From: "H. Peter Anvin" <h...@linux.intel.com>
If we get a page fault due to SMAP, trigger an oops rather than
spinning forever.
Signed-off-by: H. Peter Anvin <h...@linux.intel.com>
---
arch/x86/mm/fault.c | 18 ++++++++++++++++++
1 files changed, 18 insertions(+), 0 deletions(-)
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 76dcd9d..f2fb75d 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -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);
/*
--
1.7.6.5
--
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