ARM: 8178/1: fix set_tls for !CONFIG_KUSER_HELPERS
commit
9cc6d9e5daaa147a9a3e31557efcb331989e77be upstream.
Joachim Eastwood reports that commit
fbfb872f5f41 "ARM: 8148/1: flush
TLS and thumbee register state during exec" causes a boot-time crash
on a Cortex-M4 nommu system:
Freeing unused kernel memory: 68K (
281e5000 -
281f6000)
Unhandled exception: IPSR =
00000005 LR =
fffffff1
CPU: 0 PID: 1 Comm: swapper Not tainted
3.17.0-rc6-00313-gd2205fa30aa7 #191
task:
29834000 ti:
29832000 task.ti:
29832000
PC is at flush_thread+0x2e/0x40
LR is at flush_thread+0x21/0x40
pc : [<
2800954a>] lr : [<
2800953d>] psr:
4100000b
sp :
29833d60 ip :
00000000 fp :
00000001
r10:
00003cf8 r9 :
29b1f000 r8 :
00000000
r7 :
29b0bc00 r6 :
29834000 r5 :
29832000 r4 :
29832000
r3 :
ffff0ff0 r2 :
29832000 r1 :
00000000 r0 :
282121f0
xPSR:
4100000b
CPU: 0 PID: 1 Comm: swapper Not tainted
3.17.0-rc6-00313-gd2205fa30aa7 #191
[<
2800afa5>] (unwind_backtrace) from [<
2800a327>] (show_stack+0xb/0xc)
[<
2800a327>] (show_stack) from [<
2800a963>] (__invalid_entry+0x4b/0x4c)
The problem is that set_tls is attempting to clear the TLS location in
the kernel-user helper page, which isn't set up on V7M.
Fix this by guarding the write to the kuser helper page with
a CONFIG_KUSER_HELPERS ifdef.
Fixes: fbfb872f5f41 ARM: 8148/1: flush TLS and thumbee register state during exec
Reported-by: Joachim Eastwood <manabian@gmail.com>
Tested-by: Joachim Eastwood <manabian@gmail.com>
Signed-off-by: Nathan Lynch <nathan_lynch@mentor.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>