[GWP-ASan] Provide runtime configuration through an env var + sysprop.
This patch introduces GWP-ASan system properties and environment
variables to control the internal sampling rates of GWP-ASan. This can
be used for:
1. "Torture testing" the system, i.e. running it under an extremely
high sampling rate under GWP-ASan.
2. Increasing sampling remotely to allow further crash report
collection of rare issues.
There are three sets of system properites:
1. libc.debug.gwp_asan.*.system_default: Default values for native
executables and system apps.
2. libc.debug.gwp_asan.*.app_default: Default values for non-system
apps, and
3. libc.debug.gwp_asan.*.<basename/app_name>: Default values for an
individual app or native process.
There are three variables that can be changed:
1. The allocation sampling rate (default: 2500) - using the environment
variable GWP_ASAN_SAMPLE_RATE or the libc.debug.gwp_asan.sample_rate.*
system property.
2. The process sampling rate (default: 128 for system apps/processes, 1
for opted-in apps) - using the environment variable
GWP_ASAN_PROCESS_SAMPLING or the libc.debug.gwp_asan.process_sampling.*
system property,
3. The number of slots available (default: 32) - using the environment
variable GWP_ASAN_MAX_ALLOCS or the libc.debug.gwp_asan.max_allocs.*
system property.
If not specified, #3 will be calculated as a ratio of the default
|2500 SampleRate : 32 slots|. So, a sample rate of "1250" (i.e. twice as
frequent sampling) will result in a doubling of the max_allocs to "64".
Bug: 219651032
Test: atest bionic-unit-tests
Change-Id: Idb40a2a4d074e01ce3c4e635ad639a91a32d570f
diff --git a/libc/bionic/libc_init_static.cpp b/libc/bionic/libc_init_static.cpp
index 815b938..575da62 100644
--- a/libc/bionic/libc_init_static.cpp
+++ b/libc/bionic/libc_init_static.cpp
@@ -38,6 +38,7 @@
#include "libc_init_common.h"
#include "pthread_internal.h"
+#include "sysprop_helpers.h"
#include "platform/bionic/macros.h"
#include "platform/bionic/mte.h"
@@ -164,30 +165,6 @@
layout.finish_layout();
}
-// Get the presiding config string, in the following order of priority:
-// 1. Environment variables.
-// 2. System properties, in the order they're specified in sys_prop_names.
-// If neither of these options are specified, this function returns false.
-// Otherwise, it returns true, and the presiding options string is written to
-// the `options` buffer of size `size`. If this function returns true, `options`
-// is guaranteed to be null-terminated. `options_size` should be at least
-// PROP_VALUE_MAX.
-bool get_config_from_env_or_sysprops(const char* env_var_name, const char* const* sys_prop_names,
- size_t sys_prop_names_size, char* options,
- size_t options_size) {
- const char* env = getenv(env_var_name);
- if (env && *env != '\0') {
- strncpy(options, env, options_size);
- options[options_size - 1] = '\0'; // Ensure null-termination.
- return true;
- }
-
- for (size_t i = 0; i < sys_prop_names_size; ++i) {
- if (__system_property_get(sys_prop_names[i], options) && *options != '\0') return true;
- }
- return false;
-}
-
#ifdef __aarch64__
static bool __read_memtag_note(const ElfW(Nhdr)* note, const char* name, const char* desc,
unsigned* result) {