lkml.org 
[lkml]   [2015]   [Nov]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[RESEND PATCH] ARM: errata: Workaround for Cortex-A12 erratum 818325
Date
From: Huang Tao <huangtao@rock-chips.com>

On Cortex-A12 (r0p0..r0p1-00lac0-rc11), when a CPU executes a sequence of
two conditional store instructions with opposite condition code and
updating the same register, the system might enter a deadlock if the
second conditional instruction is an UNPREDICTABLE STR or STM
instruction. This workaround setting bit[12] of the Feature Register
prevents the erratum. This bit disables an optimisation applied to a
sequence of 2 instructions that use opposing condition codes.

Signed-off-by: Huang Tao <huangtao@rock-chips.com>
Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Signed-off-by: Caesar Wang <wxt@rock-chips.com>

---

arch/arm/Kconfig | 13 +++++++++++++
arch/arm/mm/proc-v7.S | 12 ++++++++++++
2 files changed, 25 insertions(+)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 639411f..554b57a 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1263,6 +1263,19 @@ config ARM_ERRATA_773022
loop buffer may deliver incorrect instructions. This
workaround disables the loop buffer to avoid the erratum.

+config ARM_ERRATA_818325
+ bool "ARM errata: Execution of an UNPREDICTABLE STR or STM instruction might deadlock"
+ depends on CPU_V7
+ help
+ This option enables the workaround for the 818325 Cortex-A12
+ (r0p0..r0p1-00lac0-rc11) erratum. When a CPU executes a sequence of
+ two conditional store instructions with opposite condition code and
+ updating the same register, the system might enter a deadlock if the
+ second conditional instruction is an UNPREDICTABLE STR or STM
+ instruction. This workaround setting bit[12] of the Feature Register
+ prevents the erratum. This bit disables an optimisation applied to a
+ sequence of 2 instructions that use opposing condition codes.
+
endmenu

source "arch/arm/common/Kconfig"
diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
index de2b246..2b338ec 100644
--- a/arch/arm/mm/proc-v7.S
+++ b/arch/arm/mm/proc-v7.S
@@ -439,6 +439,18 @@ __v7_setup_cont:
teq r0, r10
beq __ca9_errata

+ /* Cortex-A12 Errata */
+ ldr r10, =0x00000c0d @ Cortex-A12 primary part number
+ teq r0, r10
+ bne 5f
+#ifdef CONFIG_ARM_ERRATA_818325
+ teq r6, #0x00 @ present in r0p0
+ teqne r6, #0x01 @ present in r0p1-00lac0-rc11
+ mrceq p15, 0, r10, c15, c0, 1 @ read diagnostic register
+ orreq r10, r10, #1 << 12 @ set bit #12
+ mcreq p15, 0, r10, c15, c0, 1 @ write diagnostic register
+ isb
+#endif
/* Cortex-A15 Errata */
ldr r10, =0x00000c0f @ Cortex-A15 primary part number
teq r0, r10
--
1.9.1


\
 
 \ /
  Last update: 2015-11-03 09:41    [W:0.606 / U:1.528 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site