mcc
mcc is a machine code compiler.
Log | Files | << Repositories
tree 7b8ef09c2cd9a75d4a21641cf69a9d0817767738 parent ff8d72389ceaa418bf7acde18b77deae2ed0edfa author esote <esote.net@gmail.com> 1558063048 -0500 committer esote <esote.net@gmail.com> 1558063048 -0500 gpgsig -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQTXAxYDuIzimYoNSPuhTmRAjzzC8gUCXSArFwAKCRChTmRAjzzC 8h6UAQCPCNJCSkBokGxHzgsZyP8IlC0TeDOSq11MTtAT/JEzZwD9Hi64eoJUjMhu 6sy4jI65Q8b59Jj9fKrOLJOrw9hL2wc= =59ga -----END PGP SIGNATURE----- Keep track of elf + program hdr offset Wrap macros to ensure correct evaluation order. Show logical address alignment values.
mcc.c | 59 +++++++++++++++++++++++++++++++++-------------------------- 1 file changed, 33 insertions(+), 26 deletions(-)
diff --git a/mcc.c b/mcc.c
index a887bba..3b700a1 100644
--- a/mcc.c
+++ b/mcc.c
@@ -28,9 +28,9 @@
uint32_t byte_len(FILE *const);
-void write_elf_hdr(FILE *const, uint32_t const);
+uint32_t write_elf_hdr(FILE *const, uint32_t const);
-void write_text_hdr(FILE *const, uint32_t const);
+void write_text_hdr(FILE *const, uint32_t const, uint32_t const);
void write_bss_hdr(FILE *const, uint32_t const);
void write_mcode(FILE *const, FILE *const);
@@ -38,23 +38,27 @@ void write_mcode(FILE *const, FILE *const);
void write_section_names(FILE *const);
void write_null_section(FILE *const);
-void write_text_section(FILE *const, uint32_t const);
+void write_text_section(FILE *const, uint32_t const, uint32_t const);
void write_bss_section(FILE *const, uint32_t const);
-void write_shstrtab_section(FILE *const, uint32_t const);
+void write_shstrtab_section(FILE *const, uint32_t const, uint32_t const);
#define BSS_VADDR 0x804a000
#define TEXT_VADDR 0x8049000
/* length of section header string including null terminator */
-#define NULL_LEN 0+1
-#define SHSTRTAB_LEN 9+1
-#define TEXT_LEN 5+1
-#define BSS_LEN 4+1
+#define NULL_LEN (0 + 1)
+#define SHSTRTAB_LEN (9 + 1)
+#define TEXT_LEN (5 + 1)
+#define BSS_LEN (4 + 1)
+
+#define SHSTRTAB_ADDRALIGN (1 << 0)
+#define BSS_ADDRALIGN (1 << 2)
+#define TEXT_ADDRALIGN (1 << 4)
/* index in section header string table section */
#define SHSTRTAB_INDEX 1
-#define TEXT_INDEX SHSTRTAB_LEN+1
-#define BSS_INDEX SHSTRTAB_LEN+TEXT_LEN+1
+#define TEXT_INDEX (SHSTRTAB_LEN + 1)
+#define BSS_INDEX (SHSTRTAB_LEN + TEXT_LEN+1)
#define PAGE_SIZE 4096
@@ -71,6 +75,7 @@ main(int argc, char *argv[])
char const *oname;
uint32_t len;
uint32_t mem;
+ uint32_t off;
int ch;
oname = "a.out";
@@ -114,9 +119,9 @@ main(int argc, char *argv[])
len = byte_len(in);
- write_elf_hdr(out, len);
+ off = write_elf_hdr(out, len);
- write_text_hdr(out, len);
+ write_text_hdr(out, off, len);
write_bss_hdr(out, mem);
write_mcode(in, out);
@@ -124,9 +129,9 @@ main(int argc, char *argv[])
write_section_names(out);
write_null_section(out);
- write_text_section(out, len);
+ write_text_section(out, off, len);
write_bss_section(out, mem);
- write_shstrtab_section(out, len);
+ write_shstrtab_section(out, off, len);
if (fclose(in) == EOF) {
err(1, "close in");
@@ -182,7 +187,7 @@ out:
return len / 8;
}
-void
+uint32_t
write_elf_hdr(FILE *const out, uint32_t const len)
{
Elf32_Ehdr e = {0};
@@ -226,10 +231,13 @@ write_elf_hdr(FILE *const out, uint32_t const len)
if (fwrite(&e, sizeof(Elf32_Ehdr), 1, out) != 1) {
err(1, "write elf hdr");
}
+
+ /* return offset to mcode */
+ return e.e_ehsize + e.e_phnum * e.e_phentsize;
}
void
-write_text_hdr(FILE *const out, uint32_t const len)
+write_text_hdr(FILE *const out, uint32_t const off, uint32_t const len)
{
Elf32_Phdr text = {0};
@@ -237,8 +245,7 @@ write_text_hdr(FILE *const out, uint32_t const len)
text.p_offset = 0;
text.p_vaddr = TEXT_VADDR;
text.p_paddr = text.p_vaddr;
- /* TODO magic */
- text.p_filesz = len + sizeof(Elf32_Ehdr) + 2 * sizeof(Elf32_Phdr);
+ text.p_filesz = len + off;
text.p_memsz = text.p_filesz;
/* TODO support self-modifying (PF_X | PF_R | PF_W) */
text.p_flags = PF_X | PF_R;
@@ -344,19 +351,19 @@ write_null_section(FILE *const out)
}
void
-write_text_section(FILE *const out, uint32_t const len)
+write_text_section(FILE *const out, uint32_t const off, uint32_t const len)
{
Elf32_Shdr text = {0};
text.sh_name = TEXT_INDEX;
text.sh_type = SHT_PROGBITS;
text.sh_flags = SHF_ALLOC | SHF_EXECINSTR;
- text.sh_addr = TEXT_VADDR + sizeof(Elf32_Ehdr) + 2 * sizeof(Elf32_Phdr);
- text.sh_offset = sizeof(Elf32_Ehdr) + 2 * sizeof(Elf32_Phdr);
+ text.sh_addr = TEXT_VADDR + off;
+ text.sh_offset = off;
text.sh_size = len;
text.sh_link = 0;
text.sh_info = 0;
- text.sh_addralign = 0x10;
+ text.sh_addralign = TEXT_ADDRALIGN;
text.sh_entsize = 0;
if (fwrite(&text, sizeof(Elf32_Shdr), 1, out) != 1) {
@@ -378,7 +385,7 @@ write_bss_section(FILE *const out, uint32_t const mem)
bss.sh_size = mem;
bss.sh_link = 0;
bss.sh_info = 0;
- bss.sh_addralign = 0x04;
+ bss.sh_addralign = BSS_ADDRALIGN;
bss.sh_entsize = 0;
if (fwrite(&bss, sizeof(Elf32_Shdr), 1, out) != 1) {
@@ -387,7 +394,7 @@ write_bss_section(FILE *const out, uint32_t const mem)
}
void
-write_shstrtab_section(FILE *const out, uint32_t const len)
+write_shstrtab_section(FILE *const out, uint32_t const off, uint32_t const len)
{
Elf32_Shdr shstrtab = {0};
@@ -396,11 +403,11 @@ write_shstrtab_section(FILE *const out, uint32_t const len)
shstrtab.sh_flags = 0;
shstrtab.sh_addr = 0;
/* TODO magic */
- shstrtab.sh_offset = sizeof(Elf32_Ehdr) + 2*sizeof(Elf32_Phdr) + len;
+ shstrtab.sh_offset = off + len;
shstrtab.sh_size = NULL_LEN + SHSTRTAB_LEN + TEXT_LEN + BSS_LEN;
shstrtab.sh_link = 0;
shstrtab.sh_info = 0;
- shstrtab.sh_addralign = 0x01;
+ shstrtab.sh_addralign = SHSTRTAB_ADDRALIGN;
shstrtab.sh_entsize = 0;
if (fwrite(&shstrtab, sizeof(Elf32_Shdr), 1, out) != 1) {