selftest/vm: fix map_fixed_noreplace test failure

On the latest RHEL the test fails due to executable mapped at 256MB
address

     # ./map_fixed_noreplace
    mmap() @ 0x10000000-0x10050000 p=0xffffffffffffffff result=File exists
    10000000-10010000 r-xp 00000000 fd:04 34905657                           /root/rpmbuild/BUILD/kernel-5.14.0-56.el9/linux-5.14.0-56.el9.ppc64le/tools/testing/selftests/vm/map_fixed_noreplace
    10010000-10020000 r--p 00000000 fd:04 34905657                           /root/rpmbuild/BUILD/kernel-5.14.0-56.el9/linux-5.14.0-56.el9.ppc64le/tools/testing/selftests/vm/map_fixed_noreplace
    10020000-10030000 rw-p 00010000 fd:04 34905657                           /root/rpmbuild/BUILD/kernel-5.14.0-56.el9/linux-5.14.0-56.el9.ppc64le/tools/testing/selftests/vm/map_fixed_noreplace
    10029b90000-10029bc0000 rw-p 00000000 00:00 0                            [heap]
    7fffbb510000-7fffbb750000 r-xp 00000000 fd:04 24534                      /usr/lib64/libc.so.6
    7fffbb750000-7fffbb760000 r--p 00230000 fd:04 24534                      /usr/lib64/libc.so.6
    7fffbb760000-7fffbb770000 rw-p 00240000 fd:04 24534                      /usr/lib64/libc.so.6
    7fffbb780000-7fffbb7a0000 r--p 00000000 00:00 0                          [vvar]
    7fffbb7a0000-7fffbb7b0000 r-xp 00000000 00:00 0                          [vdso]
    7fffbb7b0000-7fffbb800000 r-xp 00000000 fd:04 24514                      /usr/lib64/ld64.so.2
    7fffbb800000-7fffbb810000 r--p 00040000 fd:04 24514                      /usr/lib64/ld64.so.2
    7fffbb810000-7fffbb820000 rw-p 00050000 fd:04 24514                      /usr/lib64/ld64.so.2
    7fffd93f0000-7fffd9420000 rw-p 00000000 00:00 0                          [stack]
    Error: couldn't map the space we need for the test

Fix this by finding a free address using mmap instead of hardcoding
BASE_ADDRESS.

Link: https://lkml.kernel.org/r/20220217083417.373823-1-aneesh.kumar@linux.ibm.com
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Jann Horn <jannh@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/tools/testing/selftests/vm/map_fixed_noreplace.c b/tools/testing/selftests/vm/map_fixed_noreplace.c
index d91bde5..eed4432 100644 (file)
--- a/tools/testing/selftests/vm/map_fixed_noreplace.c
+++ b/tools/testing/selftests/vm/map_fixed_noreplace.c
@@ -17,9 +17,6 @@
 #define MAP_FIXED_NOREPLACE 0x100000
 #endif
 
-#define BASE_ADDRESS   (256ul * 1024 * 1024)
-
-
 static void dump_maps(void)
 {
        char cmd[32];
@@ -28,18 +25,46 @@ static void dump_maps(void)
        system(cmd);
 }
 
+static unsigned long find_base_addr(unsigned long size)
+{
+       void *addr;
+       unsigned long flags;
+
+       flags = MAP_PRIVATE | MAP_ANONYMOUS;
+       addr = mmap(NULL, size, PROT_NONE, flags, -1, 0);
+       if (addr == MAP_FAILED) {
+               printf("Error: couldn't map the space we need for the test\n");
+               return 0;
+       }
+
+       if (munmap(addr, size) != 0) {
+               printf("Error: couldn't map the space we need for the test\n");
+               return 0;
+       }
+       return (unsigned long)addr;
+}
+
 int main(void)
 {
+       unsigned long base_addr;
        unsigned long flags, addr, size, page_size;
        char *p;
 
        page_size = sysconf(_SC_PAGE_SIZE);
 
+       //let's find a base addr that is free before we start the tests
+       size = 5 * page_size;
+       base_addr = find_base_addr(size);
+       if (!base_addr) {
+               printf("Error: couldn't map the space we need for the test\n");
+               return 1;
+       }
+
        flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED_NOREPLACE;
 
        // Check we can map all the areas we need below
        errno = 0;
-       addr = BASE_ADDRESS;
+       addr = base_addr;
        size = 5 * page_size;
        p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
 
@@ -60,7 +85,7 @@ int main(void)
        printf("unmap() successful\n");
 
        errno = 0;
-       addr = BASE_ADDRESS + page_size;
+       addr = base_addr + page_size;
        size = 3 * page_size;
        p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
        printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
@@ -80,7 +105,7 @@ int main(void)
         *     +4 |  free  | new
         */
        errno = 0;
-       addr = BASE_ADDRESS;
+       addr = base_addr;
        size = 5 * page_size;
        p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
        printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
@@ -101,7 +126,7 @@ int main(void)
         *     +4 |  free  |
         */
        errno = 0;
-       addr = BASE_ADDRESS + (2 * page_size);
+       addr = base_addr + (2 * page_size);
        size = page_size;
        p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
        printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
@@ -121,7 +146,7 @@ int main(void)
         *     +4 |  free  | new
         */
        errno = 0;
-       addr = BASE_ADDRESS + (3 * page_size);
+       addr = base_addr + (3 * page_size);
        size = 2 * page_size;
        p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
        printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
@@ -141,7 +166,7 @@ int main(void)
         *     +4 |  free  |
         */
        errno = 0;
-       addr = BASE_ADDRESS;
+       addr = base_addr;
        size = 2 * page_size;
        p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
        printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
@@ -161,7 +186,7 @@ int main(void)
         *     +4 |  free  |
         */
        errno = 0;
-       addr = BASE_ADDRESS;
+       addr = base_addr;
        size = page_size;
        p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
        printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
@@ -181,7 +206,7 @@ int main(void)
         *     +4 |  free  |  new
         */
        errno = 0;
-       addr = BASE_ADDRESS + (4 * page_size);
+       addr = base_addr + (4 * page_size);
        size = page_size;
        p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
        printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
@@ -192,7 +217,7 @@ int main(void)
                return 1;
        }
 
-       addr = BASE_ADDRESS;
+       addr = base_addr;
        size = 5 * page_size;
        if (munmap((void *)addr, size) != 0) {
                dump_maps();