• Nathan Lynch's avatar
    ARM: 8178/1: fix set_tls for !CONFIG_KUSER_HELPERS · 9cc6d9e5
    Nathan Lynch authored
    Joachim Eastwood reports that commit fbfb872f "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: fbfb872f ARM: 8148/1: flush TLS and thumbee register state during exec
    Reported-by: default avatarJoachim Eastwood <manabian@gmail.com>
    Tested-by: default avatarJoachim Eastwood <manabian@gmail.com>
    Cc: stable@vger.kernel.org
    Signed-off-by: default avatarNathan Lynch <nathan_lynch@mentor.com>
    Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
    9cc6d9e5
tls.h 3.05 KB