• Li Bin's avatar
    arm64: ftrace: fix function_graph tracer panic · ee556d00
    Li Bin authored
    When function graph tracer is enabled, the following operation
    will trigger panic:
    
    mount -t debugfs nodev /sys/kernel
    echo next_tgid > /sys/kernel/tracing/set_ftrace_filter
    echo function_graph > /sys/kernel/tracing/current_tracer
    ls /proc/
    
    ------------[ cut here ]------------
    [  198.501417] Unable to handle kernel paging request at virtual address cb88537fdc8ba316
    [  198.506126] pgd = ffffffc008f79000
    [  198.509363] [cb88537fdc8ba316] *pgd=00000000488c6003, *pud=00000000488c6003, *pmd=0000000000000000
    [  198.517726] Internal error: Oops: 94000005 [#1] SMP
    [  198.518798] Modules linked in:
    [  198.520582] CPU: 1 PID: 1388 Comm: ls Tainted: G
    [  198.521800] Hardware name: linux,dummy-virt (DT)
    [  198.522852] task: ffffffc0fa9e8000 ti: ffffffc0f9ab0000 task.ti: ffffffc0f9ab0000
    [  198.524306] PC is at next_tgid+0x30/0x100
    [  198.525205] LR is at return_to_handler+0x0/0x20
    [  198.526090] pc : [<ffffffc0002a1070>] lr : [<ffffffc0000907c0>] pstate: 60000145
    [  198.527392] sp : ffffffc0f9ab3d40
    [  198.528084] x29: ffffffc0f9ab3d40 x28: ffffffc0f9ab0000
    [  198.529406] x27: ffffffc000d6a000 x26: ffffffc000b786e8
    [  198.530659] x25: ffffffc0002a1900 x24: ffffffc0faf16c00
    [  198.531942] x23: ffffffc0f9ab3ea0 x22: 0000000000000002
    [  198.533202] x21: ffffffc000d85050 x20: 0000000000000002
    [  198.534446] x19: 0000000000000002 x18: 0000000000000000
    [  198.535719] x17: 000000000049fa08 x16: ffffffc000242efc
    [  198.537030] x15: 0000007fa472b54c x14: ffffffffff000000
    [  198.538347] x13: ffffffc0fada84a0 x12: 0000000000000001
    [  198.539634] x11: ffffffc0f9ab3d70 x10: ffffffc0f9ab3d70
    [  198.540915] x9 : ffffffc0000907c0 x8 : ffffffc0f9ab3d40
    [  198.542215] x7 : 0000002e330f08f0 x6 : 0000000000000015
    [  198.543508] x5 : 0000000000000f08 x4 : ffffffc0f9835ec0
    [  198.544792] x3 : cb88537fdc8ba316 x2 : cb88537fdc8ba306
    [  198.546108] x1 : 0000000000000002 x0 : ffffffc000d85050
    [  198.547432]
    [  198.547920] Process ls (pid: 1388, stack limit = 0xffffffc0f9ab0020)
    [  198.549170] Stack: (0xffffffc0f9ab3d40 to 0xffffffc0f9ab4000)
    [  198.582568] Call trace:
    [  198.583313] [<ffffffc0002a1070>] next_tgid+0x30/0x100
    [  198.584359] [<ffffffc0000907bc>] ftrace_graph_caller+0x6c/0x70
    [  198.585503] [<ffffffc0000907bc>] ftrace_graph_caller+0x6c/0x70
    [  198.586574] [<ffffffc0000907bc>] ftrace_graph_caller+0x6c/0x70
    [  198.587660] [<ffffffc0000907bc>] ftrace_graph_caller+0x6c/0x70
    [  198.588896] Code: aa0003f5 2a0103f4 b4000102 91004043 (885f7c60)
    [  198.591092] ---[ end trace 6a346f8f20949ac8 ]---
    
    This is because when using function graph tracer, if the traced
    function return value is in multi regs ([x0-x7]), return_to_handler
    may corrupt them. So in return_to_handler, the parameter regs should
    be protected properly.
    
    Cc: <stable@vger.kernel.org> # 3.18+
    Signed-off-by: default avatarLi Bin <huawei.libin@huawei.com>
    Acked-by: default avatarAKASHI Takahiro <takahiro.akashi@linaro.org>
    Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
    ee556d00
entry-ftrace.S 6.25 KB