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Diffstat (limited to 'arch/um/kernel/trap_kern.c')
-rw-r--r--arch/um/kernel/trap_kern.c30
1 files changed, 29 insertions, 1 deletions
diff --git a/arch/um/kernel/trap_kern.c b/arch/um/kernel/trap_kern.c
index 87cc6fd76ce..0d4c10a7360 100644
--- a/arch/um/kernel/trap_kern.c
+++ b/arch/um/kernel/trap_kern.c
@@ -18,6 +18,7 @@
#include "asm/a.out.h"
#include "asm/current.h"
#include "asm/irq.h"
+#include "sysdep/sigcontext.h"
#include "user_util.h"
#include "kern_util.h"
#include "kern.h"
@@ -25,6 +26,9 @@
#include "mconsole_kern.h"
#include "mem.h"
#include "mem_kern.h"
+#ifdef CONFIG_MODE_SKAS
+#include "skas.h"
+#endif
/* Note this is constrained to return 0, -EFAULT, -EACCESS, -ENOMEM by segv(). */
int handle_page_fault(unsigned long address, unsigned long ip,
@@ -39,6 +43,12 @@ int handle_page_fault(unsigned long address, unsigned long ip,
int err = -EFAULT;
*code_out = SEGV_MAPERR;
+
+ /* If the fault was during atomic operation, don't take the fault, just
+ * fail. */
+ if (in_atomic())
+ goto out_nosemaphore;
+
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
if(!vma)
@@ -85,10 +95,20 @@ survive:
pte = pte_offset_kernel(pmd, address);
} while(!pte_present(*pte));
err = 0;
+ /* The below warning was added in place of
+ * pte_mkyoung(); if (is_write) pte_mkdirty();
+ * If it's triggered, we'd see normally a hang here (a clean pte is
+ * marked read-only to emulate the dirty bit).
+ * However, the generic code can mark a PTE writable but clean on a
+ * concurrent read fault, triggering this harmlessly. So comment it out.
+ */
+#if 0
WARN_ON(!pte_young(*pte) || (is_write && !pte_dirty(*pte)));
+#endif
flush_tlb_page(vma, address);
out:
up_read(&mm->mmap_sem);
+out_nosemaphore:
return(err);
/*
@@ -125,7 +145,15 @@ unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user, void *sc)
}
else if(current->mm == NULL)
panic("Segfault with no mm");
- err = handle_page_fault(address, ip, is_write, is_user, &si.si_code);
+
+ if (SEGV_IS_FIXABLE(&fi) || SEGV_MAYBE_FIXABLE(&fi))
+ err = handle_page_fault(address, ip, is_write, is_user, &si.si_code);
+ else {
+ err = -EFAULT;
+ /* A thread accessed NULL, we get a fault, but CR2 is invalid.
+ * This code is used in __do_copy_from_user() of TT mode. */
+ address = 0;
+ }
catcher = current->thread.fault_catcher;
if(!err)