projects / lttng-ust.git / blame
| Commit | Line | Data |
|---|---|---|
| 97572c04 MD |
1 | /* |
| 2 | * SPDX-License-Identifier: MIT | |
| 3 | * | |
| 4 | * Copyright (C) 2024-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
| 5 | */ | |
| 6 | ||
| 7 | #define _LGPL_SOURCE | |
| 8 | #include "common/getenv.h" | |
| 9 | #include "common/logging.h" | |
| 10 | #include "common/populate.h" | |
| 11 | ||
| 12 | enum populate_policy { | |
| 13 | POPULATE_UNSET, | |
| 14 | ||
| 15 | POPULATE_NONE, | |
| 16 | POPULATE_CPU_POSSIBLE, | |
| 17 | ||
| 18 | POPULATE_UNKNOWN, | |
| 19 | }; | |
| 20 | ||
| 21 | static enum populate_policy map_populate_policy = POPULATE_UNSET; | |
| 22 | ||
| 23 | static void init_map_populate_policy(void) | |
| 24 | { | |
| 25 | const char *populate_env_str; | |
| 26 | ||
| 27 | if (map_populate_policy != POPULATE_UNSET) | |
| 28 | return; | |
| 29 | ||
| 30 | populate_env_str = lttng_ust_getenv("LTTNG_UST_MAP_POPULATE_POLICY"); | |
| 31 | if (!populate_env_str) { | |
| 32 | map_populate_policy = POPULATE_NONE; | |
| 33 | return; | |
| 34 | } | |
| 35 | if (!strcmp(populate_env_str, "none")) { | |
| 36 | map_populate_policy = POPULATE_NONE; | |
| 37 | } else if (!strcmp(populate_env_str, "cpu_possible")) { | |
| 38 | map_populate_policy = POPULATE_CPU_POSSIBLE; | |
| 39 | } else { | |
| 40 | /* | |
| 41 | * populate_env_str is an untrusted environment variable | |
| 42 | * input (can be provided to setuid/setgid binaries), so | |
| 43 | * don't even try to print it. | |
| 44 | */ | |
| 45 | WARN("Unknown policy for LTTNG_UST_MAP_POPULATE_POLICY environment variable."); | |
| 46 | map_populate_policy = POPULATE_UNKNOWN; | |
| 47 | } | |
| 48 | } | |
| 49 | ||
| 50 | /* | |
| 51 | * Return the shared page populate policy for global pages. Returns true | |
| 52 | * if shared memory pages should be pre-populated, false otherwise. | |
| 53 | */ | |
| 54 | bool lttng_ust_map_populate_is_enabled(void) | |
| 55 | { | |
| 56 | init_map_populate_policy(); | |
| 57 | ||
| 58 | switch (map_populate_policy) { | |
| 59 | case POPULATE_UNKNOWN: /* Fall-through */ | |
| 60 | case POPULATE_NONE: | |
| 61 | return false; | |
| 62 | case POPULATE_CPU_POSSIBLE: | |
| 63 | return true; | |
| 64 | default: | |
| 65 | abort(); | |
| 66 | } | |
| 67 | return false; | |
| 68 | } | |
| 69 | ||
| 70 | /* | |
| 71 | * Return the shared page populate policy based on the @cpu number | |
| 72 | * provided as input. Returns true if shared memory pages should be | |
| 73 | * pre-populated, false otherwise. | |
| 74 | * | |
| 75 | * The @cpu argument is currently unused except for negative value | |
| 76 | * validation. It is present to eventually match cpu affinity or cpu | |
| 77 | * online masks if those features are added in the future. | |
| 78 | */ | |
| 79 | bool lttng_ust_map_populate_cpu_is_enabled(int cpu) | |
| 80 | { | |
| 81 | /* Reject invalid cpu number. */ | |
| 82 | if (cpu < 0) | |
| 83 | return false; | |
| 84 | ||
| 85 | return lttng_ust_map_populate_is_enabled(); | |
| 86 | } |