aboutsummaryrefslogtreecommitdiff
path: root/tinycc/i386-link.c
diff options
context:
space:
mode:
Diffstat (limited to 'tinycc/i386-link.c')
-rw-r--r--tinycc/i386-link.c325
1 files changed, 325 insertions, 0 deletions
diff --git a/tinycc/i386-link.c b/tinycc/i386-link.c
new file mode 100644
index 0000000..2fb1463
--- /dev/null
+++ b/tinycc/i386-link.c
@@ -0,0 +1,325 @@
+#ifdef TARGET_DEFS_ONLY
+
+#define EM_TCC_TARGET EM_386
+
+/* relocation type for 32 bit data relocation */
+#define R_DATA_32 R_386_32
+#define R_DATA_PTR R_386_32
+#define R_JMP_SLOT R_386_JMP_SLOT
+#define R_GLOB_DAT R_386_GLOB_DAT
+#define R_COPY R_386_COPY
+#define R_RELATIVE R_386_RELATIVE
+
+#define R_NUM R_386_NUM
+
+#define ELF_START_ADDR 0x08048000
+#define ELF_PAGE_SIZE 0x1000
+
+#define PCRELATIVE_DLLPLT 0
+#define RELOCATE_DLLPLT 1
+
+#else /* !TARGET_DEFS_ONLY */
+
+#include "tcc.h"
+
+#ifdef NEED_RELOC_TYPE
+/* Returns 1 for a code relocation, 0 for a data relocation. For unknown
+ relocations, returns -1. */
+int code_reloc (int reloc_type)
+{
+ switch (reloc_type) {
+ case R_386_RELATIVE:
+ case R_386_16:
+ case R_386_32:
+ case R_386_GOTPC:
+ case R_386_GOTOFF:
+ case R_386_GOT32:
+ case R_386_GOT32X:
+ case R_386_GLOB_DAT:
+ case R_386_COPY:
+ case R_386_TLS_GD:
+ case R_386_TLS_LDM:
+ case R_386_TLS_LDO_32:
+ case R_386_TLS_LE:
+ return 0;
+
+ case R_386_PC16:
+ case R_386_PC32:
+ case R_386_PLT32:
+ case R_386_JMP_SLOT:
+ return 1;
+ }
+ return -1;
+}
+
+/* Returns an enumerator to describe whether and when the relocation needs a
+ GOT and/or PLT entry to be created. See tcc.h for a description of the
+ different values. */
+int gotplt_entry_type (int reloc_type)
+{
+ switch (reloc_type) {
+ case R_386_RELATIVE:
+ case R_386_16:
+ case R_386_GLOB_DAT:
+ case R_386_JMP_SLOT:
+ case R_386_COPY:
+ return NO_GOTPLT_ENTRY;
+
+ case R_386_32:
+ /* This relocations shouldn't normally need GOT or PLT
+ slots if it weren't for simplicity in the code generator.
+ See our caller for comments. */
+ return AUTO_GOTPLT_ENTRY;
+
+ case R_386_PC16:
+ case R_386_PC32:
+ return AUTO_GOTPLT_ENTRY;
+
+ case R_386_GOTPC:
+ case R_386_GOTOFF:
+ return BUILD_GOT_ONLY;
+
+ case R_386_GOT32:
+ case R_386_GOT32X:
+ case R_386_PLT32:
+ case R_386_TLS_GD:
+ case R_386_TLS_LDM:
+ case R_386_TLS_LDO_32:
+ case R_386_TLS_LE:
+ return ALWAYS_GOTPLT_ENTRY;
+ }
+ return -1;
+}
+
+#ifdef NEED_BUILD_GOT
+ST_FUNC unsigned create_plt_entry(TCCState *s1, unsigned got_offset, struct sym_attr *attr)
+{
+ Section *plt = s1->plt;
+ uint8_t *p;
+ int modrm;
+ unsigned plt_offset, relofs;
+
+ /* on i386 if we build a DLL, we add a %ebx offset */
+ if (s1->output_type & TCC_OUTPUT_DYN)
+ modrm = 0xa3;
+ else
+ modrm = 0x25;
+
+ /* empty PLT: create PLT0 entry that pushes the library identifier
+ (GOT + PTR_SIZE) and jumps to ld.so resolution routine
+ (GOT + 2 * PTR_SIZE) */
+ if (plt->data_offset == 0) {
+ p = section_ptr_add(plt, 16);
+ p[0] = 0xff; /* pushl got + PTR_SIZE */
+ p[1] = modrm + 0x10;
+ write32le(p + 2, PTR_SIZE);
+ p[6] = 0xff; /* jmp *(got + PTR_SIZE * 2) */
+ p[7] = modrm;
+ write32le(p + 8, PTR_SIZE * 2);
+ }
+ plt_offset = plt->data_offset;
+
+ /* The PLT slot refers to the relocation entry it needs via offset.
+ The reloc entry is created below, so its offset is the current
+ data_offset */
+ relofs = s1->plt->reloc ? s1->plt->reloc->data_offset : 0;
+
+ /* Jump to GOT entry where ld.so initially put the address of ip + 4 */
+ p = section_ptr_add(plt, 16);
+ p[0] = 0xff; /* jmp *(got + x) */
+ p[1] = modrm;
+ write32le(p + 2, got_offset);
+ p[6] = 0x68; /* push $xxx */
+ write32le(p + 7, relofs - sizeof (ElfW_Rel));
+ p[11] = 0xe9; /* jmp plt_start */
+ write32le(p + 12, -(plt->data_offset));
+ return plt_offset;
+}
+
+/* relocate the PLT: compute addresses and offsets in the PLT now that final
+ address for PLT and GOT are known (see fill_program_header) */
+ST_FUNC void relocate_plt(TCCState *s1)
+{
+ uint8_t *p, *p_end;
+
+ if (!s1->plt)
+ return;
+
+ p = s1->plt->data;
+ p_end = p + s1->plt->data_offset;
+
+ if (!(s1->output_type & TCC_OUTPUT_DYN) && p < p_end) {
+ add32le(p + 2, s1->got->sh_addr);
+ add32le(p + 8, s1->got->sh_addr);
+ p += 16;
+ while (p < p_end) {
+ add32le(p + 2, s1->got->sh_addr);
+ p += 16;
+ }
+ }
+
+ if (s1->plt->reloc) {
+ ElfW_Rel *rel;
+ int x = s1->plt->sh_addr + 16 + 6;
+ p = s1->got->data;
+ for_each_elem(s1->plt->reloc, 0, rel, ElfW_Rel) {
+ write32le(p + rel->r_offset, x);
+ x += 16;
+ }
+ }
+}
+#endif
+#endif
+
+void relocate(TCCState *s1, ElfW_Rel *rel, int type, unsigned char *ptr, addr_t addr, addr_t val)
+{
+ int sym_index, esym_index;
+
+ sym_index = ELFW(R_SYM)(rel->r_info);
+
+ switch (type) {
+ case R_386_32:
+ if (s1->output_type & TCC_OUTPUT_DYN) {
+ esym_index = get_sym_attr(s1, sym_index, 0)->dyn_index;
+ qrel->r_offset = rel->r_offset;
+ if (esym_index) {
+ qrel->r_info = ELFW(R_INFO)(esym_index, R_386_32);
+ qrel++;
+ return;
+ } else {
+ qrel->r_info = ELFW(R_INFO)(0, R_386_RELATIVE);
+ qrel++;
+ }
+ }
+ add32le(ptr, val);
+ return;
+ case R_386_PC32:
+ if (s1->output_type == TCC_OUTPUT_DLL) {
+ /* DLL relocation */
+ esym_index = get_sym_attr(s1, sym_index, 0)->dyn_index;
+ if (esym_index) {
+ qrel->r_offset = rel->r_offset;
+ qrel->r_info = ELFW(R_INFO)(esym_index, R_386_PC32);
+ qrel++;
+ return;
+ }
+ }
+ add32le(ptr, val - addr);
+ return;
+ case R_386_PLT32:
+ add32le(ptr, val - addr);
+ return;
+ case R_386_GLOB_DAT:
+ case R_386_JMP_SLOT:
+ write32le(ptr, val);
+ return;
+ case R_386_GOTPC:
+ add32le(ptr, s1->got->sh_addr - addr);
+ return;
+ case R_386_GOTOFF:
+ add32le(ptr, val - s1->got->sh_addr);
+ return;
+ case R_386_GOT32:
+ case R_386_GOT32X:
+ /* we load the got offset */
+ add32le(ptr, get_sym_attr(s1, sym_index, 0)->got_offset);
+ return;
+ case R_386_16:
+ if (s1->output_format != TCC_OUTPUT_FORMAT_BINARY) {
+ output_file:
+ tcc_error_noabort("can only produce 16-bit binary files");
+ }
+ write16le(ptr, read16le(ptr) + val);
+ return;
+ case R_386_PC16:
+ if (s1->output_format != TCC_OUTPUT_FORMAT_BINARY)
+ goto output_file;
+ write16le(ptr, read16le(ptr) + val - addr);
+ return;
+ case R_386_RELATIVE:
+#ifdef TCC_TARGET_PE
+ add32le(ptr, val - s1->pe_imagebase);
+#endif
+ /* do nothing */
+ return;
+ case R_386_COPY:
+ /* This relocation must copy initialized data from the library
+ to the program .bss segment. Currently made like for ARM
+ (to remove noise of default case). Is this true?
+ */
+ return;
+ case R_386_TLS_GD:
+ {
+ static const unsigned char expect[] = {
+ /* lea 0(,%ebx,1),%eax */
+ 0x8d, 0x04, 0x1d, 0x00, 0x00, 0x00, 0x00,
+ /* call __tls_get_addr@PLT */
+ 0xe8, 0xfc, 0xff, 0xff, 0xff };
+ static const unsigned char replace[] = {
+ /* mov %gs:0,%eax */
+ 0x65, 0xa1, 0x00, 0x00, 0x00, 0x00,
+ /* sub 0,%eax */
+ 0x81, 0xe8, 0x00, 0x00, 0x00, 0x00 };
+
+ if (memcmp (ptr-3, expect, sizeof(expect)) == 0) {
+ ElfW(Sym) *sym;
+ Section *sec;
+ int32_t x;
+
+ memcpy(ptr-3, replace, sizeof(replace));
+ rel[1].r_info = ELFW(R_INFO)(0, R_386_NONE);
+ sym = &((ElfW(Sym) *)symtab_section->data)[sym_index];
+ sec = s1->sections[sym->st_shndx];
+ x = sym->st_value - sec->sh_addr - sec->data_offset;
+ add32le(ptr + 5, -x);
+ }
+ else
+ tcc_error_noabort("unexpected R_386_TLS_GD pattern");
+ }
+ return;
+ case R_386_TLS_LDM:
+ {
+ static const unsigned char expect[] = {
+ /* lea 0(%ebx),%eax */
+ 0x8d, 0x83, 0x00, 0x00, 0x00, 0x00,
+ /* call __tls_get_addr@PLT */
+ 0xe8, 0xfc, 0xff, 0xff, 0xff };
+ static const unsigned char replace[] = {
+ /* mov %gs:0,%eax */
+ 0x65, 0xa1, 0x00, 0x00, 0x00, 0x00,
+ /* nop */
+ 0x90,
+ /* lea 0(%esi,%eiz,1),%esi */
+ 0x8d, 0x74, 0x26, 0x00 };
+
+ if (memcmp (ptr-2, expect, sizeof(expect)) == 0) {
+ memcpy(ptr-2, replace, sizeof(replace));
+ rel[1].r_info = ELFW(R_INFO)(0, R_386_NONE);
+ }
+ else
+ tcc_error_noabort("unexpected R_386_TLS_LDM pattern");
+ }
+ return;
+ case R_386_TLS_LDO_32:
+ case R_386_TLS_LE:
+ {
+ ElfW(Sym) *sym;
+ Section *sec;
+ int32_t x;
+
+ sym = &((ElfW(Sym) *)symtab_section->data)[sym_index];
+ sec = s1->sections[sym->st_shndx];
+ x = val - sec->sh_addr - sec->data_offset;
+ add32le(ptr, x);
+ }
+ return;
+ case R_386_NONE:
+ return;
+ default:
+ fprintf(stderr,"FIXME: handle reloc type %d at %x [%p] to %x\n",
+ type, (unsigned)addr, ptr, (unsigned)val);
+ return;
+ }
+}
+
+#endif /* !TARGET_DEFS_ONLY */
generated by cgit v1.2.3 (git 2.39.1) at 2025-12-16 15:47:31 +0000