From: Becky Bruce Date: Fri, 9 Nov 2007 22:17:49 +0000 (+1100) Subject: [POWERPC] Avoid unpaired stwcx. on some processors X-Git-Tag: v2.6.24-rc3~146^2~4 X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=b64f87c16f3c00fe593f632e1ee5798ba3f4f3f4;p=linux-2.6-omap-h63xx.git [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 Signed-off-by: Paul Mackerras --- diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S index a7572cf464b..69a91bd4611 100644 --- a/arch/powerpc/kernel/entry_32.S +++ b/arch/powerpc/kernel/entry_32.S @@ -251,6 +251,9 @@ syscall_exit_cont: bne- 2f 1: #endif /* CONFIG_44x */ +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) @@ -717,6 +720,9 @@ 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 b19bfef2034..59e77eb6333 100644 --- a/arch/ppc/kernel/entry.S +++ b/arch/ppc/kernel/entry.S @@ -251,6 +251,9 @@ syscall_exit_cont: bne- 2f 1: #endif /* CONFIG_44x */ +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) @@ -713,6 +716,9 @@ 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 9d74338e3de..4525c784dfd 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 | \