4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Christophe Leroy christophe.leroy@c-s.fr
commit 252eb55816a6f69ef9464cad303cdb3326cdc61d upstream.
On powerpc32, patch_instruction() is called by apply_feature_fixups() which is called from early_init()
There is the following note in front of early_init(): * Note that the kernel may be running at an address which is different * from the address that it was linked at, so we must use RELOC/PTRRELOC * to access static data (including strings). -- paulus
Therefore, slab_is_available() cannot be called yet, and text_poke_area must be addressed with PTRRELOC()
Fixes: 95902e6c8864 ("powerpc/mm: Implement STRICT_KERNEL_RWX on PPC32") Reported-by: Meelis Roos mroos@linux.ee Signed-off-by: Christophe Leroy christophe.leroy@c-s.fr Signed-off-by: Michael Ellerman mpe@ellerman.id.au Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/powerpc/lib/code-patching.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)
--- a/arch/powerpc/lib/code-patching.c +++ b/arch/powerpc/lib/code-patching.c @@ -21,6 +21,7 @@ #include <asm/tlbflush.h> #include <asm/page.h> #include <asm/code-patching.h> +#include <asm/setup.h>
static int __patch_instruction(unsigned int *addr, unsigned int instr) { @@ -146,11 +147,8 @@ int patch_instruction(unsigned int *addr * During early early boot patch_instruction is called * when text_poke_area is not ready, but we still need * to allow patching. We just do the plain old patching - * We use slab_is_available and per cpu read * via this_cpu_read - * of text_poke_area. Per-CPU areas might not be up early - * this can create problems with just using this_cpu_read() */ - if (!slab_is_available() || !this_cpu_read(text_poke_area)) + if (!this_cpu_read(*PTRRELOC(&text_poke_area))) return __patch_instruction(addr, instr);
local_irq_save(flags);