[PATCH] 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()

Fixes: 1c38a84d4586 ("powerpc: Avoid code patching freed init sections")
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
---
 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 14535ad4cdd1..c312955977ce 100644
--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c

@@ -23,7 +23,7 @@ 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 && 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;
 	}

-- 
2.13.3

Oops, forgot to tell it's for 4.9. Resending with proper subject.

Le 15/05/2019 à 08:39, Christophe Leroy a écrit :

On Wed, May 15, 2019 at 06:40:47AM +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()

Fixes: 1c38a84d4586 ("powerpc: Avoid code patching freed init sections")
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

Now queued up, thanks.

greg k-h

Le 15/05/2019 à 10:29, Greg KH a écrit :

On Wed, May 15, 2019 at 06:40:47AM +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()

Fixes: 1c38a84d4586 ("powerpc: Avoid code patching freed init sections")
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

Now queued up, thanks.

Should go to 4.4 as well since the commit it fixes is now queued for 4.4 
([PATCH 4.4 056/266] powerpc: Avoid code patching freed init sections)

Christophe

On Wed, May 15, 2019 at 02:35:36PM +0200, Christophe Leroy wrote:

Le 15/05/2019 à 10:29, Greg KH a écrit :

quoted

On Wed, May 15, 2019 at 06:40:47AM +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()

Fixes: 1c38a84d4586 ("powerpc: Avoid code patching freed init sections")
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

Now queued up, thanks.

Should go to 4.4 as well since the commit it fixes is now queued for 4.4
([PATCH 4.4 056/266] powerpc: Avoid code patching freed init sections)

Ok, can someone send me a backport that actually applies there?

thanks,

greg k-h

Le 15/05/2019 à 15:08, Greg KH a écrit :

On Wed, May 15, 2019 at 02:35:36PM +0200, Christophe Leroy wrote:

quoted

Le 15/05/2019 à 10:29, Greg KH a écrit :

quoted

On Wed, May 15, 2019 at 06:40:47AM +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()

Fixes: 1c38a84d4586 ("powerpc: Avoid code patching freed init sections")
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

Now queued up, thanks.

Should go to 4.4 as well since the commit it fixes is now queued for 4.4
([PATCH 4.4 056/266] powerpc: Avoid code patching freed init sections)

Ok, can someone send me a backport that actually applies there?

Done

Christophe