Commit 5e91bf5c authored by Vineet Gupta's avatar Vineet Gupta
Browse files

ARC: mm: do_page_fault refactor #7: fold the various error handling 

 - single up_read() call vs. 4
 - so much easier on eyes

Technically it seems like @bad_area label moved up, but even in old
regime, it was a special case of delivering SIGSEGV unconditionally
which we now do as well, although with checks.

Also note that @fault needs to be initialized since we can land in
@bad_area (which reads it) without setting it up with return value of
handle_mm_fault() - failing to do so did bite us although as a side
effect of different patch: see [1]

[1]: http://lists.infradead.org/pipermail/linux-snps-arc/2019-May/005803.html



Signed-off-by: default avatarVineet Gupta <vgupta@synopsys.com>
parent 98cb57ad

arch/arc/mm/fault.c

+14 −34
Original line number Diff line number Diff line
@@ -63,9 +63,9 @@ void do_page_fault(unsigned long address, struct pt_regs *regs) 
	struct vm_area_struct *vma = NULL;

	struct task_struct *tsk = current;

	struct mm_struct *mm = tsk->mm;

	int si_code = SEGV_MAPERR;

	int sig, si_code = SEGV_MAPERR;

	unsigned int write = 0, exec = 0, mask;

	vm_fault_t fault;			/* handle_mm_fault() output */

	vm_fault_t fault = VM_FAULT_SIGSEGV;	/* handle_mm_fault() output */

	unsigned int flags;			/* handle_mm_fault() input */



	/*
@@ -174,47 +174,27 @@ retry: 
		return;

	}



	if (fault & VM_FAULT_OOM)

		goto out_of_memory;

	else if (fault & VM_FAULT_SIGSEGV)

		goto bad_area;

	else if (fault & VM_FAULT_SIGBUS)

		goto do_sigbus;



	/* no man's land */

	BUG();



	/*

	 * Something tried to access memory that isn't in our memory map..

	 * Fix it, but check if it's kernel or user first..

	 */

bad_area:

	up_read(&mm->mmap_sem);



	if (!user_mode(regs))

		goto no_context;



	tsk->thread.fault_address = address;

	force_sig_fault(SIGSEGV, si_code, (void __user *)address, tsk);

	return;



out_of_memory:

	up_read(&mm->mmap_sem);



	if (!user_mode(regs))

		goto no_context;



	if (fault & VM_FAULT_OOM) {

		pagefault_out_of_memory();

		return;

	}



do_sigbus:

	up_read(&mm->mmap_sem);



	if (!user_mode(regs))

		goto no_context;

	if (fault & VM_FAULT_SIGBUS) {

		sig = SIGBUS;

		si_code = BUS_ADRERR;

	}

	else {

		sig = SIGSEGV;

	}



	tsk->thread.fault_address = address;

	force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address, tsk);

	force_sig_fault(sig, si_code, (void __user *)address, tsk);

	return;



no_context:

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