diff options
Diffstat (limited to 'src/shared/efivars.c')
| -rw-r--r-- | src/shared/efivars.c | 233 |
1 files changed, 233 insertions, 0 deletions
diff --git a/src/shared/efivars.c b/src/shared/efivars.c new file mode 100644 index 0000000000..3bd47b8868 --- /dev/null +++ b/src/shared/efivars.c @@ -0,0 +1,233 @@ +/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ + +/*** + This file is part of systemd. + + Copyright 2013 Lennart Poettering + + systemd is free software; you can redistribute it and/or modify it + under the terms of the GNU Lesser General Public License as published by + the Free Software Foundation; either version 2.1 of the License, or + (at your option) any later version. + + systemd is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with systemd; If not, see <http://www.gnu.org/licenses/>. +***/ + +#include <unistd.h> +#include <fcntl.h> + +#include "util.h" +#include "utf8.h" +#include "efivars.h" + +#define EFI_VENDOR_LOADER SD_ID128_MAKE(4a,67,b0,82,0a,4c,41,cf,b6,c7,44,0b,29,bb,8c,4f) + +int efi_get_variable(sd_id128_t vendor, const char *name, uint32_t *attribute, void **value, size_t *size) { + _cleanup_close_ int fd = -1; + _cleanup_free_ char *p = NULL; + uint32_t a; + ssize_t n; + struct stat st; + void *r; + + assert(name); + assert(value); + assert(size); + + if (asprintf(&p, + "/sys/firmware/efi/efivars/%s-%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x", + name, SD_ID128_FORMAT_VAL(vendor)) < 0) + return -ENOMEM; + + fd = open(p, O_RDONLY|O_NOCTTY|O_CLOEXEC); + if (fd < 0) + return -errno; + + if (fstat(fd, &st) < 0) + return -errno; + if (st.st_size < 4) + return -EIO; + if (st.st_size > 4*1024*1024 + 4) + return -E2BIG; + + n = read(fd, &a, sizeof(a)); + if (n < 0) + return (int) n; + if (n != sizeof(a)) + return -EIO; + + r = malloc(st.st_size - 4 + 2); + if (!r) + return -ENOMEM; + + n = read(fd, r, (size_t) st.st_size - 4); + if (n < 0) { + free(r); + return (int) -n; + } + if (n != (ssize_t) st.st_size - 4) { + free(r); + return -EIO; + } + + /* Always NUL terminate (2 bytes, to protect UTF-16) */ + ((char*) r)[st.st_size - 4] = 0; + ((char*) r)[st.st_size - 4 + 1] = 0; + + *value = r; + *size = (size_t) st.st_size; + + if (attribute) + *attribute = a; + + return 0; +} + +static int read_bogomips(unsigned long *u) { + _cleanup_fclose_ FILE *f = NULL; + + f = fopen("/proc/cpuinfo", "re"); + if (!f) + return -errno; + + while (!feof(f)) { + char line[LINE_MAX]; + char *x; + unsigned long a, b; + + if (!fgets(line, sizeof(line), f)) + return -EIO; + + char_array_0(line); + truncate_nl(line); + + if (!startswith(line, "bogomips")) + continue; + + x = line + 8; + x += strspn(x, WHITESPACE); + if (*x != ':') + continue; + x++; + x += strspn(x, WHITESPACE); + + if (sscanf(x, "%lu.%lu", &a, &b) != 2) + continue; + + *u = a * 1000000L + b * 10000L; + return 0; + } + + return -EIO; +} + +static int read_ticks(sd_id128_t vendor, const char *name, unsigned long speed, usec_t *u) { + _cleanup_free_ void *i = NULL; + _cleanup_free_ char *j = NULL; + size_t is; + int r; + uint64_t x; + + assert(name); + assert(u); + + r = efi_get_variable(EFI_VENDOR_LOADER, name, NULL, &i, &is); + if (r < 0) + return r; + + j = utf16_to_utf8(i, is); + if (!j) + return -ENOMEM; + + r = safe_atou64(j, &x); + if (r < 0) + return r; + + *u = USEC_PER_SEC * x / speed; + return 0; +} + +static int get_boot_usec(usec_t *firmware, usec_t *loader) { + uint64_t x, y; + int r; + unsigned long bogomips; + + assert(firmware); + assert(loader); + + /* Returns the usec after the CPU was turned on. The two + * timestamps are: the firmware finished, and the boot loader + * finished. */ + + /* We assume that the kernel's bogomips value is calibrated to + * twice the CPU frequency, and use this to convert the TSC + * ticks into usec. Of course, bogomips are only vaguely + * defined. If this breaks one day we can come up with + * something better. However, for now this saves us from doing + * a local calibration loop. */ + + r = read_bogomips(&bogomips); + if (r < 0) + return r; + + r = read_ticks(EFI_VENDOR_LOADER, "LoaderTicksInit", bogomips / 2, &x); + if (r < 0) + return r; + + r = read_ticks(EFI_VENDOR_LOADER, "LoaderTicksExec", bogomips / 2, &y); + if (r < 0) + return r; + + if (y == 0 || y < x) + return -EIO; + + if (y > USEC_PER_HOUR) + return -EIO; + + *firmware = x; + *loader = y; + + return 0; +} + +int efi_get_boot_timestamps(const dual_timestamp *n, dual_timestamp *firmware, dual_timestamp *loader) { + usec_t x, y, a; + int r; + dual_timestamp _n; + + assert(firmware); + assert(loader); + + if (!n) { + dual_timestamp_get(&_n); + n = &_n; + } + + r = get_boot_usec(&x, &y); + if (r < 0) + return r; + + /* Let's convert this to timestamps where the firmware + * began/loader began working. To make this more confusing: + * since usec_t is unsigned and the kernel's monotonic clock + * begins at kernel initialization we'll actually initialize + * the monotonic timestamps here as negative of the actual + * value. */ + + firmware->monotonic = y; + loader->monotonic = y - x; + + a = n->monotonic + firmware->monotonic; + firmware->realtime = n->realtime > a ? n->realtime - a : 0; + + a = n->monotonic + loader->monotonic; + loader->realtime = n->realtime > a ? n->realtime - a : 0; + + return 0; +} |