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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* Copyright (c) 2020 SUSE LLC <mdoucha@suse.cz>
*/
#ifndef TST_MEMUTILS_H__
#define TST_MEMUTILS_H__
/*
* Fill up to maxsize physical memory with fillchar, then free it for reuse.
* If maxsize is zero, fill as much memory as possible. This function is
* intended for data disclosure vulnerability tests to reduce the probability
* that a vulnerable kernel will leak a block of memory that was full of
* zeroes by chance.
*
* The function keeps a safety margin to avoid invoking OOM killer and
* respects the limitations of available address space. (Less than 3GB can be
* polluted on a 32bit system regardless of available physical RAM.)
*/
void tst_pollute_memory(size_t maxsize, int fillchar);
/*
* Read the value of MemAvailable from /proc/meminfo, if no support on
* older kernels, return 'MemFree + Cached' for instead.
*/
long long tst_available_mem(void);
/*
* Read the value of SwapFree from /proc/meminfo.
*/
long long tst_available_swap(void);
/*
* Enable OOM protection to prevent process($PID) being killed by OOM Killer.
* echo -1000 >/proc/$PID/oom_score_adj
*
* If the pid is 0 which means it will set on current(self) process.
*
* Unless the process has CAP_SYS_RESOURCE this call will be no-op because
* setting adj value < 0 requires it.
*
* CAP_SYS_RESOURCE:
* set /proc/[pid]/oom_score_adj to a value lower than the value last set
* by a process with CAP_SYS_RESOURCE.
*
* Note:
* This exported tst_enable_oom_protection function can be used at anywhere
* you want to protect, but please remember that if you do enable protection
* on a process($PID) that all the children will inherit its score and be
* ignored by OOM Killer as well. So that's why tst_disable_oom_protection()
* to be used in combination.
*/
void tst_enable_oom_protection(pid_t pid);
/*
* Disable the OOM protection for the process($PID).
* echo 0 >/proc/$PID/oom_score_adj
*/
void tst_disable_oom_protection(pid_t pid);
#endif /* TST_MEMUTILS_H__ */
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