linux-kernel - [ 23/73] arm64: Ignore the write ESR flag on cache maintenance faults

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Message-Id: <20130509222528.840584177@linuxfoundation.org>
Date:	Thu,  9 May 2013 15:25:13 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Catalin Marinas <catalin.marinas@....com>,
	Tim Northover <Tim.Northover@....com>
Subject: [ 23/73] arm64: Ignore the write ESR flag on cache maintenance faults

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

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

From: Catalin Marinas <catalin.marinas@....com>

commit 0e7f7bcc3fc87489cda5aa6aff8ce40eed912279 upstream.

ESR.WnR bit is always set on data cache maintenance faults even though
the page is not required to have write permission. If a translation
fault (page not yet mapped) happens for read-only user address range,
Linux incorrectly assumes a permission fault. This patch adds the check
of the ESR.CM bit during the page fault handling to ignore the 'write'
flag.

Signed-off-by: Catalin Marinas <catalin.marinas@....com>
Reported-by: Tim Northover <Tim.Northover@....com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/arm64/mm/fault.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -148,6 +148,7 @@ void do_bad_area(unsigned long addr, uns
 #define VM_FAULT_BADACCESS	0x020000
 
 #define ESR_WRITE		(1 << 6)
+#define ESR_CM			(1 << 8)
 #define ESR_LNX_EXEC		(1 << 24)
 
 /*
@@ -206,7 +207,7 @@ static int __kprobes do_page_fault(unsig
 	struct task_struct *tsk;
 	struct mm_struct *mm;
 	int fault, sig, code;
-	int write = esr & ESR_WRITE;
+	bool write = (esr & ESR_WRITE) && !(esr & ESR_CM);
 	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
 		(write ? FAULT_FLAG_WRITE : 0);
 


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