[POWERPC] Avoid unpaired stwcx. on some processors
The context switch code in the kernel issues a dummy stwcx. to clear the
reservation, as recommended by the architecture. However, some processors
can have issues if this stwcx to address A occurs while the reservation
is already held to a different address B. To avoid this problem, the dummy
stwcx. needs to be paired with a dummy lwarx to the same address.
This adds the dummy lwarx, and creates a cpu feature bit to indicate
which cpus are affected. Tested on mpc8641_hpcn_defconfig in
arch/powerpc; build tested in arch/ppc.
Signed-off-by: Becky Bruce <becky.bruce@freescale.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/include/asm-powerpc/cputable.h b/include/asm-powerpc/cputable.h
index 9d74338..4525c78 100644
--- a/include/asm-powerpc/cputable.h
+++ b/include/asm-powerpc/cputable.h
@@ -138,6 +138,7 @@
#define CPU_FTR_FPU_UNAVAILABLE ASM_CONST(0x0000000000800000)
#define CPU_FTR_UNIFIED_ID_CACHE ASM_CONST(0x0000000001000000)
#define CPU_FTR_SPE ASM_CONST(0x0000000002000000)
+#define CPU_FTR_NEED_PAIRED_STWCX ASM_CONST(0x0000000004000000)
/*
* Add the 64-bit processor unique features in the top half of the word;
@@ -261,25 +262,25 @@
#define CPU_FTRS_7450_20 (CPU_FTR_COMMON | \
CPU_FTR_USE_TB | CPU_FTR_L2CR | CPU_FTR_ALTIVEC_COMP | \
CPU_FTR_L3CR | CPU_FTR_HPTE_TABLE | CPU_FTR_SPEC7450 | \
- CPU_FTR_NEED_COHERENT | CPU_FTR_PPC_LE)
+ CPU_FTR_NEED_COHERENT | CPU_FTR_PPC_LE | CPU_FTR_NEED_PAIRED_STWCX)
#define CPU_FTRS_7450_21 (CPU_FTR_COMMON | \
CPU_FTR_USE_TB | \
CPU_FTR_MAYBE_CAN_NAP | CPU_FTR_L2CR | CPU_FTR_ALTIVEC_COMP | \
CPU_FTR_L3CR | CPU_FTR_HPTE_TABLE | CPU_FTR_SPEC7450 | \
CPU_FTR_NAP_DISABLE_L2_PR | CPU_FTR_L3_DISABLE_NAP | \
- CPU_FTR_NEED_COHERENT | CPU_FTR_PPC_LE)
+ CPU_FTR_NEED_COHERENT | CPU_FTR_PPC_LE | CPU_FTR_NEED_PAIRED_STWCX)
#define CPU_FTRS_7450_23 (CPU_FTR_COMMON | \
- CPU_FTR_USE_TB | \
+ CPU_FTR_USE_TB | CPU_FTR_NEED_PAIRED_STWCX | \
CPU_FTR_MAYBE_CAN_NAP | CPU_FTR_L2CR | CPU_FTR_ALTIVEC_COMP | \
CPU_FTR_L3CR | CPU_FTR_HPTE_TABLE | CPU_FTR_SPEC7450 | \
CPU_FTR_NAP_DISABLE_L2_PR | CPU_FTR_NEED_COHERENT | CPU_FTR_PPC_LE)
#define CPU_FTRS_7455_1 (CPU_FTR_COMMON | \
- CPU_FTR_USE_TB | \
+ CPU_FTR_USE_TB | CPU_FTR_NEED_PAIRED_STWCX | \
CPU_FTR_L2CR | CPU_FTR_ALTIVEC_COMP | CPU_FTR_L3CR | \
CPU_FTR_HPTE_TABLE | CPU_FTR_SPEC7450 | CPU_FTR_HAS_HIGH_BATS | \
CPU_FTR_NEED_COHERENT | CPU_FTR_PPC_LE)
#define CPU_FTRS_7455_20 (CPU_FTR_COMMON | \
- CPU_FTR_USE_TB | \
+ CPU_FTR_USE_TB | CPU_FTR_NEED_PAIRED_STWCX | \
CPU_FTR_MAYBE_CAN_NAP | CPU_FTR_L2CR | CPU_FTR_ALTIVEC_COMP | \
CPU_FTR_L3CR | CPU_FTR_HPTE_TABLE | CPU_FTR_SPEC7450 | \
CPU_FTR_NAP_DISABLE_L2_PR | CPU_FTR_L3_DISABLE_NAP | \
@@ -289,31 +290,32 @@
CPU_FTR_MAYBE_CAN_NAP | CPU_FTR_L2CR | CPU_FTR_ALTIVEC_COMP | \
CPU_FTR_L3CR | CPU_FTR_HPTE_TABLE | CPU_FTR_SPEC7450 | \
CPU_FTR_NAP_DISABLE_L2_PR | CPU_FTR_HAS_HIGH_BATS | \
- CPU_FTR_NEED_COHERENT | CPU_FTR_PPC_LE)
+ CPU_FTR_NEED_COHERENT | CPU_FTR_PPC_LE | CPU_FTR_NEED_PAIRED_STWCX)
#define CPU_FTRS_7447_10 (CPU_FTR_COMMON | \
CPU_FTR_USE_TB | \
CPU_FTR_MAYBE_CAN_NAP | CPU_FTR_L2CR | CPU_FTR_ALTIVEC_COMP | \
CPU_FTR_L3CR | CPU_FTR_HPTE_TABLE | CPU_FTR_SPEC7450 | \
CPU_FTR_NAP_DISABLE_L2_PR | CPU_FTR_HAS_HIGH_BATS | \
- CPU_FTR_NEED_COHERENT | CPU_FTR_NO_BTIC | CPU_FTR_PPC_LE)
+ CPU_FTR_NEED_COHERENT | CPU_FTR_NO_BTIC | CPU_FTR_PPC_LE | \
+ CPU_FTR_NEED_PAIRED_STWCX)
#define CPU_FTRS_7447 (CPU_FTR_COMMON | \
CPU_FTR_USE_TB | \
CPU_FTR_MAYBE_CAN_NAP | CPU_FTR_L2CR | CPU_FTR_ALTIVEC_COMP | \
CPU_FTR_L3CR | CPU_FTR_HPTE_TABLE | CPU_FTR_SPEC7450 | \
CPU_FTR_NAP_DISABLE_L2_PR | CPU_FTR_HAS_HIGH_BATS | \
- CPU_FTR_NEED_COHERENT | CPU_FTR_PPC_LE)
+ CPU_FTR_NEED_COHERENT | CPU_FTR_PPC_LE | CPU_FTR_NEED_PAIRED_STWCX)
#define CPU_FTRS_7447A (CPU_FTR_COMMON | \
CPU_FTR_USE_TB | \
CPU_FTR_MAYBE_CAN_NAP | CPU_FTR_L2CR | CPU_FTR_ALTIVEC_COMP | \
CPU_FTR_HPTE_TABLE | CPU_FTR_SPEC7450 | \
CPU_FTR_NAP_DISABLE_L2_PR | CPU_FTR_HAS_HIGH_BATS | \
- CPU_FTR_NEED_COHERENT | CPU_FTR_PPC_LE)
+ CPU_FTR_NEED_COHERENT | CPU_FTR_PPC_LE | CPU_FTR_NEED_PAIRED_STWCX)
#define CPU_FTRS_7448 (CPU_FTR_COMMON | \
CPU_FTR_USE_TB | \
CPU_FTR_MAYBE_CAN_NAP | CPU_FTR_L2CR | CPU_FTR_ALTIVEC_COMP | \
CPU_FTR_HPTE_TABLE | CPU_FTR_SPEC7450 | \
CPU_FTR_NAP_DISABLE_L2_PR | CPU_FTR_HAS_HIGH_BATS | \
- CPU_FTR_PPC_LE)
+ CPU_FTR_PPC_LE | CPU_FTR_NEED_PAIRED_STWCX)
#define CPU_FTRS_82XX (CPU_FTR_COMMON | \
CPU_FTR_MAYBE_CAN_DOZE | CPU_FTR_USE_TB)
#define CPU_FTRS_G2_LE (CPU_FTR_COMMON | CPU_FTR_MAYBE_CAN_DOZE | \