Commit 40d3cd66 authored by H. Peter Anvin's avatar H. Peter Anvin
Browse files

x86, smap: A page fault due to SMAP is an oops 



If we get a page fault due to SMAP, trigger an oops rather than
spinning forever.

Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1348256595-29119-11-git-send-email-hpa@linux.intel.com
parent 52b6179a

arch/x86/mm/fault.c

+18 −0
Original line number Diff line number Diff line
@@ -995,6 +995,17 @@ static int fault_in_kernel_space(unsigned long address) 
	return address >= TASK_SIZE_MAX;

}



static inline bool smap_violation(int error_code, struct pt_regs *regs)

{

	if (error_code & PF_USER)

		return false;



	if (!user_mode_vm(regs) && (regs->flags & X86_EFLAGS_AC))

		return false;



	return true;

}



/*

 * This routine handles page faults.  It determines the address,

 * and the problem, and then passes it off to one of the appropriate
@@ -1088,6 +1099,13 @@ do_page_fault(struct pt_regs *regs, unsigned long error_code) 
	if (unlikely(error_code & PF_RSVD))

		pgtable_bad(regs, error_code, address);



	if (static_cpu_has(X86_FEATURE_SMAP)) {

		if (unlikely(smap_violation(error_code, regs))) {

			bad_area_nosemaphore(regs, error_code, address);

			return;

		}

	}



	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);



	/*

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