Re: [PATCH v2] powerpc/ftrace: Ignore ftrace locations in exit text sections

On Tue, 13 Feb 2024 23:24:10 +0530, Naveen N Rao wrote:

Michael reported that we are seeing ftrace bug on bootup when KASAN is
enabled, and if we are using -fpatchable-function-entry:

    ftrace: allocating 47780 entries in 18 pages
    ftrace-powerpc: 0xc0000000020b3d5c: No module provided for non-kernel address
    ------------[ ftrace bug ]------------
    ftrace faulted on modifying
    [<c0000000020b3d5c>] 0xc0000000020b3d5c
    Initializing ftrace call sites
    ftrace record flags: 0
     (0)
     expected tramp: c00000000008cef4
    ------------[ cut here ]------------
    WARNING: CPU: 0 PID: 0 at kernel/trace/ftrace.c:2180 ftrace_bug+0x3c0/0x424
    Modules linked in:
    CPU: 0 PID: 0 Comm: swapper Not tainted 6.5.0-rc3-00120-g0f71dcfb4aef #860
    Hardware name: IBM pSeries (emulated by qemu) POWER9 (raw) 0x4e1202 0xf000005 of:SLOF,HEAD hv:linux,kvm pSeries
    NIP:  c0000000003aa81c LR: c0000000003aa818 CTR: 0000000000000000
    REGS: c0000000033cfab0 TRAP: 0700   Not tainted  (6.5.0-rc3-00120-g0f71dcfb4aef)
    MSR:  8000000002021033 <SF,VEC,ME,IR,DR,RI,LE>  CR: 28028240  XER: 00000000
    CFAR: c0000000002781a8 IRQMASK: 3
    ...
    NIP [c0000000003aa81c] ftrace_bug+0x3c0/0x424
    LR [c0000000003aa818] ftrace_bug+0x3bc/0x424
    Call Trace:
     ftrace_bug+0x3bc/0x424 (unreliable)
     ftrace_process_locs+0x5f4/0x8a0
     ftrace_init+0xc0/0x1d0
     start_kernel+0x1d8/0x484

[...]

Applied to powerpc/fixes.

[1/1] powerpc/ftrace: Ignore ftrace locations in exit text sections
      https://git.kernel.org/powerpc/c/ea73179e64131bcd29ba6defd33732abdf8ca14b

cheers