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Diffstat (limited to 'util/pgtblgen/pgtblgen.c')
| -rw-r--r-- | util/pgtblgen/pgtblgen.c | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/util/pgtblgen/pgtblgen.c b/util/pgtblgen/pgtblgen.c new file mode 100644 index 0000000000..efbad55204 --- /dev/null +++ b/util/pgtblgen/pgtblgen.c @@ -0,0 +1,168 @@ +/* + * This file is part of pgtblgen. + * + * Copyright (c) 2019 Patrick Rudolph <siro@das-labor.org> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * This program 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 General Public License for more details. + */ + +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <string.h> +#include <sys/types.h> +#include <sys/stat.h> +#include <fcntl.h> +#include <errno.h> +#include <inttypes.h> + +static void usage(char *argv[]) +{ + printf("usage: %s -b <addr> -a <arch> -o <file>\n", argv[0]); + printf(" -a\t architecure. Supported: x86_64\n"); + printf(" -b\t base address\n"); + printf(" -b\t the file to write to\n"); + printf(" -h\t show this help text\n"); +} + +/* + * For reference see "AMD64 ArchitectureProgrammer's Manual Volume 2", + * Document 24593-Rev. 3.31-July 2019 Chapter 5.3.4 + * + * Page table attributes: WB, User+Supervisor, Present, Writeable + */ +#define PRES (1ULL << 0) +#define RW (1ULL << 1) +#define US (1ULL << 2) +#define PS (1ULL << 7) +#define _GEN_DIR(a) (PRES | RW | US | (a)) +#define _GEN_PAGE(a) (PRES | RW | US | PS | (a)) + +/* + * Generate x86_64 page tables. + * The page tables needs to be placed at @base_address, and identity map + * the first @size_gib GiB of physical memory. + */ +static int gen_pgtbl_x86_64(const uint64_t base_address, + const size_t size_gib, + void **out_buf, + size_t *out_size) +{ + uint64_t *entry; + + if (!out_size || !out_buf) + return 1; + + *out_size = (size_gib + 2) * 4096; + *out_buf = malloc(*out_size); + if (!*out_buf) + return 1; + + memset(*out_buf, 0, *out_size); + entry = (uint64_t *)*out_buf; + + /* Generate one PM4LE entry - point to PDPE */ + entry[0] = _GEN_DIR(base_address + 4096); + entry += 512; + + /* PDPE table - point to PDE */ + for (size_t i = 0; i < size_gib; i++) + entry[i] = _GEN_DIR(base_address + 4096 * (i + 2)); + entry += 512; + + /* PDE tables - identity map 2MiB pages */ + for (size_t g = 0; g < size_gib; g++) { + for (size_t i = 0; i < 512; i++) { + uint64_t addr = ((1ULL << (12 + 9)) * i) | ((1ULL << (12 + 9 + 9)) * g); + entry[i] = _GEN_PAGE(addr); + } + entry += 512; + } + + return 0; +} + +int main(int argc, char *argv[]) +{ + int ret = 1; + uint64_t base_address = 0; + char *filename = NULL; + char *arch = NULL; + void *buf = NULL; + size_t buf_size = 0; + int c; + + while ((c = getopt(argc, argv, "ho:a:b:")) != -1) + switch (c) { + case '?': /* falltrough */ + case 'h': + usage(argv); + return 0; + case 'o': + filename = optarg; + break; + case 'a': + arch = optarg; + break; + case 'b': + base_address = strtoull(optarg, NULL, 0); + break; + default: + break; + } + + if (!filename) { + fprintf(stderr, "E: Missing filename.\n"); + goto done; + } + if (!arch) { + fprintf(stderr, "E: Missing architecture.\n"); + goto done; + } else if (strcmp(arch, "x86_64") != 0) { + fprintf(stderr, "E: Unsupported architecture.\n"); + goto done; + } + if (base_address & 4095) { + fprintf(stderr, "E: Base address not 4 KiB aligned\n"); + goto done; + } + + /* FIXME: Identity map 4GiB for now, increase if necessary */ + if (strcmp(arch, "x86_64") == 0) + ret = gen_pgtbl_x86_64(base_address, 4, &buf, &buf_size); + + if (ret) { + fprintf(stderr, "Failed to generate page tables\n"); + goto done; + } + + // write the table + FILE *fd = fopen(filename, "wb"); + if (!fd) { + fprintf(stderr, "%s open failed: %s\n", filename, strerror(errno)); + goto done; + } + + if (fwrite(buf, 1, buf_size, fd) != buf_size) { + fprintf(stderr, "%s write failed: %s\n", filename, strerror(errno)); + fclose(fd); + goto done; + } + + if (fclose(fd)) { + fprintf(stderr, "%s close failed: %s\n", filename, strerror(errno)); + goto done; + } + + ret = 0; +done: + free(buf); + return ret; +} |