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 patch 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 <[EMAIL PROTECTED]>
---
arch/powerpc/kernel/entry_32.S | 6 ++++++
arch/ppc/kernel/entry.S | 6 ++++++
include/asm-powerpc/cputable.h | 22 ++++++++++++----------
3 files changed, 24 insertions(+), 10 deletions(-)
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 21d889e..6461dca 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -244,6 +244,9 @@ syscall_exit_cont:
andis. r10,r0,[EMAIL PROTECTED]
bnel- load_dbcr0
#endif
+BEGIN_FTR_SECTION
+ lwarx r7,0,r1
+END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX)
stwcx. r0,0,r1 /* to clear the reservation */
lwz r4,_LINK(r1)
lwz r5,_CCR(r1)
@@ -694,6 +697,9 @@ restore:
mtctr r11
PPC405_ERR77(0,r1)
+BEGIN_FTR_SECTION
+ lwarx r11,0,r1
+END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX)
stwcx. r0,0,r1 /* to clear the reservation */
#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE))
diff --git a/arch/ppc/kernel/entry.S b/arch/ppc/kernel/entry.S
index fba7ca1..aa57dee 100644
--- a/arch/ppc/kernel/entry.S
+++ b/arch/ppc/kernel/entry.S
@@ -244,6 +244,9 @@ syscall_exit_cont:
andis. r10,r0,[EMAIL PROTECTED]
bnel- load_dbcr0
#endif
+BEGIN_FTR_SECTION
+ lwarx r7,0,r1
+END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX)
stwcx. r0,0,r1 /* to clear the reservation */
lwz r4,_LINK(r1)
lwz r5,_CCR(r1)
@@ -690,6 +693,9 @@ restore:
mtctr r11
PPC405_ERR77(0,r1)
+BEGIN_FTR_SECTION
+ lwarx r11,0,r1
+END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX)
stwcx. r0,0,r1 /* to clear the reservation */
#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE))
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 @@ extern void do_feature_fixups(unsigned long value, void
*fixup_start,
#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 @@ extern void do_feature_fixups(unsigned long value, void
*fixup_start,
#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 @@ extern void do_feature_fixups(unsigned long value, void
*fixup_start,
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 | \
--
1.5.3
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