selftests/powerpc: Add test of fork with mapping above 512TB (16391bfc) · Commits · 戴 / test

tools/testing/selftests/powerpc/mm/.gitignore

+2 −1

Original line number	Diff line number	Diff line
		@@ -4,3 +4,4 @@ tempfile
		prot_sao
		segv_errors
		wild_bctr
		large_vm_fork_separation
		No newline at end of file

tools/testing/selftests/powerpc/mm/Makefile

+3 −1

Original line number	Diff line number	Diff line
		@@ -2,7 +2,8 @@
		noarg:
		$(MAKE) -C ../

		TEST_GEN_PROGS := hugetlb_vs_thp_test subpage_prot prot_sao segv_errors wild_bctr
		TEST_GEN_PROGS := hugetlb_vs_thp_test subpage_prot prot_sao segv_errors wild_bctr \
		large_vm_fork_separation
		TEST_GEN_FILES := tempfile

		top_srcdir = ../../../../..
		@@ -13,6 +14,7 @@ $(TEST_GEN_PROGS): ../harness.c
		$(OUTPUT)/prot_sao: ../utils.c

		$(OUTPUT)/wild_bctr: CFLAGS += -m64
		$(OUTPUT)/large_vm_fork_separation: CFLAGS += -m64

		$(OUTPUT)/tempfile:
		dd if=/dev/zero of=$@ bs=64k count=1

tools/testing/selftests/powerpc/mm/large_vm_fork_separation.c

0 → 100644

+87 −0

Original line number	Diff line number	Diff line
		// SPDX-License-Identifier: GPL-2.0+
		//
		// Copyright 2019, Michael Ellerman, IBM Corp.
		//
		// Test that allocating memory beyond the memory limit and then forking is
		// handled correctly, ie. the child is able to access the mappings beyond the
		// memory limit and the child's writes are not visible to the parent.

		#include <stdio.h>
		#include <stdlib.h>
		#include <sys/mman.h>
		#include <sys/types.h>
		#include <sys/wait.h>
		#include <unistd.h>

		#include "utils.h"


		#ifndef MAP_FIXED_NOREPLACE
		#define MAP_FIXED_NOREPLACE MAP_FIXED // "Should be safe" above 512TB
		#endif


		static int test(void)
		{
		int p2c[2], c2p[2], rc, status, c, *p;
		unsigned long page_size;
		pid_t pid;

		page_size = sysconf(_SC_PAGESIZE);
		SKIP_IF(page_size != 65536);

		// Create a mapping at 512TB to allocate an extended_id
		p = mmap((void *)(512ul << 40), page_size, PROT_READ \| PROT_WRITE,
		MAP_PRIVATE \| MAP_ANONYMOUS \| MAP_FIXED_NOREPLACE, -1, 0);
		if (p == MAP_FAILED) {
		perror("mmap");
		printf("Error: couldn't mmap(), confirm kernel has 4TB support?\n");
		return 1;
		}

		printf("parent writing %p = 1\n", p);
		*p = 1;

		FAIL_IF(pipe(p2c) == -1 \|\| pipe(c2p) == -1);

		pid = fork();
		if (pid == 0) {
		FAIL_IF(read(p2c[0], &c, 1) != 1);

		pid = getpid();
		printf("child writing %p = %d\n", p, pid);
		*p = pid;

		FAIL_IF(write(c2p[1], &c, 1) != 1);
		FAIL_IF(read(p2c[0], &c, 1) != 1);
		exit(0);
		}

		c = 0;
		FAIL_IF(write(p2c[1], &c, 1) != 1);
		FAIL_IF(read(c2p[0], &c, 1) != 1);

		// Prevent compiler optimisation
		barrier();

		rc = 0;
		printf("parent reading %p = %d\n", p, *p);
		if (*p != 1) {
		printf("Error: BUG! parent saw child's write! p = %d\n", p);
		rc = 1;
		}

		FAIL_IF(write(p2c[1], &c, 1) != 1);
		FAIL_IF(waitpid(pid, &status, 0) == -1);
		FAIL_IF(!WIFEXITED(status) \|\| WEXITSTATUS(status));

		if (rc == 0)
		printf("success: test completed OK\n");

		return rc;
		}

		int main(void)
		{
		return test_harness(test, "large_vm_fork_separation");
		}

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