diff options
| author | Max Filippov <jcmvbkbc@gmail.com> | 2018-11-26 13:29:41 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-12-05 19:41:23 +0100 |
| commit | d039837ab8cb7fb7095ec9746fb04a854987179e (patch) | |
| tree | 47026a182983b5584119318ce23299457836ed10 /arch/xtensa/kernel | |
| parent | 83f00ab9a7c03e9f1410727d985b7fe9473002e1 (diff) | |
xtensa: enable coprocessors that are being flushed
commit 2958b66694e018c552be0b60521fec27e8d12988 upstream.
coprocessor_flush_all may be called from a context of a thread that is
different from the thread being flushed. In that case contents of the
cpenable special register may not match ti->cpenable of the target
thread, resulting in unhandled coprocessor exception in the kernel
context.
Set cpenable special register to the ti->cpenable of the target register
for the duration of the flush and restore it afterwards.
This fixes the following crash caused by coprocessor register inspection
in native gdb:
(gdb) p/x $w0
Illegal instruction in kernel: sig: 9 [#1] PREEMPT
Call Trace:
___might_sleep+0x184/0x1a4
__might_sleep+0x41/0xac
exit_signals+0x14/0x218
do_exit+0xc9/0x8b8
die+0x99/0xa0
do_illegal_instruction+0x18/0x6c
common_exception+0x77/0x77
coprocessor_flush+0x16/0x3c
arch_ptrace+0x46c/0x674
sys_ptrace+0x2ce/0x3b4
system_call+0x54/0x80
common_exception+0x77/0x77
note: gdb[100] exited with preempt_count 1
Killed
Cc: stable@vger.kernel.org
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/xtensa/kernel')
| -rw-r--r-- | arch/xtensa/kernel/process.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/arch/xtensa/kernel/process.c b/arch/xtensa/kernel/process.c index ff4f0ecb03dd..f1c46bc5d465 100644 --- a/arch/xtensa/kernel/process.c +++ b/arch/xtensa/kernel/process.c @@ -88,18 +88,21 @@ void coprocessor_release_all(struct thread_info *ti) void coprocessor_flush_all(struct thread_info *ti) { - unsigned long cpenable; + unsigned long cpenable, old_cpenable; int i; preempt_disable(); + RSR_CPENABLE(old_cpenable); cpenable = ti->cpenable; + WSR_CPENABLE(cpenable); for (i = 0; i < XCHAL_CP_MAX; i++) { if ((cpenable & 1) != 0 && coprocessor_owner[i] == ti) coprocessor_flush(ti, i); cpenable >>= 1; } + WSR_CPENABLE(old_cpenable); preempt_enable(); } |