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 <[email protected]> Cc: James Hogan <[email protected]> --- arch/mips/mm/c-r4k.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/arch/mips/mm/c-r4k.c b/arch/mips/mm/c-r4k.c index caac3d7..a49010c 100644 --- a/arch/mips/mm/c-r4k.c +++ b/arch/mips/mm/c-r4k.c @@ -449,6 +449,7 @@ static inline void local_r4k___flush_cache_all(void * args) default: r4k_blast_dcache(); + mb(); /* cache instructions may be reordered */ r4k_blast_icache(); break; } @@ -493,8 +494,10 @@ static inline void local_r4k_flush_cache_range(void * args) return; r4k_blast_dcache(); - if (exec) + if (exec) { + mb(); /* cache instructions may be reordered */ r4k_blast_icache(); + } } static void r4k_flush_cache_range(struct vm_area_struct *vma, @@ -599,8 +602,13 @@ static inline void local_r4k_flush_cache_page(void *args) 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) { @@ -660,6 +668,7 @@ static inline void local_r4k_flush_icache_range(unsigned long start, unsigned lo R4600_HIT_CACHEOP_WAR_IMPL; protected_blast_dcache_range(start, end); } + mb(); /* cache instructions may be reordered */ } if (end - start > icache_size) @@ -798,6 +807,8 @@ static void local_r4k_flush_cache_sigtramp(void * arg) protected_writeback_dcache_line(addr & ~(dc_lsize - 1)); if (!cpu_icache_snoops_remote_store && scache_size) protected_writeback_scache_line(addr & ~(sc_lsize - 1)); + if ((dc_lsize || scache_size) && ic_lsize) + mb(); /* cache instructions may be reordered */ if (ic_lsize) protected_flush_icache_line(addr & ~(ic_lsize - 1)); if (MIPS4K_ICACHE_REFILL_WAR) { -- 2.7.1
