Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Ingo Molnar:
 "The main changes in this cycle are:

   - rwsem scalability improvements, phase #2, by Waiman Long, which are
     rather impressive:

       "On a 2-socket 40-core 80-thread Skylake system with 40 reader
        and writer locking threads, the min/mean/max locking operations
        done in a 5-second testing window before the patchset were:

         40 readers, Iterations Min/Mean/Max = 1,807/1,808/1,810
         40 writers, Iterations Min/Mean/Max = 1,807/50,344/151,255

        After the patchset, they became:

         40 readers, Iterations Min/Mean/Max = 30,057/31,359/32,741
         40 writers, Iterations Min/Mean/Max = 94,466/95,845/97,098"

     There's a lot of changes to the locking implementation that makes
     it similar to qrwlock, including owner handoff for more fair
     locking.

     Another microbenchmark shows how across the spectrum the
     improvements are:

       "With a locking microbenchmark running on 5.1 based kernel, the
        total locking rates (in kops/s) on a 2-socket Skylake system
        with equal numbers of readers and writers (mixed) before and
        after this patchset were:

        # of Threads   Before Patch      After Patch
        ------------   ------------      -----------
             2            2,618             4,193
             4            1,202             3,726
             8              802             3,622
            16              729             3,359
            32              319             2,826
            64              102             2,744"

     The changes are extensive and the patch-set has been through
     several iterations addressing various locking workloads. There
     might be more regressions, but unless they are pathological I
     believe we want to use this new implementation as the baseline
     going forward.

   - jump-label optimizations by Daniel Bristot de Oliveira: the primary
     motivation was to remove IPI disturbance of isolated RT-workload
     CPUs, which resulted in the implementation of batched jump-label
     updates. Beyond the improvement of the real-time characteristics
     kernel, in one test this patchset improved static key update
     overhead from 57 msecs to just 1.4 msecs - which is a nice speedup
     as well.

   - atomic64_t cross-arch type cleanups by Mark Rutland: over the last
     ~10 years of atomic64_t existence the various types used by the
     APIs only had to be self-consistent within each architecture -
     which means they became wildly inconsistent across architectures.
     Mark puts and end to this by reworking all the atomic64
     implementations to use 's64' as the base type for atomic64_t, and
     to ensure that this type is consistently used for parameters and
     return values in the API, avoiding further problems in this area.

   - A large set of small improvements to lockdep by Yuyang Du: type
     cleanups, output cleanups, function return type and othr cleanups
     all around the place.

   - A set of percpu ops cleanups and fixes by Peter Zijlstra.

   - Misc other changes - please see the Git log for more details"

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (82 commits)
  locking/lockdep: increase size of counters for lockdep statistics
  locking/atomics: Use sed(1) instead of non-standard head(1) option
  locking/lockdep: Move mark_lock() inside CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE_LOCKING
  x86/jump_label: Make tp_vec_nr static
  x86/percpu: Optimize raw_cpu_xchg()
  x86/percpu, sched/fair: Avoid local_clock()
  x86/percpu, x86/irq: Relax {set,get}_irq_regs()
  x86/percpu: Relax smp_processor_id()
  x86/percpu: Differentiate this_cpu_{}() and __this_cpu_{}()
  locking/rwsem: Guard against making count negative
  locking/rwsem: Adaptive disabling of reader optimistic spinning
  locking/rwsem: Enable time-based spinning on reader-owned rwsem
  locking/rwsem: Make rwsem->owner an atomic_long_t
  locking/rwsem: Enable readers spinning on writer
  locking/rwsem: Clarify usage of owner's nonspinaable bit
  locking/rwsem: Wake up almost all readers in wait queue
  locking/rwsem: More optimal RT task handling of null owner
  locking/rwsem: Always release wait_lock before waking up tasks
  locking/rwsem: Implement lock handoff to prevent lock starvation
  locking/rwsem: Make rwsem_spin_on_owner() return owner state
  ...

1 files changed, 120 insertions, 34 deletions

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 390596b761e3..bd542f9b0953 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -14,6 +14,7 @@
 #include <linux/kdebug.h>
 #include <linux/kprobes.h>
 #include <linux/mmu_context.h>
+#include <linux/bsearch.h>
 #include <asm/text-patching.h>
 #include <asm/alternative.h>
 #include <asm/sections.h>
@@ -848,81 +849,133 @@ static void do_sync_core(void *info)
 	sync_core();
 }
 
-static bool bp_patching_in_progress;
-static void *bp_int3_handler, *bp_int3_addr;
+static struct bp_patching_desc {
+	struct text_poke_loc *vec;
+	int nr_entries;
+} bp_patching;
+
+static int patch_cmp(const void *key, const void *elt)
+{
+	struct text_poke_loc *tp = (struct text_poke_loc *) elt;
+
+	if (key < tp->addr)
+		return -1;
+	if (key > tp->addr)
+		return 1;
+	return 0;
+}
+NOKPROBE_SYMBOL(patch_cmp);
 
 int poke_int3_handler(struct pt_regs *regs)
 {
+	struct text_poke_loc *tp;
+	unsigned char int3 = 0xcc;
+	void *ip;
+
 	/*
 	 * Having observed our INT3 instruction, we now must observe
-	 * bp_patching_in_progress.
+	 * bp_patching.nr_entries.
 	 *
-	 * 	in_progress = TRUE		INT3
+	 * 	nr_entries != 0			INT3
 	 * 	WMB				RMB
-	 * 	write INT3			if (in_progress)
+	 * 	write INT3			if (nr_entries)
 	 *
-	 * Idem for bp_int3_handler.
+	 * Idem for other elements in bp_patching.
 	 */
 	smp_rmb();
 
-	if (likely(!bp_patching_in_progress))
+	if (likely(!bp_patching.nr_entries))
 		return 0;
 
-	if (user_mode(regs) || regs->ip != (unsigned long)bp_int3_addr)
+	if (user_mode(regs))
 		return 0;
 
-	/* set up the specified breakpoint handler */
-	regs->ip = (unsigned long) bp_int3_handler;
+	/*
+	 * Discount the sizeof(int3). See text_poke_bp_batch().
+	 */
+	ip = (void *) regs->ip - sizeof(int3);
+
+	/*
+	 * Skip the binary search if there is a single member in the vector.
+	 */
+	if (unlikely(bp_patching.nr_entries > 1)) {
+		tp = bsearch(ip, bp_patching.vec, bp_patching.nr_entries,
+			     sizeof(struct text_poke_loc),
+			     patch_cmp);
+		if (!tp)
+			return 0;
+	} else {
+		tp = bp_patching.vec;
+		if (tp->addr != ip)
+			return 0;
+	}
+
+	/* set up the specified breakpoint detour */
+	regs->ip = (unsigned long) tp->detour;
 
 	return 1;
 }
 NOKPROBE_SYMBOL(poke_int3_handler);
 
 /**
- * text_poke_bp() -- update instructions on live kernel on SMP
- * @addr:	address to patch
- * @opcode:	opcode of new instruction
- * @len:	length to copy
- * @handler:	address to jump to when the temporary breakpoint is hit
+ * text_poke_bp_batch() -- update instructions on live kernel on SMP
+ * @tp:			vector of instructions to patch
+ * @nr_entries:		number of entries in the vector
  *
  * Modify multi-byte instruction by using int3 breakpoint on SMP.
  * We completely avoid stop_machine() here, and achieve the
  * synchronization using int3 breakpoint.
  *
  * The way it is done:
- *	- add a int3 trap to the address that will be patched
+ * 	- For each entry in the vector:
+ *		- add a int3 trap to the address that will be patched
  *	- sync cores
- *	- update all but the first byte of the patched range
+ *	- For each entry in the vector:
+ *		- update all but the first byte of the patched range
  *	- sync cores
- *	- replace the first byte (int3) by the first byte of
- *	  replacing opcode
+ *	- For each entry in the vector:
+ *		- replace the first byte (int3) by the first byte of
+ *		  replacing opcode
  *	- sync cores
  */
-void text_poke_bp(void *addr, const void *opcode, size_t len, void *handler)
+void text_poke_bp_batch(struct text_poke_loc *tp, unsigned int nr_entries)
 {
+	int patched_all_but_first = 0;
 	unsigned char int3 = 0xcc;
-
-	bp_int3_handler = handler;
-	bp_int3_addr = (u8 *)addr + sizeof(int3);
-	bp_patching_in_progress = true;
+	unsigned int i;
 
 	lockdep_assert_held(&text_mutex);
 
+	bp_patching.vec = tp;
+	bp_patching.nr_entries = nr_entries;
+
 	/*
 	 * Corresponding read barrier in int3 notifier for making sure the
-	 * in_progress and handler are correctly ordered wrt. patching.
+	 * nr_entries and handler are correctly ordered wrt. patching.
 	 */
 	smp_wmb();
 
-	text_poke(addr, &int3, sizeof(int3));
+	/*
+	 * First step: add a int3 trap to the address that will be patched.
+	 */
+	for (i = 0; i < nr_entries; i++)
+		text_poke(tp[i].addr, &int3, sizeof(int3));
 
 	on_each_cpu(do_sync_core, NULL, 1);
 
-	if (len - sizeof(int3) > 0) {
-		/* patch all but the first byte */
-		text_poke((char *)addr + sizeof(int3),
-			  (const char *) opcode + sizeof(int3),
-			  len - sizeof(int3));
+	/*
+	 * Second step: update all but the first byte of the patched range.
+	 */
+	for (i = 0; i < nr_entries; i++) {
+		if (tp[i].len - sizeof(int3) > 0) {
+			text_poke((char *)tp[i].addr + sizeof(int3),
+				  (const char *)tp[i].opcode + sizeof(int3),
+				  tp[i].len - sizeof(int3));
+			patched_all_but_first++;
+		}
+	}
+
+	if (patched_all_but_first) {
 		/*
 		 * According to Intel, this core syncing is very likely
 		 * not necessary and we'd be safe even without it. But
@@ -931,14 +984,47 @@ void text_poke_bp(void *addr, const void *opcode, size_t len, void *handler)
 		on_each_cpu(do_sync_core, NULL, 1);
 	}
 
-	/* patch the first byte */
-	text_poke(addr, opcode, sizeof(int3));
+	/*
+	 * Third step: replace the first byte (int3) by the first byte of
+	 * replacing opcode.
+	 */
+	for (i = 0; i < nr_entries; i++)
+		text_poke(tp[i].addr, tp[i].opcode, sizeof(int3));
 
 	on_each_cpu(do_sync_core, NULL, 1);
 	/*
 	 * sync_core() implies an smp_mb() and orders this store against
 	 * the writing of the new instruction.
 	 */
-	bp_patching_in_progress = false;
+	bp_patching.vec = NULL;
+	bp_patching.nr_entries = 0;
 }
 
+/**
+ * text_poke_bp() -- update instructions on live kernel on SMP
+ * @addr:	address to patch
+ * @opcode:	opcode of new instruction
+ * @len:	length to copy
+ * @handler:	address to jump to when the temporary breakpoint is hit
+ *
+ * Update a single instruction with the vector in the stack, avoiding
+ * dynamically allocated memory. This function should be used when it is
+ * not possible to allocate memory.
+ */
+void text_poke_bp(void *addr, const void *opcode, size_t len, void *handler)
+{
+	struct text_poke_loc tp = {
+		.detour = handler,
+		.addr = addr,
+		.len = len,
+	};
+
+	if (len > POKE_MAX_OPCODE_SIZE) {
+		WARN_ONCE(1, "len is larger than %d\n", POKE_MAX_OPCODE_SIZE);
+		return;
+	}
+
+	memcpy((void *)tp.opcode, opcode, len);
+
+	text_poke_bp_batch(&tp, 1);
+}