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Diffstat (limited to 'src/ldso/dynlink.c')
-rw-r--r--src/ldso/dynlink.c347
1 files changed, 174 insertions, 173 deletions
diff --git a/src/ldso/dynlink.c b/src/ldso/dynlink.c
index f6ed8011..1008e3ea 100644
--- a/src/ldso/dynlink.c
+++ b/src/ldso/dynlink.c
@@ -19,26 +19,13 @@
#include <dlfcn.h>
#include "pthread_impl.h"
#include "libc.h"
+#include "dynlink.h"
static int errflag;
static char errbuf[128];
#ifdef SHARED
-#if ULONG_MAX == 0xffffffff
-typedef Elf32_Ehdr Ehdr;
-typedef Elf32_Phdr Phdr;
-typedef Elf32_Sym Sym;
-#define R_TYPE(x) ((x)&255)
-#define R_SYM(x) ((x)>>8)
-#else
-typedef Elf64_Ehdr Ehdr;
-typedef Elf64_Phdr Phdr;
-typedef Elf64_Sym Sym;
-#define R_TYPE(x) ((x)&0xffffffff)
-#define R_SYM(x) ((x)>>32)
-#endif
-
#define MAXP2(a,b) (-(-(a)&-(b)))
#define ALIGN(x,y) ((x)+(y)-1 & -(y))
@@ -88,6 +75,7 @@ struct dso {
volatile int new_dtv_idx, new_tls_idx;
struct td_index *td_index;
struct dso *fini_next;
+ int rel_early_relative, rel_update_got;
char *shortname;
char buf[];
};
@@ -97,26 +85,6 @@ struct symdef {
struct dso *dso;
};
-enum {
- REL_ERR,
- REL_SYMBOLIC,
- REL_GOT,
- REL_PLT,
- REL_RELATIVE,
- REL_OFFSET,
- REL_OFFSET32,
- REL_COPY,
- REL_SYM_OR_REL,
- REL_TLS, /* everything past here is TLS */
- REL_DTPMOD,
- REL_DTPOFF,
- REL_TPOFF,
- REL_TPOFF_NEG,
- REL_TLSDESC,
-};
-
-#include "reloc.h"
-
int __init_tp(void *);
void __init_libc(char **, char *);
@@ -129,7 +97,8 @@ static struct builtin_tls {
} builtin_tls[1];
#define MIN_TLS_ALIGN offsetof(struct builtin_tls, pt)
-static struct dso *head, *tail, *ldso, *fini_head;
+static struct dso ldso;
+static struct dso *head, *tail, *fini_head;
static char *env_path, *sys_path;
static unsigned long long gencnt;
static int runtime;
@@ -145,14 +114,19 @@ static pthread_mutex_t init_fini_lock = { ._m_type = PTHREAD_MUTEX_RECURSIVE };
struct debug *_dl_debug_addr = &debug;
-#define AUX_CNT 38
-#define DYN_CNT 34
+static int dl_strcmp(const char *l, const char *r)
+{
+ for (; *l==*r && *l; l++, r++);
+ return *(unsigned char *)l - *(unsigned char *)r;
+}
+#define strcmp(l,r) dl_strcmp(l,r)
static void decode_vec(size_t *v, size_t *a, size_t cnt)
{
- memset(a, 0, cnt*sizeof(size_t));
- for (; v[0]; v+=2) if (v[0]<cnt) {
- a[0] |= 1ULL<<v[0];
+ size_t i;
+ for (i=0; i<cnt; i++) a[i] = 0;
+ for (; v[0]; v+=2) if (v[0]-1<cnt-1) {
+ a[0] |= 1UL<<v[0];
a[v[0]] = v[1];
}
}
@@ -276,8 +250,6 @@ static struct symdef find_sym(struct dso *dso, const char *s, int need_def)
return def;
}
-#define NO_INLINE_ADDEND (1<<REL_COPY | 1<<REL_GOT | 1<<REL_PLT)
-
ptrdiff_t __tlsdesc_static(), __tlsdesc_dynamic();
static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stride)
@@ -288,7 +260,7 @@ static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stri
Sym *sym;
const char *name;
void *ctx;
- int astype, type;
+ int type;
int sym_index;
struct symdef def;
size_t *reloc_addr;
@@ -297,14 +269,8 @@ static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stri
size_t addend;
for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) {
- astype = R_TYPE(rel[1]);
- if (!astype) continue;
- type = remap_rel(astype);
- if (!type) {
- error("Error relocating %s: unsupported relocation type %d",
- dso->name, astype);
- continue;
- }
+ if (dso->rel_early_relative && IS_RELATIVE(rel[1])) continue;
+ type = R_TYPE(rel[1]);
sym_index = R_SYM(rel[1]);
reloc_addr = (void *)(base + rel[0]);
if (sym_index) {
@@ -324,14 +290,19 @@ static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stri
def.dso = dso;
}
+ int gotplt = (type == REL_GOT || type == REL_PLT);
+ if (dso->rel_update_got && !gotplt) continue;
+
addend = stride>2 ? rel[2]
- : (1<<type & NO_INLINE_ADDEND) ? 0
+ : gotplt || type==REL_COPY ? 0
: *reloc_addr;
sym_val = def.sym ? (size_t)def.dso->base+def.sym->st_value : 0;
tls_val = def.sym ? def.sym->st_value : 0;
switch(type) {
+ case REL_NONE:
+ break;
case REL_OFFSET:
addend -= (size_t)reloc_addr;
case REL_SYMBOLIC:
@@ -395,6 +366,10 @@ static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stri
#endif
}
break;
+ default:
+ error("Error relocating %s: unsupported relocation type %d",
+ dso->name, type);
+ continue;
}
}
}
@@ -711,22 +686,22 @@ static struct dso *load_library(const char *name, struct dso *needed_by)
if (!(reported & mask)) {
reported |= mask;
dprintf(1, "\t%s => %s (%p)\n",
- name, ldso->name,
- ldso->base);
+ name, ldso.name,
+ ldso.base);
}
}
is_self = 1;
}
}
}
- if (!strcmp(name, ldso->name)) is_self = 1;
+ if (!strcmp(name, ldso.name)) is_self = 1;
if (is_self) {
- if (!ldso->prev) {
- tail->next = ldso;
- ldso->prev = tail;
- tail = ldso->next ? ldso->next : ldso;
+ if (!ldso.prev) {
+ tail->next = &ldso;
+ ldso.prev = tail;
+ tail = ldso.next ? ldso.next : &ldso;
}
- return ldso;
+ return &ldso;
}
if (strchr(name, '/')) {
pathname = name;
@@ -752,13 +727,13 @@ static struct dso *load_library(const char *name, struct dso *needed_by)
if (!sys_path) {
char *prefix = 0;
size_t prefix_len;
- if (ldso->name[0]=='/') {
+ if (ldso.name[0]=='/') {
char *s, *t, *z;
- for (s=t=z=ldso->name; *s; s++)
+ for (s=t=z=ldso.name; *s; s++)
if (*s=='/') z=t, t=s;
- prefix_len = z-ldso->name;
+ prefix_len = z-ldso.name;
if (prefix_len < PATH_MAX)
- prefix = ldso->name;
+ prefix = ldso.name;
}
if (!prefix) {
prefix = "";
@@ -910,21 +885,40 @@ static void make_global(struct dso *p)
for (; p; p=p->next) p->global = 1;
}
+static void do_mips_relocs(struct dso *p, size_t *got)
+{
+ size_t i, j, rel[2];
+ unsigned char *base = p->base;
+ i=0; search_vec(p->dynv, &i, DT_MIPS_LOCAL_GOTNO);
+ if (p->rel_early_relative) {
+ got += i;
+ } else {
+ while (i--) *got++ += (size_t)base;
+ }
+ j=0; search_vec(p->dynv, &j, DT_MIPS_GOTSYM);
+ i=0; search_vec(p->dynv, &i, DT_MIPS_SYMTABNO);
+ Sym *sym = p->syms + j;
+ rel[0] = (unsigned char *)got - base;
+ for (i-=j; i; i--, sym++, rel[0]+=sizeof(size_t)) {
+ rel[1] = sym-p->syms << 8 | R_MIPS_JUMP_SLOT;
+ do_relocs(p, rel, sizeof rel, 2);
+ }
+}
+
static void reloc_all(struct dso *p)
{
size_t dyn[DYN_CNT] = {0};
for (; p; p=p->next) {
if (p->relocated) continue;
decode_vec(p->dynv, dyn, DYN_CNT);
-#ifdef NEED_ARCH_RELOCS
- do_arch_relocs(p, head);
-#endif
+ if (NEED_MIPS_GOT_RELOCS)
+ do_mips_relocs(p, (void *)(p->base+dyn[DT_PLTGOT]));
do_relocs(p, (void *)(p->base+dyn[DT_JMPREL]), dyn[DT_PLTRELSZ],
2+(dyn[DT_PLTREL]==DT_RELA));
do_relocs(p, (void *)(p->base+dyn[DT_REL]), dyn[DT_RELSZ], 2);
do_relocs(p, (void *)(p->base+dyn[DT_RELA]), dyn[DT_RELASZ], 3);
- if (p->relro_start != p->relro_end &&
+ if (head != &ldso && p->relro_start != p->relro_end &&
mprotect(p->base+p->relro_start, p->relro_end-p->relro_start, PROT_READ) < 0) {
error("Error relocating %s: RELRO protection failed: %m",
p->name);
@@ -1121,19 +1115,52 @@ static void update_tls_size()
tls_align);
}
-void *__dynlink(int argc, char **argv)
+/* Stage 1 of the dynamic linker is defined in dlstart.c. It calls the
+ * following stage 2 and stage 3 functions via primitive symbolic lookup
+ * since it does not have access to their addresses to begin with. */
+
+/* Stage 2 of the dynamic linker is called after relative relocations
+ * have been processed. It can make function calls to static functions
+ * and access string literals and static data, but cannot use extern
+ * symbols. Its job is to perform symbolic relocations on the dynamic
+ * linker itself, but some of the relocations performed may need to be
+ * replaced later due to copy relocations in the main program. */
+
+void __dls2(unsigned char *base)
{
- size_t aux[AUX_CNT] = {0};
+ Ehdr *ehdr = (void *)base;
+ ldso.base = base;
+ ldso.name = ldso.shortname = "libc.so";
+ ldso.global = 1;
+ ldso.phnum = ehdr->e_phnum;
+ ldso.phdr = (void *)(base + ehdr->e_phoff);
+ ldso.phentsize = ehdr->e_phentsize;
+ ldso.rel_early_relative = 1;
+ kernel_mapped_dso(&ldso);
+ decode_dyn(&ldso);
+
+ head = &ldso;
+ reloc_all(&ldso);
+
+ ldso.relocated = 0;
+ ldso.rel_update_got = 1;
+}
+
+/* Stage 3 of the dynamic linker is called with the dynamic linker/libc
+ * fully functional. Its job is to load (if not already loaded) and
+ * process dependencies and relocations for the main application and
+ * transfer control to its entry point. */
+
+_Noreturn void __dls3(size_t *sp)
+{
+ static struct dso app, vdso;
+ size_t aux[AUX_CNT] = {0}, *auxv;
size_t i;
- Phdr *phdr;
- Ehdr *ehdr;
- static struct dso builtin_dsos[3];
- struct dso *const app = builtin_dsos+0;
- struct dso *const lib = builtin_dsos+1;
- struct dso *const vdso = builtin_dsos+2;
char *env_preload=0;
size_t vdso_base;
- size_t *auxv;
+ int argc = *sp;
+ char **argv = (void *)(sp+1);
+ char **argv_orig = argv;
char **envp = argv+argc+1;
void *initial_tls;
@@ -1157,60 +1184,42 @@ void *__dynlink(int argc, char **argv)
libc.page_size = aux[AT_PAGESZ];
libc.auxv = auxv;
- /* If the dynamic linker was invoked as a program itself, AT_BASE
- * will not be set. In that case, we assume the base address is
- * the start of the page containing the PHDRs; I don't know any
- * better approach... */
- if (!aux[AT_BASE]) {
- aux[AT_BASE] = aux[AT_PHDR] & -PAGE_SIZE;
- aux[AT_PHDR] = aux[AT_PHENT] = aux[AT_PHNUM] = 0;
- }
-
- /* The dynamic linker load address is passed by the kernel
- * in the AUX vector, so this is easy. */
- lib->base = (void *)aux[AT_BASE];
- lib->name = lib->shortname = "libc.so";
- lib->global = 1;
- ehdr = (void *)lib->base;
- lib->phnum = ehdr->e_phnum;
- lib->phdr = (void *)(aux[AT_BASE]+ehdr->e_phoff);
- lib->phentsize = ehdr->e_phentsize;
- kernel_mapped_dso(lib);
- decode_dyn(lib);
-
- if (aux[AT_PHDR]) {
+ /* If the main program was already loaded by the kernel,
+ * AT_PHDR will point to some location other than the dynamic
+ * linker's program headers. */
+ if (aux[AT_PHDR] != (size_t)ldso.phdr) {
size_t interp_off = 0;
size_t tls_image = 0;
/* Find load address of the main program, via AT_PHDR vs PT_PHDR. */
- app->phdr = phdr = (void *)aux[AT_PHDR];
- app->phnum = aux[AT_PHNUM];
- app->phentsize = aux[AT_PHENT];
+ Phdr *phdr = app.phdr = (void *)aux[AT_PHDR];
+ app.phnum = aux[AT_PHNUM];
+ app.phentsize = aux[AT_PHENT];
for (i=aux[AT_PHNUM]; i; i--, phdr=(void *)((char *)phdr + aux[AT_PHENT])) {
if (phdr->p_type == PT_PHDR)
- app->base = (void *)(aux[AT_PHDR] - phdr->p_vaddr);
+ app.base = (void *)(aux[AT_PHDR] - phdr->p_vaddr);
else if (phdr->p_type == PT_INTERP)
interp_off = (size_t)phdr->p_vaddr;
else if (phdr->p_type == PT_TLS) {
tls_image = phdr->p_vaddr;
- app->tls_len = phdr->p_filesz;
- app->tls_size = phdr->p_memsz;
- app->tls_align = phdr->p_align;
+ app.tls_len = phdr->p_filesz;
+ app.tls_size = phdr->p_memsz;
+ app.tls_align = phdr->p_align;
}
}
- if (app->tls_size) app->tls_image = (char *)app->base + tls_image;
- if (interp_off) lib->name = (char *)app->base + interp_off;
+ if (app.tls_size) app.tls_image = (char *)app.base + tls_image;
+ if (interp_off) ldso.name = (char *)app.base + interp_off;
if ((aux[0] & (1UL<<AT_EXECFN))
&& strncmp((char *)aux[AT_EXECFN], "/proc/", 6))
- app->name = (char *)aux[AT_EXECFN];
+ app.name = (char *)aux[AT_EXECFN];
else
- app->name = argv[0];
- kernel_mapped_dso(app);
+ app.name = argv[0];
+ kernel_mapped_dso(&app);
} else {
int fd;
char *ldname = argv[0];
size_t l = strlen(ldname);
if (l >= 3 && !strcmp(ldname+l-3, "ldd")) ldd_mode = 1;
- *argv++ = (void *)-1;
+ argv++;
while (argv[0] && argv[0][0]=='-' && argv[0][1]=='-') {
char *opt = argv[0]+2;
*argv++ = (void *)-1;
@@ -1229,8 +1238,8 @@ void *__dynlink(int argc, char **argv)
} else {
argv[0] = 0;
}
- argv[-1] = (void *)-1;
}
+ argv[-1] = (void *)(argc - (argv-argv_orig));
if (!argv[0]) {
dprintf(2, "musl libc\n"
"Version %s\n"
@@ -1246,96 +1255,88 @@ void *__dynlink(int argc, char **argv)
_exit(1);
}
runtime = 1;
- ehdr = (void *)map_library(fd, app);
+ Ehdr *ehdr = (void *)map_library(fd, &app);
if (!ehdr) {
dprintf(2, "%s: %s: Not a valid dynamic program\n", ldname, argv[0]);
_exit(1);
}
runtime = 0;
close(fd);
- lib->name = ldname;
- app->name = argv[0];
- aux[AT_ENTRY] = (size_t)app->base + ehdr->e_entry;
+ ldso.name = ldname;
+ app.name = argv[0];
+ aux[AT_ENTRY] = (size_t)app.base + ehdr->e_entry;
/* Find the name that would have been used for the dynamic
* linker had ldd not taken its place. */
if (ldd_mode) {
- for (i=0; i<app->phnum; i++) {
- if (app->phdr[i].p_type == PT_INTERP)
- lib->name = (void *)(app->base
- + app->phdr[i].p_vaddr);
+ for (i=0; i<app.phnum; i++) {
+ if (app.phdr[i].p_type == PT_INTERP)
+ ldso.name = (void *)(app.base
+ + app.phdr[i].p_vaddr);
}
- dprintf(1, "\t%s (%p)\n", lib->name, lib->base);
+ dprintf(1, "\t%s (%p)\n", ldso.name, ldso.base);
}
}
- if (app->tls_size) {
- app->tls_id = tls_cnt = 1;
+ if (app.tls_size) {
+ app.tls_id = tls_cnt = 1;
#ifdef TLS_ABOVE_TP
- app->tls_offset = 0;
- tls_offset = app->tls_size
- + ( -((uintptr_t)app->tls_image + app->tls_size)
- & (app->tls_align-1) );
+ app.tls_offset = 0;
+ tls_offset = app.tls_size
+ + ( -((uintptr_t)app.tls_image + app.tls_size)
+ & (app.tls_align-1) );
#else
- tls_offset = app->tls_offset = app->tls_size
- + ( -((uintptr_t)app->tls_image + app->tls_size)
- & (app->tls_align-1) );
+ tls_offset = app.tls_offset = app.tls_size
+ + ( -((uintptr_t)app.tls_image + app.tls_size)
+ & (app.tls_align-1) );
#endif
- tls_align = MAXP2(tls_align, app->tls_align);
+ tls_align = MAXP2(tls_align, app.tls_align);
}
- app->global = 1;
- decode_dyn(app);
+ app.global = 1;
+ decode_dyn(&app);
/* Attach to vdso, if provided by the kernel */
if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR)) {
- ehdr = (void *)vdso_base;
- vdso->phdr = phdr = (void *)(vdso_base + ehdr->e_phoff);
- vdso->phnum = ehdr->e_phnum;
- vdso->phentsize = ehdr->e_phentsize;
+ Ehdr *ehdr = (void *)vdso_base;
+ Phdr *phdr = vdso.phdr = (void *)(vdso_base + ehdr->e_phoff);
+ vdso.phnum = ehdr->e_phnum;
+ vdso.phentsize = ehdr->e_phentsize;
for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
if (phdr->p_type == PT_DYNAMIC)
- vdso->dynv = (void *)(vdso_base + phdr->p_offset);
+ vdso.dynv = (void *)(vdso_base + phdr->p_offset);
if (phdr->p_type == PT_LOAD)
- vdso->base = (void *)(vdso_base - phdr->p_vaddr + phdr->p_offset);
+ vdso.base = (void *)(vdso_base - phdr->p_vaddr + phdr->p_offset);
}
- vdso->name = "";
- vdso->shortname = "linux-gate.so.1";
- vdso->global = 1;
- decode_dyn(vdso);
- vdso->prev = lib;
- lib->next = vdso;
+ vdso.name = "";
+ vdso.shortname = "linux-gate.so.1";
+ vdso.global = 1;
+ vdso.relocated = 1;
+ decode_dyn(&vdso);
+ vdso.prev = &ldso;
+ ldso.next = &vdso;
}
- /* Initial dso chain consists only of the app. We temporarily
- * append the dynamic linker/libc so we can relocate it, then
- * restore the initial chain in preparation for loading third
- * party libraries (preload/needed). */
- head = tail = app;
- ldso = lib;
- app->next = lib;
- reloc_all(lib);
- app->next = 0;
-
- /* PAST THIS POINT, ALL LIBC INTERFACES ARE FULLY USABLE. */
+ /* Initial dso chain consists only of the app. */
+ head = tail = &app;
/* Donate unused parts of app and library mapping to malloc */
- reclaim_gaps(app);
- reclaim_gaps(lib);
+ reclaim_gaps(&app);
+ reclaim_gaps(&ldso);
/* Load preload/needed libraries, add their symbols to the global
- * namespace, and perform all remaining relocations. The main
- * program must be relocated LAST since it may contain copy
- * relocations which depend on libraries' relocations. */
+ * namespace, and perform all remaining relocations. */
if (env_preload) load_preload(env_preload);
- load_deps(app);
- make_global(app);
+ load_deps(&app);
+ make_global(&app);
#ifndef DYNAMIC_IS_RO
- for (i=0; app->dynv[i]; i+=2)
- if (app->dynv[i]==DT_DEBUG)
- app->dynv[i+1] = (size_t)&debug;
+ for (i=0; app.dynv[i]; i+=2)
+ if (app.dynv[i]==DT_DEBUG)
+ app.dynv[i+1] = (size_t)&debug;
#endif
- reloc_all(app->next);
- reloc_all(app);
+ /* The main program must be relocated LAST since it may contin
+ * copy relocations which depend on libraries' relocations. */
+ reloc_all(app.next);
+ reloc_all(&app);
update_tls_size();
if (libc.tls_size > sizeof builtin_tls) {
@@ -1359,14 +1360,13 @@ void *__dynlink(int argc, char **argv)
/* Switch to runtime mode: any further failures in the dynamic
* linker are a reportable failure rather than a fatal startup
- * error. If the dynamic loader (dlopen) will not be used, free
- * all memory used by the dynamic linker. */
+ * error. */
runtime = 1;
debug.ver = 1;
debug.bp = _dl_debug_state;
debug.head = head;
- debug.base = lib->base;
+ debug.base = ldso.base;
debug.state = 0;
_dl_debug_state();
@@ -1375,7 +1375,8 @@ void *__dynlink(int argc, char **argv)
errno = 0;
do_init_fini(tail);
- return (void *)aux[AT_ENTRY];
+ CRTJMP((void *)aux[AT_ENTRY], argv-1);
+ for(;;);
}
void *dlopen(const char *file, int mode)