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

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

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1348256595-29119-11-git-send-email-hpa@linux.intel.com
This commit is contained in:
H. Peter Anvin 2012-09-21 12:43:14 -07:00
parent 52b6179ac8
commit 40d3cd6695
1 changed files with 18 additions and 0 deletions
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18
arch/x86/mm/fault.c
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@ -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);
/*