From cfd9d70a855edf6adb37d0ed88be9e35274dbe49 Mon Sep 17 00:00:00 2001 From: Vineet Gupta Date: Thu, 13 Nov 2014 19:27:24 +0530 Subject: [PATCH] ARCv2: mm: TLB Miss optim: SMP builds can cache pgd pointer in mmu scratch reg ARC700 exception (and intr handling) didn't have auto stack switching thus had to rely on stashing a reg temporarily (to free it up) at a known place in memory, allowing to code up the low level stack switching. This however was not re-entrant in SMP which thus had to repurpose the per-cpu MMU SCRATCH DATA register otherwise used to "cache" the task pdg pointer (vs. reading it from mm struct) The newer HS cores do have auto-stack switching and thus even SMP builds can use the MMU SCRATCH reg as originally intended. This patch fixes the restriction to ARC700 SMP builds only Signed-off-by: Vineet Gupta --- arch/arc/include/asm/entry-compact.h | 4 ++-- arch/arc/include/asm/mmu.h | 4 ++++ arch/arc/include/asm/mmu_context.h | 2 +- arch/arc/include/asm/pgtable.h | 2 +- arch/arc/mm/tlb.c | 2 +- arch/arc/mm/tlbex.S | 2 +- 6 files changed, 10 insertions(+), 6 deletions(-) diff --git a/arch/arc/include/asm/entry-compact.h b/arch/arc/include/asm/entry-compact.h index 66a2923..c3aa775 100644 --- a/arch/arc/include/asm/entry-compact.h +++ b/arch/arc/include/asm/entry-compact.h @@ -130,7 +130,7 @@ * to be saved again on kernel mode stack, as part of pt_regs. *-------------------------------------------------------------*/ .macro PROLOG_FREEUP_REG reg, mem -#ifdef CONFIG_SMP +#ifndef ARC_USE_SCRATCH_REG sr \reg, [ARC_REG_SCRATCH_DATA0] #else st \reg, [\mem] @@ -138,7 +138,7 @@ .endm .macro PROLOG_RESTORE_REG reg, mem -#ifdef CONFIG_SMP +#ifndef ARC_USE_SCRATCH_REG lr \reg, [ARC_REG_SCRATCH_DATA0] #else ld \reg, [\mem] diff --git a/arch/arc/include/asm/mmu.h b/arch/arc/include/asm/mmu.h index 98cadf1..0abacb8 100644 --- a/arch/arc/include/asm/mmu.h +++ b/arch/arc/include/asm/mmu.h @@ -40,6 +40,10 @@ #define ARC_REG_SCRATCH_DATA0 0x46c #endif +#if defined(CONFIG_ISA_ARCV2) || !defined(CONFIG_SMP) +#define ARC_USE_SCRATCH_REG +#endif + /* Bits in MMU PID register */ #define __TLB_ENABLE (1 << 31) #define __PROG_ENABLE (1 << 30) diff --git a/arch/arc/include/asm/mmu_context.h b/arch/arc/include/asm/mmu_context.h index 0354708..3a5e6a5 100644 --- a/arch/arc/include/asm/mmu_context.h +++ b/arch/arc/include/asm/mmu_context.h @@ -144,7 +144,7 @@ static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, */ cpumask_set_cpu(cpu, mm_cpumask(next)); -#ifndef CONFIG_SMP +#ifdef ARC_USE_SCRATCH_REG /* PGD cached in MMU reg to avoid 3 mem lookups: task->mm->pgd */ write_aux_reg(ARC_REG_SCRATCH_DATA0, next->pgd); #endif diff --git a/arch/arc/include/asm/pgtable.h b/arch/arc/include/asm/pgtable.h index 7addd03..ea14a8b 100644 --- a/arch/arc/include/asm/pgtable.h +++ b/arch/arc/include/asm/pgtable.h @@ -351,7 +351,7 @@ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr, * Thus use this macro only when you are certain that "current" is current * e.g. when dealing with signal frame setup code etc */ -#ifndef CONFIG_SMP +#ifdef ARC_USE_SCRATCH_REG #define pgd_offset_fast(mm, addr) \ ({ \ pgd_t *pgd_base = (pgd_t *) read_aux_reg(ARC_REG_SCRATCH_DATA0); \ diff --git a/arch/arc/mm/tlb.c b/arch/arc/mm/tlb.c index 10025e1..417f05a 100644 --- a/arch/arc/mm/tlb.c +++ b/arch/arc/mm/tlb.c @@ -868,7 +868,7 @@ void arc_mmu_init(void) write_aux_reg(ARC_REG_PID, MMU_ENABLE); /* In smp we use this reg for interrupt 1 scratch */ -#ifndef CONFIG_SMP +#ifdef ARC_USE_SCRATCH_REG /* swapper_pg_dir is the pgd for the kernel, used by vmalloc */ write_aux_reg(ARC_REG_SCRATCH_DATA0, swapper_pg_dir); #endif diff --git a/arch/arc/mm/tlbex.S b/arch/arc/mm/tlbex.S index c55d95d..d6fbded 100644 --- a/arch/arc/mm/tlbex.S +++ b/arch/arc/mm/tlbex.S @@ -193,7 +193,7 @@ ex_saved_reg1: lr r2, [efa] -#ifndef CONFIG_SMP +#ifdef ARC_USE_SCRATCH_REG lr r1, [ARC_REG_SCRATCH_DATA0] ; current pgd #else GET_CURR_TASK_ON_CPU r1 -- 2.7.4