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mmu-hash64: Factor SLB N bit into permissions bits

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Currently, for 64-bit hash mmu, the execute protection bit placed into the
qemu tlb is based only on the N (No execute) bit from the PTE.  However,
No Execute can also be set at the segment level.  We do check this on
execute faults, but this still means we could incorrectly allow execution
of code from a No Execute segment, if a prior read or write fault caused
the page to be loaded into the qemu tlb with PROT_EXEC set.

To correct this, we (re-)check the segment level no execute permission when
generating the protection bits for the qemu tlb.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Alexander Graf <agraf@suse.de>
This commit is contained in:
David Gibson 2013-03-12 00:31:41 +00:00 committed by Alexander Graf
parent e01b444523
commit 57d0a39d98
1 changed files with 2 additions and 1 deletions
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3
target-ppc/mmu-hash64.c
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@ -272,7 +272,8 @@ static int ppc_hash64_pte_prot(CPUPPCState *env,
}
/* No execute if either noexec or guarded bits set */
if (!(pte.pte1 & HPTE64_R_N) || (pte.pte1 & HPTE64_R_G)) {
if (!(pte.pte1 & HPTE64_R_N) || (pte.pte1 & HPTE64_R_G)
|| (slb->vsid & SLB_VSID_N)) {
prot |= PAGE_EXEC;
}