[PATCH stable 4.4] powerpc/lib: fix book3s/32 boot failure due to code patching

[Backport of upstream commit b45ba4a51cde29b2939365ef0c07ad34c8321789]

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 init_mem_is_free must be accessed with PTRRELOC()

Link: https://bugzilla.kernel.org/show_bug.cgi?id=203597
Signed-off-by: Christophe Leroy <redacted>

---
Can't apply the upstream commit as such due to several other unrelated stuff
like for instance STRICT_KERNEL_RWX which are missing.
So instead, using same approach as for commit 252eb55816a6f69ef9464cad303cdb3326cdc61d

Removed the Fixes: tag as I don't know yet the commit Id of the fixed commit on 4.4 branch.
---
 arch/powerpc/lib/code-patching.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
index 2604192c0719..65ce778aee46 100644
--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c

@@ -28,7 +28,7 @@ int patch_instruction(unsigned int *addr, unsigned int instr)
 	int err;
 
 	/* Make sure we aren't patching a freed init section */
-	if (init_mem_is_free && is_init(addr)) {
+	if (*PTRRELOC(&init_mem_is_free) && is_init(addr)) {
 		pr_debug("Skipping init section patching addr: 0x%px\n", addr);
 		return 0;
 	}

-- 
2.13.3

On Wed, May 15, 2019 at 01:30:42PM +0000, Christophe Leroy wrote:

[Backport of upstream commit b45ba4a51cde29b2939365ef0c07ad34c8321789]

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 init_mem_is_free must be accessed with PTRRELOC()

Link: https://bugzilla.kernel.org/show_bug.cgi?id=203597
Signed-off-by: Christophe Leroy <redacted>

---
Can't apply the upstream commit as such due to several other unrelated stuff
like for instance STRICT_KERNEL_RWX which are missing.
So instead, using same approach as for commit 252eb55816a6f69ef9464cad303cdb3326cdc61d

Removed the Fixes: tag as I don't know yet the commit Id of the fixed commit on 4.4 branch.
---
 arch/powerpc/lib/code-patching.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Now added, thanks.

greg k-h

Le 15/05/2019 à 16:16, Greg KH a écrit :

On Wed, May 15, 2019 at 01:30:42PM +0000, Christophe Leroy wrote:

quoted

[Backport of upstream commit b45ba4a51cde29b2939365ef0c07ad34c8321789]

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 init_mem_is_free must be accessed with PTRRELOC()

Link: https://bugzilla.kernel.org/show_bug.cgi?id=203597
Signed-off-by: Christophe Leroy <redacted>

---
Can't apply the upstream commit as such due to several other unrelated stuff
like for instance STRICT_KERNEL_RWX which are missing.
So instead, using same approach as for commit 252eb55816a6f69ef9464cad303cdb3326cdc61d

Removed the Fixes: tag as I don't know yet the commit Id of the fixed commit on 4.4 branch.
---
  arch/powerpc/lib/code-patching.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

Now added, thanks.

Thanks,

However you took the commit log from the upstream commit, which doesn't 
corresponds exactly to the change being done here and described in the 
backport patch

Christophe