svn commit: r356056 - head/libexec/rtld-elf/powerpc
Brandon Bergren
bdragon at FreeBSD.org
Tue Dec 24 16:13:15 UTC 2019
Author: bdragon
Date: Tue Dec 24 16:13:15 2019
New Revision: 356056
URL: https://svnweb.freebsd.org/changeset/base/356056
Log:
[PowerPC] powerpc32 rtld IFUNC handling code
As PowerPC is moving to clang, we can finally start taking advantage of
IFUNC.
Implement the MD parts of IFUNC handling for rtld.
Currently, it is necessary to look for R_PPC_IRELATIVE in the PLT in
addition to RELA. This is an ABI violation, but LLD9 has some .iplt bugs
that require this as a workaround.
Reviewed by: jhibbits
Differential Revision: https://reviews.freebsd.org/D22855
Modified:
head/libexec/rtld-elf/powerpc/reloc.c
head/libexec/rtld-elf/powerpc/rtld_machdep.h
Modified: head/libexec/rtld-elf/powerpc/reloc.c
==============================================================================
--- head/libexec/rtld-elf/powerpc/reloc.c Tue Dec 24 16:07:35 2019 (r356055)
+++ head/libexec/rtld-elf/powerpc/reloc.c Tue Dec 24 16:13:15 2019 (r356056)
@@ -166,82 +166,84 @@ static int
reloc_nonplt_object(Obj_Entry *obj_rtld __unused, Obj_Entry *obj,
const Elf_Rela *rela, SymCache *cache, int flags, RtldLockState *lockstate)
{
- Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
- const Elf_Sym *def;
- const Obj_Entry *defobj;
- Elf_Addr tmp;
+ const Elf_Sym *def = NULL;
+ const Obj_Entry *defobj;
+ Elf_Addr *where, symval = 0;
+ /*
+ * First, resolve symbol for relocations which
+ * reference symbols.
+ */
switch (ELF_R_TYPE(rela->r_info)) {
- case R_PPC_NONE:
- break;
-
- case R_PPC_ADDR32: /* word32 S + A */
- case R_PPC_GLOB_DAT: /* word32 S + A */
+ case R_PPC_UADDR32: /* word32 S + A */
+ case R_PPC_ADDR32:
+ case R_PPC_GLOB_DAT: /* word32 S + A */
+ case R_PPC_DTPMOD32:
+ case R_PPC_TPREL32:
+ case R_PPC_DTPREL32:
def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
flags, cache, lockstate);
if (def == NULL) {
return (-1);
}
- tmp = (Elf_Addr)(defobj->relocbase + def->st_value +
- rela->r_addend);
-
- /* Don't issue write if unnecessary; avoid COW page fault */
- if (*where != tmp) {
- *where = tmp;
- }
- break;
-
- case R_PPC_RELATIVE: /* word32 B + A */
- tmp = (Elf_Addr)(obj->relocbase + rela->r_addend);
-
- /* As above, don't issue write unnecessarily */
- if (*where != tmp) {
- *where = tmp;
- }
- break;
-
- case R_PPC_COPY:
/*
- * These are deferred until all other relocations
- * have been done. All we do here is make sure
- * that the COPY relocation is not in a shared
- * library. They are allowed only in executable
- * files.
+ * If symbol is IFUNC, only perform relocation
+ * when caller allowed it by passing
+ * SYMLOOK_IFUNC flag. Skip the relocations
+ * otherwise.
+ *
+ * Also error out in case IFUNC relocations
+ * are specified for TLS, which cannot be
+ * usefully interpreted.
*/
- if (!obj->mainprog) {
- _rtld_error("%s: Unexpected R_COPY "
- " relocation in shared library",
- obj->path);
- return (-1);
+ if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) {
+ switch (ELF_R_TYPE(rela->r_info)) {
+ case R_PPC_UADDR32:
+ case R_PPC_ADDR32:
+ case R_PPC_GLOB_DAT:
+ if ((flags & SYMLOOK_IFUNC) == 0) {
+ dbg("Non-PLT reference to IFUNC found!");
+ obj->non_plt_gnu_ifunc = true;
+ return (0);
+ }
+ symval = (Elf_Addr)rtld_resolve_ifunc(
+ defobj, def);
+ break;
+ default:
+ _rtld_error("%s: IFUNC for TLS reloc",
+ obj->path);
+ return (-1);
+ }
+ } else {
+ if ((flags & SYMLOOK_IFUNC) != 0)
+ return (0);
+ symval = (Elf_Addr)defobj->relocbase +
+ def->st_value;
}
break;
+ default:
+ if ((flags & SYMLOOK_IFUNC) != 0)
+ return (0);
+ }
+ where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
- case R_PPC_JMP_SLOT:
- /*
- * These will be handled by the plt/jmpslot routines
- */
+ switch (ELF_R_TYPE(rela->r_info)) {
+ case R_PPC_NONE:
break;
-
+ case R_PPC_UADDR32:
+ case R_PPC_ADDR32:
+ case R_PPC_GLOB_DAT:
+ /* Don't issue write if unnecessary; avoid COW page fault */
+ if (*where != symval + rela->r_addend) {
+ *where = symval + rela->r_addend;
+ }
+ break;
case R_PPC_DTPMOD32:
- def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
- flags, cache, lockstate);
-
- if (def == NULL)
- return (-1);
-
*where = (Elf_Addr) defobj->tlsindex;
-
break;
-
case R_PPC_TPREL32:
- def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
- flags, cache, lockstate);
-
- if (def == NULL)
- return (-1);
-
/*
* We lazily allocate offsets for static TLS as we
* see the first relocation that references the
@@ -262,27 +264,52 @@ reloc_nonplt_object(Obj_Entry *obj_rtld __unused, Obj_
*(Elf_Addr **)where = *where * sizeof(Elf_Addr)
+ (Elf_Addr *)(def->st_value + rela->r_addend
+ defobj->tlsoffset - TLS_TP_OFFSET - TLS_TCB_SIZE);
-
break;
-
case R_PPC_DTPREL32:
- def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
- flags, cache, lockstate);
-
- if (def == NULL)
- return (-1);
-
*where += (Elf_Addr)(def->st_value + rela->r_addend
- TLS_DTV_OFFSET);
+ break;
+ case R_PPC_RELATIVE: /* word32 B + A */
+ symval = (Elf_Addr)(obj->relocbase + rela->r_addend);
+ /* As above, don't issue write unnecessarily */
+ if (*where != symval) {
+ *where = symval;
+ }
break;
-
+ case R_PPC_COPY:
+ /*
+ * These are deferred until all other relocations
+ * have been done. All we do here is make sure
+ * that the COPY relocation is not in a shared
+ * library. They are allowed only in executable
+ * files.
+ */
+ if (!obj->mainprog) {
+ _rtld_error("%s: Unexpected R_COPY "
+ " relocation in shared library",
+ obj->path);
+ return (-1);
+ }
+ break;
+ case R_PPC_IRELATIVE:
+ /*
+ * These will be handled by reloc_iresolve().
+ */
+ obj->irelative = true;
+ break;
+ case R_PPC_JMP_SLOT:
+ /*
+ * These will be handled by the plt/jmpslot routines
+ */
+ break;
+
default:
_rtld_error("%s: Unsupported relocation type %d"
" in non-PLT relocations\n", obj->path,
ELF_R_TYPE(rela->r_info));
return (-1);
- }
+ }
return (0);
}
@@ -300,10 +327,6 @@ reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld, int
SymCache *cache;
int r = -1;
- if ((flags & SYMLOOK_IFUNC) != 0)
- /* XXX not implemented */
- return (0);
-
/*
* The dynamic loader may be called from a thread, we have
* limited amounts of stack available so we cannot use alloca().
@@ -404,7 +427,6 @@ reloc_plt_object(Obj_Entry *obj, const Elf_Rela *rela)
return (0);
}
-
/*
* Process the PLT relocations.
*/
@@ -420,6 +442,17 @@ reloc_plt(Obj_Entry *obj, int flags __unused, RtldLock
relalim = (const Elf_Rela *)((const char *)obj->pltrela +
obj->pltrelasize);
for (rela = obj->pltrela; rela < relalim; rela++) {
+ if (ELF_R_TYPE(rela->r_info) == R_PPC_IRELATIVE) {
+ dbg("ABI violation - found IRELATIVE in the PLT.");
+ obj->irelative = true;
+ continue;
+ }
+
+ /*
+ * PowerPC(64) .rela.plt is composed of an array of
+ * R_PPC_JMP_SLOT relocations. Unlike other platforms,
+ * this is the ONLY relocation type that is valid here.
+ */
assert(ELF_R_TYPE(rela->r_info) == R_PPC_JMP_SLOT);
if (reloc_plt_object(obj, rela) < 0) {
@@ -438,7 +471,6 @@ reloc_plt(Obj_Entry *obj, int flags __unused, RtldLock
return (0);
}
-
/*
* LD_BIND_NOW was set - force relocation for all jump slots
*/
@@ -455,6 +487,9 @@ reloc_jmpslots(Obj_Entry *obj, int flags, RtldLockStat
relalim = (const Elf_Rela *)((const char *)obj->pltrela +
obj->pltrelasize);
for (rela = obj->pltrela; rela < relalim; rela++) {
+ /* This isn't actually a jump slot, ignore it. */
+ if (ELF_R_TYPE(rela->r_info) == R_PPC_IRELATIVE)
+ continue;
assert(ELF_R_TYPE(rela->r_info) == R_PPC_JMP_SLOT);
where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
@@ -466,15 +501,18 @@ reloc_jmpslots(Obj_Entry *obj, int flags, RtldLockStat
target = (Elf_Addr)(defobj->relocbase + def->st_value);
-#if 0
- /* PG XXX */
- dbg("\"%s\" in \"%s\" --> %p in \"%s\"",
- defobj->strtab + def->st_name, basename(obj->path),
- (void *)target, basename(defobj->path));
-#endif
-
- reloc_jmpslot(where, target, defobj, obj,
- (const Elf_Rel *) rela);
+ if (def == &sym_zero) {
+ /* Zero undefined weak symbols */
+ *where = 0;
+ } else {
+ if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) {
+ /* LD_BIND_NOW, ifunc in shared lib.*/
+ obj->gnu_ifunc = true;
+ continue;
+ }
+ reloc_jmpslot(where, target, defobj, obj,
+ (const Elf_Rel *) rela);
+ }
}
obj->jmpslots_done = true;
@@ -484,9 +522,7 @@ reloc_jmpslots(Obj_Entry *obj, int flags, RtldLockStat
/*
- * Update the value of a PLT jump slot. Branch directly to the target if
- * it is within +/- 32Mb, otherwise go indirectly via the pltcall
- * trampoline call and jump table.
+ * Update the value of a PLT jump slot.
*/
Elf_Addr
reloc_jmpslot(Elf_Addr *wherep, Elf_Addr target,
@@ -501,22 +537,32 @@ reloc_jmpslot(Elf_Addr *wherep, Elf_Addr target,
if (ld_bind_not)
goto out;
+
/*
- * At the PLT entry pointed at by `wherep', construct
- * a direct transfer to the now fully resolved function
- * address.
+ * Process Secure-PLT.
*/
- offset = target - (Elf_Addr)wherep;
-
if (obj->gotptr != NULL) {
assert(wherep >= (Elf_Word *)obj->pltgot);
assert(wherep <
(Elf_Word *)obj->pltgot + obj->pltrelasize);
- *wherep = target;
+ if (*wherep != target)
+ *wherep = target;
goto out;
}
+ /*
+ * BSS-PLT optimization:
+ * Branch directly to the target if it is within +/- 32Mb,
+ * otherwise go indirectly via the pltcall trampoline call and
+ * jump table.
+ */
+ offset = target - (Elf_Addr)wherep;
if (abs((int)offset) < 32*1024*1024) { /* inside 32MB? */
+ /*
+ * At the PLT entry pointed at by `wherep', construct
+ * a direct transfer to the now fully resolved function
+ * address.
+ */
/* b value # branch directly */
*wherep = 0x48000000 | (offset & 0x03fffffc);
__syncicache(wherep, 4);
@@ -557,11 +603,52 @@ out:
}
int
-reloc_iresolve(Obj_Entry *obj __unused,
- struct Struct_RtldLockState *lockstate __unused)
+reloc_iresolve(Obj_Entry *obj,
+ struct Struct_RtldLockState *lockstate)
{
+ /*
+ * Since PLT slots on PowerPC are always R_PPC_JMP_SLOT,
+ * R_PPC_IRELATIVE is in RELA.
+ */
+ const Elf_Rela *relalim;
+ const Elf_Rela *rela;
+ Elf_Addr *where, target, *ptr;
- /* XXX not implemented */
+ if (!obj->irelative)
+ return (0);
+
+ relalim = (const Elf_Rela *)((const char *)obj->rela + obj->relasize);
+ for (rela = obj->rela; rela < relalim; rela++) {
+ if (ELF_R_TYPE(rela->r_info) == R_PPC_IRELATIVE) {
+ ptr = (Elf_Addr *)(obj->relocbase + rela->r_addend);
+ where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
+
+ lock_release(rtld_bind_lock, lockstate);
+ target = call_ifunc_resolver(ptr);
+ wlock_acquire(rtld_bind_lock, lockstate);
+
+ *where = target;
+ }
+ }
+ /*
+ * XXX Remove me when lld is fixed!
+ * LLD currently makes illegal relocations in the PLT.
+ */
+ relalim = (const Elf_Rela *)((const char *)obj->pltrela + obj->pltrelasize);
+ for (rela = obj->pltrela; rela < relalim; rela++) {
+ if (ELF_R_TYPE(rela->r_info) == R_PPC_IRELATIVE) {
+ ptr = (Elf_Addr *)(obj->relocbase + rela->r_addend);
+ where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
+
+ lock_release(rtld_bind_lock, lockstate);
+ target = call_ifunc_resolver(ptr);
+ wlock_acquire(rtld_bind_lock, lockstate);
+
+ *where = target;
+ }
+ }
+
+ obj->irelative = false;
return (0);
}
@@ -569,8 +656,32 @@ int
reloc_gnu_ifunc(Obj_Entry *obj __unused, int flags __unused,
struct Struct_RtldLockState *lockstate __unused)
{
+ const Elf_Rela *relalim;
+ const Elf_Rela *rela;
+ Elf_Addr *where, target;
+ const Elf_Sym *def;
+ const Obj_Entry *defobj;
- /* XXX not implemented */
+ if (!obj->gnu_ifunc)
+ return (0);
+ relalim = (const Elf_Rela *)((const char *)obj->pltrela + obj->pltrelasize);
+ for (rela = obj->pltrela; rela < relalim; rela++) {
+ if (ELF_R_TYPE(rela->r_info) == R_PPC_JMP_SLOT) {
+ where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
+ def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
+ SYMLOOK_IN_PLT | flags, NULL, lockstate);
+ if (def == NULL)
+ return (-1);
+ if (ELF_ST_TYPE(def->st_info) != STT_GNU_IFUNC)
+ continue;
+ lock_release(rtld_bind_lock, lockstate);
+ target = (Elf_Addr)rtld_resolve_ifunc(defobj, def);
+ wlock_acquire(rtld_bind_lock, lockstate);
+ reloc_jmpslot(where, target, defobj, obj,
+ (const Elf_Rel *)rela);
+ }
+ }
+ obj->gnu_ifunc = false;
return (0);
}
@@ -662,6 +773,27 @@ init_pltgot(Obj_Entry *obj)
* The icache will be sync'd in reloc_plt, which is called
* after all the slots have been updated
*/
+}
+
+/*
+ * 32 bit cpu feature flag fields.
+ */
+u_long cpu_features;
+u_long cpu_features2;
+
+void
+powerpc_abi_variant_hook(Elf_Auxinfo** aux_info)
+{
+ /*
+ * Since aux_info[] is easier to work with than aux, go ahead and
+ * initialize cpu_features / cpu_features2.
+ */
+ cpu_features = -1UL;
+ cpu_features2 = -1UL;
+ if (aux_info[AT_HWCAP] != NULL)
+ cpu_features = aux_info[AT_HWCAP]->a_un.a_val;
+ if (aux_info[AT_HWCAP2] != NULL)
+ cpu_features2 = aux_info[AT_HWCAP2]->a_un.a_val;
}
void
Modified: head/libexec/rtld-elf/powerpc/rtld_machdep.h
==============================================================================
--- head/libexec/rtld-elf/powerpc/rtld_machdep.h Tue Dec 24 16:07:35 2019 (r356055)
+++ head/libexec/rtld-elf/powerpc/rtld_machdep.h Tue Dec 24 16:13:15 2019 (r356056)
@@ -53,8 +53,13 @@ void reloc_non_plt_self(Elf_Dyn *dynp, Elf_Addr relocb
#define call_init_pointer(obj, target) \
(((InitArrFunc)(target))(main_argc, main_argv, environ))
+extern u_long cpu_features; /* r3 */
+extern u_long cpu_features2; /* r4 */
+/* r5-10: ifunc resolver parameters reserved for future assignment. */
#define call_ifunc_resolver(ptr) \
- (((Elf_Addr (*)(void))ptr)())
+ (((Elf_Addr (*)(uint32_t, uint32_t, uint32_t, uint32_t, uint32_t, \
+ uint32_t, uint32_t, uint32_t))ptr)((uint32_t)cpu_features, \
+ (uint32_t)cpu_features2, 0, 0, 0, 0, 0, 0))
/*
* PLT functions. Not really correct prototypes, but the
@@ -91,6 +96,7 @@ extern void *__tls_get_addr(tls_index* ti);
#define RTLD_DEFAULT_STACK_PF_EXEC PF_X
#define RTLD_DEFAULT_STACK_EXEC PROT_EXEC
-#define md_abi_variant_hook(x)
+extern void powerpc_abi_variant_hook(Elf_Auxinfo **);
+#define md_abi_variant_hook(x) powerpc_abi_variant_hook(x)
#endif
More information about the svn-src-head
mailing list