diff options
| author | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2018-04-27 07:36:50 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-04-29 11:31:59 +0200 |
| commit | 7ae60d00c31e5db697a1518ce94749a0852c1d0c (patch) | |
| tree | 555163a9ecc866716b31cbb229a10189834e1ba3 | |
| parent | 49a48a0ec7c1f078fc6215ccaf2a5d277c5495c0 (diff) | |
s390: do not bypass BPENTER for interrupt system calls
[ Upstream commit d5feec04fe578c8dbd9e2e1439afc2f0af761ed4 ]
The system call path can be interrupted before the switch back to the
standard branch prediction with BPENTER has been done. The critical
section cleanup code skips forward to .Lsysc_do_svc and bypasses the
BPENTER. In this case the kernel and all subsequent code will run with
the limited branch prediction.
Fixes: eacf67eb9b32 ("s390: run user space and KVM guests with modified branch prediction")
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/s390/kernel/entry.S | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S index 8cbe75d7353d..c3e28af207cf 100644 --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -1316,7 +1316,8 @@ cleanup_critical: srag %r9,%r9,23 jz 0f mvc __TI_last_break(8,%r12),16(%r11) -0: # set up saved register r11 +0: BPENTER __TI_flags(%r12),_TIF_ISOLATE_BP + # set up saved register r11 lg %r15,__LC_KERNEL_STACK la %r9,STACK_FRAME_OVERHEAD(%r15) stg %r9,24(%r11) # r11 pt_regs pointer |