diff options
Diffstat (limited to 'linux-user/gen-vdso-elfn.c.inc')
| -rw-r--r-- | linux-user/gen-vdso-elfn.c.inc | 307 |
1 files changed, 307 insertions, 0 deletions
diff --git a/linux-user/gen-vdso-elfn.c.inc b/linux-user/gen-vdso-elfn.c.inc new file mode 100644 index 0000000000..7034c36d5e --- /dev/null +++ b/linux-user/gen-vdso-elfn.c.inc @@ -0,0 +1,307 @@ +/* + * Post-process a vdso elf image for inclusion into qemu. + * Elf size specialization. + * + * Copyright 2023 Linaro, Ltd. + * + * SPDX-License-Identifier: GPL-2.0-or-later + */ + +static void elfN(bswap_ehdr)(ElfN(Ehdr) *ehdr) +{ + bswaps(&ehdr->e_type); /* Object file type */ + bswaps(&ehdr->e_machine); /* Architecture */ + bswaps(&ehdr->e_version); /* Object file version */ + bswaps(&ehdr->e_entry); /* Entry point virtual address */ + bswaps(&ehdr->e_phoff); /* Program header table file offset */ + bswaps(&ehdr->e_shoff); /* Section header table file offset */ + bswaps(&ehdr->e_flags); /* Processor-specific flags */ + bswaps(&ehdr->e_ehsize); /* ELF header size in bytes */ + bswaps(&ehdr->e_phentsize); /* Program header table entry size */ + bswaps(&ehdr->e_phnum); /* Program header table entry count */ + bswaps(&ehdr->e_shentsize); /* Section header table entry size */ + bswaps(&ehdr->e_shnum); /* Section header table entry count */ + bswaps(&ehdr->e_shstrndx); /* Section header string table index */ +} + +static void elfN(bswap_phdr)(ElfN(Phdr) *phdr) +{ + bswaps(&phdr->p_type); /* Segment type */ + bswaps(&phdr->p_flags); /* Segment flags */ + bswaps(&phdr->p_offset); /* Segment file offset */ + bswaps(&phdr->p_vaddr); /* Segment virtual address */ + bswaps(&phdr->p_paddr); /* Segment physical address */ + bswaps(&phdr->p_filesz); /* Segment size in file */ + bswaps(&phdr->p_memsz); /* Segment size in memory */ + bswaps(&phdr->p_align); /* Segment alignment */ +} + +static void elfN(bswap_shdr)(ElfN(Shdr) *shdr) +{ + bswaps(&shdr->sh_name); + bswaps(&shdr->sh_type); + bswaps(&shdr->sh_flags); + bswaps(&shdr->sh_addr); + bswaps(&shdr->sh_offset); + bswaps(&shdr->sh_size); + bswaps(&shdr->sh_link); + bswaps(&shdr->sh_info); + bswaps(&shdr->sh_addralign); + bswaps(&shdr->sh_entsize); +} + +static void elfN(bswap_sym)(ElfN(Sym) *sym) +{ + bswaps(&sym->st_name); + bswaps(&sym->st_value); + bswaps(&sym->st_size); + bswaps(&sym->st_shndx); +} + +static void elfN(bswap_dyn)(ElfN(Dyn) *dyn) +{ + bswaps(&dyn->d_tag); /* Dynamic type tag */ + bswaps(&dyn->d_un.d_ptr); /* Dynamic ptr or val, in union */ +} + +static void elfN(search_symtab)(ElfN(Shdr) *shdr, unsigned sym_idx, + void *buf, bool need_bswap) +{ + unsigned str_idx = shdr[sym_idx].sh_link; + ElfN(Sym) *sym = buf + shdr[sym_idx].sh_offset; + unsigned sym_n = shdr[sym_idx].sh_size / sizeof(*sym); + const char *str = buf + shdr[str_idx].sh_offset; + + for (unsigned i = 0; i < sym_n; ++i) { + const char *name; + + if (need_bswap) { + elfN(bswap_sym)(sym + i); + } + name = str + sym[i].st_name; + + if (sigreturn_sym && strcmp(sigreturn_sym, name) == 0) { + sigreturn_addr = sym[i].st_value; + } + if (rt_sigreturn_sym && strcmp(rt_sigreturn_sym, name) == 0) { + rt_sigreturn_addr = sym[i].st_value; + } + } +} + +static void elfN(process)(FILE *outf, void *buf, bool need_bswap) +{ + ElfN(Ehdr) *ehdr = buf; + ElfN(Phdr) *phdr; + ElfN(Shdr) *shdr; + unsigned phnum, shnum; + unsigned dynamic_ofs = 0; + unsigned dynamic_addr = 0; + unsigned symtab_idx = 0; + unsigned dynsym_idx = 0; + unsigned first_segsz = 0; + int errors = 0; + + if (need_bswap) { + elfN(bswap_ehdr)(ehdr); + } + + phnum = ehdr->e_phnum; + phdr = buf + ehdr->e_phoff; + if (need_bswap) { + for (unsigned i = 0; i < phnum; ++i) { + elfN(bswap_phdr)(phdr + i); + } + } + + shnum = ehdr->e_shnum; + shdr = buf + ehdr->e_shoff; + if (need_bswap) { + for (unsigned i = 0; i < shnum; ++i) { + elfN(bswap_shdr)(shdr + i); + } + } + for (unsigned i = 0; i < shnum; ++i) { + switch (shdr[i].sh_type) { + case SHT_SYMTAB: + symtab_idx = i; + break; + case SHT_DYNSYM: + dynsym_idx = i; + break; + } + } + + /* + * Validate the VDSO is created as we expect: that PT_PHDR, + * PT_DYNAMIC, and PT_NOTE located in a writable data segment. + * PHDR and DYNAMIC require relocation, and NOTE will get the + * linux version number. + */ + for (unsigned i = 0; i < phnum; ++i) { + if (phdr[i].p_type != PT_LOAD) { + continue; + } + if (first_segsz != 0) { + fprintf(stderr, "Multiple LOAD segments\n"); + errors++; + } + if (phdr[i].p_offset != 0) { + fprintf(stderr, "LOAD segment does not cover EHDR\n"); + errors++; + } + if (phdr[i].p_vaddr != 0) { + fprintf(stderr, "LOAD segment not loaded at address 0\n"); + errors++; + } + first_segsz = phdr[i].p_filesz; + if (first_segsz < ehdr->e_phoff + phnum * sizeof(*phdr)) { + fprintf(stderr, "LOAD segment does not cover PHDRs\n"); + errors++; + } + if ((phdr[i].p_flags & (PF_R | PF_W)) != (PF_R | PF_W)) { + fprintf(stderr, "LOAD segment is not read-write\n"); + errors++; + } + } + for (unsigned i = 0; i < phnum; ++i) { + const char *which; + + switch (phdr[i].p_type) { + case PT_PHDR: + which = "PT_PHDR"; + break; + case PT_NOTE: + which = "PT_NOTE"; + break; + case PT_DYNAMIC: + dynamic_ofs = phdr[i].p_offset; + dynamic_addr = phdr[i].p_vaddr; + which = "PT_DYNAMIC"; + break; + default: + continue; + } + if (first_segsz < phdr[i].p_vaddr + phdr[i].p_filesz) { + fprintf(stderr, "LOAD segment does not cover %s\n", which); + errors++; + } + } + if (errors) { + exit(EXIT_FAILURE); + } + + /* Relocate the program headers. */ + for (unsigned i = 0; i < phnum; ++i) { + output_reloc(outf, buf, &phdr[i].p_vaddr); + output_reloc(outf, buf, &phdr[i].p_paddr); + } + + /* Relocate the DYNAMIC entries. */ + if (dynamic_addr) { + ElfN(Dyn) *dyn = buf + dynamic_ofs; + __typeof(dyn->d_tag) tag; + + do { + + if (need_bswap) { + elfN(bswap_dyn)(dyn); + } + tag = dyn->d_tag; + + switch (tag) { + case DT_HASH: + case DT_SYMTAB: + case DT_STRTAB: + case DT_VERDEF: + case DT_VERSYM: + case DT_PLTGOT: + case DT_ADDRRNGLO ... DT_ADDRRNGHI: + /* These entries store an address in the entry. */ + output_reloc(outf, buf, &dyn->d_un.d_val); + break; + + case DT_NULL: + case DT_STRSZ: + case DT_SONAME: + case DT_DEBUG: + case DT_FLAGS: + case DT_FLAGS_1: + case DT_SYMBOLIC: + case DT_BIND_NOW: + case DT_VERDEFNUM: + case DT_VALRNGLO ... DT_VALRNGHI: + /* These entries store an integer in the entry. */ + break; + + case DT_SYMENT: + if (dyn->d_un.d_val != sizeof(ElfN(Sym))) { + fprintf(stderr, "VDSO has incorrect dynamic symbol size\n"); + errors++; + } + break; + + case DT_REL: + case DT_RELSZ: + case DT_RELA: + case DT_RELASZ: + /* + * These entries indicate that the VDSO was built incorrectly. + * It should not have any real relocations. + * ??? The RISC-V toolchain will emit these even when there + * are no relocations. Validate zeros. + */ + if (dyn->d_un.d_val != 0) { + fprintf(stderr, "VDSO has dynamic relocations\n"); + errors++; + } + break; + case DT_RELENT: + case DT_RELAENT: + case DT_TEXTREL: + /* These entries store an integer in the entry. */ + /* Should not be required; see above. */ + break; + + case DT_NEEDED: + case DT_VERNEED: + case DT_PLTREL: + case DT_JMPREL: + case DT_RPATH: + case DT_RUNPATH: + fprintf(stderr, "VDSO has external dependencies\n"); + errors++; + break; + + default: + /* This is probably something target specific. */ + fprintf(stderr, "VDSO has unknown DYNAMIC entry (%lx)\n", + (unsigned long)tag); + errors++; + break; + } + dyn++; + } while (tag != DT_NULL); + if (errors) { + exit(EXIT_FAILURE); + } + } + + /* Relocate the dynamic symbol table. */ + if (dynsym_idx) { + ElfN(Sym) *sym = buf + shdr[dynsym_idx].sh_offset; + unsigned sym_n = shdr[dynsym_idx].sh_size / sizeof(*sym); + + for (unsigned i = 0; i < sym_n; ++i) { + output_reloc(outf, buf, &sym[i].st_value); + } + } + + /* Search both dynsym and symtab for the signal return symbols. */ + if (dynsym_idx) { + elfN(search_symtab)(shdr, dynsym_idx, buf, need_bswap); + } + if (symtab_idx) { + elfN(search_symtab)(shdr, symtab_idx, buf, need_bswap); + } +} |