If a page is marked read only we should print out that fact, instead of printing out that there was a page fault. Right now we get a cryptic error message that something went wrong with an unhandled fault, but we don't evaluate the esr to figure out that it was a read/write permission fault.
Instead of seeing: Unable to handle kernel paging request at virtual address ffff000008e460d8 pgd = ffff800003504000 [ffff000008e460d8] *pgd=0000000083473003, *pud=0000000083503003, *pmd=0000000000000000 Internal error: Oops: 9600004f [#1] PREEMPT SMP we'll see: Internal error: Attempting to write read-only memory: 9600004f [#1] PREEMPT SMP Cc: Laura Abbott <[email protected]> Cc: Mark Rutland <[email protected]> Signed-off-by: Stephen Boyd <[email protected]> --- arch/arm64/mm/fault.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 156169c6981b..752507fa80ec 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -331,6 +331,11 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, if (!search_exception_tables(regs->pc)) die("Accessing user space memory outside uaccess.h routines", regs, esr); + } else if (is_permission_fault(esr, regs)) { + if (esr & ESR_ELx_WNR) + die("Attempting to write read-only memory", regs, esr); + else + die("Attempting to read unreadable memory", regs, esr); } /* -- 2.10.0.297.gf6727b0
