powerpc/32: Fix crash during static key init

We cannot do those initializations from apply_feature_fixups() as
this function runs in a very restricted environment on 32-bit where
the kernel isn't running at its linked address and the PTRRELOC()
macro must be used for any global accesss.

Instead, split them into a separtate steup_feature_keys() function
which is called in a more suitable spot on ppc32.

Fixes: 309b315b ("powerpc: Call jump_label_init() in apply_feature_fixups()")
Reported-and-tested-by: Christian Kujau <lists@nerdbynature.de>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/feature-fixups.h

@@ -186,6 +186,7 @@ label##3:					       	\
 
 #ifndef __ASSEMBLY__
 void apply_feature_fixups(void);
+void setup_feature_keys(void);
 #endif
 
 #endif /* __ASM_POWERPC_FEATURE_FIXUPS_H */

arch/powerpc/kernel/setup_32.c

@@ -100,6 +100,9 @@ extern unsigned int memset_nocache_branch; /* Insn to be replaced by NOP */
 
 notrace void __init machine_init(u64 dt_ptr)
 {
+	/* Configure static keys first, now that we're relocated. */
+	setup_feature_keys();
+
 	/* Enable early debugging if any specified (see udbg.h) */
 	udbg_early_init();
 

arch/powerpc/kernel/setup_64.c

@@ -300,6 +300,7 @@ void __init early_setup(unsigned long dt_ptr)
 
 	/* Apply all the dynamic patching */
 	apply_feature_fixups();
+	setup_feature_keys();
 
 	/* Initialize the hash table or TLB handling */
 	early_init_mmu();

arch/powerpc/lib/feature-fixups.c

@@ -188,7 +188,10 @@ void __init apply_feature_fixups(void)
 			  &__start___fw_ftr_fixup, &__stop___fw_ftr_fixup);
 #endif
 	do_final_fixups();
+}
 
+void __init setup_feature_keys(void)
+{
 	/*
 	 * Initialise jump label. This causes all the cpu/mmu_has_feature()
 	 * checks to take on their correct polarity based on the current set of