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arm64: head.S: ensure idmap_t0sz is visible 

We write idmap_t0sz with SCTLR_EL1.{C,M} clear, but we only have the
guarnatee that the kernel Image is clean, not invalid in the caches, and
therefore we might read a stale value once the MMU is enabled.

This patch ensures we invalidate the corresponding cacheline after the
write as we do for all other data written before we set SCTLR_EL1.{C.M},
guaranteeing that the value will be visible later. We rely on the DSBs
in __create_page_tables to complete the maintenance.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
CC: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Mark Rutland 2015-03-24 15:10:21 +00:00 committed by Will Deacon
parent d5efd9cc9c
commit 0c20856c26
1 changed files with 4 additions and 1 deletions
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arch/arm64/kernel/head.S
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@ -414,7 +414,10 @@ __create_page_tables:
cmp x5, TCR_T0SZ(VA_BITS) // default T0SZ small enough?
b.ge 1f // .. then skip additional level
str_l x5, idmap_t0sz, x6
adr_l x6, idmap_t0sz
str x5, [x6]
dmb sy
dc ivac, x6 // Invalidate potentially stale cache line
create_table_entry x0, x3, EXTRA_SHIFT, EXTRA_PTRS, x5, x6
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