linux-kernel - [PATCH 4.3 081/125] arm64: page-align sections for DEBUG

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Date:	Mon,  7 Dec 2015 10:01:34 -0500
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Mark Rutland <mark.rutland@....com>,
	Jeremy Linton <jeremy.linton@....com>,
	Laura Abbott <laura@...bott.name>,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	Suzuki Poulose <suzuki.poulose@....com>,
	Will Deacon <will.deacon@....com>,
	Catalin Marinas <catalin.marinas@....com>
Subject: [PATCH 4.3 081/125] arm64: page-align sections for DEBUG_RODATA

4.3-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mark Rutland <mark.rutland@....com>

commit cb083816ab5ac3d10a9417527f07fc5962cc3808 upstream.

A kernel built with DEBUG_RO_DATA && !CONFIG_DEBUG_ALIGN_RODATA doesn't
have .text aligned to a page boundary, though fixup_executable works at
page-granularity thanks to its use of create_mapping. If .text is not
page-aligned, the first page it exists in may be marked non-executable,
leading to failures when an attempt is made to execute code in said
page.

This patch upgrades ALIGN_DEBUG_RO and ALIGN_DEBUG_RO_MIN to force page
alignment for DEBUG_RO_DATA && !CONFIG_DEBUG_ALIGN_RODATA kernels,
ensuring that all sections with specific RWX permission requirements are
mapped with the correct permissions.

Signed-off-by: Mark Rutland <mark.rutland@....com>
Reported-by: Jeremy Linton <jeremy.linton@....com>
Reviewed-by: Laura Abbott <laura@...bott.name>
Acked-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc: Suzuki Poulose <suzuki.poulose@....com>
Cc: Will Deacon <will.deacon@....com>
Fixes: da141706aea52c1a ("arm64: add better page protections to arm64")
Signed-off-by: Catalin Marinas <catalin.marinas@....com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/arm64/kernel/vmlinux.lds.S |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -60,9 +60,12 @@ PECOFF_FILE_ALIGNMENT = 0x200;
 #define PECOFF_EDATA_PADDING
 #endif
 
-#ifdef CONFIG_DEBUG_ALIGN_RODATA
+#if defined(CONFIG_DEBUG_ALIGN_RODATA)
 #define ALIGN_DEBUG_RO			. = ALIGN(1<<SECTION_SHIFT);
 #define ALIGN_DEBUG_RO_MIN(min)		ALIGN_DEBUG_RO
+#elif defined(CONFIG_DEBUG_RODATA)
+#define ALIGN_DEBUG_RO			. = ALIGN(1<<PAGE_SHIFT);
+#define ALIGN_DEBUG_RO_MIN(min)		ALIGN_DEBUG_RO
 #else
 #define ALIGN_DEBUG_RO
 #define ALIGN_DEBUG_RO_MIN(min)		. = ALIGN(min);


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