add_argument('--output', dest='output',
                     help='Output file')
-parser.add_argument('--map', dest='mapfile',
-                    help='Map file to read for symbols to export')
+parser.add_argument('--symbols', dest='symbols_file',
+                    help='Nm command output to read for symbols to export')
 parser.add_argument('--exports', dest='exports',
                     help='Symbols to export')
 parser.add_argument('--section-header', dest='section_header',
@@ -65,15 +65,23 @@ exports = []
 if args.exports is not None:
     exports = dict([(name, None) for name in args.exports.split(',')])
 
-# Parse mapfile, look for ther symbols we want to export.
-if args.mapfile is not None:
-    symbol_re = re.compile(r'\s{15,}0x([0-9a-f]+)\s+(\S+)\n')
-    for line in open(args.mapfile):
-        m = symbol_re.match(line)
-        if not m or m.group(2) not in exports:
+# Parse symbols file, look for symbols we want to export.
+if args.symbols_file is not None:
+    dummy_start = -1
+    for line in open(args.symbols_file):
+        v = line.split()
+        if len(v) != 3 or v[1].upper() != 'T':
             continue
-        addr = int(m.group(1), 16)
-        exports[m.group(2)] = addr
+        addr = int(v[0], 16)
+        if v[2] == 'dummy_start':
+            dummy_start = addr
+            continue
+        if v[2] not in exports:
+            continue
+        exports[v[2]] = addr
+    if dummy_start != 0:
+        raise Exception("dummy_start symbol expected to be present and 0")
+
 for (name, addr) in exports.items():
     if addr is None:
         raise Exception("Required export symbols %s not found" % name)
-- 
2.34.1