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

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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
This commit is contained in:
Catalin Marinas 2013-05-07 16:57:06 +01:00
parent ed1f23637a
commit 0e7f7bcc3f
1 changed files with 2 additions and 1 deletions
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3
arch/arm64/mm/fault.c
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@ -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);