X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=src%2Fldso%2Fdlstart.c;h=46f50114c0c434329ec0d0c37fdce28fc766ae66;hb=2683e267fa6c20d2e7a498a85f79a1dfc4301f23;hp=5f84465c6182d549fec5350aba79d2edef72a91b;hpb=0e0e49421f08cfd670975ecd3604f7f9015e1833;p=musl

diff --git a/src/ldso/dlstart.c b/src/ldso/dlstart.c
index 5f84465c..46f50114 100644
--- a/src/ldso/dlstart.c
+++ b/src/ldso/dlstart.c
@@ -9,10 +9,19 @@
 
 #include "crt_arch.h"
 
+#ifndef GETFUNCSYM
+#define GETFUNCSYM(fp, sym, got) do { \
+	__attribute__((__visibility__("hidden"))) void sym(); \
+	static void (*static_func_ptr)() = sym; \
+	__asm__ __volatile__ ( "" : "+m"(static_func_ptr) : : "memory"); \
+	*(fp) = static_func_ptr; } while(0)
+#endif
+
 __attribute__((__visibility__("hidden")))
 void _dlstart_c(size_t *sp, size_t *dynv)
 {
 	size_t i, aux[AUX_CNT], dyn[DYN_CNT];
+	size_t *rel, rel_size, base;
 
 	int argc = *sp;
 	char **argv = (void *)(sp+1);
@@ -24,22 +33,82 @@ void _dlstart_c(size_t *sp, size_t *dynv)
 	for (i=0; auxv[i]; i+=2) if (auxv[i]<AUX_CNT)
 		aux[auxv[i]] = auxv[i+1];
 
+#if DL_FDPIC
+	struct fdpic_loadseg *segs, fakeseg;
+	size_t j;
+	if (dynv) {
+		/* crt_arch.h entry point asm is responsible for reserving
+		 * space and moving the extra fdpic arguments to the stack
+		 * vector where they are easily accessible from C. */
+		segs = ((struct fdpic_loadmap *)(sp[-1] ? sp[-1] : sp[-2]))->segs;
+	} else {
+		/* If dynv is null, the entry point was started from loader
+		 * that is not fdpic-aware. We can assume normal fixed-
+		 * displacement ELF loading was performed, but when ldso was
+		 * run as a command, finding the Ehdr is a heursitic: we
+		 * have to assume Phdrs start in the first 4k of the file. */
+		base = aux[AT_BASE];
+		if (!base) base = aux[AT_PHDR] & -4096;
+		segs = &fakeseg;
+		segs[0].addr = base;
+		segs[0].p_vaddr = 0;
+		segs[0].p_memsz = -1;
+		Ehdr *eh = (void *)base;
+		Phdr *ph = (void *)(base + eh->e_phoff);
+		size_t phnum = eh->e_phnum;
+		size_t phent = eh->e_phentsize;
+		while (phnum-- && ph->p_type != PT_DYNAMIC)
+			ph = (void *)((size_t)ph + phent);
+		dynv = (void *)(base + ph->p_vaddr);
+	}
+#endif
+
 	for (i=0; i<DYN_CNT; i++) dyn[i] = 0;
 	for (i=0; dynv[i]; i+=2) if (dynv[i]<DYN_CNT)
 		dyn[dynv[i]] = dynv[i+1];
 
+#if DL_FDPIC
+	for (i=0; i<DYN_CNT; i++) {
+		if (i==DT_RELASZ || i==DT_RELSZ) continue;
+		if (!dyn[i]) continue;
+		for (j=0; dyn[i]-segs[j].p_vaddr >= segs[j].p_memsz; j++);
+		dyn[i] += segs[j].addr - segs[j].p_vaddr;
+	}
+	base = 0;
+
+	const Sym *syms = (void *)dyn[DT_SYMTAB];
+
+	rel = (void *)dyn[DT_RELA];
+	rel_size = dyn[DT_RELASZ];
+	for (; rel_size; rel+=3, rel_size-=3*sizeof(size_t)) {
+		if (!IS_RELATIVE(rel[1], syms)) continue;
+		for (j=0; rel[0]-segs[j].p_vaddr >= segs[j].p_memsz; j++);
+		size_t *rel_addr = (void *)
+			(rel[0] + segs[j].addr - segs[j].p_vaddr);
+		if (R_TYPE(rel[1]) == REL_FUNCDESC_VAL) {
+			*rel_addr += segs[rel_addr[1]].addr
+				- segs[rel_addr[1]].p_vaddr
+				+ syms[R_SYM(rel[1])].st_value;
+			rel_addr[1] = dyn[DT_PLTGOT];
+		} else {
+			size_t val = syms[R_SYM(rel[1])].st_value;
+			for (j=0; val-segs[j].p_vaddr >= segs[j].p_memsz; j++);
+			*rel_addr = rel[2] + segs[j].addr - segs[j].p_vaddr + val;
+		}
+	}
+#else
 	/* If the dynamic linker is invoked as a command, its load
 	 * address is not available in the aux vector. Instead, compute
 	 * the load address as the difference between &_DYNAMIC and the
 	 * virtual address in the PT_DYNAMIC program header. */
-	unsigned char *base = (void *)aux[AT_BASE];
+	base = aux[AT_BASE];
 	if (!base) {
 		size_t phnum = aux[AT_PHNUM];
 		size_t phentsize = aux[AT_PHENT];
 		Phdr *ph = (void *)aux[AT_PHDR];
 		for (i=phnum; i--; ph = (void *)((char *)ph + phentsize)) {
 			if (ph->p_type == PT_DYNAMIC) {
-				base = (void *)((size_t)dynv - ph->p_vaddr);
+				base = (size_t)dynv - ph->p_vaddr;
 				break;
 			}
 		}
@@ -53,47 +122,29 @@ void _dlstart_c(size_t *sp, size_t *dynv)
 		size_t *got = (void *)(base + dyn[DT_PLTGOT]);
 		for (i=0; dynv[i]; i+=2) if (dynv[i]==DT_MIPS_LOCAL_GOTNO)
 			local_cnt = dynv[i+1];
-		for (i=0; i<local_cnt; i++) got[i] += (size_t)base;
+		for (i=0; i<local_cnt; i++) got[i] += base;
 	}
 
-	size_t *rel, rel_size;
-
 	rel = (void *)(base+dyn[DT_REL]);
 	rel_size = dyn[DT_RELSZ];
 	for (; rel_size; rel+=2, rel_size-=2*sizeof(size_t)) {
-		if (!IS_RELATIVE(rel[1])) continue;
+		if (!IS_RELATIVE(rel[1], 0)) continue;
 		size_t *rel_addr = (void *)(base + rel[0]);
-		*rel_addr += (size_t)base;
+		*rel_addr += base;
 	}
 
 	rel = (void *)(base+dyn[DT_RELA]);
 	rel_size = dyn[DT_RELASZ];
 	for (; rel_size; rel+=3, rel_size-=3*sizeof(size_t)) {
-		if (!IS_RELATIVE(rel[1])) continue;
+		if (!IS_RELATIVE(rel[1], 0)) continue;
 		size_t *rel_addr = (void *)(base + rel[0]);
-		*rel_addr = (size_t)base + rel[2];
+		*rel_addr = base + rel[2];
 	}
+#endif
 
-	const char *strings = (void *)(base + dyn[DT_STRTAB]);
-	const Sym *syms = (void *)(base + dyn[DT_SYMTAB]);
-
-	/* Call dynamic linker stage-2, __dls2 */
-	for (i=0; ;i++) {
-		const char *s = strings + syms[i].st_name;
-		if (s[0]=='_' && s[1]=='_' && s[2]=='d'
-		 && s[3]=='l' && s[4]=='s' && s[5]=='2' && !s[6])
-			break;
-	}
-	((stage2_func)(base + syms[i].st_value))(base);
-
-	/* Call dynamic linker stage-3, __dls3 */
-	for (i=0; ;i++) {
-		const char *s = strings + syms[i].st_name;
-		if (s[0]=='_' && s[1]=='_' && s[2]=='d'
-		 && s[3]=='l' && s[4]=='s' && s[5]=='3' && !s[6])
-			break;
-	}
-	((stage3_func)(base + syms[i].st_value))(sp);
+	stage2_func dls2;
+	GETFUNCSYM(&dls2, __dls2, base+dyn[DT_PLTGOT]);
+	dls2((void *)base, sp);
 }
 
 #endif