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// SPDX-License-Identifier: GPL-2.0
/*
* Basic tests for PR_GET/SET_THP_DISABLE prctl calls
*
* Author(s): Usama Arif <usamaarif642@gmail.com>
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>
#include <linux/mman.h>
#include <sys/prctl.h>
#include <sys/wait.h>
#include "../kselftest_harness.h"
#include "thp_settings.h"
#include "vm_util.h"
#ifndef PR_THP_DISABLE_EXCEPT_ADVISED
#define PR_THP_DISABLE_EXCEPT_ADVISED (1 << 1)
#endif
enum thp_collapse_type {
THP_COLLAPSE_NONE,
THP_COLLAPSE_MADV_NOHUGEPAGE,
THP_COLLAPSE_MADV_HUGEPAGE, /* MADV_HUGEPAGE before access */
THP_COLLAPSE_MADV_COLLAPSE, /* MADV_COLLAPSE after access */
};
/*
* Function to mmap a buffer, fault it in, madvise it appropriately (before
* page fault for MADV_HUGE, and after for MADV_COLLAPSE), and check if the
* mmap region is huge.
* Returns:
* 0 if test doesn't give hugepage
* 1 if test gives a hugepage
* -errno if mmap fails
*/
static int test_mmap_thp(enum thp_collapse_type madvise_buf, size_t pmdsize)
{
char *mem, *mmap_mem;
size_t mmap_size;
int ret;
/* For alignment purposes, we need twice the THP size. */
mmap_size = 2 * pmdsize;
mmap_mem = (char *)mmap(NULL, mmap_size, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (mmap_mem == MAP_FAILED)
return -errno;
/* We need a THP-aligned memory area. */
mem = (char *)(((uintptr_t)mmap_mem + pmdsize) & ~(pmdsize - 1));
if (madvise_buf == THP_COLLAPSE_MADV_HUGEPAGE)
madvise(mem, pmdsize, MADV_HUGEPAGE);
else if (madvise_buf == THP_COLLAPSE_MADV_NOHUGEPAGE)
madvise(mem, pmdsize, MADV_NOHUGEPAGE);
/* Ensure memory is allocated */
memset(mem, 1, pmdsize);
if (madvise_buf == THP_COLLAPSE_MADV_COLLAPSE)
madvise(mem, pmdsize, MADV_COLLAPSE);
/* HACK: make sure we have a separate VMA that we can check reliably. */
mprotect(mem, pmdsize, PROT_READ);
ret = check_huge_anon(mem, 1, pmdsize);
munmap(mmap_mem, mmap_size);
return ret;
}
static void prctl_thp_disable_completely_test(struct __test_metadata *const _metadata,
size_t pmdsize,
enum thp_enabled thp_policy)
{
ASSERT_EQ(prctl(PR_GET_THP_DISABLE, NULL, NULL, NULL, NULL), 1);
/* tests after prctl overrides global policy */
ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_NONE, pmdsize), 0);
ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_MADV_NOHUGEPAGE, pmdsize), 0);
ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_MADV_HUGEPAGE, pmdsize), 0);
ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_MADV_COLLAPSE, pmdsize), 0);
/* Reset to global policy */
ASSERT_EQ(prctl(PR_SET_THP_DISABLE, 0, NULL, NULL, NULL), 0);
/* tests after prctl is cleared, and only global policy is effective */
ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_NONE, pmdsize),
thp_policy == THP_ALWAYS ? 1 : 0);
ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_MADV_NOHUGEPAGE, pmdsize), 0);
ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_MADV_HUGEPAGE, pmdsize),
thp_policy == THP_NEVER ? 0 : 1);
ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_MADV_COLLAPSE, pmdsize), 1);
}
FIXTURE(prctl_thp_disable_completely)
{
struct thp_settings settings;
size_t pmdsize;
};
FIXTURE_VARIANT(prctl_thp_disable_completely)
{
enum thp_enabled thp_policy;
};
FIXTURE_VARIANT_ADD(prctl_thp_disable_completely, never)
{
.thp_policy = THP_NEVER,
};
FIXTURE_VARIANT_ADD(prctl_thp_disable_completely, madvise)
{
.thp_policy = THP_MADVISE,
};
FIXTURE_VARIANT_ADD(prctl_thp_disable_completely, always)
{
.thp_policy = THP_ALWAYS,
};
FIXTURE_SETUP(prctl_thp_disable_completely)
{
if (!thp_available())
SKIP(return, "Transparent Hugepages not available\n");
self->pmdsize = read_pmd_pagesize();
if (!self->pmdsize)
SKIP(return, "Unable to read PMD size\n");
if (prctl(PR_SET_THP_DISABLE, 1, NULL, NULL, NULL))
SKIP(return, "Unable to disable THPs completely for the process\n");
thp_save_settings();
thp_read_settings(&self->settings);
self->settings.thp_enabled = variant->thp_policy;
self->settings.hugepages[sz2ord(self->pmdsize, getpagesize())].enabled = THP_INHERIT;
thp_write_settings(&self->settings);
}
FIXTURE_TEARDOWN(prctl_thp_disable_completely)
{
thp_restore_settings();
}
TEST_F(prctl_thp_disable_completely, nofork)
{
prctl_thp_disable_completely_test(_metadata, self->pmdsize, variant->thp_policy);
}
TEST_F(prctl_thp_disable_completely, fork)
{
int ret = 0;
pid_t pid;
/* Make sure prctl changes are carried across fork */
pid = fork();
ASSERT_GE(pid, 0);
if (!pid) {
prctl_thp_disable_completely_test(_metadata, self->pmdsize, variant->thp_policy);
return;
}
wait(&ret);
if (WIFEXITED(ret))
ret = WEXITSTATUS(ret);
else
ret = -EINVAL;
ASSERT_EQ(ret, 0);
}
static void prctl_thp_disable_except_madvise_test(struct __test_metadata *const _metadata,
size_t pmdsize,
enum thp_enabled thp_policy)
{
ASSERT_EQ(prctl(PR_GET_THP_DISABLE, NULL, NULL, NULL, NULL), 3);
/* tests after prctl overrides global policy */
ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_NONE, pmdsize), 0);
ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_MADV_NOHUGEPAGE, pmdsize), 0);
ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_MADV_HUGEPAGE, pmdsize),
thp_policy == THP_NEVER ? 0 : 1);
ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_MADV_COLLAPSE, pmdsize), 1);
/* Reset to global policy */
ASSERT_EQ(prctl(PR_SET_THP_DISABLE, 0, NULL, NULL, NULL), 0);
/* tests after prctl is cleared, and only global policy is effective */
ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_NONE, pmdsize),
thp_policy == THP_ALWAYS ? 1 : 0);
ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_MADV_NOHUGEPAGE, pmdsize), 0);
ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_MADV_HUGEPAGE, pmdsize),
thp_policy == THP_NEVER ? 0 : 1);
ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_MADV_COLLAPSE, pmdsize), 1);
}
FIXTURE(prctl_thp_disable_except_madvise)
{
struct thp_settings settings;
size_t pmdsize;
};
FIXTURE_VARIANT(prctl_thp_disable_except_madvise)
{
enum thp_enabled thp_policy;
};
FIXTURE_VARIANT_ADD(prctl_thp_disable_except_madvise, never)
{
.thp_policy = THP_NEVER,
};
FIXTURE_VARIANT_ADD(prctl_thp_disable_except_madvise, madvise)
{
.thp_policy = THP_MADVISE,
};
FIXTURE_VARIANT_ADD(prctl_thp_disable_except_madvise, always)
{
.thp_policy = THP_ALWAYS,
};
FIXTURE_SETUP(prctl_thp_disable_except_madvise)
{
if (!thp_available())
SKIP(return, "Transparent Hugepages not available\n");
self->pmdsize = read_pmd_pagesize();
if (!self->pmdsize)
SKIP(return, "Unable to read PMD size\n");
if (prctl(PR_SET_THP_DISABLE, 1, PR_THP_DISABLE_EXCEPT_ADVISED, NULL, NULL))
SKIP(return, "Unable to set PR_THP_DISABLE_EXCEPT_ADVISED\n");
thp_save_settings();
thp_read_settings(&self->settings);
self->settings.thp_enabled = variant->thp_policy;
self->settings.hugepages[sz2ord(self->pmdsize, getpagesize())].enabled = THP_INHERIT;
thp_write_settings(&self->settings);
}
FIXTURE_TEARDOWN(prctl_thp_disable_except_madvise)
{
thp_restore_settings();
}
TEST_F(prctl_thp_disable_except_madvise, nofork)
{
prctl_thp_disable_except_madvise_test(_metadata, self->pmdsize, variant->thp_policy);
}
TEST_F(prctl_thp_disable_except_madvise, fork)
{
int ret = 0;
pid_t pid;
/* Make sure prctl changes are carried across fork */
pid = fork();
ASSERT_GE(pid, 0);
if (!pid) {
prctl_thp_disable_except_madvise_test(_metadata, self->pmdsize,
variant->thp_policy);
return;
}
wait(&ret);
if (WIFEXITED(ret))
ret = WEXITSTATUS(ret);
else
ret = -EINVAL;
ASSERT_EQ(ret, 0);
}
TEST_HARNESS_MAIN
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