• Changbin Du's avatar
    riscv: fix oops caused by irqsoff latency tracer · 22e2100b
    Changbin Du authored
    The trace_hardirqs_{on,off}() require the caller to setup frame pointer
    properly. This because these two functions use macro 'CALLER_ADDR1' (aka.
    __builtin_return_address(1)) to acquire caller info. If the $fp is used
    for other purpose, the code generated this macro (as below) could trigger
    memory access fault.
    
       0xffffffff8011510e <+80>:    ld      a1,-16(s0)
       0xffffffff80115112 <+84>:    ld      s2,-8(a1)  # <-- paging fault here
    
    The oops message during booting if compiled with 'irqoff' tracer enabled:
    [    0.039615][    T0] Unable to handle kernel NULL pointer dereference at virtual address 00000000000000f8
    [    0.041925][    T0] Oops [#1]
    [    0.042063][    T0] Modules linked in:
    [    0.042864][    T0] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.17.0-rc1-00233-g9a20c48d1ed2 #29
    [    0.043568][    T0] Hardware name: riscv-virtio,qemu (DT)
    [    0.044343][    T0] epc : trace_hardirqs_on+0x56/0xe2
    [    0.044601][    T0]  ra : restore_all+0x12/0x6e
    [    0.044721][    T0] epc : ffffffff80126a5c ra : ffffffff80003b94 sp : ffffffff81403db0
    [    0.044801][    T0]  gp : ffffffff8163acd8 tp : ffffffff81414880 t0 : 0000000000000020
    [    0.044882][    T0]  t1 : 0098968000000000 t2 : 0000000000000000 s0 : ffffffff81403de0
    [    0.044967][    T0]  s1 : 0000000000000000 a0 : 0000000000000001 a1 : 0000000000000100
    [    0.045046][    T0]  a2 : 0000000000000000 a3 : 0000000000000000 a4 : 0000000000000000
    [    0.045124][    T0]  a5 : 0000000000000000 a6 : 0000000000000000 a7 : 0000000054494d45
    [    0.045210][    T0]  s2 : ffffffff80003b94 s3 : ffffffff81a8f1b0 s4 : ffffffff80e27b50
    [    0.045289][    T0]  s5 : ffffffff81414880 s6 : ffffffff8160fa00 s7 : 00000000800120e8
    [    0.045389][    T0]  s8 : 0000000080013100 s9 : 000000000000007f s10: 0000000000000000
    [    0.045474][    T0]  s11: 0000000000000000 t3 : 7fffffffffffffff t4 : 0000000000000000
    [    0.045548][    T0]  t5 : 0000000000000000 t6 : ffffffff814aa368
    [    0.045620][    T0] status: 0000000200000100 badaddr: 00000000000000f8 cause: 000000000000000d
    [    0.046402][    T0] [<ffffffff80003b94>] restore_all+0x12/0x6e
    
    This because the $fp(aka. $s0) register is not used as frame pointer in the
    assembly entry code.
    
    	resume_kernel:
    		REG_L s0, TASK_TI_PREEMPT_COUNT(tp)
    		bnez s0, restore_all
    		REG_L s0, TASK_TI_FLAGS(tp)
                    andi s0, s0, _TIF_NEED_RESCHED
                    beqz s0, restore_all
                    call preempt_schedule_irq
                    j restore_all
    
    To fix above issue, here we add one extra level wrapper for function
    trace_hardirqs_{on,off}() so they can be safely called by low level entry
    code.
    Signed-off-by: default avatarChangbin Du <changbin.du@gmail.com>
    Fixes: 3c469798 ("riscv: Enable LOCKDEP_SUPPORT & fixup TRACE_IRQFLAGS_SUPPORT")
    Cc: stable@vger.kernel.org
    Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
    22e2100b
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