/* * mem.spin: Promela code to validate memory barriers with OOO memory. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. * * Copyright (c) 2009 Mathieu Desnoyers */ /* Promela validation variables. */ /* specific defines "included" here */ /* DEFINES file "included" here */ #define NR_READERS 1 #define NR_WRITERS 1 #define NR_PROCS 2 #define get_pid() (_pid) #define get_readerid() (get_pid()) /* * Produced process control and data flow. Updated after each instruction to * show which variables are ready. Using one-hot bit encoding per variable to * save state space. Used as triggers to execute the instructions having those * variables as input. Leaving bits active to inhibit instruction execution. * Scheme used to make instruction disabling and automatic dependency fall-back * automatic. */ #define CONSUME_TOKENS(state, bits, notbits) \ ((!(state & (notbits))) && (state & (bits)) == (bits)) #define PRODUCE_TOKENS(state, bits) \ state = state | (bits); #define CLEAR_TOKENS(state, bits) \ state = state & ~(bits) /* * Types of dependency : * * Data dependency * * - True dependency, Read-after-Write (RAW) * * This type of dependency happens when a statement depends on the result of a * previous statement. This applies to any statement which needs to read a * variable written by a preceding statement. * * - False dependency, Write-after-Read (WAR) * * Typically, variable renaming can ensure that this dependency goes away. * However, if the statements must read and then write from/to the same variable * in the OOO memory model, renaming may be impossible, and therefore this * causes a WAR dependency. * * - Output dependency, Write-after-Write (WAW) * * Two writes to the same variable in subsequent statements. Variable renaming * can ensure this is not needed, but can be required when writing multiple * times to the same OOO mem model variable. * * Control dependency * * Execution of a given instruction depends on a previous instruction evaluating * in a way that allows its execution. E.g. : branches. * * Useful considerations for joining dependencies after branch * * - Pre-dominance * * "We say box i dominates box j if every path (leading from input to output * through the diagram) which passes through box j must also pass through box * i. Thus box i dominates box j if box j is subordinate to box i in the * program." * * http://www.hipersoft.rice.edu/grads/publications/dom14.pdf * Other classic algorithm to calculate dominance : Lengauer-Tarjan (in gcc) * * - Post-dominance * * Just as pre-dominance, but with arcs of the data flow inverted, and input vs * output exchanged. Therefore, i post-dominating j ensures that every path * passing by j will pass by i before reaching the output. * * Other considerations * * Note about "volatile" keyword dependency : The compiler will order volatile * accesses so they appear in the right order on a given CPU. They can be * reordered by the CPU instruction scheduling. This therefore cannot be * considered as a depencency. * * References : * * Cooper, Keith D.; & Torczon, Linda. (2005). Engineering a Compiler. Morgan * Kaufmann. ISBN 1-55860-698-X. * Kennedy, Ken; & Allen, Randy. (2001). Optimizing Compilers for Modern * Architectures: A Dependence-based Approach. Morgan Kaufmann. ISBN * 1-55860-286-0. * Muchnick, Steven S. (1997). Advanced Compiler Design and Implementation. * Morgan Kaufmann. ISBN 1-55860-320-4. */ /* * Note about loops and nested calls * * To keep this model simple, loops expressed in the framework will behave as if * there was a core synchronizing instruction between loops. To see the effect * of loop unrolling, manually unrolling loops is required. Note that if loops * end or start with a core synchronizing instruction, the model is appropriate. * Nested calls are not supported. */ /* * Each process have its own data in cache. Caches are randomly updated. * smp_wmb and smp_rmb forces cache updates (write and read), smp_mb forces * both. */ typedef per_proc_byte { byte val[NR_PROCS]; }; /* Bitfield has a maximum of 8 procs */ typedef per_proc_bit { byte bitfield; }; #define DECLARE_CACHED_VAR(type, x) \ type mem_##x; \ per_proc_##type cached_##x; \ per_proc_bit cache_dirty_##x; #define INIT_CACHED_VAR(x, v, j) \ mem_##x = v; \ cache_dirty_##x.bitfield = 0; \ j = 0; \ do \ :: j < NR_PROCS -> \ cached_##x.val[j] = v; \ j++ \ :: j >= NR_PROCS -> break \ od; #define IS_CACHE_DIRTY(x, id) (cache_dirty_##x.bitfield & (1 << id)) #define READ_CACHED_VAR(x) (cached_##x.val[get_pid()]) #define WRITE_CACHED_VAR(x, v) \ atomic { \ cached_##x.val[get_pid()] = v; \ cache_dirty_##x.bitfield = \ cache_dirty_##x.bitfield | (1 << get_pid()); \ } #define CACHE_WRITE_TO_MEM(x, id) \ if \ :: IS_CACHE_DIRTY(x, id) -> \ mem_##x = cached_##x.val[id]; \ cache_dirty_##x.bitfield = \ cache_dirty_##x.bitfield & (~(1 << id)); \ :: else -> \ skip \ fi; #define CACHE_READ_FROM_MEM(x, id) \ if \ :: !IS_CACHE_DIRTY(x, id) -> \ cached_##x.val[id] = mem_##x;\ :: else -> \ skip \ fi; /* * May update other caches if cache is dirty, or not. */ #define RANDOM_CACHE_WRITE_TO_MEM(x, id)\ if \ :: 1 -> CACHE_WRITE_TO_MEM(x, id); \ :: 1 -> skip \ fi; #define RANDOM_CACHE_READ_FROM_MEM(x, id)\ if \ :: 1 -> CACHE_READ_FROM_MEM(x, id); \ :: 1 -> skip \ fi; /* Must consume all prior read tokens. All subsequent reads depend on it. */ inline smp_rmb(i, j) { atomic { CACHE_READ_FROM_MEM(urcu_gp_ctr, get_pid()); i = 0; do :: i < NR_READERS -> CACHE_READ_FROM_MEM(urcu_active_readers[i], get_pid()); i++ :: i >= NR_READERS -> break od; CACHE_READ_FROM_MEM(generation_ptr, get_pid()); } } /* Must consume all prior write tokens. All subsequent writes depend on it. */ inline smp_wmb(i, j) { atomic { CACHE_WRITE_TO_MEM(urcu_gp_ctr, get_pid()); i = 0; do :: i < NR_READERS -> CACHE_WRITE_TO_MEM(urcu_active_readers[i], get_pid()); i++ :: i >= NR_READERS -> break od; CACHE_WRITE_TO_MEM(generation_ptr, get_pid()); } } /* Synchronization point. Must consume all prior read and write tokens. All * subsequent reads and writes depend on it. */ inline smp_mb(i, j) { atomic { smp_wmb(i, j); smp_rmb(i, j); } } #ifdef REMOTE_BARRIERS bit reader_barrier[NR_READERS]; /* * We cannot leave the barriers dependencies in place in REMOTE_BARRIERS mode * because they would add unexisting core synchronization and would therefore * create an incomplete model. * Therefore, we model the read-side memory barriers by completely disabling the * memory barriers and their dependencies from the read-side. One at a time * (different verification runs), we make a different instruction listen for * signals. */ #define smp_mb_reader(i, j) /* * Service 0, 1 or many barrier requests. */ inline smp_mb_recv(i, j) { do :: (reader_barrier[get_readerid()] == 1) -> smp_mb(i, j); reader_barrier[get_readerid()] = 0; :: 1 -> skip; :: 1 -> break; od; } inline smp_mb_send(i, j) { smp_mb(i, j); i = 0; do :: i < NR_READERS -> reader_barrier[i] = 1; do :: (reader_barrier[i] == 1) -> skip; :: (reader_barrier[i] == 0) -> break; od; i++; :: i >= NR_READERS -> break od; smp_mb(i, j); } #else #define smp_mb_send smp_mb #define smp_mb_reader smp_mb #define smp_mb_recv(i, j) #endif /* Keep in sync manually with smp_rmb, wmp_wmb, ooo_mem and init() */ DECLARE_CACHED_VAR(byte, urcu_gp_ctr); /* Note ! currently only two readers */ DECLARE_CACHED_VAR(byte, urcu_active_readers[NR_READERS]); /* pointer generation */ DECLARE_CACHED_VAR(byte, generation_ptr); byte last_free_gen = 0; bit free_done = 0; byte read_generation[NR_READERS]; bit data_access[NR_READERS]; bit write_lock = 0; bit init_done = 0; bit sighand_exec = 0; inline wait_init_done() { do :: init_done == 0 -> skip; :: else -> break; od; } inline ooo_mem(i) { atomic { RANDOM_CACHE_WRITE_TO_MEM(urcu_gp_ctr, get_pid()); i = 0; do :: i < NR_READERS -> RANDOM_CACHE_WRITE_TO_MEM(urcu_active_readers[i], get_pid()); i++ :: i >= NR_READERS -> break od; RANDOM_CACHE_WRITE_TO_MEM(generation_ptr, get_pid()); RANDOM_CACHE_READ_FROM_MEM(urcu_gp_ctr, get_pid()); i = 0; do :: i < NR_READERS -> RANDOM_CACHE_READ_FROM_MEM(urcu_active_readers[i], get_pid()); i++ :: i >= NR_READERS -> break od; RANDOM_CACHE_READ_FROM_MEM(generation_ptr, get_pid()); } } /* * Bit encoding, urcu_reader : */ int _proc_urcu_reader; #define proc_urcu_reader _proc_urcu_reader /* Body of PROCEDURE_READ_LOCK */ #define READ_PROD_A_READ (1 << 0) #define READ_PROD_B_IF_TRUE (1 << 1) #define READ_PROD_B_IF_FALSE (1 << 2) #define READ_PROD_C_IF_TRUE_READ (1 << 3) #define PROCEDURE_READ_LOCK(base, consumetoken, producetoken) \ :: CONSUME_TOKENS(proc_urcu_reader, consumetoken, READ_PROD_A_READ << base) -> \ ooo_mem(i); \ tmp = READ_CACHED_VAR(urcu_active_readers[get_readerid()]); \ PRODUCE_TOKENS(proc_urcu_reader, READ_PROD_A_READ << base); \ :: CONSUME_TOKENS(proc_urcu_reader, \ READ_PROD_A_READ << base, /* RAW, pre-dominant */ \ (READ_PROD_B_IF_TRUE | READ_PROD_B_IF_FALSE) << base) -> \ if \ :: (!(tmp & RCU_GP_CTR_NEST_MASK)) -> \ PRODUCE_TOKENS(proc_urcu_reader, READ_PROD_B_IF_TRUE << base); \ :: else -> \ PRODUCE_TOKENS(proc_urcu_reader, READ_PROD_B_IF_FALSE << base); \ fi; \ /* IF TRUE */ \ :: CONSUME_TOKENS(proc_urcu_reader, READ_PROD_B_IF_TRUE << base, \ READ_PROD_C_IF_TRUE_READ << base) -> \ ooo_mem(i); \ tmp2 = READ_CACHED_VAR(urcu_gp_ctr); \ PRODUCE_TOKENS(proc_urcu_reader, READ_PROD_C_IF_TRUE_READ << base); \ :: CONSUME_TOKENS(proc_urcu_reader, \ (READ_PROD_C_IF_TRUE_READ /* pre-dominant */ \ | READ_PROD_A_READ) << base, /* WAR */ \ producetoken) -> \ ooo_mem(i); \ WRITE_CACHED_VAR(urcu_active_readers[get_readerid()], tmp2); \ PRODUCE_TOKENS(proc_urcu_reader, producetoken); \ /* IF_MERGE implies \ * post-dominance */ \ /* ELSE */ \ :: CONSUME_TOKENS(proc_urcu_reader, \ (READ_PROD_B_IF_FALSE /* pre-dominant */ \ | READ_PROD_A_READ) << base, /* WAR */ \ producetoken) -> \ ooo_mem(i); \ WRITE_CACHED_VAR(urcu_active_readers[get_readerid()], \ tmp + 1); \ PRODUCE_TOKENS(proc_urcu_reader, producetoken); \ /* IF_MERGE implies \ * post-dominance */ \ /* ENDIF */ \ skip /* Body of PROCEDURE_READ_LOCK */ #define READ_PROC_READ_UNLOCK (1 << 0) #define PROCEDURE_READ_UNLOCK(base, consumetoken, producetoken) \ :: CONSUME_TOKENS(proc_urcu_reader, \ consumetoken, \ READ_PROC_READ_UNLOCK << base) -> \ ooo_mem(i); \ tmp2 = READ_CACHED_VAR(urcu_active_readers[get_readerid()]); \ PRODUCE_TOKENS(proc_urcu_reader, READ_PROC_READ_UNLOCK << base); \ :: CONSUME_TOKENS(proc_urcu_reader, \ consumetoken \ | (READ_PROC_READ_UNLOCK << base), /* WAR */ \ producetoken) -> \ ooo_mem(i); \ WRITE_CACHED_VAR(urcu_active_readers[get_readerid()], tmp2 - 1); \ PRODUCE_TOKENS(proc_urcu_reader, producetoken); \ skip #define READ_PROD_NONE (1 << 0) /* PROCEDURE_READ_LOCK base = << 1 : 1 to 5 */ #define READ_LOCK_BASE 1 #define READ_LOCK_OUT (1 << 5) #define READ_PROC_FIRST_MB (1 << 6) /* PROCEDURE_READ_LOCK (NESTED) base : << 7 : 7 to 11 */ #define READ_LOCK_NESTED_BASE 7 #define READ_LOCK_NESTED_OUT (1 << 11) #define READ_PROC_READ_GEN (1 << 12) /* PROCEDURE_READ_UNLOCK (NESTED) base = << 13 : 13 to 14 */ #define READ_UNLOCK_NESTED_BASE 13 #define READ_UNLOCK_NESTED_OUT (1 << 14) #define READ_PROC_SECOND_MB (1 << 15) /* PROCEDURE_READ_UNLOCK base = << 16 : 16 to 17 */ #define READ_UNLOCK_BASE 16 #define READ_UNLOCK_OUT (1 << 17) /* PROCEDURE_READ_LOCK_UNROLL base = << 18 : 18 to 22 */ #define READ_LOCK_UNROLL_BASE 18 #define READ_LOCK_OUT_UNROLL (1 << 22) #define READ_PROC_THIRD_MB (1 << 23) #define READ_PROC_READ_GEN_UNROLL (1 << 24) #define READ_PROC_FOURTH_MB (1 << 25) /* PROCEDURE_READ_UNLOCK_UNROLL base = << 26 : 26 to 27 */ #define READ_UNLOCK_UNROLL_BASE 26 #define READ_UNLOCK_OUT_UNROLL (1 << 27) /* Should not include branches */ #define READ_PROC_ALL_TOKENS (READ_PROD_NONE \ | READ_LOCK_OUT \ | READ_PROC_FIRST_MB \ | READ_LOCK_NESTED_OUT \ | READ_PROC_READ_GEN \ | READ_UNLOCK_NESTED_OUT \ | READ_PROC_SECOND_MB \ | READ_UNLOCK_OUT \ | READ_LOCK_OUT_UNROLL \ | READ_PROC_THIRD_MB \ | READ_PROC_READ_GEN_UNROLL \ | READ_PROC_FOURTH_MB \ | READ_UNLOCK_OUT_UNROLL) /* Must clear all tokens, including branches */ #define READ_PROC_ALL_TOKENS_CLEAR ((1 << 28) - 1) inline urcu_one_read(i, j, nest_i, tmp, tmp2) { PRODUCE_TOKENS(proc_urcu_reader, READ_PROD_NONE); #ifdef NO_MB PRODUCE_TOKENS(proc_urcu_reader, READ_PROC_FIRST_MB); PRODUCE_TOKENS(proc_urcu_reader, READ_PROC_SECOND_MB); PRODUCE_TOKENS(proc_urcu_reader, READ_PROC_THIRD_MB); PRODUCE_TOKENS(proc_urcu_reader, READ_PROC_FOURTH_MB); #endif #ifdef REMOTE_BARRIERS PRODUCE_TOKENS(proc_urcu_reader, READ_PROC_FIRST_MB); PRODUCE_TOKENS(proc_urcu_reader, READ_PROC_SECOND_MB); PRODUCE_TOKENS(proc_urcu_reader, READ_PROC_THIRD_MB); PRODUCE_TOKENS(proc_urcu_reader, READ_PROC_FOURTH_MB); #endif do :: 1 -> #ifdef REMOTE_BARRIERS /* * Signal-based memory barrier will only execute when the * execution order appears in program order. */ if :: 1 -> atomic { if :: CONSUME_TOKENS(proc_urcu_reader, READ_PROD_NONE, READ_LOCK_OUT | READ_LOCK_NESTED_OUT | READ_PROC_READ_GEN | READ_UNLOCK_NESTED_OUT | READ_UNLOCK_OUT | READ_LOCK_OUT_UNROLL | READ_PROC_READ_GEN_UNROLL | READ_UNLOCK_OUT_UNROLL) || CONSUME_TOKENS(proc_urcu_reader, READ_PROD_NONE | READ_LOCK_OUT, READ_LOCK_NESTED_OUT | READ_PROC_READ_GEN | READ_UNLOCK_NESTED_OUT | READ_UNLOCK_OUT | READ_LOCK_OUT_UNROLL | READ_PROC_READ_GEN_UNROLL | READ_UNLOCK_OUT_UNROLL) || CONSUME_TOKENS(proc_urcu_reader, READ_PROD_NONE | READ_LOCK_OUT | READ_LOCK_NESTED_OUT, READ_PROC_READ_GEN | READ_UNLOCK_NESTED_OUT | READ_UNLOCK_OUT | READ_LOCK_OUT_UNROLL | READ_PROC_READ_GEN_UNROLL | READ_UNLOCK_OUT_UNROLL) || CONSUME_TOKENS(proc_urcu_reader, READ_PROD_NONE | READ_LOCK_OUT | READ_LOCK_NESTED_OUT | READ_PROC_READ_GEN, READ_UNLOCK_NESTED_OUT | READ_UNLOCK_OUT | READ_LOCK_OUT_UNROLL | READ_PROC_READ_GEN_UNROLL | READ_UNLOCK_OUT_UNROLL) || CONSUME_TOKENS(proc_urcu_reader, READ_PROD_NONE | READ_LOCK_OUT | READ_LOCK_NESTED_OUT | READ_PROC_READ_GEN | READ_UNLOCK_NESTED_OUT, READ_UNLOCK_OUT | READ_LOCK_OUT_UNROLL | READ_PROC_READ_GEN_UNROLL | READ_UNLOCK_OUT_UNROLL) || CONSUME_TOKENS(proc_urcu_reader, READ_PROD_NONE | READ_LOCK_OUT | READ_LOCK_NESTED_OUT | READ_PROC_READ_GEN | READ_UNLOCK_NESTED_OUT | READ_UNLOCK_OUT, READ_LOCK_OUT_UNROLL | READ_PROC_READ_GEN_UNROLL | READ_UNLOCK_OUT_UNROLL) || CONSUME_TOKENS(proc_urcu_reader, READ_PROD_NONE | READ_LOCK_OUT | READ_LOCK_NESTED_OUT | READ_PROC_READ_GEN | READ_UNLOCK_NESTED_OUT | READ_UNLOCK_OUT | READ_LOCK_OUT_UNROLL, READ_PROC_READ_GEN_UNROLL | READ_UNLOCK_OUT_UNROLL) || CONSUME_TOKENS(proc_urcu_reader, READ_PROD_NONE | READ_LOCK_OUT | READ_LOCK_NESTED_OUT | READ_PROC_READ_GEN | READ_UNLOCK_NESTED_OUT | READ_UNLOCK_OUT | READ_LOCK_OUT_UNROLL | READ_PROC_READ_GEN_UNROLL, READ_UNLOCK_OUT_UNROLL) || CONSUME_TOKENS(proc_urcu_reader, READ_PROD_NONE | READ_LOCK_OUT | READ_LOCK_NESTED_OUT | READ_PROC_READ_GEN | READ_UNLOCK_NESTED_OUT | READ_UNLOCK_OUT | READ_LOCK_OUT_UNROLL | READ_PROC_READ_GEN_UNROLL | READ_UNLOCK_OUT_UNROLL, 0) -> goto non_atomic3; non_atomic3_end: skip; fi; } :: 1 -> skip; fi; goto non_atomic3_skip; non_atomic3: smp_mb_recv(i, j); goto non_atomic3_end; non_atomic3_skip: #endif /* REMOTE_BARRIERS */ atomic { if PROCEDURE_READ_LOCK(READ_LOCK_BASE, READ_PROD_NONE, READ_LOCK_OUT); :: CONSUME_TOKENS(proc_urcu_reader, READ_LOCK_OUT, /* post-dominant */ READ_PROC_FIRST_MB) -> smp_mb_reader(i, j); PRODUCE_TOKENS(proc_urcu_reader, READ_PROC_FIRST_MB); PROCEDURE_READ_LOCK(READ_LOCK_NESTED_BASE, READ_PROC_FIRST_MB | READ_LOCK_OUT, READ_LOCK_NESTED_OUT); :: CONSUME_TOKENS(proc_urcu_reader, READ_PROC_FIRST_MB, /* mb() orders reads */ READ_PROC_READ_GEN) -> ooo_mem(i); read_generation[get_readerid()] = READ_CACHED_VAR(generation_ptr); goto non_atomic; non_atomic_end: PRODUCE_TOKENS(proc_urcu_reader, READ_PROC_READ_GEN); /* Note : we remove the nested memory barrier from the read unlock * model, given it is not usually needed. The implementation has the barrier * because the performance impact added by a branch in the common case does not * justify it. */ PROCEDURE_READ_UNLOCK(READ_UNLOCK_NESTED_BASE, READ_PROC_FIRST_MB | READ_LOCK_OUT | READ_LOCK_NESTED_OUT, READ_UNLOCK_NESTED_OUT); :: CONSUME_TOKENS(proc_urcu_reader, READ_PROC_READ_GEN /* mb() orders reads */ | READ_PROC_FIRST_MB /* mb() ordered */ | READ_LOCK_OUT /* post-dominant */ | READ_LOCK_NESTED_OUT /* post-dominant */ | READ_UNLOCK_NESTED_OUT, READ_PROC_SECOND_MB) -> smp_mb_reader(i, j); PRODUCE_TOKENS(proc_urcu_reader, READ_PROC_SECOND_MB); PROCEDURE_READ_UNLOCK(READ_UNLOCK_BASE, READ_PROC_SECOND_MB /* mb() orders reads */ | READ_PROC_FIRST_MB /* mb() orders reads */ | READ_LOCK_NESTED_OUT /* RAW */ | READ_LOCK_OUT /* RAW */ | READ_UNLOCK_NESTED_OUT, /* RAW */ READ_UNLOCK_OUT); /* Unrolling loop : second consecutive lock */ /* reading urcu_active_readers, which have been written by * READ_UNLOCK_OUT : RAW */ PROCEDURE_READ_LOCK(READ_LOCK_UNROLL_BASE, READ_UNLOCK_OUT /* RAW */ | READ_PROC_SECOND_MB /* mb() orders reads */ | READ_PROC_FIRST_MB /* mb() orders reads */ | READ_LOCK_NESTED_OUT /* RAW */ | READ_LOCK_OUT /* RAW */ | READ_UNLOCK_NESTED_OUT, /* RAW */ READ_LOCK_OUT_UNROLL); :: CONSUME_TOKENS(proc_urcu_reader, READ_PROC_FIRST_MB /* mb() ordered */ | READ_PROC_SECOND_MB /* mb() ordered */ | READ_LOCK_OUT_UNROLL /* post-dominant */ | READ_LOCK_NESTED_OUT | READ_LOCK_OUT | READ_UNLOCK_NESTED_OUT | READ_UNLOCK_OUT, READ_PROC_THIRD_MB) -> smp_mb_reader(i, j); PRODUCE_TOKENS(proc_urcu_reader, READ_PROC_THIRD_MB); :: CONSUME_TOKENS(proc_urcu_reader, READ_PROC_FIRST_MB /* mb() orders reads */ | READ_PROC_SECOND_MB /* mb() orders reads */ | READ_PROC_THIRD_MB, /* mb() orders reads */ READ_PROC_READ_GEN_UNROLL) -> ooo_mem(i); read_generation[get_readerid()] = READ_CACHED_VAR(generation_ptr); goto non_atomic2; non_atomic2_end: PRODUCE_TOKENS(proc_urcu_reader, READ_PROC_READ_GEN_UNROLL); :: CONSUME_TOKENS(proc_urcu_reader, READ_PROC_READ_GEN_UNROLL /* mb() orders reads */ | READ_PROC_FIRST_MB /* mb() ordered */ | READ_PROC_SECOND_MB /* mb() ordered */ | READ_PROC_THIRD_MB /* mb() ordered */ | READ_LOCK_OUT_UNROLL /* post-dominant */ | READ_LOCK_NESTED_OUT | READ_LOCK_OUT | READ_UNLOCK_NESTED_OUT | READ_UNLOCK_OUT, READ_PROC_FOURTH_MB) -> smp_mb_reader(i, j); PRODUCE_TOKENS(proc_urcu_reader, READ_PROC_FOURTH_MB); PROCEDURE_READ_UNLOCK(READ_UNLOCK_UNROLL_BASE, READ_PROC_FOURTH_MB /* mb() orders reads */ | READ_PROC_THIRD_MB /* mb() orders reads */ | READ_LOCK_OUT_UNROLL /* RAW */ | READ_PROC_SECOND_MB /* mb() orders reads */ | READ_PROC_FIRST_MB /* mb() orders reads */ | READ_LOCK_NESTED_OUT /* RAW */ | READ_LOCK_OUT /* RAW */ | READ_UNLOCK_NESTED_OUT, /* RAW */ READ_UNLOCK_OUT_UNROLL); :: CONSUME_TOKENS(proc_urcu_reader, READ_PROC_ALL_TOKENS, 0) -> CLEAR_TOKENS(proc_urcu_reader, READ_PROC_ALL_TOKENS_CLEAR); break; fi; } od; /* * Dependency between consecutive loops : * RAW dependency on * WRITE_CACHED_VAR(urcu_active_readers[get_readerid()], tmp2 - 1) * tmp = READ_CACHED_VAR(urcu_active_readers[get_readerid()]); * between loops. * _WHEN THE MB()s are in place_, they add full ordering of the * generation pointer read wrt active reader count read, which ensures * execution will not spill across loop execution. * However, in the event mb()s are removed (execution using signal * handler to promote barrier()() -> smp_mb()), nothing prevents one loop * to spill its execution on other loop's execution. */ goto end; non_atomic: data_access[get_readerid()] = 1; data_access[get_readerid()] = 0; goto non_atomic_end; non_atomic2: data_access[get_readerid()] = 1; data_access[get_readerid()] = 0; goto non_atomic2_end; end: skip; } active proctype urcu_reader() { byte i, j, nest_i; byte tmp, tmp2; wait_init_done(); assert(get_pid() < NR_PROCS); end_reader: do :: 1 -> /* * We do not test reader's progress here, because we are mainly * interested in writer's progress. The reader never blocks * anyway. We have to test for reader/writer's progress * separately, otherwise we could think the writer is doing * progress when it's blocked by an always progressing reader. */ #ifdef READER_PROGRESS progress_reader: #endif urcu_one_read(i, j, nest_i, tmp, tmp2); od; } /* no name clash please */ #undef proc_urcu_reader /* Model the RCU update process. */ /* * Bit encoding, urcu_writer : * Currently only supports one reader. */ int _proc_urcu_writer; #define proc_urcu_writer _proc_urcu_writer #define WRITE_PROD_NONE (1 << 0) #define WRITE_PROC_FIRST_MB (1 << 1) /* first flip */ #define WRITE_PROC_FIRST_READ_GP (1 << 2) #define WRITE_PROC_FIRST_WRITE_GP (1 << 3) #define WRITE_PROC_FIRST_WAIT (1 << 4) #define WRITE_PROC_FIRST_WAIT_LOOP (1 << 5) /* second flip */ #define WRITE_PROC_SECOND_READ_GP (1 << 6) #define WRITE_PROC_SECOND_WRITE_GP (1 << 7) #define WRITE_PROC_SECOND_WAIT (1 << 8) #define WRITE_PROC_SECOND_WAIT_LOOP (1 << 9) #define WRITE_PROC_SECOND_MB (1 << 10) #define WRITE_PROC_ALL_TOKENS (WRITE_PROD_NONE \ | WRITE_PROC_FIRST_MB \ | WRITE_PROC_FIRST_READ_GP \ | WRITE_PROC_FIRST_WRITE_GP \ | WRITE_PROC_FIRST_WAIT \ | WRITE_PROC_SECOND_READ_GP \ | WRITE_PROC_SECOND_WRITE_GP \ | WRITE_PROC_SECOND_WAIT \ | WRITE_PROC_SECOND_MB) #define WRITE_PROC_ALL_TOKENS_CLEAR ((1 << 11) - 1) active proctype urcu_writer() { byte i, j; byte tmp, tmp2, tmpa; byte old_gen; wait_init_done(); assert(get_pid() < NR_PROCS); do :: (READ_CACHED_VAR(generation_ptr) < 5) -> #ifdef WRITER_PROGRESS progress_writer1: #endif ooo_mem(i); atomic { old_gen = READ_CACHED_VAR(generation_ptr); WRITE_CACHED_VAR(generation_ptr, old_gen + 1); } ooo_mem(i); do :: 1 -> atomic { if :: write_lock == 0 -> write_lock = 1; break; :: else -> skip; fi; } od; PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROD_NONE); #ifdef NO_MB PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROC_FIRST_MB); PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROC_SECOND_MB); #endif #ifdef SINGLE_FLIP PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROC_SECOND_READ_GP); PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROC_SECOND_WRITE_GP); PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROC_SECOND_WAIT); #endif do :: CONSUME_TOKENS(proc_urcu_writer, WRITE_PROD_NONE, WRITE_PROC_FIRST_MB) -> smp_mb_send(i, j); PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROC_FIRST_MB); /* first flip */ :: CONSUME_TOKENS(proc_urcu_writer, WRITE_PROC_FIRST_MB, WRITE_PROC_FIRST_READ_GP) -> tmpa = READ_CACHED_VAR(urcu_gp_ctr); PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROC_FIRST_READ_GP); :: CONSUME_TOKENS(proc_urcu_writer, WRITE_PROC_FIRST_MB | WRITE_PROC_FIRST_READ_GP, WRITE_PROC_FIRST_WRITE_GP) -> ooo_mem(i); WRITE_CACHED_VAR(urcu_gp_ctr, tmpa ^ RCU_GP_CTR_BIT); PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROC_FIRST_WRITE_GP); :: CONSUME_TOKENS(proc_urcu_writer, //WRITE_PROC_FIRST_WRITE_GP /* TEST ADDING SYNC CORE */ WRITE_PROC_FIRST_MB, /* can be reordered before/after flips */ WRITE_PROC_FIRST_WAIT | WRITE_PROC_FIRST_WAIT_LOOP) -> ooo_mem(i); /* ONLY WAITING FOR READER 0 */ tmp2 = READ_CACHED_VAR(urcu_active_readers[0]); if :: (tmp2 & RCU_GP_CTR_NEST_MASK) && ((tmp2 ^ RCU_GP_CTR_BIT) & RCU_GP_CTR_BIT) -> PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROC_FIRST_WAIT_LOOP); :: else -> PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROC_FIRST_WAIT); fi; :: CONSUME_TOKENS(proc_urcu_writer, //WRITE_PROC_FIRST_WRITE_GP /* TEST ADDING SYNC CORE */ WRITE_PROC_FIRST_WRITE_GP | WRITE_PROC_FIRST_READ_GP | WRITE_PROC_FIRST_WAIT_LOOP | WRITE_PROC_FIRST_MB, /* can be reordered before/after flips */ 0) -> #ifndef GEN_ERROR_WRITER_PROGRESS smp_mb_send(i, j); #else ooo_mem(i); #endif /* This instruction loops to WRITE_PROC_FIRST_WAIT */ CLEAR_TOKENS(proc_urcu_writer, WRITE_PROC_FIRST_WAIT_LOOP | WRITE_PROC_FIRST_WAIT); /* second flip */ :: CONSUME_TOKENS(proc_urcu_writer, WRITE_PROC_FIRST_WAIT /* Control dependency : need to branch out of * the loop to execute the next flip (CHECK) */ | WRITE_PROC_FIRST_WRITE_GP | WRITE_PROC_FIRST_READ_GP | WRITE_PROC_FIRST_MB, WRITE_PROC_SECOND_READ_GP) -> //smp_mb_send(i, j); //TEST ooo_mem(i); tmpa = READ_CACHED_VAR(urcu_gp_ctr); PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROC_SECOND_READ_GP); :: CONSUME_TOKENS(proc_urcu_writer, WRITE_PROC_FIRST_MB | WRITE_PROC_FIRST_READ_GP | WRITE_PROC_FIRST_WRITE_GP | WRITE_PROC_SECOND_READ_GP, WRITE_PROC_SECOND_WRITE_GP) -> ooo_mem(i); WRITE_CACHED_VAR(urcu_gp_ctr, tmpa ^ RCU_GP_CTR_BIT); PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROC_SECOND_WRITE_GP); :: CONSUME_TOKENS(proc_urcu_writer, //WRITE_PROC_FIRST_WRITE_GP /* TEST ADDING SYNC CORE */ WRITE_PROC_FIRST_WAIT | WRITE_PROC_FIRST_MB, /* can be reordered before/after flips */ WRITE_PROC_SECOND_WAIT | WRITE_PROC_SECOND_WAIT_LOOP) -> ooo_mem(i); /* ONLY WAITING FOR READER 0 */ tmp2 = READ_CACHED_VAR(urcu_active_readers[0]); if :: (tmp2 & RCU_GP_CTR_NEST_MASK) && ((tmp2 ^ 0) & RCU_GP_CTR_BIT) -> PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROC_SECOND_WAIT_LOOP); :: else -> PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROC_SECOND_WAIT); fi; :: CONSUME_TOKENS(proc_urcu_writer, //WRITE_PROC_FIRST_WRITE_GP /* TEST ADDING SYNC CORE */ WRITE_PROC_SECOND_WRITE_GP | WRITE_PROC_FIRST_WRITE_GP | WRITE_PROC_SECOND_READ_GP | WRITE_PROC_FIRST_READ_GP | WRITE_PROC_SECOND_WAIT_LOOP | WRITE_PROC_FIRST_MB, /* can be reordered before/after flips */ 0) -> #ifndef GEN_ERROR_WRITER_PROGRESS smp_mb_send(i, j); #else ooo_mem(i); #endif /* This instruction loops to WRITE_PROC_SECOND_WAIT */ CLEAR_TOKENS(proc_urcu_writer, WRITE_PROC_SECOND_WAIT_LOOP | WRITE_PROC_SECOND_WAIT); :: CONSUME_TOKENS(proc_urcu_writer, WRITE_PROC_FIRST_WAIT | WRITE_PROC_SECOND_WAIT | WRITE_PROC_FIRST_READ_GP | WRITE_PROC_SECOND_READ_GP | WRITE_PROC_FIRST_WRITE_GP | WRITE_PROC_SECOND_WRITE_GP | WRITE_PROC_FIRST_MB, WRITE_PROC_SECOND_MB) -> smp_mb_send(i, j); PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROC_SECOND_MB); :: CONSUME_TOKENS(proc_urcu_writer, WRITE_PROC_ALL_TOKENS, 0) -> CLEAR_TOKENS(proc_urcu_writer, WRITE_PROC_ALL_TOKENS_CLEAR); break; od; write_lock = 0; /* free-up step, e.g., kfree(). */ atomic { last_free_gen = old_gen; free_done = 1; } :: else -> break; od; /* * Given the reader loops infinitely, let the writer also busy-loop * with progress here so, with weak fairness, we can test the * writer's progress. */ end_writer: do :: 1 -> #ifdef WRITER_PROGRESS progress_writer2: #endif skip; od; } /* no name clash please */ #undef proc_urcu_writer /* Leave after the readers and writers so the pid count is ok. */ init { byte i, j; atomic { INIT_CACHED_VAR(urcu_gp_ctr, 1, j); INIT_CACHED_VAR(generation_ptr, 0, j); i = 0; do :: i < NR_READERS -> INIT_CACHED_VAR(urcu_active_readers[i], 0, j); read_generation[i] = 1; data_access[i] = 0; i++; :: i >= NR_READERS -> break od; init_done = 1; } }