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modify_prot_start_ptes() performs the break-before-make TLB invalidation
required by erratum 2645198 with __flush_tlb_range(), whose third
argument is the end address of the range. It passes nr * PAGE_SIZE
instead of addr + nr * PAGE_SIZE, so __do_flush_tlb_range() computes the
page count as (nr * PAGE_SIZE - addr) >> PAGE_SHIFT.
For addr > nr * PAGE_SIZE that subtraction underflows, the page count
exceeds the batching limit and the flush degenerates to flush_tlb_mm(),
so a single-page mprotect broadcasts an ASID-wide invalidation and a
full-range mmu notifier call.
For addr <= nr * PAGE_SIZE only [addr, nr * PAGE_SIZE) is invalidated,
and when the cleared batch starts below nr * PAGE_SIZE the tail is left
in the TLB. The workaround then no longer covers the whole batch, and
for addr == nr * PAGE_SIZE the flush is empty.
On affected Cortex-A715 CPUs, this can corrupt ESR_ELx and FAR_ELx on the
next instruction abort caused by a permission fault.
Pass addr + nr * PAGE_SIZE as the end address.
Fixes: 7efa1cd5f89b5 ("arm64: add batched versions of ptep_modify_prot_start/commit")
Cc: stable@vger.kernel.org
Assisted-by: LLM
Signed-off-by: Andrea Parri <parri.andrea@gmail.com>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
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__init_el2_fgt2() writes one mask to both HDFGRTR2_EL2 and HDFGWTR2_EL2.
PMZR_EL0 is write-only, so its trap bit, nPMZR_EL0, exists only in
HDFGWTR2_EL2 and is therefore never set: a PMZR_EL0 write from the host
traps to EL2, where the nVHE hypervisor has no handler and BUG()s. The
kernel never writes PMZR_EL0, but kernel.perf_user_access=1 has the PMU
driver set PMUSERENR_EL0.UEN for a task with a user-read event, so a
write from EL0 reaches the trap and takes the host down without a panic
message.
Accumulate the HDFGWTR2_EL2 bits separately, as __init_el2_fgt() already
does for HDFGWTR_EL2, and set nPMZR_EL0 with the other FEAT_PMUv3p9
bits.
Fixes: 858c7bfcb35e1 ("arm64/boot: Enable EL2 requirements for FEAT_PMUv3p9")
Cc: stable@vger.kernel.org
Signed-off-by: Fuad Tabba <fuad.tabba@linux.dev>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oliver Upton <oupton@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
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