kprobes: remove duplicated strong free_insn_page in x86 and s390

free_insn_page() in x86 and s390 is same with the common weak function in
kernel/kprobes.c. Plus, the comment "Recover page to RW mode before
releasing it" in x86 seems insensible to be there since resetting mapping
is done by common code in vfree() of module_memfree(). So drop these two
duplicated strong functions and related comment, then mark the common one
in kernel/kprobes.c strong.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Barry Song <[e-mail]>
Acked-by: Masami Hiramatsu <[e-mail]>
Acked-by: Heiko Carstens <[e-mail]>
Reviewed-by: Christoph Hellwig <[e-mail]>
Cc: "H. Peter Anvin" <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Borislav Petkov <[e-mail]>
Cc: Vasily Gorbik <[e-mail]>
Cc: Christian Borntraeger <[e-mail]>
Cc: "Naveen N. Rao" <[e-mail]>
Cc: Anil S Keshavamurthy <[e-mail]>
Cc: David S. Miller <[e-mail]>
Cc: Qi Liu <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

arch/s390/kernel/kprobes.c

···
 	return page;
 }
 
-void free_insn_page(void *page)
-{
-	module_memfree(page);
-}
-
 static void *alloc_s390_insn_page(void)
 {
 	if (xchg(&insn_page_in_use, 1) == 1)

arch/x86/kernel/kprobes/core.c

···
 	return page;
 }
 
-/* Recover page to RW mode before releasing it */
-void free_insn_page(void *page)
-{
-	module_memfree(page);
-}
-
 /* Kprobe x86 instruction emulation - only regs->ip or IF flag modifiers */
 
 static void kprobe_emulate_ifmodifiers(struct kprobe *p, struct pt_regs *regs)

include/linux/kprobes.h

···
 void dump_kprobe(struct kprobe *kp);
 
 void *alloc_insn_page(void);
-void free_insn_page(void *page);
 
 int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
 		       char *sym);

kernel/kprobes.c

···
 	return module_alloc(PAGE_SIZE);
 }
 
-void __weak free_insn_page(void *page)
+static void free_insn_page(void *page)
 {
 	module_memfree(page);
 }