[v2,0/3] scripts/qemu-gdb: Make coroutine dumps to work with coredumps

Message

Peter Xu Dec. 12, 2024, 8:47 p.m. UTC

v1: https://lore.kernel.org/r/[e-mail]

Changelog: in previous v1, I got a wrong cut-off accident in commit
message, which is now fixed (along with some small touchup elsewhere).
When at it, I also tried to make it look even better to be as close as gdb
bt, so it looks like this now:

  Coroutine at 0x7f9f4c57c748:
  #0  0x55ae6c0dc9a8 in qemu_coroutine_switch<+120> () at ../util/coroutine-ucontext.c:321
  #1  0x55ae6c0da2f8 in qemu_aio_coroutine_enter<+356> () at ../util/qemu-coroutine.c:293
  #2  0x55ae6c0da3f1 in qemu_coroutine_enter<+34> () at ../util/qemu-coroutine.c:316
  #3  0x55ae6baf775e in migration_incoming_process<+43> () at ../migration/migration.c:876
  #4  0x55ae6baf7ab4 in migration_ioc_process_incoming<+490> () at ../migration/migration.c:1008
  #5  0x55ae6bae9ae7 in migration_channel_process_incoming<+145> () at ../migration/channel.c:45
  #6  0x55ae6bb18e35 in socket_accept_incoming_migration<+118> () at ../migration/socket.c:132
  #7  0x55ae6be939ef in qio_net_listener_channel_func<+131> () at ../io/net-listener.c:54
  #8  0x55ae6be8ce1a in qio_channel_fd_source_dispatch<+78> () at ../io/channel-watch.c:84
  #9  0x7f9f5b26728c in g_main_context_dispatch_unlocked.lto_priv<+315> ()
  #10  0x7f9f5b267555 in g_main_context_dispatch<+36> ()
  #11  0x55ae6c0d91a7 in glib_pollfds_poll<+90> () at ../util/main-loop.c:287
  #12  0x55ae6c0d9235 in os_host_main_loop_wait<+128> () at ../util/main-loop.c:310
  #13  0x55ae6c0d9364 in main_loop_wait<+203> () at ../util/main-loop.c:589
  #14  0x55ae6bac212a in qemu_main_loop<+41> () at ../system/runstate.c:835
  #15  0x55ae6bfdf522 in qemu_default_main<+19> () at ../system/main.c:37
  #16  0x55ae6bfdf55f in main<+40> () at ../system/main.c:48
  #17  0x7f9f59d42248 in __libc_start_call_main<+119> ()
  #18  0x7f9f59d4230b in __libc_start_main_impl<+138> ()

Coroutines are used in many cases in block layers. It's also used in live
migration when on destination side, and it'll be handy to diagnose crashes
within a coroutine when we want to also know what other coroutines are
doing.

This series adds initial support for that, not pretty but it should start
working.  Since we can't use the trick to modify registers on the fly in
non-live gdb sessions, we do manual unwinds.

One thing to mention is there's a similar but more generic solution
mentioned on the list from Niall:

https://lore.kernel.org/r/[e-mail]

That adds more dependency on both gdb and qemu in the future, however more
generic.  So this series is an intermediate quick solution as for now,
which should work for most older qemu/gdb binaries too.

Thanks,

Peter Xu (3):
  scripts/qemu-gdb: Always do full stack dump for python errors
  scripts/qemu-gdb: Simplify fs_base fetching for coroutines
  scripts/qemu-gdb: Support coroutine dumps in coredumps

 scripts/qemu-gdb.py          |   2 +
 scripts/qemugdb/coroutine.py | 102 +++++++++++++++++++++++++----------
 2 files changed, 77 insertions(+), 27 deletions(-)