diff options
Diffstat (limited to 'tools')
17 files changed, 78 insertions, 37 deletions
diff --git a/tools/memory-model/Documentation/explanation.txt b/tools/memory-model/Documentation/explanation.txt index 1b09f3175a1f..0cbd1ef8f86d 100644 --- a/tools/memory-model/Documentation/explanation.txt +++ b/tools/memory-model/Documentation/explanation.txt @@ -804,7 +804,7 @@ type of fence: Second, some types of fence affect the way the memory subsystem propagates stores. When a fence instruction is executed on CPU C: - For each other CPU C', smb_wmb() forces all po-earlier stores + For each other CPU C', smp_wmb() forces all po-earlier stores on C to propagate to C' before any po-later stores do. For each other CPU C', any store which propagates to C before diff --git a/tools/memory-model/Documentation/recipes.txt b/tools/memory-model/Documentation/recipes.txt index ee4309a87fc4..af72700cc20a 100644 --- a/tools/memory-model/Documentation/recipes.txt +++ b/tools/memory-model/Documentation/recipes.txt @@ -126,7 +126,7 @@ However, it is not necessarily the case that accesses ordered by locking will be seen as ordered by CPUs not holding that lock. Consider this example: - /* See Z6.0+pooncelock+pooncelock+pombonce.litmus. */ + /* See Z6.0+pooncerelease+poacquirerelease+fencembonceonce.litmus. */ void CPU0(void) { spin_lock(&mylock); @@ -292,7 +292,7 @@ and to use smp_load_acquire() instead of smp_rmb(). However, the older smp_wmb() and smp_rmb() APIs are still heavily used, so it is important to understand their use cases. The general approach is shown below: - /* See MP+wmbonceonce+rmbonceonce.litmus. */ + /* See MP+fencewmbonceonce+fencermbonceonce.litmus. */ void CPU0(void) { WRITE_ONCE(x, 1); @@ -322,9 +322,9 @@ the following write-side code fragment: And the xlog_valid_lsn() function in fs/xfs/xfs_log_priv.h contains the corresponding read-side code fragment: - cur_cycle = ACCESS_ONCE(log->l_curr_cycle); + cur_cycle = READ_ONCE(log->l_curr_cycle); smp_rmb(); - cur_block = ACCESS_ONCE(log->l_curr_block); + cur_block = READ_ONCE(log->l_curr_block); Alternatively, consider the following comment in function perf_output_put_handle() in kernel/events/ring_buffer.c: @@ -360,7 +360,7 @@ can be seen in the LB+poonceonces.litmus litmus test. One way of avoiding the counter-intuitive outcome is through the use of a control dependency paired with a full memory barrier: - /* See LB+ctrlonceonce+mbonceonce.litmus. */ + /* See LB+fencembonceonce+ctrlonceonce.litmus. */ void CPU0(void) { r0 = READ_ONCE(x); @@ -476,7 +476,7 @@ that one CPU first stores to one variable and then loads from a second, while another CPU stores to the second variable and then loads from the first. Preserving order requires nothing less than full barriers: - /* See SB+mbonceonces.litmus. */ + /* See SB+fencembonceonces.litmus. */ void CPU0(void) { WRITE_ONCE(x, 1); diff --git a/tools/memory-model/README b/tools/memory-model/README index 734f7feaa5dc..ee987ce20aae 100644 --- a/tools/memory-model/README +++ b/tools/memory-model/README @@ -35,13 +35,13 @@ BASIC USAGE: HERD7 The memory model is used, in conjunction with "herd7", to exhaustively explore the state space of small litmus tests. -For example, to run SB+mbonceonces.litmus against the memory model: +For example, to run SB+fencembonceonces.litmus against the memory model: - $ herd7 -conf linux-kernel.cfg litmus-tests/SB+mbonceonces.litmus + $ herd7 -conf linux-kernel.cfg litmus-tests/SB+fencembonceonces.litmus Here is the corresponding output: - Test SB+mbonceonces Allowed + Test SB+fencembonceonces Allowed States 3 0:r0=0; 1:r0=1; 0:r0=1; 1:r0=0; @@ -50,8 +50,8 @@ Here is the corresponding output: Witnesses Positive: 0 Negative: 3 Condition exists (0:r0=0 /\ 1:r0=0) - Observation SB+mbonceonces Never 0 3 - Time SB+mbonceonces 0.01 + Observation SB+fencembonceonces Never 0 3 + Time SB+fencembonceonces 0.01 Hash=d66d99523e2cac6b06e66f4c995ebb48 The "Positive: 0 Negative: 3" and the "Never 0 3" each indicate that @@ -67,16 +67,16 @@ BASIC USAGE: KLITMUS7 The "klitmus7" tool converts a litmus test into a Linux kernel module, which may then be loaded and run. -For example, to run SB+mbonceonces.litmus against hardware: +For example, to run SB+fencembonceonces.litmus against hardware: $ mkdir mymodules - $ klitmus7 -o mymodules litmus-tests/SB+mbonceonces.litmus + $ klitmus7 -o mymodules litmus-tests/SB+fencembonceonces.litmus $ cd mymodules ; make $ sudo sh run.sh The corresponding output includes: - Test SB+mbonceonces Allowed + Test SB+fencembonceonces Allowed Histogram (3 states) 644580 :>0:r0=1; 1:r0=0; 644328 :>0:r0=0; 1:r0=1; @@ -86,8 +86,8 @@ The corresponding output includes: Positive: 0, Negative: 2000000 Condition exists (0:r0=0 /\ 1:r0=0) is NOT validated Hash=d66d99523e2cac6b06e66f4c995ebb48 - Observation SB+mbonceonces Never 0 2000000 - Time SB+mbonceonces 0.16 + Observation SB+fencembonceonces Never 0 2000000 + Time SB+fencembonceonces 0.16 The "Positive: 0 Negative: 2000000" and the "Never 0 2000000" indicate that during two million trials, the state specified in this litmus diff --git a/tools/memory-model/linux-kernel.bell b/tools/memory-model/linux-kernel.bell index 64f5740e0e75..b84fb2f67109 100644 --- a/tools/memory-model/linux-kernel.bell +++ b/tools/memory-model/linux-kernel.bell @@ -13,7 +13,7 @@ "Linux-kernel memory consistency model" -enum Accesses = 'once (*READ_ONCE,WRITE_ONCE,ACCESS_ONCE*) || +enum Accesses = 'once (*READ_ONCE,WRITE_ONCE*) || 'release (*smp_store_release*) || 'acquire (*smp_load_acquire*) || 'noreturn (* R of non-return RMW *) diff --git a/tools/memory-model/litmus-tests/IRIW+mbonceonces+OnceOnce.litmus b/tools/memory-model/litmus-tests/IRIW+fencembonceonces+OnceOnce.litmus index 98a3716efa37..e729d2776e89 100644 --- a/tools/memory-model/litmus-tests/IRIW+mbonceonces+OnceOnce.litmus +++ b/tools/memory-model/litmus-tests/IRIW+fencembonceonces+OnceOnce.litmus @@ -1,4 +1,4 @@ -C IRIW+mbonceonces+OnceOnce +C IRIW+fencembonceonces+OnceOnce (* * Result: Never diff --git a/tools/memory-model/litmus-tests/ISA2+pooncelock+pooncelock+pombonce.litmus b/tools/memory-model/litmus-tests/ISA2+pooncelock+pooncelock+pombonce.litmus index 7a39a0aaa976..0f749e419b34 100644 --- a/tools/memory-model/litmus-tests/ISA2+pooncelock+pooncelock+pombonce.litmus +++ b/tools/memory-model/litmus-tests/ISA2+pooncelock+pooncelock+pombonce.litmus @@ -1,4 +1,4 @@ -C ISA2+pooncelock+pooncelock+pombonce.litmus +C ISA2+pooncelock+pooncelock+pombonce (* * Result: Sometimes diff --git a/tools/memory-model/litmus-tests/LB+ctrlonceonce+mbonceonce.litmus b/tools/memory-model/litmus-tests/LB+fencembonceonce+ctrlonceonce.litmus index de6708229dd1..4727f5aaf03b 100644 --- a/tools/memory-model/litmus-tests/LB+ctrlonceonce+mbonceonce.litmus +++ b/tools/memory-model/litmus-tests/LB+fencembonceonce+ctrlonceonce.litmus @@ -1,4 +1,4 @@ -C LB+ctrlonceonce+mbonceonce +C LB+fencembonceonce+ctrlonceonce (* * Result: Never diff --git a/tools/memory-model/litmus-tests/MP+wmbonceonce+rmbonceonce.litmus b/tools/memory-model/litmus-tests/MP+fencewmbonceonce+fencermbonceonce.litmus index c078f38ff27a..a273da9faa6d 100644 --- a/tools/memory-model/litmus-tests/MP+wmbonceonce+rmbonceonce.litmus +++ b/tools/memory-model/litmus-tests/MP+fencewmbonceonce+fencermbonceonce.litmus @@ -1,4 +1,4 @@ -C MP+wmbonceonce+rmbonceonce +C MP+fencewmbonceonce+fencermbonceonce (* * Result: Never diff --git a/tools/memory-model/litmus-tests/R+mbonceonces.litmus b/tools/memory-model/litmus-tests/R+fencembonceonces.litmus index a0e884ad2132..222a0b850b4a 100644 --- a/tools/memory-model/litmus-tests/R+mbonceonces.litmus +++ b/tools/memory-model/litmus-tests/R+fencembonceonces.litmus @@ -1,4 +1,4 @@ -C R+mbonceonces +C R+fencembonceonces (* * Result: Never diff --git a/tools/memory-model/litmus-tests/README b/tools/memory-model/litmus-tests/README index 17eb9a8c222d..4581ec2d3c57 100644 --- a/tools/memory-model/litmus-tests/README +++ b/tools/memory-model/litmus-tests/README @@ -18,7 +18,7 @@ CoWW+poonceonce.litmus Test of write-write coherence, that is, whether or not two successive writes to the same variable are ordered. -IRIW+mbonceonces+OnceOnce.litmus +IRIW+fencembonceonces+OnceOnce.litmus Test of independent reads from independent writes with smp_mb() between each pairs of reads. In other words, is smp_mb() sufficient to cause two different reading processes to agree on @@ -47,7 +47,7 @@ ISA2+pooncerelease+poacquirerelease+poacquireonce.litmus Can a release-acquire chain order a prior store against a later load? -LB+ctrlonceonce+mbonceonce.litmus +LB+fencembonceonce+ctrlonceonce.litmus Does a control dependency and an smp_mb() suffice for the load-buffering litmus test, where each process reads from one of two variables then writes to the other? @@ -88,14 +88,14 @@ MP+porevlocks.litmus As below, but with the first access of the writer process and the second access of reader process protected by a lock. -MP+wmbonceonce+rmbonceonce.litmus +MP+fencewmbonceonce+fencermbonceonce.litmus Does a smp_wmb() (between the stores) and an smp_rmb() (between the loads) suffice for the message-passing litmus test, where one process writes data and then a flag, and the other process reads the flag and then the data. (This is similar to the ISA2 tests, but with two processes instead of three.) -R+mbonceonces.litmus +R+fencembonceonces.litmus This is the fully ordered (via smp_mb()) version of one of the classic counterintuitive litmus tests that illustrates the effects of store propagation delays. @@ -103,7 +103,7 @@ R+mbonceonces.litmus R+poonceonces.litmus As above, but without the smp_mb() invocations. -SB+mbonceonces.litmus +SB+fencembonceonces.litmus This is the fully ordered (again, via smp_mb() version of store buffering, which forms the core of Dekker's mutual-exclusion algorithm. @@ -111,15 +111,24 @@ SB+mbonceonces.litmus SB+poonceonces.litmus As above, but without the smp_mb() invocations. +SB+rfionceonce-poonceonces.litmus + This litmus test demonstrates that LKMM is not fully multicopy + atomic. (Neither is it other multicopy atomic.) This litmus test + also demonstrates the "locations" debugging aid, which designates + additional registers and locations to be printed out in the dump + of final states in the herd7 output. Without the "locations" + statement, only those registers and locations mentioned in the + "exists" clause will be printed. + S+poonceonces.litmus As below, but without the smp_wmb() and acquire load. -S+wmbonceonce+poacquireonce.litmus +S+fencewmbonceonce+poacquireonce.litmus Can a smp_wmb(), instead of a release, and an acquire order a prior store against a subsequent store? WRC+poonceonces+Once.litmus -WRC+pooncerelease+rmbonceonce+Once.litmus +WRC+pooncerelease+fencermbonceonce+Once.litmus These two are members of an extension of the MP litmus-test class in which the first write is moved to a separate process. The second is forbidden because smp_store_release() is @@ -134,7 +143,7 @@ Z6.0+pooncelock+poonceLock+pombonce.litmus As above, but with smp_mb__after_spinlock() immediately following the spin_lock(). -Z6.0+pooncerelease+poacquirerelease+mbonceonce.litmus +Z6.0+pooncerelease+poacquirerelease+fencembonceonce.litmus Is the ordering provided by a release-acquire chain sufficient to make ordering apparent to accesses by a process that does not participate in that release-acquire chain? diff --git a/tools/memory-model/litmus-tests/S+wmbonceonce+poacquireonce.litmus b/tools/memory-model/litmus-tests/S+fencewmbonceonce+poacquireonce.litmus index c53350205d28..18479823cd6c 100644 --- a/tools/memory-model/litmus-tests/S+wmbonceonce+poacquireonce.litmus +++ b/tools/memory-model/litmus-tests/S+fencewmbonceonce+poacquireonce.litmus @@ -1,4 +1,4 @@ -C S+wmbonceonce+poacquireonce +C S+fencewmbonceonce+poacquireonce (* * Result: Never diff --git a/tools/memory-model/litmus-tests/SB+mbonceonces.litmus b/tools/memory-model/litmus-tests/SB+fencembonceonces.litmus index 74b874ffa8da..ed5fff18d223 100644 --- a/tools/memory-model/litmus-tests/SB+mbonceonces.litmus +++ b/tools/memory-model/litmus-tests/SB+fencembonceonces.litmus @@ -1,4 +1,4 @@ -C SB+mbonceonces +C SB+fencembonceonces (* * Result: Never diff --git a/tools/memory-model/litmus-tests/SB+rfionceonce-poonceonces.litmus b/tools/memory-model/litmus-tests/SB+rfionceonce-poonceonces.litmus new file mode 100644 index 000000000000..04a16603660b --- /dev/null +++ b/tools/memory-model/litmus-tests/SB+rfionceonce-poonceonces.litmus @@ -0,0 +1,32 @@ +C SB+rfionceonce-poonceonces + +(* + * Result: Sometimes + * + * This litmus test demonstrates that LKMM is not fully multicopy atomic. + *) + +{} + +P0(int *x, int *y) +{ + int r1; + int r2; + + WRITE_ONCE(*x, 1); + r1 = READ_ONCE(*x); + r2 = READ_ONCE(*y); +} + +P1(int *x, int *y) +{ + int r3; + int r4; + + WRITE_ONCE(*y, 1); + r3 = READ_ONCE(*y); + r4 = READ_ONCE(*x); +} + +locations [0:r1; 1:r3; x; y] (* Debug aid: Print things not in "exists". *) +exists (0:r2=0 /\ 1:r4=0) diff --git a/tools/memory-model/litmus-tests/WRC+pooncerelease+rmbonceonce+Once.litmus b/tools/memory-model/litmus-tests/WRC+pooncerelease+fencermbonceonce+Once.litmus index ad3448b941e6..e9947250d7de 100644 --- a/tools/memory-model/litmus-tests/WRC+pooncerelease+rmbonceonce+Once.litmus +++ b/tools/memory-model/litmus-tests/WRC+pooncerelease+fencermbonceonce+Once.litmus @@ -1,4 +1,4 @@ -C WRC+pooncerelease+rmbonceonce+Once +C WRC+pooncerelease+fencermbonceonce+Once (* * Result: Never diff --git a/tools/memory-model/litmus-tests/Z6.0+pooncerelease+poacquirerelease+mbonceonce.litmus b/tools/memory-model/litmus-tests/Z6.0+pooncerelease+poacquirerelease+fencembonceonce.litmus index a20fc3fafb53..88e70b87a683 100644 --- a/tools/memory-model/litmus-tests/Z6.0+pooncerelease+poacquirerelease+mbonceonce.litmus +++ b/tools/memory-model/litmus-tests/Z6.0+pooncerelease+poacquirerelease+fencembonceonce.litmus @@ -1,4 +1,4 @@ -C Z6.0+pooncerelease+poacquirerelease+mbonceonce +C Z6.0+pooncerelease+poacquirerelease+fencembonceonce (* * Result: Sometimes diff --git a/tools/memory-model/scripts/checkalllitmus.sh b/tools/memory-model/scripts/checkalllitmus.sh index af0aa15ab84e..ca528f9a24d4 100644..100755 --- a/tools/memory-model/scripts/checkalllitmus.sh +++ b/tools/memory-model/scripts/checkalllitmus.sh @@ -9,7 +9,7 @@ # appended. # # Usage: -# sh checkalllitmus.sh [ directory ] +# checkalllitmus.sh [ directory ] # # The LINUX_HERD_OPTIONS environment variable may be used to specify # arguments to herd, whose default is defined by the checklitmus.sh script. diff --git a/tools/memory-model/scripts/checklitmus.sh b/tools/memory-model/scripts/checklitmus.sh index e2e477472844..bf12a75c0719 100644..100755 --- a/tools/memory-model/scripts/checklitmus.sh +++ b/tools/memory-model/scripts/checklitmus.sh @@ -8,7 +8,7 @@ # with ".out" appended. # # Usage: -# sh checklitmus.sh file.litmus +# checklitmus.sh file.litmus # # The LINUX_HERD_OPTIONS environment variable may be used to specify # arguments to herd, which default to "-conf linux-kernel.cfg". Thus, |