Displaying 2 results from an estimated 2 matches for "hlist_pprev_rcu".
2014 Dec 09
4
[LLVMdev] dmb ishld in AArch64
...memory access around DMB should not be reordered, but when compiling the Linux kernel, I found load/store 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 shou...
2014 Dec 09
2
[LLVMdev] dmb ishld in AArch64
...er function should map to a
> native store-release operation (stlr).
I guess it's because we disabled the integrated-asm, so it won't complain when compiling the kernel.
> Also, isn't the reordering wrong 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, [...