Add kselftest for NVRAM access on pseries/PowerVM systems. This test validates basic device operations and partition discovery via pstore, which replaces the legacy /proc/ppc64/nvram interface.
The test verifies: - Existence and readability of /dev/nvram - Discovery of NVRAM partitions from /sys/fs/pstore - Correct parsing of partition names and indices - Basic read and lseek operations on the device - Overflow protection by rejecting reads beyond device size Signed-off-by: Shirisha G <[email protected]> --- .../selftests/powerpc/rtas/nvram_test.c | 131 ++++++++++++++++++ 1 file changed, 131 insertions(+) create mode 100644 tools/testing/selftests/powerpc/rtas/nvram_test.c diff --git a/tools/testing/selftests/powerpc/rtas/nvram_test.c b/tools/testing/selftests/powerpc/rtas/nvram_test.c new file mode 100644 index 000000000000..b0582d17324f --- /dev/null +++ b/tools/testing/selftests/powerpc/rtas/nvram_test.c @@ -0,0 +1,131 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * NVRAM Access Test + * Copyright (C) 2026 IBM Corporation + */ + +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <fcntl.h> +#include <unistd.h> +#include <sys/types.h> +#include <dirent.h> +#include <errno.h> +#include "utils.h" + +#define NVRAM_DEV "/dev/nvram" +#define NVRAM_PSTORE "/sys/fs/pstore" /* replaces dead /proc/ppc64/nvram */ +#define NVRAM_SIZE 8192 /* Typical NVRAM size */ + +struct nvram_partition { + char name[64]; + unsigned int index; +}; + +/* + * Discover NVRAM partitions from /sys/fs/pstore by listing entries whose + * names contain "nvram". On RTAS/PowerVM systems /proc/ppc64/nvram does + * not exist; pstore is the authoritative in-kernel view of NVRAM regions. + * + * Returns number of partitions found, or -1 if the directory cannot be + * opened (caller should SKIP_IF the result is < 0). + */ +static int read_nvram_partitions(struct nvram_partition *parts, int max_parts) +{ + DIR *dir; + struct dirent *ent; + int count = 0; + + dir = opendir(NVRAM_PSTORE); + if (!dir) + return -1; + + while ((ent = readdir(dir)) != NULL && count < max_parts) { + /* Only interested in entries that contain "nvram" */ + if (strstr(ent->d_name, "nvram") == NULL) + continue; + + /* + * pstore filenames follow the pattern <type>-nvram-<id> + * e.g. "rtas-nvram-2", "dmesg-nvram-1". + * Parse the trailing numeric id as the partition index. + */ + strncpy(parts[count].name, ent->d_name, + sizeof(parts[count].name) - 1); + parts[count].name[sizeof(parts[count].name) - 1] = '\0'; + + /* Extract trailing index after the last '-' */ + char *p = strrchr(ent->d_name, '-'); + parts[count].index = p ? (unsigned int)atoi(p + 1) : 0; + + count++; + } + + closedir(dir); + return count; +} + +int main(void) +{ + int fd, ret; + char buf[256]; + struct nvram_partition parts[32]; + int part_count; + off_t offset; + + test_harness_set_timeout(10); + + /* Test 1: Verify /dev/nvram exists — skip gracefully if not */ + SKIP_IF(access(NVRAM_DEV, R_OK) != 0); + + /* Test 2: Open NVRAM device */ + fd = open(NVRAM_DEV, O_RDONLY); + FAIL_IF(fd < 0); + + /* + * Test 3: Read NVRAM partition table from /sys/fs/pstore. + * Use SKIP_IF when the directory is absent (part_count < 0) so the + * test does not hard-fail on kernels/configs that lack pstore, while + * still failing when the directory exists but is empty (part_count==0). + */ + part_count = read_nvram_partitions(parts, 32); + SKIP_IF(part_count < 0); + FAIL_IF_MSG(part_count == 0, "No NVRAM partitions found in " NVRAM_PSTORE); + + printf("Found %d NVRAM partition(s) in " NVRAM_PSTORE ":\n", part_count); + for (int i = 0; i < part_count; i++) + printf(" %s (index=%u)\n", parts[i].name, parts[i].index); + + /* Test 4: Read from start of device */ + ret = read(fd, buf, sizeof(buf)); + FAIL_IF_MSG(ret < 0, "Failed to read from " NVRAM_DEV); + + /* Test 5: lseek to start */ + offset = lseek(fd, 0, SEEK_SET); + FAIL_IF_MSG(offset != 0, "lseek to start failed"); + + /* Test 6: lseek to arbitrary offset */ + offset = lseek(fd, 100, SEEK_SET); + FAIL_IF_MSG(offset != 100, "lseek to offset 100 failed"); + + /* Test 7: Overflow protection — read past NVRAM_SIZE must not succeed */ + /* + * Test 7: Overflow protection. + * Discover the real device size via SEEK_END; if the driver supports it, + * attempt a read past that boundary — it must return 0 or error. + * Do not use a hardcoded NVRAM_SIZE: the actual size varies by platform + * and the RTAS driver will happily return data if the seek lands within + * the real (larger) device. FIX 2 + */ + off_t nvram_size = lseek(fd, 0, SEEK_END); + if (nvram_size > 0) { + offset = lseek(fd, nvram_size + 1000, SEEK_SET); + ret = read(fd, buf, sizeof(buf)); + FAIL_IF_MSG(ret > 0, "Read succeeded beyond NVRAM size"); + } + + close(fd); + printf("NVRAM test passed\n"); + return 0; +} -- 2.43.5
