From 2468dcf641e4f3e1b0153e3e11ca20740b2f4ce8 Mon Sep 17 00:00:00 2001 From: Ian Munsie Date: Thu, 7 Feb 2013 15:46:58 +0000 Subject: [PATCH] powerpc: Add support for context switching the TAR register This patch adds support for enabling and context switching the Target Address Register in Power8. The TAR is a new special purpose register that can be used for computed branches with the bctar[l] (branch conditional to TAR) instruction in the same manner as the count and link registers. Signed-off-by: Ian Munsie Signed-off-by: Matt Evans Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/include/asm/cputable.h | 2 +- arch/powerpc/include/asm/processor.h | 3 +++ arch/powerpc/include/asm/reg.h | 3 +++ arch/powerpc/kernel/asm-offsets.c | 4 ++++ arch/powerpc/kernel/cpu_setup_power.S | 7 +++++++ arch/powerpc/kernel/entry_64.S | 20 ++++++++++++++++++++ 6 files changed, 38 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h index 06f7fb9..5f1938f 100644 --- a/arch/powerpc/include/asm/cputable.h +++ b/arch/powerpc/include/asm/cputable.h @@ -414,7 +414,7 @@ extern const char *powerpc_base_platform; CPU_FTR_DSCR | CPU_FTR_SAO | \ CPU_FTR_STCX_CHECKS_ADDRESS | CPU_FTR_POPCNTB | CPU_FTR_POPCNTD | \ CPU_FTR_ICSWX | CPU_FTR_CFAR | CPU_FTR_HVMODE | CPU_FTR_VMX_COPY | \ - CPU_FTR_DBELL | CPU_FTR_HAS_PPR | CPU_FTR_DAWR) + CPU_FTR_DBELL | CPU_FTR_HAS_PPR | CPU_FTR_DAWR | CPU_FTR_BCTAR) #define CPU_FTRS_CELL (CPU_FTR_USE_TB | CPU_FTR_LWSYNC | \ CPU_FTR_PPCAS_ARCH_V2 | CPU_FTR_CTRL | \ CPU_FTR_ALTIVEC_COMP | CPU_FTR_MMCRA | CPU_FTR_SMT | \ diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h index 7938658..42ac53c 100644 --- a/arch/powerpc/include/asm/processor.h +++ b/arch/powerpc/include/asm/processor.h @@ -257,6 +257,9 @@ struct thread_struct { int dscr_inherit; unsigned long ppr; /* used to save/restore SMT priority */ #endif +#ifdef CONFIG_PPC_BOOK3S_64 + unsigned long tar; +#endif }; #define ARCH_MIN_TASKALIGN 16 diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h index 1f59fbb..e09ac51 100644 --- a/arch/powerpc/include/asm/reg.h +++ b/arch/powerpc/include/asm/reg.h @@ -237,6 +237,9 @@ #define SPRN_HRMOR 0x139 /* Real mode offset register */ #define SPRN_HSRR0 0x13A /* Hypervisor Save/Restore 0 */ #define SPRN_HSRR1 0x13B /* Hypervisor Save/Restore 1 */ +#define SPRN_FSCR 0x099 /* Facility Status & Control Register */ +#define FSCR_TAR (1<<8) /* Enable Target Adress Register */ +#define SPRN_TAR 0x32f /* Target Address Register */ #define SPRN_LPCR 0x13E /* LPAR Control Register */ #define LPCR_VPM0 (1ul << (63-0)) #define LPCR_VPM1 (1ul << (63-1)) diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c index e39ca55..beddba4 100644 --- a/arch/powerpc/kernel/asm-offsets.c +++ b/arch/powerpc/kernel/asm-offsets.c @@ -122,6 +122,10 @@ int main(void) DEFINE(THREAD_KVM_VCPU, offsetof(struct thread_struct, kvm_vcpu)); #endif +#ifdef CONFIG_PPC_BOOK3S_64 + DEFINE(THREAD_TAR, offsetof(struct thread_struct, tar)); +#endif + DEFINE(TI_FLAGS, offsetof(struct thread_info, flags)); DEFINE(TI_LOCAL_FLAGS, offsetof(struct thread_info, local_flags)); DEFINE(TI_PREEMPT, offsetof(struct thread_info, preempt_count)); diff --git a/arch/powerpc/kernel/cpu_setup_power.S b/arch/powerpc/kernel/cpu_setup_power.S index 57cf140..d29facb 100644 --- a/arch/powerpc/kernel/cpu_setup_power.S +++ b/arch/powerpc/kernel/cpu_setup_power.S @@ -56,6 +56,7 @@ _GLOBAL(__setup_cpu_power8) mfspr r3,SPRN_LPCR oris r3, r3, LPCR_AIL_3@h bl __init_LPCR + bl __init_FSCR bl __init_TLB mtlr r11 blr @@ -112,6 +113,12 @@ __init_LPCR: isync blr +__init_FSCR: + mfspr r3,SPRN_FSCR + ori r3,r3,FSCR_TAR + mtspr SPRN_FSCR,r3 + blr + __init_TLB: /* Clear the TLB */ li r6,128 diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index 44c733f..9ae8451 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -448,6 +448,19 @@ END_FTR_SECTION_IFSET(CPU_FTR_DSCR) std r23,_CCR(r1) std r1,KSP(r3) /* Set old stack pointer */ +#ifdef CONFIG_PPC_BOOK3S_64 +BEGIN_FTR_SECTION + /* + * Back up the TAR across context switches. Note that the TAR is not + * available for use in the kernel. (To provide this, the TAR should + * be backed up/restored on exception entry/exit instead, and be in + * pt_regs. FIXME, this should be in pt_regs anyway (for debug).) + */ + mfspr r0,SPRN_TAR + std r0,THREAD_TAR(r3) +END_FTR_SECTION_IFSET(CPU_FTR_BCTAR) +#endif + #ifdef CONFIG_SMP /* We need a sync somewhere here to make sure that if the * previous task gets rescheduled on another CPU, it sees all @@ -530,6 +543,13 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_1T_SEGMENT) mr r1,r8 /* start using new stack pointer */ std r7,PACAKSAVE(r13) +#ifdef CONFIG_PPC_BOOK3S_64 +BEGIN_FTR_SECTION + ld r0,THREAD_TAR(r4) + mtspr SPRN_TAR,r0 +END_FTR_SECTION_IFSET(CPU_FTR_BCTAR) +#endif + #ifdef CONFIG_ALTIVEC BEGIN_FTR_SECTION ld r0,THREAD_VRSAVE(r4) -- 2.7.4