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m68k: Fix task info flags handling for 68000

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The logic for deciding what to do after a syscall should be checking
if any of the lower byte bits are set and then checking if the reschedule
bit is set.

Currently we are loading the top word, checking if any bits are set
(which never seems to be true) and thus jumping over loading the
whole long and checking if the reschedule bit is set.

We get the thread info in two places so split that logic out in
a macro and then fix the code so that it loads the byte of the flags
we need to check, checks if anything is set and then checks if
the reschedule bit in particular is set.

Reported-by: Christoph Plattner <christoph.plattner@gmx.at>
Signed-off-by: Daniel Palmer <daniel@0x0f.com>
Signed-off-by: Greg Ungerer <gerg@kernel.org>
This commit is contained in:
Daniel Palmer 2026-04-04 11:31:08 +09:00 committed by Greg Ungerer
parent 591cd656a1
commit 2c6805145e
1 changed files with 13 additions and 8 deletions
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21
arch/m68k/68000/entry.S
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@ -18,6 +18,13 @@
.text
/* get thread_info pointer into a2 */
.macro getthreadinfo
movel %sp,%d1
andl #-THREAD_SIZE,%d1
movel %d1,%a2
.endm
.globl system_call
.globl resume
.globl ret_from_exception
@ -70,9 +77,8 @@ ENTRY(system_call)
movel %sp@(PT_OFF_ORIG_D0),%d0
movel %sp,%d1 /* get thread_info pointer */
andl #-THREAD_SIZE,%d1
movel %d1,%a2
/* Doing a trace ? */
getthreadinfo
btst #(TIF_SYSCALL_TRACE%8),%a2@(TINFO_FLAGS+(31-TIF_SYSCALL_TRACE)/8)
jne do_trace
cmpl #NR_syscalls,%d0
@ -96,16 +102,15 @@ Luser_return:
/* heavy interrupt load*/
andw #ALLOWINT,%sr
movel %sp,%d1 /* get thread_info pointer */
andl #-THREAD_SIZE,%d1
movel %d1,%a2
getthreadinfo
1:
move %a2@(TINFO_FLAGS),%d1 /* thread_info->flags */
/* check if any of the flags are set */
moveb %a2@(TINFO_FLAGS + 3),%d1 /* thread_info->flags (low 8 bits) */
jne Lwork_to_do
RESTORE_ALL
Lwork_to_do:
movel %a2@(TINFO_FLAGS),%d1 /* thread_info->flags */
/* check if reschedule needs to be called */
btst #TIF_NEED_RESCHED,%d1
jne reschedule