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| author |   Max Filippov <jcmvbkbc@gmail.com> | 2018-11-26 13:29:41 -0800 |
|---|---|---|
| committer | Max Filippov <jcmvbkbc@gmail.com> | 2018-11-26 18:37:47 -0800 |
| commit | 2958b66694e018c552be0b60521fec27e8d12988 (patch) | |
| tree | 60b3cfc5e1aa1a7f91736874a919012fa45175a2 /arch | |
| parent | Linux 4.20-rc4 (diff) | |
| download | linux-dev-2958b66694e018c552be0b60521fec27e8d12988.tar.xz linux-dev-2958b66694e018c552be0b60521fec27e8d12988.zip | |
xtensa: enable coprocessors that are being flushed
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>
Diffstat (limited to 'arch')
| -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 483dcfb6e681..4bb68133a72a 100644 --- a/arch/xtensa/kernel/process.c +++ b/arch/xtensa/kernel/process.c @@ -94,18 +94,21 @@ 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(); } |