1 files changed, 150 insertions, 0 deletions

diff --git a/arch/tile/lib/cacheflush.c b/arch/tile/lib/cacheflush.c
index 11b6164c209..9c0ec22009a 100644
--- a/arch/tile/lib/cacheflush.c
+++ b/arch/tile/lib/cacheflush.c
@@ -12,12 +12,162 @@
  *   more details.
  */
 
+#include <linux/export.h>
 #include <asm/page.h>
 #include <asm/cacheflush.h>
 #include <arch/icache.h>
+#include <arch/spr_def.h>
 
 
 void __flush_icache_range(unsigned long start, unsigned long end)
 {
 	invalidate_icache((const void *)start, end - start, PAGE_SIZE);
 }
+
+
+/* Force a load instruction to issue. */
+static inline void force_load(char *p)
+{
+	*(volatile char *)p;
+}
+
+/*
+ * Flush and invalidate a VA range that is homed remotely on a single
+ * core (if "!hfh") or homed via hash-for-home (if "hfh"), waiting
+ * until the memory controller holds the flushed values.
+ */
+void __attribute__((optimize("omit-frame-pointer")))
+finv_buffer_remote(void *buffer, size_t size, int hfh)
+{
+	char *p, *base;
+	size_t step_size, load_count;
+
+	/*
+	 * On TILEPro the striping granularity is a fixed 8KB; on
+	 * TILE-Gx it is configurable, and we rely on the fact that
+	 * the hypervisor always configures maximum striping, so that
+	 * bits 9 and 10 of the PA are part of the stripe function, so
+	 * every 512 bytes we hit a striping boundary.
+	 *
+	 */
+#ifdef __tilegx__
+	const unsigned long STRIPE_WIDTH = 512;
+#else
+	const unsigned long STRIPE_WIDTH = 8192;
+#endif
+
+#ifdef __tilegx__
+	/*
+	 * On TILE-Gx, we must disable the dstream prefetcher before doing
+	 * a cache flush; otherwise, we could end up with data in the cache
+	 * that we don't want there.  Note that normally we'd do an mf
+	 * after the SPR write to disabling the prefetcher, but we do one
+	 * below, before any further loads, so there's no need to do it
+	 * here.
+	 */
+	uint_reg_t old_dstream_pf = __insn_mfspr(SPR_DSTREAM_PF);
+	__insn_mtspr(SPR_DSTREAM_PF, 0);
+#endif
+
+	/*
+	 * Flush and invalidate the buffer out of the local L1/L2
+	 * and request the home cache to flush and invalidate as well.
+	 */
+	__finv_buffer(buffer, size);
+
+	/*
+	 * Wait for the home cache to acknowledge that it has processed
+	 * all the flush-and-invalidate requests.  This does not mean
+	 * that the flushed data has reached the memory controller yet,
+	 * but it does mean the home cache is processing the flushes.
+	 */
+	__insn_mf();
+
+	/*
+	 * Issue a load to the last cache line, which can't complete
+	 * until all the previously-issued flushes to the same memory
+	 * controller have also completed.  If we weren't striping
+	 * memory, that one load would be sufficient, but since we may
+	 * be, we also need to back up to the last load issued to
+	 * another memory controller, which would be the point where
+	 * we crossed a "striping" boundary (the granularity of striping
+	 * across memory controllers).  Keep backing up and doing this
+	 * until we are before the beginning of the buffer, or have
+	 * hit all the controllers.
+	 *
+	 * If we are flushing a hash-for-home buffer, it's even worse.
+	 * Each line may be homed on a different tile, and each tile
+	 * may have up to four lines that are on different
+	 * controllers.  So as we walk backwards, we have to touch
+	 * enough cache lines to satisfy these constraints.  In
+	 * practice this ends up being close enough to "load from
+	 * every cache line on a full memory stripe on each
+	 * controller" that we simply do that, to simplify the logic.
+	 *
+	 * On TILE-Gx the hash-for-home function is much more complex,
+	 * with the upshot being we can't readily guarantee we have
+	 * hit both entries in the 128-entry AMT that were hit by any
+	 * load in the entire range, so we just re-load them all.
+	 * With larger buffers, we may want to consider using a hypervisor
+	 * trap to issue loads directly to each hash-for-home tile for
+	 * each controller (doing it from Linux would trash the TLB).
+	 */
+	if (hfh) {
+		step_size = L2_CACHE_BYTES;
+#ifdef __tilegx__
+		load_count = (size + L2_CACHE_BYTES - 1) / L2_CACHE_BYTES;
+#else
+		load_count = (STRIPE_WIDTH / L2_CACHE_BYTES) *
+			      (1 << CHIP_LOG_NUM_MSHIMS());
+#endif
+	} else {
+		step_size = STRIPE_WIDTH;
+		load_count = (1 << CHIP_LOG_NUM_MSHIMS());
+	}
+
+	/* Load the last byte of the buffer. */
+	p = (char *)buffer + size - 1;
+	force_load(p);
+
+	/* Bump down to the end of the previous stripe or cache line. */
+	p -= step_size;
+	p = (char *)((unsigned long)p | (step_size - 1));
+
+	/* Figure out how far back we need to go. */
+	base = p - (step_size * (load_count - 2));
+	if ((unsigned long)base < (unsigned long)buffer)
+		base = buffer;
+
+	/*
+	 * Fire all the loads we need.  The MAF only has eight entries
+	 * so we can have at most eight outstanding loads, so we
+	 * unroll by that amount.
+	 */
+#pragma unroll 8
+	for (; p >= base; p -= step_size)
+		force_load(p);
+
+	/*
+	 * Repeat, but with finv's instead of loads, to get rid of the
+	 * data we just loaded into our own cache and the old home L3.
+	 * No need to unroll since finv's don't target a register.
+	 * The finv's are guaranteed not to actually flush the data in
+	 * the buffer back to their home, since we just read it, so the
+	 * lines are clean in cache; we will only invalidate those lines.
+	 */
+	p = (char *)buffer + size - 1;
+	__insn_finv(p);
+	p -= step_size;
+	p = (char *)((unsigned long)p | (step_size - 1));
+	for (; p >= base; p -= step_size)
+		__insn_finv(p);
+
+	/* Wait for these finv's (and thus the first finvs) to be done. */
+	__insn_mf();
+
+#ifdef __tilegx__
+	/* Reenable the prefetcher. */
+	__insn_mtspr(SPR_DSTREAM_PF, old_dstream_pf);
+#endif
+}
+EXPORT_SYMBOL_GPL(finv_buffer_remote);