diff options
Diffstat (limited to 'linker/linker_main.cpp')
| -rw-r--r-- | linker/linker_main.cpp | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/linker/linker_main.cpp b/linker/linker_main.cpp index 11d3d2914..fd1592d33 100644 --- a/linker/linker_main.cpp +++ b/linker/linker_main.cpp @@ -63,6 +63,8 @@ static ElfW(Addr) get_elf_exec_load_bias(const ElfW(Ehdr)* elf); static void get_elf_base_from_phdr(const ElfW(Phdr)* phdr_table, size_t phdr_count, ElfW(Addr)* base, ElfW(Addr)* load_bias); +static void set_bss_vma_name(soinfo* si); + // These should be preserved static to avoid emitting // RELATIVE relocations for the part of the code running // before linker links itself. @@ -366,6 +368,8 @@ static ElfW(Addr) linker_main(KernelArgumentBlock& args, const char* exe_to_load si->set_main_executable(); init_link_map_head(*si); + set_bss_vma_name(si); + // Use the executable's PT_INTERP string as the solinker filename in the // dynamic linker's module list. gdb reads both PT_INTERP and the module list, // and if the paths for the linker are different, gdb will report that the @@ -570,6 +574,31 @@ static void get_elf_base_from_phdr(const ElfW(Phdr)* phdr_table, size_t phdr_cou async_safe_fatal("Could not find a PHDR: broken executable?"); } +/* + * Set anonymous VMA name for .bss section. For DSOs loaded by the linker, this + * is done by ElfReader. This function is here for DSOs loaded by the kernel, + * namely the linker itself and the main executable. + */ +static void set_bss_vma_name(soinfo* si) { + for (size_t i = 0; i < si->phnum; ++i) { + auto phdr = &si->phdr[i]; + + if (phdr->p_type != PT_LOAD) { + continue; + } + + ElfW(Addr) seg_start = phdr->p_vaddr + si->load_bias; + ElfW(Addr) seg_page_end = PAGE_END(seg_start + phdr->p_memsz); + ElfW(Addr) seg_file_end = PAGE_END(seg_start + phdr->p_filesz); + + if (seg_page_end > seg_file_end) { + prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, + reinterpret_cast<void*>(seg_file_end), seg_page_end - seg_file_end, + ".bss"); + } + } +} + // Detect an attempt to run the linker on itself. e.g.: // /system/bin/linker64 /system/bin/linker64 // Use priority-1 to run this constructor before other constructors. @@ -660,6 +689,9 @@ __linker_init_post_relocation(KernelArgumentBlock& args, soinfo& tmp_linker_so) // couldn't make system calls on x86 at that point, but we can now... if (!tmp_linker_so.protect_relro()) __linker_cannot_link(args.argv[0]); + // And we can set VMA name for the bss section now + set_bss_vma_name(&tmp_linker_so); + // Initialize the linker's static libc's globals __libc_init_globals(); |