From 67bf04a5c2574e9495f660f418f6df776821d578 Mon Sep 17 00:00:00 2001 From: Jack Steiner Date: Tue, 15 Dec 2009 16:48:11 -0800 Subject: [PATCH] gru: fix prefetch and speculation bugs Fix several bugs related to prefetch, ordering & speculation: - GRU cch_allocate() instruction causes cacheable memory to be created. Add a barriers to prevent speculation from prefetching data before it exists. - Add memory barriers before cache-flush instructions to ensure that previously stored data is included in the line flushed to memory. Signed-off-by: Jack Steiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/misc/sgi-gru/gru_instructions.h | 1 + drivers/misc/sgi-gru/grufault.c | 2 ++ drivers/misc/sgi-gru/gruhandles.c | 22 ++++++++++++++++++++-- drivers/misc/sgi-gru/grukservices.c | 10 ++++++---- drivers/misc/sgi-gru/grumain.c | 9 +++++++++ 5 files changed, 38 insertions(+), 6 deletions(-) diff --git a/drivers/misc/sgi-gru/gru_instructions.h b/drivers/misc/sgi-gru/gru_instructions.h index e033b6c..32f358d 100644 --- a/drivers/misc/sgi-gru/gru_instructions.h +++ b/drivers/misc/sgi-gru/gru_instructions.h @@ -325,6 +325,7 @@ static inline void gru_flush_cache(void *p) static inline void gru_start_instruction(struct gru_instruction *ins, int op32) { gru_ordered_store_int(ins, op32); + mb(); gru_flush_cache(ins); } diff --git a/drivers/misc/sgi-gru/grufault.c b/drivers/misc/sgi-gru/grufault.c index 7466234..d3cacd6 100644 --- a/drivers/misc/sgi-gru/grufault.c +++ b/drivers/misc/sgi-gru/grufault.c @@ -333,6 +333,7 @@ static int gru_try_dropin(struct gru_thread_state *gts, */ if (tfh->status != TFHSTATUS_EXCEPTION) { gru_flush_cache(tfh); + sync_core(); if (tfh->status != TFHSTATUS_EXCEPTION) goto failnoexception; STAT(tfh_stale_on_fault); @@ -599,6 +600,7 @@ int gru_get_exception_detail(unsigned long arg) cbrnum = thread_cbr_number(gts, ucbnum); cbe = get_cbe_by_index(gts->ts_gru, cbrnum); gru_flush_cache(cbe); /* CBE not coherent */ + sync_core(); /* make sure we are have current data */ excdet.opc = cbe->opccpy; excdet.exopc = cbe->exopccpy; excdet.ecause = cbe->ecause; diff --git a/drivers/misc/sgi-gru/gruhandles.c b/drivers/misc/sgi-gru/gruhandles.c index 806419a..f1117a7 100644 --- a/drivers/misc/sgi-gru/gruhandles.c +++ b/drivers/misc/sgi-gru/gruhandles.c @@ -91,9 +91,18 @@ static int wait_instruction_complete(void *h, enum mcs_op opc) int cch_allocate(struct gru_context_configuration_handle *cch) { + int ret; + cch->opc = CCHOP_ALLOCATE; start_instruction(cch); - return wait_instruction_complete(cch, cchop_allocate); + ret = wait_instruction_complete(cch, cchop_allocate); + + /* + * Stop speculation into the GSEG being mapped by the previous ALLOCATE. + * The GSEG memory does not exist until the ALLOCATE completes. + */ + sync_core(); + return ret; } int cch_start(struct gru_context_configuration_handle *cch) @@ -112,9 +121,18 @@ int cch_interrupt(struct gru_context_configuration_handle *cch) int cch_deallocate(struct gru_context_configuration_handle *cch) { + int ret; + cch->opc = CCHOP_DEALLOCATE; start_instruction(cch); - return wait_instruction_complete(cch, cchop_deallocate); + ret = wait_instruction_complete(cch, cchop_deallocate); + + /* + * Stop speculation into the GSEG being unmapped by the previous + * DEALLOCATE. + */ + sync_core(); + return ret; } int cch_interrupt_sync(struct gru_context_configuration_handle diff --git a/drivers/misc/sgi-gru/grukservices.c b/drivers/misc/sgi-gru/grukservices.c index 24ec109..8c81aca 100644 --- a/drivers/misc/sgi-gru/grukservices.c +++ b/drivers/misc/sgi-gru/grukservices.c @@ -395,6 +395,7 @@ int gru_get_cb_exception_detail(void *cb, cbrnum = thread_cbr_number(bs->bs_kgts, get_cb_number(cb)); cbe = get_cbe(GRUBASE(cb), cbrnum); gru_flush_cache(cbe); /* CBE not coherent */ + sync_core(); excdet->opc = cbe->opccpy; excdet->exopc = cbe->exopccpy; excdet->ecause = cbe->ecause; @@ -461,9 +462,10 @@ int gru_check_status_proc(void *cb) int ret; ret = gen->istatus; - if (ret != CBS_EXCEPTION) - return ret; - return gru_retry_exception(cb); + if (ret == CBS_EXCEPTION) + ret = gru_retry_exception(cb); + rmb(); + return ret; } @@ -475,7 +477,7 @@ int gru_wait_proc(void *cb) ret = gru_wait_idle_or_exception(gen); if (ret == CBS_EXCEPTION) ret = gru_retry_exception(cb); - + rmb(); return ret; } diff --git a/drivers/misc/sgi-gru/grumain.c b/drivers/misc/sgi-gru/grumain.c index 9440288..a383271 100644 --- a/drivers/misc/sgi-gru/grumain.c +++ b/drivers/misc/sgi-gru/grumain.c @@ -499,6 +499,9 @@ static void gru_load_context_data(void *save, void *grubase, int ctxnum, memset(cbe + i * GRU_HANDLE_STRIDE, 0, GRU_CACHE_LINE_BYTES); } + /* Flush CBE to hide race in context restart */ + mb(); + gru_flush_cache(cbe + i * GRU_HANDLE_STRIDE); cb += GRU_HANDLE_STRIDE; } @@ -519,6 +522,12 @@ static void gru_unload_context_data(void *save, void *grubase, int ctxnum, cb = gseg + GRU_CB_BASE; cbe = grubase + GRU_CBE_BASE; length = hweight64(dsrmap) * GRU_DSR_AU_BYTES; + + /* CBEs may not be coherent. Flush them from cache */ + for_each_cbr_in_allocation_map(i, &cbrmap, scr) + gru_flush_cache(cbe + i * GRU_HANDLE_STRIDE); + mb(); /* Let the CL flush complete */ + gru_prefetch_context(gseg, cb, cbe, cbrmap, length); for_each_cbr_in_allocation_map(i, &cbrmap, scr) { -- 2.7.4