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| author | Miquel Raynal <miquel.raynal@bootlin.com> | 2022-05-20 13:58:54 +0200 |
|---|---|---|
| committer | Miquel Raynal <miquel.raynal@bootlin.com> | 2022-05-20 13:58:54 +0200 |
| commit | e6828be5edcfea25cd70a2d1de41085c67ef9fa5 (patch) | |
| tree | 489ae4cdb47a4d83940e2472f49a3c601806b70e /scripts/gcc-plugins/latent_entropy_plugin.c | |
| parent | 1fefc8ecb834c88edfc27e712d683872d0c541dd (diff) | |
| parent | c47452194641b5d27c20e557c84a46c85fd7ce37 (diff) | |
| download | lwn-e6828be5edcfea25cd70a2d1de41085c67ef9fa5.tar.gz lwn-e6828be5edcfea25cd70a2d1de41085c67ef9fa5.zip | |
Merge tag 'spi-nor/for-5.19' into mtd/next
SPI NOR core changes:
- Read back written SR value to make sure the write was done correctly.
- Introduce a common function for Read ID that manufacturer drivers can
use to verify the Octal DTR switch worked correctly.
- Add helpers for read/write any register commands so manufacturer
drivers don't open code it every time.
- Clarify rdsr dummy cycles documentation.
- Add debugfs entry to expose internal flash parameters and state.
SPI NOR manufacturer drivers changes:
- Add support for Winbond W25Q512NW-IM, and Eon EN25QH256A.
- Move spi_nor_write_ear() to Winbond module since only Winbond flashes
use it.
- Rework Micron and Cypress Octal DTR enable methods to improve
readability.
- Use the common Read ID function to verify switch to Octal DTR mode for
Micron and Cypress flashes.
- Skip polling status on volatile register writes for Micron and Cypress
flashes since the operation is instant.
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Diffstat (limited to 'scripts/gcc-plugins/latent_entropy_plugin.c')
| -rw-r--r-- | scripts/gcc-plugins/latent_entropy_plugin.c | 44 |
1 files changed, 27 insertions, 17 deletions
diff --git a/scripts/gcc-plugins/latent_entropy_plugin.c b/scripts/gcc-plugins/latent_entropy_plugin.c index 589454bce930..8425da41de0d 100644 --- a/scripts/gcc-plugins/latent_entropy_plugin.c +++ b/scripts/gcc-plugins/latent_entropy_plugin.c @@ -86,25 +86,31 @@ static struct plugin_info latent_entropy_plugin_info = { .help = "disable\tturn off latent entropy instrumentation\n", }; -static unsigned HOST_WIDE_INT seed; -/* - * get_random_seed() (this is a GCC function) generates the seed. - * This is a simple random generator without any cryptographic security because - * the entropy doesn't come from here. - */ +static unsigned HOST_WIDE_INT deterministic_seed; +static unsigned HOST_WIDE_INT rnd_buf[32]; +static size_t rnd_idx = ARRAY_SIZE(rnd_buf); +static int urandom_fd = -1; + static unsigned HOST_WIDE_INT get_random_const(void) { - unsigned int i; - unsigned HOST_WIDE_INT ret = 0; - - for (i = 0; i < 8 * sizeof(ret); i++) { - ret = (ret << 1) | (seed & 1); - seed >>= 1; - if (ret & 1) - seed ^= 0xD800000000000000ULL; + if (deterministic_seed) { + unsigned HOST_WIDE_INT w = deterministic_seed; + w ^= w << 13; + w ^= w >> 7; + w ^= w << 17; + deterministic_seed = w; + return deterministic_seed; } - return ret; + if (urandom_fd < 0) { + urandom_fd = open("/dev/urandom", O_RDONLY); + gcc_assert(urandom_fd >= 0); + } + if (rnd_idx >= ARRAY_SIZE(rnd_buf)) { + gcc_assert(read(urandom_fd, rnd_buf, sizeof(rnd_buf)) == sizeof(rnd_buf)); + rnd_idx = 0; + } + return rnd_buf[rnd_idx++]; } static tree tree_get_random_const(tree type) @@ -537,8 +543,6 @@ static void latent_entropy_start_unit(void *gcc_data __unused, tree type, id; int quals; - seed = get_random_seed(false); - if (in_lto_p) return; @@ -573,6 +577,12 @@ __visible int plugin_init(struct plugin_name_args *plugin_info, const struct plugin_argument * const argv = plugin_info->argv; int i; + /* + * Call get_random_seed() with noinit=true, so that this returns + * 0 in the case where no seed has been passed via -frandom-seed. + */ + deterministic_seed = get_random_seed(true); + static const struct ggc_root_tab gt_ggc_r_gt_latent_entropy[] = { { .base = &latent_entropy_decl, |