On 07/01/2026 16:48, Kevin Brodsky wrote:
> pfnmap currently checks the target file in FIXTURE_SETUP(pfnmap),
> meaning once for every test, and skips the test if any check fails.
> 
> The target file is the same for every test so this is a little
> overkill. More importantly, this approach means that the whole suite
> will report PASS even if all the tests are skipped because kernel
> configuration (e.g. CONFIG_STRICT_DEVMEM=y) prevented /dev/mem from
> being mapped, for instance.
> 
> Let's ensure that KSFT_SKIP is returned as exit code if any check
> fails by performing the checks in pfnmap_init(), run once. That
> function also takes care of finding the offset of the pages to be
> mapped and saves it in a global. The file is still mapped/unmapped
> for every test, as some of them modify the mapping.
> 
> Signed-off-by: Kevin Brodsky <[email protected]>
> ---
>  tools/testing/selftests/mm/pfnmap.c | 81 ++++++++++++++++++++---------
>  1 file changed, 55 insertions(+), 26 deletions(-)
> 
> diff --git a/tools/testing/selftests/mm/pfnmap.c 
> b/tools/testing/selftests/mm/pfnmap.c
> index 35b0e3ed54cd..e41d5464130b 100644
> --- a/tools/testing/selftests/mm/pfnmap.c
> +++ b/tools/testing/selftests/mm/pfnmap.c
> @@ -25,8 +25,11 @@
>  #include "kselftest_harness.h"
>  #include "vm_util.h"
>  
> +#define DEV_MEM_NPAGES       2
> +
>  static sigjmp_buf sigjmp_buf_env;
>  static char *file = "/dev/mem";
> +static off_t file_offset;
>  
>  static void signal_handler(int sig)
>  {
> @@ -88,7 +91,7 @@ static int find_ram_target(off_t *offset,
>                       break;
>  
>               /* We need two pages. */
> -             if (end > start + 2 * pagesize) {
> +             if (end > start + DEV_MEM_NPAGES * pagesize) {
>                       fclose(file);
>                       *offset = start;
>                       return 0;
> @@ -97,9 +100,49 @@ static int find_ram_target(off_t *offset,
>       return -ENOENT;
>  }
>  
> +static void pfnmap_init(void)
> +{
> +     size_t pagesize = getpagesize();
> +     size_t size = DEV_MEM_NPAGES * pagesize;
> +     int fd;
> +     void *addr;
> +
> +     if (strncmp(file, "/dev/mem", strlen("/dev/mem")) == 0) {
> +             int err = find_ram_target(&file_offset, pagesize);
> +
> +             if (err)
> +                     ksft_exit_skip("Cannot find ram target in 
> '/proc/iomem': %s\n",
> +                                    strerror(-err));
> +     } else {
> +             file_offset = 0;
> +     }
> +
> +     /*
> +      * Make sure we can open and map the file, and perform some basic
> +      * checks; skip the whole suite if anything goes wrong.
> +      * A fresh mapping is then created for every test case by
> +      * FIXTURE_SETUP(pfnmap).
> +      */
> +     fd = open(file, O_RDONLY);
> +     if (fd < 0)
> +             ksft_exit_skip("Cannot open '%s': %s\n", file, strerror(errno));
> +
> +     addr = mmap(NULL, size, PROT_READ, MAP_SHARED, fd, file_offset);
> +     if (addr == MAP_FAILED)
> +             ksft_exit_skip("Cannot mmap '%s': %s\n", file, strerror(errno));
> +
> +     if (!check_vmflag_pfnmap(addr))
> +             ksft_exit_skip("Invalid file: '%s'. Not pfnmap'ed\n", file);
> +
> +     if (test_read_access(addr, size))
> +             ksft_exit_skip("Cannot read-access mmap'ed '%s'\n", file);
> +
> +     munmap(addr, size);
> +     close(fd);
> +}
> +
>  FIXTURE(pfnmap)
>  {
> -     off_t offset;
>       size_t pagesize;
>       int dev_mem_fd;
>       char *addr1;
> @@ -112,31 +155,13 @@ FIXTURE_SETUP(pfnmap)
>  {
>       self->pagesize = getpagesize();
>  
> -     if (strncmp(file, "/dev/mem", strlen("/dev/mem")) == 0) {
> -             /* We'll require two physical pages throughout our tests ... */
> -             if (find_ram_target(&self->offset, self->pagesize))
> -                     SKIP(return,
> -                                "Cannot find ram target in '/proc/iomem'\n");
> -     } else {
> -             self->offset = 0;
> -     }
> -
>       self->dev_mem_fd = open(file, O_RDONLY);
> -     if (self->dev_mem_fd < 0)
> -             SKIP(return, "Cannot open '%s'\n", file);
> +     ASSERT_GE(self->dev_mem_fd, 0);
>  
> -     self->size1 = self->pagesize * 2;
> +     self->size1 = DEV_MEM_NPAGES * self->pagesize;
>       self->addr1 = mmap(NULL, self->size1, PROT_READ, MAP_SHARED,
> -                        self->dev_mem_fd, self->offset);
> -     if (self->addr1 == MAP_FAILED)
> -             SKIP(return, "Cannot mmap '%s'\n", file);
> -
> -     if (!check_vmflag_pfnmap(self->addr1))
> -             SKIP(return, "Invalid file: '%s'. Not pfnmap'ed\n", file);

I wonder if we still want this check per-fd, but upgraded to a fail?

Either way:

Reviewed-by: Ryan Roberts <[email protected]>

> -
> -     /* ... and want to be able to read from them. */
> -     if (test_read_access(self->addr1, self->size1))
> -             SKIP(return, "Cannot read-access mmap'ed '%s'\n", file);
> +                        self->dev_mem_fd, file_offset);
> +     ASSERT_NE(self->addr1, MAP_FAILED);
>  
>       self->size2 = 0;
>       self->addr2 = MAP_FAILED;
> @@ -189,7 +214,7 @@ TEST_F(pfnmap, munmap_split)
>        */
>       self->size2 = self->pagesize;
>       self->addr2 = mmap(NULL, self->pagesize, PROT_READ, MAP_SHARED,
> -                        self->dev_mem_fd, self->offset);
> +                        self->dev_mem_fd, file_offset);
>       ASSERT_NE(self->addr2, MAP_FAILED);
>  }
>  
> @@ -258,8 +283,12 @@ int main(int argc, char **argv)
>               if (strcmp(argv[i], "--") == 0) {
>                       if (i + 1 < argc && strlen(argv[i + 1]) > 0)
>                               file = argv[i + 1];
> -                     return test_harness_run(i, argv);
> +                     argc = i;
> +                     break;
>               }
>       }
> +
> +     pfnmap_init();
> +
>       return test_harness_run(argc, argv);
>  }


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