[PATCH 4.9 50/51] powerpc/lib: fix book3s/32 boot failure due to code patching

From: Greg Kroah-Hartman
Date: Wed May 15 2019 - 08:01:27 EST

From: Christophe Leroy <christophe.leroy@xxxxxx>

commit b45ba4a51cde29b2939365ef0c07ad34c8321789 upstream.

Commit 51c3c62b58b3 ("powerpc: Avoid code patching freed init
sections") accesses 'init_mem_is_free' flag too early, before the
kernel is relocated. This provokes early boot failure (before the
console is active).

As it is not necessary to do this verification that early, this
patch moves the test into patch_instruction() instead of

This modification also has the advantage of avoiding unnecessary

Fixes: 51c3c62b58b3 ("powerpc: Avoid code patching freed init sections")
Cc: stable@xxxxxxxxxxxxxxx # 4.13+
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

arch/powerpc/lib/code-patching.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c
@@ -23,7 +23,7 @@ int patch_instruction(unsigned int *addr
int err;

/* Make sure we aren't patching a freed init section */
- if (init_mem_is_free && init_section_contains(addr, 4)) {
+ if (*PTRRELOC(&init_mem_is_free) && init_section_contains(addr, 4)) {
pr_debug("Skipping init section patching addr: 0x%px\n", addr);
return 0;