This consolidates page fault information capture and move them bit earlier. While here it also adds an wrapper is_write_abort(). It also saves some cycles by replacing multiple user_mode() calls into a single one earlier during the fault.
Signed-off-by: Anshuman Khandual <[email protected]> Cc: Catalin Marinas <[email protected]> Cc: Will Deacon <[email protected]> Cc: Mark Rutland <[email protected]> Cc: James Morse <[email protected]> Cc: Andrey Konovalov <[email protected]> --- arch/arm64/mm/fault.c | 22 +++++++++++++++------- 1 file changed, 15 insertions(+), 7 deletions(-) diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index da02678..170c71f 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -435,6 +435,11 @@ static bool is_el0_instruction_abort(unsigned int esr) return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_LOW; } +static bool is_write_abort(unsigned int esr) +{ + return (esr & ESR_ELx_WNR) && !(esr & ESR_ELx_CM); +} + static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, struct pt_regs *regs) { @@ -443,6 +448,9 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, vm_fault_t fault, major = 0; unsigned long vm_flags = VM_READ | VM_WRITE; unsigned int mm_flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; + bool is_user = user_mode(regs); + bool is_el0_exec = is_el0_instruction_abort(esr); + bool is_write = is_write_abort(esr); if (notify_page_fault(regs, esr)) return 0; @@ -454,12 +462,12 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, if (faulthandler_disabled() || !mm) goto no_context; - if (user_mode(regs)) + if (is_user) mm_flags |= FAULT_FLAG_USER; - if (is_el0_instruction_abort(esr)) { + if (is_el0_exec) { vm_flags = VM_EXEC; - } else if ((esr & ESR_ELx_WNR) && !(esr & ESR_ELx_CM)) { + } else if (is_write) { vm_flags = VM_WRITE; mm_flags |= FAULT_FLAG_WRITE; } @@ -487,7 +495,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, * we can bug out early if this is from code which shouldn't. */ if (!down_read_trylock(&mm->mmap_sem)) { - if (!user_mode(regs) && !search_exception_tables(regs->pc)) + if (!is_user && !search_exception_tables(regs->pc)) goto no_context; retry: down_read(&mm->mmap_sem); @@ -498,7 +506,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, */ might_sleep(); #ifdef CONFIG_DEBUG_VM - if (!user_mode(regs) && !search_exception_tables(regs->pc)) { + if (!is_user && !search_exception_tables(regs->pc)) { up_read(&mm->mmap_sem); goto no_context; } @@ -516,7 +524,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, * in __lock_page_or_retry in mm/filemap.c. */ if (fatal_signal_pending(current)) { - if (!user_mode(regs)) + if (!is_user) goto no_context; return 0; } @@ -561,7 +569,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, * If we are in kernel mode at this point, we have no context to * handle this fault with. */ - if (!user_mode(regs)) + if (!is_user) goto no_context; if (fault & VM_FAULT_OOM) { -- 2.7.4
