lkml.org 
[lkml]   [2012]   [Aug]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[ 25/82] ARM: 7480/1: only call smp_send_stop() on SMP
    Date
    From: Greg KH <gregkh@linuxfoundation.org>

    3.5-stable review patch. If anyone has any objections, please let me know.

    ------------------

    From: Javier Martinez Canillas <javier@dowhile0.org>

    commit c5dff4ffd327088d85035bec535b7d0c9ea03151 upstream.

    On reboot or poweroff (machine_shutdown()) a call to smp_send_stop() is
    made (to stop the others CPU's) when CONFIG_SMP=y.

    arch/arm/kernel/process.c:

    void machine_shutdown(void)
    {
    #ifdef CONFIG_SMP
    smp_send_stop();
    #endif
    }

    smp_send_stop() calls the function pointer smp_cross_call(), which is set
    on the smp_init_cpus() function for OMAP processors.

    arch/arm/mach-omap2/omap-smp.c:

    void __init smp_init_cpus(void)
    {
    ...
    set_smp_cross_call(gic_raise_softirq);
    ...
    }

    But the ARM setup_arch() function only calls smp_init_cpus()
    if CONFIG_SMP=y && is_smp().

    arm/kernel/setup.c:

    void __init setup_arch(char **cmdline_p)
    {
    ...
    #ifdef CONFIG_SMP
    if (is_smp())
    smp_init_cpus();
    #endif
    ...
    }

    Newer OMAP CPU's are SMP machines so omap2plus_defconfig sets
    CONFIG_SMP=y. Unfortunately on an OMAP UP machine is_smp()
    returns false and smp_init_cpus() is never called and the
    smp_cross_call() function remains NULL.

    If the machine is rebooted or powered off, smp_send_stop() will
    be called (since CONFIG_SMP=y) leading to the following error:

    [ 42.815551] Restarting system.
    [ 42.819030] Unable to handle kernel NULL pointer dereference at virtual address 00000000
    [ 42.827667] pgd = d7a74000
    [ 42.830566] [00000000] *pgd=96ce7831, *pte=00000000, *ppte=00000000
    [ 42.837249] Internal error: Oops: 80000007 [#1] SMP ARM
    [ 42.842773] Modules linked in:
    [ 42.846008] CPU: 0 Not tainted (3.5.0-rc3-next-20120622-00002-g62e87ba-dirty #44)
    [ 42.854278] PC is at 0x0
    [ 42.856994] LR is at smp_send_stop+0x4c/0xe4
    [ 42.861511] pc : [<00000000>] lr : [<c00183a4>] psr: 60000013
    [ 42.861511] sp : d6c85e70 ip : 00000000 fp : 00000000
    [ 42.873626] r10: 00000000 r9 : d6c84000 r8 : 00000002
    [ 42.879150] r7 : c07235a0 r6 : c06dd2d0 r5 : 000f4241 r4 : d6c85e74
    [ 42.886047] r3 : 00000000 r2 : 00000000 r1 : 00000006 r0 : d6c85e74
    [ 42.892944] Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user
    [ 42.900482] Control: 10c5387d Table: 97a74019 DAC: 00000015
    [ 42.906555] Process reboot (pid: 1166, stack limit = 0xd6c842f8)
    [ 42.912902] Stack: (0xd6c85e70 to 0xd6c86000)
    [ 42.917510] 5e60: c07235a0 00000000 00000000 d6c84000
    [ 42.926177] 5e80: 01234567 c00143d0 4321fedc c00511bc d6c85ebc 00000168 00000460 00000000
    [ 42.934814] 5ea0: c1017950 a0000013 c1017900 d8014390 d7ec3858 c0498e48 c1017950 00000000
    [ 42.943481] 5ec0: d6ddde10 d6c85f78 00000003 00000000 d6ddde10 d6c84000 00000000 00000000
    [ 42.952117] 5ee0: 00000002 00000000 00000000 c0088c88 00000002 00000000 00000000 c00f4b90
    [ 42.960784] 5f00: 00000000 d6c85ebc d8014390 d7e311c8 60000013 00000103 00000002 d6c84000
    [ 42.969421] 5f20: c00f3274 d6e00a00 00000001 60000013 d6c84000 00000000 00000000 c00895d4
    [ 42.978057] 5f40: 00000002 d8007c80 d781f000 c00f6150 d8010cc0 c00f3274 d781f000 d6c84000
    [ 42.986694] 5f60: c0013020 d6e00a00 00000001 20000010 0001257c ef000000 00000000 c00895d4
    [ 42.995361] 5f80: 00000002 00000001 00000003 00000000 00000001 00000003 00000000 00000058
    [ 43.003997] 5fa0: c00130c8 c0012f00 00000001 00000003 fee1dead 28121969 01234567 00000002
    [ 43.012634] 5fc0: 00000001 00000003 00000000 00000058 00012584 0001257c 00000001 00000000
    [ 43.021270] 5fe0: 000124bc bec5cc6c 00008f9c 4a2f7c40 20000010 fee1dead 00000000 00000000
    [ 43.029968] [<c00183a4>] (smp_send_stop+0x4c/0xe4) from [<c00143d0>] (machine_restart+0xc/0x4c)
    [ 43.039154] [<c00143d0>] (machine_restart+0xc/0x4c) from [<c00511bc>] (sys_reboot+0x144/0x1f0)
    [ 43.048278] [<c00511bc>] (sys_reboot+0x144/0x1f0) from [<c0012f00>] (ret_fast_syscall+0x0/0x3c)
    [ 43.057464] Code: bad PC value
    [ 43.060760] ---[ end trace c3988d1dd0b8f0fb ]---

    Add a check so smp_cross_call() is only called when there is more than one CPU on-line.

    Signed-off-by: Javier Martinez Canillas <javier at dowhile0.org>
    Acked-by: Will Deacon <will.deacon@arm.com>
    Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    arch/arm/kernel/smp.c | 3 ++-
    1 file changed, 2 insertions(+), 1 deletion(-)

    --- a/arch/arm/kernel/smp.c
    +++ b/arch/arm/kernel/smp.c
    @@ -563,7 +563,8 @@ void smp_send_stop(void)

    cpumask_copy(&mask, cpu_online_mask);
    cpumask_clear_cpu(smp_processor_id(), &mask);
    - smp_cross_call(&mask, IPI_CPU_STOP);
    + if (!cpumask_empty(&mask))
    + smp_cross_call(&mask, IPI_CPU_STOP);

    /* Wait up to one second for other CPUs to stop */
    timeout = USEC_PER_SEC;



    \
     
     \ /
      Last update: 2012-08-14 00:42    [W:4.098 / U:0.280 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site