linux-kernel - [PATCH] scripts/gdb: Fix lx-symbols command for arm64 LLVM

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Message-ID: <20230706095915.2256452-1-koudai@google.com>
Date:   Thu,  6 Jul 2023 02:59:14 -0700
From:   Koudai Iwahori <koudai@...gle.com>
To:     Jan Kiszka <jan.kiszka@...mens.com>,
        Kieran Bingham <kbingham@...nel.org>
Cc:     Koudai Iwahori <koudai@...gle.com>, linux-kernel@...r.kernel.org
Subject: [PATCH] scripts/gdb: Fix lx-symbols command for arm64 LLVM

lx-symbols assumes that module's .text sections is located at
`module->mem[MOD_TEXT].base` and passes it to add-symbol-file command.
However, .text section follows after .plt section in modules built by
LLVM toolchain for arm64 target. Symbol addresses are skewed in GDB.

Fix this issue by using the address of .text section stored in
`module->sect_attrs`.

Signed-off-by: Koudai Iwahori <koudai@...gle.com>
---
 scripts/gdb/linux/symbols.py | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/scripts/gdb/linux/symbols.py b/scripts/gdb/linux/symbols.py
index fdad3f32c747..c8047f4441e6 100644
--- a/scripts/gdb/linux/symbols.py
+++ b/scripts/gdb/linux/symbols.py
@@ -89,23 +89,27 @@ lx-symbols command."""
                 return name
         return None
 
-    def _section_arguments(self, module):
+    def _section_arguments(self, module, module_addr):
         try:
             sect_attrs = module['sect_attrs'].dereference()
         except gdb.error:
-            return ""
+            return str(module_addr)
+
         attrs = sect_attrs['attrs']
         section_name_to_address = {
             attrs[n]['battr']['attr']['name'].string(): attrs[n]['address']
             for n in range(int(sect_attrs['nsections']))}
+
+        textaddr = section_name_to_address.get(".text", module_addr)
         args = []
         for section_name in [".data", ".data..read_mostly", ".rodata", ".bss",
-                             ".text", ".text.hot", ".text.unlikely"]:
+                             ".text.hot", ".text.unlikely"]:
             address = section_name_to_address.get(section_name)
             if address:
                 args.append(" -s {name} {addr}".format(
                     name=section_name, addr=str(address)))
-        return "".join(args)
+        return "{textaddr} {sections}".format(
+            textaddr=textaddr, sections="".join(args))
 
     def load_module_symbols(self, module):
         module_name = module['name'].string()
@@ -125,10 +129,9 @@ lx-symbols command."""
                 module_addr = hex(int(module_addr, 0) + plt_offset + plt_size)
             gdb.write("loading @{addr}: {filename}\n".format(
                 addr=module_addr, filename=module_file))
-            cmdline = "add-symbol-file {filename} {addr}{sections}".format(
+            cmdline = "add-symbol-file {filename} {sections}".format(
                 filename=module_file,
-                addr=module_addr,
-                sections=self._section_arguments(module))
+                sections=self._section_arguments(module, module_addr))
             gdb.execute(cmdline, to_string=True)
             if module_name not in self.loaded_modules:
                 self.loaded_modules.append(module_name)
-- 
2.41.0.255.g8b1d071c50-goog