The Shadow Call Stack pointer is held in x18, so update the ftrace
entry comment to indicate that it cannot be safely clobbered.
Reported-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
*
* ... where <entry> is either ftrace_caller or ftrace_regs_caller.
*
- * Each instrumented function follows the AAPCS, so here x0-x8 and x19-x30 are
- * live, and x9-x18 are safe to clobber.
+ * Each instrumented function follows the AAPCS, so here x0-x8 and x18-x30 are
+ * live (x18 holds the Shadow Call Stack pointer), and x9-x17 are safe to
+ * clobber.
*
* We save the callsite's context into a pt_regs before invoking any ftrace
* callbacks. So that we can get a sensible backtrace, we create a stack record