From 85c5e33763a731967ca59085ffe6e694f872d38e Mon Sep 17 00:00:00 2001 From: Vineet Gupta Date: Tue, 14 May 2019 14:25:54 -0700 Subject: [PATCH] ARC: mm: do_page_fault refactor #3: tidyup vma access permission code The coding pattern to NOT intialize variables at declaration time but rather near code which makes us eof them makes it much easier to grok the overall logic, specially when the init is not simply 0 or 1 Signed-off-by: Vineet Gupta --- arch/arc/mm/fault.c | 37 ++++++++++++++++++++----------------- 1 file changed, 20 insertions(+), 17 deletions(-) diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c index a3a292c58e50..8c7c81ce7f6a 100644 --- a/arch/arc/mm/fault.c +++ b/arch/arc/mm/fault.c @@ -64,9 +64,9 @@ void do_page_fault(unsigned long address, struct pt_regs *regs) struct task_struct *tsk = current; struct mm_struct *mm = tsk->mm; int si_code = SEGV_MAPERR; + unsigned int write = 0, exec = 0, mask; vm_fault_t fault; - int write = regs->ecr_cause & ECR_C_PROTV_STORE; /* ST/EX */ - unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; + unsigned int flags; /* * NOTE! We MUST NOT take any locks for this case. We may @@ -88,8 +88,18 @@ void do_page_fault(unsigned long address, struct pt_regs *regs) if (faulthandler_disabled() || !mm) goto no_context; + if (regs->ecr_cause & ECR_C_PROTV_STORE) /* ST/EX */ + write = 1; + else if ((regs->ecr_vec == ECR_V_PROTV) && + (regs->ecr_cause == ECR_C_PROTV_INST_FETCH)) + exec = 1; + + flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; if (user_mode(regs)) flags |= FAULT_FLAG_USER; + if (write) + flags |= FAULT_FLAG_WRITE; + retry: down_read(&mm->mmap_sem); @@ -102,24 +112,17 @@ void do_page_fault(unsigned long address, struct pt_regs *regs) } /* - * Ok, we have a good vm_area for this memory access, so - * we can handle it.. + * vm_area is good, now check permissions for this memory access */ - si_code = SEGV_ACCERR; + mask = VM_READ; + if (write) + mask = VM_WRITE; + if (exec) + mask = VM_EXEC; - /* Handle protection violation, execute on heap or stack */ - - if ((regs->ecr_vec == ECR_V_PROTV) && - (regs->ecr_cause == ECR_C_PROTV_INST_FETCH)) + if (!(vma->vm_flags & mask)) { + si_code = SEGV_ACCERR; goto bad_area; - - if (write) { - if (!(vma->vm_flags & VM_WRITE)) - goto bad_area; - flags |= FAULT_FLAG_WRITE; - } else { - if (!(vma->vm_flags & (VM_READ | VM_EXEC))) - goto bad_area; } /*