arm64: ftrace: fix unreachable PLT for ftrace_caller in init_module with CONFIG_DYNAMIC_FTRACE

commit a7ed7b9d upstream.

On arm64, it has been possible for a module's sections to be placed more
than 128M away from each other since commit:

  commit 3e35d303 ("arm64: module: rework module VA range selection")

Due to this, an ftrace callsite in a module's .init.text section can be
out of branch range for the module's ftrace PLT entry (in the module's
.text section). Any attempt to enable tracing of that callsite will
result in a BRK being patched into the callsite, resulting in a fatal
exception when the callsite is later executed.

Fix this by adding an additional trampoline for .init.text, which will
be within range.

No additional trampolines are necessary due to the way a given
module's executable sections are packed together. Any executable
section beginning with ".init" will be placed in MOD_INIT_TEXT,
and any other executable section, including those beginning with ".exit",
 will be placed in MOD_TEXT.

Fixes: 3e35d303 ("arm64: module: rework module VA range selection")
Cc: <stable@vger.kernel.org> # 6.5.x
Signed-off-by: panfan <panfan@qti.qualcomm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20250905032236.3220885-1-panfan@qti.qualcomm.com


Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>