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

[Michael Ellerman]

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