Subject: [PATCH] powerpc: Fix crash during static key init on ppc32

From: Benjamin Herrenschmidt <[email-masked]>
Date: Wed, 10 Aug 2016 17:27:34 +1000

We cannot do those initializations from apply_feature_fixups() as
this function runs in a very restricted environment in 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.

Signed-off-by: Benjamin Herrenschmidt <[email-masked]>
---

diff --git a/arch/powerpc/include/asm/feature-fixups.h b/arch/powerpc/include/asm/feature-fixups.h
index 57fec8a..ddf54f5 100644
--- a/arch/powerpc/include/asm/feature-fixups.h
+++ b/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 */
diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
index c3e861d..9a2ae96 100644
--- a/arch/powerpc/kernel/setup_32.c
+++ b/arch/powerpc/kernel/setup_32.c
@@ -102,6 +102,9 @@ extern unsigned int memset_nocache_branch; /* Insn to be replaced by NOP */
 
 notrace void __init machine_init(u64 dt_ptr)
 {
+	/* Configure static keys first */
+	setup_feature_keys();
+
 	/* Enable early debugging if any specified (see udbg.h) */
 	udbg_early_init();
 
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index eafb9a7..7ac8e6e 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/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();
diff --git a/arch/powerpc/lib/feature-fixups.c b/arch/powerpc/lib/feature-fixups.c
index 74145f0..043415f 100644
--- a/arch/powerpc/lib/feature-fixups.c
+++ b/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