Patch "powerpc: Fix boot on BOOK3S_32 with CONFIG_STRICT_KERNEL_RWX" has been added to the 4.14-stable tree

Patch "powerpc: Fix boot on BOOK3S_32 with CONFIG_STRICT_KERNEL_RWX" has been added to the 4.14-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    powerpc: Fix boot on BOOK3S_32 with CONFIG_STRICT_KERNEL_RWX

to the 4.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     powerpc-fix-boot-on-book3s_32-with-config_strict_kernel_rwx.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 252eb55816a6f69ef9464cad303cdb3326cdc61d Mon Sep 17 00:00:00 2001
From: Christophe Leroy <christophe.leroy@c-s.fr>
Date: Tue, 21 Nov 2017 15:28:20 +0100
Subject: powerpc: Fix boot on BOOK3S_32 with CONFIG_STRICT_KERNEL_RWX

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);


Patches currently in stable-queue which might be from christophe.leroy@c-s.fr are

queue-4.14/powerpc-fix-boot-on-book3s_32-with-config_strict_kernel_rwx.patch