[PATCH v2 3/3] ARM: errata: Workaround errata A12 825619 / A17 852421
From: Douglas Anderson
Date: Wed Mar 09 2016 - 13:45:13 EST
The workaround for both errata is to set bit 24 in the diagnostic
register. There are no known end-user bugs solved by fixing this
errata, but the fix is trivial and it seems sane to apply it.
The arguments for why this needs to be in the kernel are similar to the
arugments made in the patch "Workaround errata A12 818325/852422 A17
Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
Changes in v2:
- A12 825619 / A17 852421 new for v2.
arch/arm/Kconfig | 18 ++++++++++++++++++
arch/arm/mm/proc-v7.S | 11 +++++++++++
2 files changed, 29 insertions(+)
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index c3e46c9aacf5..cd3b3fda0e16 100644
@@ -1181,6 +1181,24 @@ config ARM_ERRATA_821420
one is in the shadow of a branch or abort, can lead to a
deadlock when the VMOV instructions are issued out-of-order.
+ bool "ARM errata: A12: DMB NSHST/ISHST mixed ... might cause deadlock"
+ depends on CPU_V7
+ This option enables the workaround for the 825619 Cortex-A12
+ (all revs) erratum. Within rare timing constraints, executing a
+ DMB NSHST or DMB ISHST instruction followed by a mix of Cacheable
+ and Device/Strongly-Ordered loads and stores might cause deadlock
+ bool "ARM errata: A17: DMB ST might fail to create order between stores"
+ depends on CPU_V7
+ This option enables the workaround for the 852421 Cortex-A17
+ (r1p0, r1p1, r1p2) erratum. Under very rare timing conditions,
+ execution of a DMB ST instruction might fail to properly order
+ stores from GroupA and stores from GroupB.
bool "ARM errata: A17: some seqs of opposed cond code instrs => deadlock or corruption"
depends on CPU_V7
diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
index a7f9e7567878..0e20537a7d14 100644
@@ -373,9 +373,20 @@ __ca12_errata:
orr r10, r10, #1 << 1 @ set bit #1
mcr p15, 0, r10, c15, c0, 2 @ write internal feature reg
+ mrc p15, 0, r10, c15, c0, 1 @ read diagnostic register
+ orr r10, r10, #1 << 24 @ set bit #24
+ mcr p15, 0, r10, c15, c0, 1 @ write diagnostic register
+ cmp r6, #0x12 @ only present up to r1p2
+ mrcle p15, 0, r10, c15, c0, 1 @ read diagnostic register
+ orrle r10, r10, #1 << 24 @ set bit #24
+ mcrle p15, 0, r10, c15, c0, 1 @ write diagnostic register
cmp r6, #0x12 @ only present up to r1p2
mrcle p15, 0, r10, c15, c0, 1 @ read diagnostic register