From fde3538a8a711aedf1173ecb2d45aed868f51c97 Mon Sep 17 00:00:00 2001 From: Markos Chandras Date: Mon, 26 Jan 2015 09:40:36 +0000 Subject: [PATCH] MIPS: asm: pgtable: Prevent HTW race when updating PTEs Whenever we modify a page table entry, we need to ensure that the HTW will not fetch a stable entry. And for that to happen we need to ensure that HTW is stopped before we modify the said entry otherwise the HTW may already be in the process of reading that entry and fetching the old information. As a result of which, we replace the htw_reset() calls with htw_{stop,start} in more appropriate places. This also removes the remaining users of htw_reset() and as a result we drop that macro Signed-off-by: Markos Chandras Cc: # 3.17+ Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/9116/ Signed-off-by: Ralf Baechle --- arch/mips/include/asm/pgtable.h | 14 ++++---------- 1 file changed, 4 insertions(+), 10 deletions(-) diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h index 45d7fd5e1466..3aa982b50a10 100644 --- a/arch/mips/include/asm/pgtable.h +++ b/arch/mips/include/asm/pgtable.h @@ -116,14 +116,6 @@ do { \ } while(0) -#define htw_reset() \ -do { \ - if (cpu_has_htw) { \ - htw_stop(); \ - htw_start(); \ - } \ -} while(0) - extern void set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_t pteval); @@ -155,12 +147,13 @@ static inline void pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *pt { pte_t null = __pte(0); + htw_stop(); /* Preserve global status for the pair */ if (ptep_buddy(ptep)->pte_low & _PAGE_GLOBAL) null.pte_low = null.pte_high = _PAGE_GLOBAL; set_pte_at(mm, addr, ptep, null); - htw_reset(); + htw_start(); } #else @@ -190,6 +183,7 @@ static inline void set_pte(pte_t *ptep, pte_t pteval) static inline void pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep) { + htw_stop(); #if !defined(CONFIG_CPU_R3000) && !defined(CONFIG_CPU_TX39XX) /* Preserve global status for the pair */ if (pte_val(*ptep_buddy(ptep)) & _PAGE_GLOBAL) @@ -197,7 +191,7 @@ static inline void pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *pt else #endif set_pte_at(mm, addr, ptep, __pte(0)); - htw_reset(); + htw_start(); } #endif -- 2.20.1