From e6e6ef4275978823ec3a84133fc91f4ffbef5c84 Mon Sep 17 00:00:00 2001 From: Paul Burton Date: Mon, 22 Feb 2016 18:09:44 +0000 Subject: [PATCH] MIPS: Add barriers between dcache & icache flushes Index-based cache operations may be arbitrarily reordered by out of order CPUs. Thus code which writes back the dcache & then invalidates the icache using indexed cache ops must include a barrier between operating on the 2 caches in order to prevent the scenario in which: - icache invalidation occurs. - icache fetch occurs, due to speculation. - dcache writeback occurs. If the above were allowed to happen then the icache would contain stale data. Forcing the dcache writeback to complete before the icache invalidation avoids this. Signed-off-by: Paul Burton Cc: James Hogan --- arch/mips/mm/c-r4k.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) --- a/arch/mips/mm/c-r4k.c +++ b/arch/mips/mm/c-r4k.c @@ -514,6 +514,7 @@ static inline void local_r4k___flush_cac default: r4k_blast_dcache(); + mb(); /* cache instructions may be reordered */ r4k_blast_icache(); break; } @@ -594,8 +595,10 @@ static inline void local_r4k_flush_cache if (cpu_has_dc_aliases || (exec && !cpu_has_ic_fills_f_dc)) r4k_blast_dcache(); /* If executable, blast stale lines from icache */ - if (exec) + if (exec) { + mb(); /* cache instructions may be reordered */ r4k_blast_icache(); + } } static void r4k_flush_cache_range(struct vm_area_struct *vma, @@ -696,8 +699,13 @@ static inline void local_r4k_flush_cache if (cpu_has_dc_aliases || (exec && !cpu_has_ic_fills_f_dc)) { vaddr ? r4k_blast_dcache_page(addr) : r4k_blast_dcache_user_page(addr); - if (exec && !cpu_icache_snoops_remote_store) + if (exec) + mb(); /* cache instructions may be reordered */ + + if (exec && !cpu_icache_snoops_remote_store) { r4k_blast_scache_page(addr); + mb(); /* cache instructions may be reordered */ + } } if (exec) { if (vaddr && cpu_has_vtag_icache && mm == current->active_mm) { @@ -764,6 +772,7 @@ static inline void __local_r4k_flush_ica else blast_dcache_range(start, end); } + mb(); /* cache instructions may be reordered */ } if (type == R4K_INDEX ||