ARM: 7752/1: errata: LoUIS bit field in CLIDR register is incorrect

On Cortex-A9 before version r1p0, the LoUIS bit field of the CLIDR
register returns zero when it should return one. This leads to cache
maintenance operations which rely on this value to not function as
intended, causing data corruption.

The workaround for this errata is to detect affected CPUs and correct
the LoUIS value read.

Acked-by: Will Deacon <will.deacon@arm.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Cc: stable@vger.kernel.org
Signed-off-by: Jon Medhurst <tixy@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

2 files changed, 18 insertions, 0 deletions

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 49d993cee512..239fa96c12bb 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1189,6 +1189,16 @@ config PL310_ERRATA_588369
            is not correctly implemented in PL310 as clean lines are not
            invalidated as a result of these operations.
 
+config ARM_ERRATA_643719
+        bool "ARM errata: LoUIS bit field in CLIDR register is incorrect"
+        depends on CPU_V7 && SMP
+        help
+          This option enables the workaround for the 643719 Cortex-A9 (prior to
+          r1p0) erratum. On affected cores the LoUIS bit field of the CLIDR
+          register returns zero when it should return one. The workaround
+          corrects this value, ensuring cache maintenance operations which use
+          it behave as intended and avoiding data corruption.
+
 config ARM_ERRATA_720789
         bool "ARM errata: TLBIASIDIS and TLBIMVAIS operations can broadcast a faulty ASID"
         depends on CPU_V7
diff --git a/arch/arm/mm/cache-v7.S b/arch/arm/mm/cache-v7.S
index 15451ee4acc8..515b00064da8 100644
--- a/arch/arm/mm/cache-v7.S
+++ b/arch/arm/mm/cache-v7.S
@@ -92,6 +92,14 @@ ENTRY(v7_flush_dcache_louis)
         mrc     p15, 1, r0, c0, c0, 1           @ read clidr, r0 = clidr
         ALT_SMP(ands    r3, r0, #(7 << 21))     @ extract LoUIS from clidr
         ALT_UP(ands     r3, r0, #(7 << 27))     @ extract LoUU from clidr
+#ifdef CONFIG_ARM_ERRATA_643719
+        ALT_SMP(mrceq   p15, 0, r2, c0, c0, 0)  @ read main ID register
+        ALT_UP(moveq    pc, lr)                 @ LoUU is zero, so nothing to do
+        ldreq   r1, =0x410fc090                 @ ID of ARM Cortex A9 r0p?
+        biceq   r2, r2, #0x0000000f             @ clear minor revision number
+        teqeq   r2, r1                          @ test for errata affected core and if so...
+        orreqs  r3, #(1 << 21)                  @   fix LoUIS value (and set flags state to 'ne')
+#endif
         ALT_SMP(mov     r3, r3, lsr #20)        @ r3 = LoUIS * 2
         ALT_UP(mov      r3, r3, lsr #26)        @ r3 = LoUU * 2
         moveq   pc, lr                          @ return if level == 0