[0/3] More machine check recovery fixes

Message

Tony Luck July 6, 2021, 7:06 p.m. UTC

Fix a couple of issues in machine check handling

1) A repeated machine check inside the kernel without calling the task
   work function between machine checks it will go into an infinite
   loop
2) Machine checks in kernel functions copying data from user addresses
   send SIGBUS to the user as if the application had consumed the
   poison. But this is wrong. The user should see either an -EFAULT
   error return or a reduced byte count (in the case of write(2)).

Tony Luck (3):
  x86/mce: Change to not send SIGBUS error during copy from user
  x86/mce: Avoid infinite loop for copy from user recovery
  x86/mce: Drop copyin special case for #MC

 arch/x86/kernel/cpu/mce/core.c | 62 ++++++++++++++++++++++++----------
 arch/x86/lib/copy_user_64.S    | 13 -------
 include/linux/sched.h          |  1 +
 3 files changed, 45 insertions(+), 31 deletions(-)