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From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Greg KH <gregkh@linuxfoundation.org>,
	erhard_f@mailbox.org, Michael Neuling <mikey@neuling.org>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
	stable@vger.kernel.org
Subject: [PATCH] powerpc/lib: fix book3s/32 boot failure due to code patching
Date: Wed, 15 May 2019 06:39:34 +0000 (UTC)	[thread overview]
Message-ID: <629c2acb1fcd09c2d2e3352370c3d9853372cf39.1557902321.git.christophe.leroy@c-s.fr> (raw)

[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 <christophe.leroy@c-s.fr>

---
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


WARNING: multiple messages have this Message-ID (diff)
From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Greg KH <gregkh@linuxfoundation.org>,
	erhard_f@mailbox.org, Michael Neuling <mikey@neuling.org>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
	stable@vger.kernel.org
Subject: [PATCH stable 4.9] powerpc/lib: fix book3s/32 boot failure due to code patching
Date: Wed, 15 May 2019 06:40:47 +0000 (UTC)	[thread overview]
Message-ID: <629c2acb1fcd09c2d2e3352370c3d9853372cf39.1557902321.git.christophe.leroy@c-s.fr> (raw)
Message-ID: <20190515064047.POz61sBEd7lNTVuHuV3Uil7QlVHShbCM9PlnA2vw0y4@z> (raw)

[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 <christophe.leroy@c-s.fr>

---
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


             reply	other threads:[~2019-05-15  6:41 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-15  6:39 Christophe Leroy [this message]
2019-05-15  6:40 ` [PATCH stable 4.9] powerpc/lib: fix book3s/32 boot failure due to code patching Christophe Leroy
2019-05-15  6:41 ` [PATCH] " Christophe Leroy
2019-05-15  8:29 ` [PATCH stable 4.9] " Greg KH
2019-05-15 12:35   ` Christophe Leroy
2019-05-15 13:08     ` Greg KH
2019-05-15 13:31       ` Christophe Leroy
  -- strict thread matches above, loose matches on Subject: below --
2018-10-01 12:21 [PATCH] " Christophe Leroy
2018-10-01 23:19 ` Michael Neuling

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