dynamic executables (PIE)

Allows to create dynamic executables, using the code path
for TCC_OUTPUT_DLL but add an .interp header (plus a FLAGS_1
entry in the dynamic section to make 'readelf' say "PIE")

Introduces TCC_OUTPUT_DYN as alias for TCC_OUTPUT_DLL.
There is no runtime option,  only one to configure:

    ./configure --config-pie

100 insertions(+), 76 deletions(-)

Author: grischka

Makefile

@@ -91,6 +91,7 @@ NATIVE_DEFINES_$(CONFIG_arm64) += -DTCC_TARGET_ARM64
 NATIVE_DEFINES_$(CONFIG_riscv64) += -DTCC_TARGET_RISCV64
 NATIVE_DEFINES_$(CONFIG_BSD) += -DTARGETOS_$(TARGETOS)
 NATIVE_DEFINES_$(CONFIG_pie) += -DCONFIG_TCC_PIE
+NATIVE_DEFINES_$(CONFIG_pic) += -DCONFIG_TCC_PIC
 NATIVE_DEFINES_no_$(CONFIG_bcheck) += -DCONFIG_TCC_BCHECK=0
 NATIVE_DEFINES_no_$(CONFIG_backtrace) += -DCONFIG_TCC_BACKTRACE=0
 NATIVE_DEFINES += $(NATIVE_DEFINES_yes) $(NATIVE_DEFINES_no_no)
@@ -275,7 +276,7 @@ libtcc.a: $(LIBTCC_OBJ)
 
 # dynamic libtcc library
 libtcc.so: $(LIBTCC_OBJ)
-	$S$(CC) -shared -Wl,-soname,$@ -o $@ $^ $(LDFLAGS)
+	$S$(CC) -shared -Wl,-soname,$@ -o $@ $^ $(LIBS) $(LDFLAGS)
 
 libtcc.so: CFLAGS+=-fPIC
 libtcc.so: LDFLAGS+=-fPIC

arm-gen.c

@@ -543,7 +543,7 @@ static void load_value(SValue *sv, int r)
 {
     o(0xE59F0000|(intr(r)<<12)); /* ldr r, [pc] */
     o(0xEA000000); /* b $+4 */
-#ifndef CONFIG_TCC_PIE
+#ifndef CONFIG_TCC_PIC
     if(sv->r & VT_SYM)
         greloc(cur_text_section, sv->sym, ind, R_ARM_ABS32);
     o(sv->c.i);

arm-link.c

@@ -380,7 +380,7 @@ void relocate(TCCState *s1, ElfW_Rel *rel, int type, unsigned char *ptr, addr_t
             return;
         case R_ARM_ABS32:
         case R_ARM_TARGET1:
-            if (s1->output_type == TCC_OUTPUT_DLL) {
+            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) {

arm64-link.c

@@ -177,7 +177,7 @@ void relocate(TCCState *s1, ElfW_Rel *rel, int type, unsigned char *ptr, addr_t
 
     switch(type) {
         case R_AARCH64_ABS64:
-            if (s1->output_type == TCC_OUTPUT_DLL) {
+            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) {
@@ -194,7 +194,7 @@ void relocate(TCCState *s1, ElfW_Rel *rel, int type, unsigned char *ptr, addr_t
             add64le(ptr, val);
             return;
         case R_AARCH64_ABS32:
-            if (s1->output_type == TCC_OUTPUT_DLL) {
+            if (s1->output_type & TCC_OUTPUT_DYN) {
                 /* XXX: this logic may depend on TCC's codegen
                    now TCC uses R_AARCH64_RELATIVE even for a 64bit pointer */
                 qrel->r_offset = rel->r_offset;

elf.h

@@ -825,6 +825,7 @@ typedef struct
 #define	DF_1_SYMINTPOSE	0x00800000	/* Object has individual interposers.  */
 #define	DF_1_GLOBAUDIT	0x01000000	/* Global auditing required.  */
 #define	DF_1_SINGLETON	0x02000000	/* Singleton symbols are used.  */
+#define	DF_1_PIE	0x08000000
 
 /* Flags for the feature selection in DT_FEATURE_1.  */
 #define DTF_1_PARINIT	0x00000001

i386-link.c

@@ -100,7 +100,7 @@ ST_FUNC unsigned create_plt_entry(TCCState *s1, unsigned got_offset, struct sym_
     unsigned plt_offset, relofs;
 
     /* on i386 if we build a DLL, we add a %ebx offset */
-    if (s1->output_type == TCC_OUTPUT_DLL)
+    if (s1->output_type & TCC_OUTPUT_DYN)
         modrm = 0xa3;
     else
         modrm = 0x25;
@@ -148,7 +148,7 @@ ST_FUNC void relocate_plt(TCCState *s1)
     p = s1->plt->data;
     p_end = p + s1->plt->data_offset;
 
-    if (s1->output_type != TCC_OUTPUT_DLL && p < p_end) {
+    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;
@@ -179,7 +179,7 @@ void relocate(TCCState *s1, ElfW_Rel *rel, int type, unsigned char *ptr, addr_t
 
     switch (type) {
         case R_386_32:
-            if (s1->output_type == TCC_OUTPUT_DLL) {
+            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) {

libtcc.c

@@ -862,13 +862,21 @@ LIBTCCAPI void tcc_delete(TCCState *s1)
 
 LIBTCCAPI int tcc_set_output_type(TCCState *s, int output_type)
 {
+#ifdef CONFIG_TCC_PIE
+    if (output_type == TCC_OUTPUT_EXE)
+        output_type |= TCC_OUTPUT_DYN;
+#endif
     s->output_type = output_type;
 
     if (!s->nostdinc) {
         /* default include paths */
         /* -isystem paths have already been handled */
         tcc_add_sysinclude_path(s, CONFIG_TCC_SYSINCLUDEPATHS);
     }
+
+    if (output_type == TCC_OUTPUT_PREPROCESS)
+        return 0;
+
 #ifdef CONFIG_TCC_BCHECK
     if (s->do_bounds_check) {
         /* if bound checking, then add corresponding sections */
@@ -905,13 +913,13 @@ LIBTCCAPI int tcc_set_output_type(TCCState *s, int output_type)
 #else
     /* paths for crt objects */
     tcc_split_path(s, &s->crt_paths, &s->nb_crt_paths, CONFIG_TCC_CRTPREFIX);
+
     /* add libc crt1/crti objects */
-    if ((output_type == TCC_OUTPUT_EXE || output_type == TCC_OUTPUT_DLL) &&
-        !s->nostdlib) {
+    if (output_type != TCC_OUTPUT_MEMORY && !s->nostdlib) {
 #if TARGETOS_OpenBSD
         if (output_type != TCC_OUTPUT_DLL)
 	    tcc_add_crt(s, "crt0.o");
-        if (output_type == TCC_OUTPUT_DLL)
+        if (output_type & TCC_OUTPUT_DYN)
             tcc_add_crt(s, "crtbeginS.o");
         else
             tcc_add_crt(s, "crtbegin.o");
@@ -921,7 +929,7 @@ LIBTCCAPI int tcc_set_output_type(TCCState *s, int output_type)
         tcc_add_crt(s, "crti.o");
         if (s->static_link)
             tcc_add_crt(s, "crtbeginT.o");
-        else if (output_type == TCC_OUTPUT_DLL)
+        else if (output_type & TCC_OUTPUT_DYN)
             tcc_add_crt(s, "crtbeginS.o");
         else
             tcc_add_crt(s, "crtbegin.o");
@@ -931,7 +939,7 @@ LIBTCCAPI int tcc_set_output_type(TCCState *s, int output_type)
         tcc_add_crt(s, "crti.o");
         if (s->static_link)
             tcc_add_crt(s, "crtbeginT.o");
-        else if (output_type == TCC_OUTPUT_DLL)
+        else if (output_type & TCC_OUTPUT_DYN)
             tcc_add_crt(s, "crtbeginS.o");
         else
             tcc_add_crt(s, "crtbegin.o");

libtcc.h

@@ -65,11 +65,11 @@ LIBTCCAPI int tcc_compile_string(TCCState *s, const char *buf);
 
 /* set output type. MUST BE CALLED before any compilation */
 LIBTCCAPI int tcc_set_output_type(TCCState *s, int output_type);
-#define TCC_OUTPUT_MEMORY   1 /* output will be run in memory (default) */
+#define TCC_OUTPUT_MEMORY   1 /* output will be run in memory */
 #define TCC_OUTPUT_EXE      2 /* executable file */
-#define TCC_OUTPUT_DLL      3 /* dynamic library */
-#define TCC_OUTPUT_OBJ      4 /* object file */
-#define TCC_OUTPUT_PREPROCESS 5 /* only preprocess (used internally) */
+#define TCC_OUTPUT_DLL      4 /* dynamic library */
+#define TCC_OUTPUT_OBJ      3 /* object file */
+#define TCC_OUTPUT_PREPROCESS 5 /* only preprocess */
 
 /* equivalent to -Lpath option */
 LIBTCCAPI int tcc_add_library_path(TCCState *s, const char *pathname);

riscv64-link.c

@@ -284,7 +284,7 @@ void relocate(TCCState *s1, ElfW_Rel *rel, int type, unsigned char *ptr,
         return;
 
     case R_RISCV_32:
-        if (s1->output_type == TCC_OUTPUT_DLL) {
+        if (s1->output_type & TCC_OUTPUT_DYN) {
             /* XXX: this logic may depend on TCC's codegen
                now TCC uses R_RISCV_RELATIVE even for a 64bit pointer */
             qrel->r_offset = rel->r_offset;
@@ -296,7 +296,7 @@ void relocate(TCCState *s1, ElfW_Rel *rel, int type, unsigned char *ptr,
         add32le(ptr, val);
         return;
     case R_RISCV_64:
-        if (s1->output_type == TCC_OUTPUT_DLL) {
+        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) {

tcc.h

@@ -236,6 +236,10 @@ extern long double strtold (const char *__nptr, char **__endptr);
 # define TCC_USING_DOUBLE_FOR_LDOUBLE 1
 #endif
 
+#ifdef CONFIG_TCC_PIE
+# define CONFIG_TCC_PIC 1
+#endif
+
 /* ------------ path configuration ------------ */
 
 #ifndef CONFIG_SYSROOT
@@ -1485,6 +1489,7 @@ ST_DATA int func_bound_add_epilog;
 #define TCC_OUTPUT_FORMAT_ELF    0 /* default output format: ELF */
 #define TCC_OUTPUT_FORMAT_BINARY 1 /* binary image output */
 #define TCC_OUTPUT_FORMAT_COFF   2 /* COFF */
+#define TCC_OUTPUT_DYN           TCC_OUTPUT_DLL
 
 #define ARMAG  "!<arch>\012"    /* For COFF and a.out archives */
 

tccdbg.c

@@ -392,9 +392,7 @@ ST_FUNC void tcc_debug_new(TCCState *s1)
 #ifdef CONFIG_TCC_BACKTRACE
     /* include stab info with standalone backtrace support */
     if (s1->do_backtrace
-        && (s1->output_type == TCC_OUTPUT_EXE
-         || s1->output_type == TCC_OUTPUT_DLL)
-         )
+        && (s1->output_type & (TCC_OUTPUT_EXE | TCC_OUTPUT_DLL)))
         shf = SHF_ALLOC | SHF_WRITE; // SHF_WRITE needed for musl/SELINUX
 #endif
     if (s1->dwarf) {