[PATCH 2/2] scripts/gdb: Support getting current task struct in UML

[Glenn Washburn]

A running x86 UML kernel reports with architecture "i386:x86-64" as
it is a sub-architecture. However, a difference with bare-metal x86
kernels is in how it manages tasks and the current task struct. To
identify that the inferior is a UML kernel and not bare-metal, the
symbol "uml_kmalloc" is checked for. If it exists, then do the UML
specific way of getting the current task struct.

Signed-off-by: Glenn Washburn <development at efficientek.com>
---
 scripts/gdb/linux/cpus.py | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/scripts/gdb/linux/cpus.py b/scripts/gdb/linux/cpus.py
index 289f0bf4d2a1..90908653f6c7 100644
--- a/scripts/gdb/linux/cpus.py
+++ b/scripts/gdb/linux/cpus.py
@@ -163,8 +163,12 @@ def get_current_task(cpu):
     task_ptr_type = task_type.get_type().pointer()
 
     if utils.is_target_arch("x86"):
-        var_ptr = gdb.parse_and_eval("&current_task")
-        return per_cpu(var_ptr, cpu).dereference()
+        if gdb.lookup_global_symbol("uml_kmalloc"):
+            var_ptr = gdb.parse_and_eval("(struct task_struct *)cpu_tasks[0].task")
+            return var_ptr.dereference()
+        else:
+            var_ptr = gdb.parse_and_eval("&current_task")
+            return per_cpu(var_ptr, cpu).dereference()
     elif utils.is_target_arch("aarch64"):
         current_task_addr = gdb.parse_and_eval("$SP_EL0")
         if((current_task_addr >> 63) != 0):
-- 
2.30.2