Commit 0e7f7bcc authored May 07, 2013 by Catalin Marinas

arm64: Ignore the 'write' ESR flag on cache maintenance faults



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@arm.com>
Reported-by: Tim Northover <Tim.Northover@arm.com>
Cc: stable@vger.kernel.org

parent ed1f2363

arch/arm64/mm/fault.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -148,6 +148,7 @@ void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *regs)
		#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(unsigned long addr, unsigned int esr,
		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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