Nicholas Piggin 4e0e45b07d powerpc: Use trap metadata to prevent double restart rather than zeroing trap
It's not very nice to zero trap for this, because then system calls no
longer have trap_is_syscall(regs) invariant, and we can't distinguish
between sc and scv system calls (in a later patch).

Take one last unused bit from the low bits of the pt_regs.trap word
for this instead. There is not a really good reason why it should be
in trap as opposed to another field, but trap has some concept of
flags and it exists. Ideally I think we would move trap to 2-byte
field and have 2 more bytes available independently.

Add a selftests case for this, which can be seen to fail if
trap_norestart() is changed to return false.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Make them static inlines]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200507121332.2233629-4-mpe@ellerman.id.au
2020-05-15 11:58:54 +10:00
..
2019-11-18 22:27:51 +11:00
2020-03-25 12:09:39 +11:00
2019-11-19 19:38:38 +11:00
2018-06-07 10:23:33 -07:00
2020-04-05 11:12:59 -07:00
2019-07-13 16:08:36 -07:00
2019-09-05 14:22:41 +10:00
2019-07-13 16:08:36 -07:00
2019-07-13 16:08:36 -07:00
2019-07-13 16:08:36 -07:00
2019-07-13 16:08:36 -07:00
2018-05-25 12:04:43 +10:00
2019-11-30 14:35:43 -08:00
2018-07-30 22:48:21 +10:00
2019-05-01 16:45:05 +10:00