1 files changed, 148 insertions, 0 deletions
diff --git a/scripts/qemugdb/coroutine.py b/scripts/qemugdb/coroutine.py
new file mode 100644
index 000000000..7db46d4b6
--- /dev/null
+++ b/scripts/qemugdb/coroutine.py
@@ -0,0 +1,148 @@
+#
+# GDB debugging support
+#
+# Copyright 2012 Red Hat, Inc. and/or its affiliates
+#
+# Authors:
+#  Avi Kivity <avi@redhat.com>
+#
+# This work is licensed under the terms of the GNU GPL, version 2
+# or later.  See the COPYING file in the top-level directory.
+
+import gdb
+
+VOID_PTR = gdb.lookup_type('void').pointer()
+
+def get_fs_base():
+    '''Fetch %fs base value using arch_prctl(ARCH_GET_FS).  This is
+       pthread_self().'''
+    # %rsp - 120 is scratch space according to the SystemV ABI
+    old = gdb.parse_and_eval('*(uint64_t*)($rsp - 120)')
+    gdb.execute('call (int)arch_prctl(0x1003, $rsp - 120)', False, True)
+    fs_base = gdb.parse_and_eval('*(uint64_t*)($rsp - 120)')
+    gdb.execute('set *(uint64_t*)($rsp - 120) = %s' % old, False, True)
+    return fs_base
+
+def pthread_self():
+    '''Fetch pthread_self() from the glibc start_thread function.'''
+    f = gdb.newest_frame()
+    while f.name() != 'start_thread':
+        f = f.older()
+        if f is None:
+            return get_fs_base()
+
+    try:
+        return f.read_var("arg")
+    except ValueError:
+        return get_fs_base()
+
+def get_glibc_pointer_guard():
+    '''Fetch glibc pointer guard value'''
+    fs_base = pthread_self()
+    return gdb.parse_and_eval('*(uint64_t*)((uint64_t)%s + 0x30)' % fs_base)
+
+def glibc_ptr_demangle(val, pointer_guard):
+    '''Undo effect of glibc's PTR_MANGLE()'''
+    return gdb.parse_and_eval('(((uint64_t)%s >> 0x11) | ((uint64_t)%s << (64 - 0x11))) ^ (uint64_t)%s' % (val, val, pointer_guard))
+
+def get_jmpbuf_regs(jmpbuf):
+    JB_RBX  = 0
+    JB_RBP  = 1
+    JB_R12  = 2
+    JB_R13  = 3
+    JB_R14  = 4
+    JB_R15  = 5
+    JB_RSP  = 6
+    JB_PC   = 7
+
+    pointer_guard = get_glibc_pointer_guard()
+    return {'rbx': jmpbuf[JB_RBX],
+        'rbp': glibc_ptr_demangle(jmpbuf[JB_RBP], pointer_guard),
+        'rsp': glibc_ptr_demangle(jmpbuf[JB_RSP], pointer_guard),
+        'r12': jmpbuf[JB_R12],
+        'r13': jmpbuf[JB_R13],
+        'r14': jmpbuf[JB_R14],
+        'r15': jmpbuf[JB_R15],
+        'rip': glibc_ptr_demangle(jmpbuf[JB_PC], pointer_guard) }
+
+def bt_jmpbuf(jmpbuf):
+    '''Backtrace a jmpbuf'''
+    regs = get_jmpbuf_regs(jmpbuf)
+    old = dict()
+
+    # remember current stack frame and select the topmost
+    # so that register modifications don't wreck it
+    selected_frame = gdb.selected_frame()
+    gdb.newest_frame().select()
+
+    for i in regs:
+        old[i] = gdb.parse_and_eval('(uint64_t)$%s' % i)
+
+    for i in regs:
+        gdb.execute('set $%s = %s' % (i, regs[i]))
+
+    gdb.execute('bt')
+
+    for i in regs:
+        gdb.execute('set $%s = %s' % (i, old[i]))
+
+    selected_frame.select()
+
+def co_cast(co):
+    return co.cast(gdb.lookup_type('CoroutineUContext').pointer())
+
+def coroutine_to_jmpbuf(co):
+    coroutine_pointer = co_cast(co)
+    return coroutine_pointer['env']['__jmpbuf']
+
+
+class CoroutineCommand(gdb.Command):
+    '''Display coroutine backtrace'''
+    def __init__(self):
+        gdb.Command.__init__(self, 'qemu coroutine', gdb.COMMAND_DATA,
+                             gdb.COMPLETE_NONE)
+
+    def invoke(self, arg, from_tty):
+        argv = gdb.string_to_argv(arg)
+        if len(argv) != 1:
+            gdb.write('usage: qemu coroutine <coroutine-pointer>\n')
+            return
+
+        bt_jmpbuf(coroutine_to_jmpbuf(gdb.parse_and_eval(argv[0])))
+
+class CoroutineBt(gdb.Command):
+    '''Display backtrace including coroutine switches'''
+    def __init__(self):
+        gdb.Command.__init__(self, 'qemu bt', gdb.COMMAND_STACK,
+                             gdb.COMPLETE_NONE)
+
+    def invoke(self, arg, from_tty):
+
+        gdb.execute("bt")
+
+        if gdb.parse_and_eval("qemu_in_coroutine()") == False:
+            return
+
+        co_ptr = gdb.parse_and_eval("qemu_coroutine_self()")
+
+        while True:
+            co = co_cast(co_ptr)
+            co_ptr = co["base"]["caller"]
+            if co_ptr == 0:
+                break
+            gdb.write("Coroutine at " + str(co_ptr) + ":\n")
+            bt_jmpbuf(coroutine_to_jmpbuf(co_ptr))
+
+class CoroutineSPFunction(gdb.Function):
+    def __init__(self):
+        gdb.Function.__init__(self, 'qemu_coroutine_sp')
+
+    def invoke(self, addr):
+        return get_jmpbuf_regs(coroutine_to_jmpbuf(addr))['rsp'].cast(VOID_PTR)
+
+class CoroutinePCFunction(gdb.Function):
+    def __init__(self):
+        gdb.Function.__init__(self, 'qemu_coroutine_pc')
+
+    def invoke(self, addr):
+        return get_jmpbuf_regs(coroutine_to_jmpbuf(addr))['rip'].cast(VOID_PTR)