Displaying 2 results from an estimated 2 matches for "f94006a8".
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f9000668
2014 Dec 09
4
[LLVMdev] dmb ishld in AArch64
...in
static inline void hlist_add_before_rcu(struct hlist_node *n,
struct hlist_node *next)
{
n->pprev = next->pprev;
n->next = next;
rcu_assign_pointer(hlist_pprev_rcu(n), n);
next->pprev = &n->next;
}
can reordered, and causes kernel crash.
f94006a8 ldr x8, [x21,#8]
f9000275 str x21, [x19]
d5033abf dmb ishst
f9400669 ldr x9, [x19,#8]
f9000668 str x8, [x19,#8] <==== reordered str
f9000133 str x19, [x9]
f90006b3 str x19, [x21,#8]
It should be:
f94006a8 ldr x8, [x21,#8]
f9000668 str x8, [x19,#8]
f9000275 str x21, [x19]
d5033abf dm...
2014 Dec 09
2
[LLVMdev] dmb ishld in AArch64
...just from a data-dependency point of
> view? It looks like it moves the hlist_pprev_rcu(n) access before the
> n->pprev assignment. Could be because of an aliasing violation, or it
> could be LLVM.
The problem is explained below, the reordering causes accessing to uninitialized data.
f94006a8 ldr x8, [x21,#8]
f9000275 str x21, [x19]
d5033abf dmb ishst
f9400669 ldr x9, [x19,#8] <==== uninitialized data
f9000668 str x8, [x19,#8] <==== initialization
f9000133 str x19, [x9] <==== accessing uninitialized address
f90006b3 str x19, [x21,#8]
> Do you have preprocessed source...