• Kevin Hao's avatar
    powerpc: Set the correct ksp_limit on ppc32 when switching to irq stack · 1a18a664
    Kevin Hao authored
    Guenter Roeck has got the following call trace on a p2020 board:
      Kernel stack overflow in process eb3e5a00, r1=eb79df90
      CPU: 0 PID: 2838 Comm: ssh Not tainted 3.13.0-rc8-juniper-00146-g19eca00 #4
      task: eb3e5a00 ti: c0616000 task.ti: ef440000
      NIP: c003a420 LR: c003a410 CTR: c0017518
      REGS: eb79dee0 TRAP: 0901   Not tainted (3.13.0-rc8-juniper-00146-g19eca00)
      MSR: 00029000 <CE,EE,ME>  CR: 24008444  XER: 00000000
      GPR00: c003a410 eb79df90 eb3e5a00 00000000 eb05d900 00000001 65d87646 00000000
      GPR08: 00000000 020b8000 00000000 00000000 44008442
      NIP [c003a420] __do_softirq+0x94/0x1ec
      LR [c003a410] __do_softirq+0x84/0x1ec
      Call Trace:
      [eb79df90] [c003a410] __do_softirq+0x84/0x1ec (unreliable)
      [eb79dfe0] [c003a970] irq_exit+0xbc/0xc8
      [eb79dff0] [c000cc1c] call_do_irq+0x24/0x3c
      [ef441f20] [c00046a8] do_IRQ+0x8c/0xf8
      [ef441f40] [c000e7f4] ret_from_except+0x0/0x18
      --- Exception: 501 at 0xfcda524
          LR = 0x10024900
      Instruction dump:
      7c781b78 3b40000a 3a73b040 543c0024 3a800000 3b3913a0 7ef5bb78 48201bf9
      5463103a 7d3b182e 7e89b92e 7c008146 <3ba00000> 7e7e9b78 48000014 57fff87f
      Kernel panic - not syncing: kernel stack overflow
      CPU: 0 PID: 2838 Comm: ssh Not tainted 3.13.0-rc8-juniper-00146-g19eca00 #4
      Call Trace:
    
    The reason is that we have used the wrong register to calculate the
    ksp_limit in commit cbc9565e (powerpc: Remove ksp_limit on ppc64).
    Just fix it.
    
    As suggested by Benjamin Herrenschmidt, also add the C prototype of the
    function in the comment in order to avoid such kind of errors in the
    future.
    
    Cc: stable@vger.kernel.org # 3.12
    Reported-by: default avatarGuenter Roeck <linux@roeck-us.net>
    Tested-by: default avatarGuenter Roeck <linux@roeck-us.net>
    Signed-off-by: default avatarKevin Hao <haokexin@gmail.com>
    Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
    1a18a664
misc_32.S 25.3 KB