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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 <vgupta@synopsys.com>
This commit is contained in:
Vineet Gupta 2019-05-14 14:25:54 -07:00
parent 13e2cc1240
commit 85c5e33763
1 changed files with 20 additions and 17 deletions
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37
arch/arc/mm/fault.c
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@ -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;
}
/*