[tip: core/urgent] entry: Unbreak single step reporting behaviour

[tip-bot2 for Yuxuan Shui]

The following commit has been merged into the core/urgent branch of tip:

Commit-ID:     41c1a06d1d1544bed9692ba72a5692454eee1945
Gitweb:        https://git.kernel.org/tip/41c1a06d1d1544bed9692ba72a5692454eee1945
Author:        Yuxuan Shui <yshuiv7@xxxxxxxxx>
AuthorDate:    Sat, 23 Jan 2021 03:21:32 -08:00
Committer:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Thu, 28 Jan 2021 13:46:55 +01:00

entry: Unbreak single step reporting behaviour

The move of TIF_SYSCALL_EMU to SYSCALL_WORK_SYSCALL_EMU broke single step
reporting. The original code reported the single step when TIF_SINGLESTEP
was set and TIF_SYSCALL_EMU was not set. The SYSCALL_WORK conversion got
the logic wrong and now the reporting only happens when both bits are set.

Restore the original behaviour.

[ tglx: Massaged changelog and dropped the pointless double negation ]

Fixes: 64eb35f701f0 ("ptrace: Migrate TIF_SYSCALL_EMU to use SYSCALL_WORK flag")
Signed-off-by: Yuxuan Shui <yshuiv7@xxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/877do3gaq9.fsf@m5Zedd9JOGzJrf0
---
 kernel/entry/common.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index 3783416..6dd82be 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -222,7 +222,7 @@ static inline bool report_single_step(unsigned long work)
  */
 static inline bool report_single_step(unsigned long work)
 {
-	if (!(work & SYSCALL_WORK_SYSCALL_EMU))
+	if (work & SYSCALL_WORK_SYSCALL_EMU)
 		return false;
 
 	return !!(current_thread_info()->flags & _TIF_SINGLESTEP);