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PowerPC PLT speculative execution barriers
- From: Alan Modra <amodra at gmail dot com>
- To: binutils at sourceware dot org
- Date: Wed, 17 Jan 2018 18:49:01 +1030
- Subject: PowerPC PLT speculative execution barriers
- Authentication-results: sourceware.org; auth=none
Spectre variant 2 mitigation for PowerPC and PowerPC64.
bfd/
* elf32-ppc.c (GLINK_ENTRY_SIZE): Handle speculation barrier.
(CRSETEQ, BEQCTRM): Define.
(is_nonpic_glink_stub): Don't check bctr.
(ppc_elf_link_hash_table_create): Init new ppc_elf_params field.
(ppc_elf_relax_section): Size speculation barrier.
(output_bctr): New function.
(write_glink_stub): Use output_bctr.
(ppc_elf_relocate_section): Use output_bctr for long branch stub.
(ppc_elf_finish_dynamic_symbol): Likewise.
(ppc_elf_finish_dynamic_sections): Use output_bctr.
* elf32-ppc.h (struct ppc_elf_params): Add plt_speculation_barrier.
* elf64-ppc.c (CRSETEQ, BEQCTRM, BEQCTRLM): Define.
(GLINK_PLTRESOLVE_SIZE): Size speculation barrier.
(size_global_entry_stubs): Handle speculation barrier sizing.
(plt_stub_size): Likewise.
(output_bctr): New function.
(build_plt_stub, build_tls_get_addr_stub): Output speculation
barrier.
(ppc_build_one_stub): Likewise for ppc_stub_plt_branch.
(ppc_size_one_stub): Size speculation barrier in ppc_stub_plt_branch.
(build_global_entry_stubs): Output speculation barrier.
(ppc64_elf_build_stubs): Likewise in __glink_PLTresolve stub.
* elf64-ppc.h (struct ppc64_elf_params): Add plt_speculation_barrier.
gold/
* options.h (plt_speculation_barrier): New option.
* powerpc.cc (beqctrm, beqctrlm, crseteq): New insn constants.
(output_bctr): New function.
(Stub_table::plt_call_size): Add space for speculation barrier.
(Stub_table::branch_stub_size): Likewise.
(Output_data_glink::pltresolve_size): Likewise.
(Stub_table::do_write): Output speculation barriers.
ld/
* emultempl/ppc32elf.em (params): Init new field.
(OPTION_PLT_SPECULATION_BARRIER): Define.
(OPTION_NO_PLT_SPECULATION_BARRIER): Define.
(PARSE_AND_LIST_LONGOPTS): Handle new options.
(PARSE_AND_LIST_ARGS_CASES): Likewise.
(PARSE_AND_LIST_OPTIONS): Likewise.
* emultempl/ppc64elf.em (params): Init new field.
(OPTION_PLT_SPECULATION_BARRIER): Define.
(OPTION_NO_PLT_SPECULATION_BARRIER): Define.
(PARSE_AND_LIST_LONGOPTS): Handle --plt-speculation-barrier.
(PARSE_AND_LIST_OPTIONS): Likewise.
(PARSE_AND_LIST_ARGS_CASES): Likewise.
* ld.texinfo (--no-plt-thread-safe): Correct itemx.
(--plt-speculation-barrier): Document.
* testsuite/ld-powerpc/elfv2exe.d,
* testsuite/ld-powerpc/elfv2so.d,
* testsuite/ld-powerpc/relbrlt.d,
* testsuite/ld-powerpc/powerpc.exp: Disable plt alignment and
speculation barriers on various tests.
diff --git a/bfd/elf32-ppc.c b/bfd/elf32-ppc.c
index efdaf04..d315ef4 100644
--- a/bfd/elf32-ppc.c
+++ b/bfd/elf32-ppc.c
@@ -69,7 +69,7 @@ static bfd_reloc_status_type ppc_elf_unhandled_reloc
/* For new-style .glink and .plt. */
#define GLINK_PLTRESOLVE 16*4
#define GLINK_ENTRY_SIZE(htab, h) \
- ((4*4 \
+ (((htab->params->plt_speculation_barrier ? 6*4 : 4*4) \
+ (h != NULL \
&& h == htab->tls_get_addr \
&& !htab->params->no_tls_get_addr_opt ? 8*4 : 0) \
@@ -155,6 +155,8 @@ static const bfd_vma ppc_elf_vxworks_pic_plt0_entry
#define BA 0x48000002
#define BCL_20_31 0x429f0005
#define BCTR 0x4e800420
+#define CRSETEQ 0x4c421242
+#define BEQCTRM 0x4dc20420
#define BEQLR 0x4d820020
#define CMPWI_11_0 0x2c0b0000
#define LIS_11 0x3d600000
@@ -2878,15 +2880,14 @@ ppc_elf_final_write_processing (bfd *abfd, bfd_boolean linker ATTRIBUTE_UNUSED)
static bfd_boolean
is_nonpic_glink_stub (bfd *abfd, asection *glink, bfd_vma off)
{
- bfd_byte buf[4 * 4];
+ bfd_byte buf[3 * 4];
if (!bfd_get_section_contents (abfd, glink, buf, off, sizeof buf))
return FALSE;
return ((bfd_get_32 (abfd, buf + 0) & 0xffff0000) == LIS_11
&& (bfd_get_32 (abfd, buf + 4) & 0xffff0000) == LWZ_11_11
- && bfd_get_32 (abfd, buf + 8) == MTCTR_11
- && bfd_get_32 (abfd, buf + 12) == BCTR);
+ && bfd_get_32 (abfd, buf + 8) == MTCTR_11);
}
static bfd_boolean
@@ -3365,7 +3366,7 @@ ppc_elf_link_hash_table_create (bfd *abfd)
{
struct ppc_elf_link_hash_table *ret;
static struct ppc_elf_params default_params
- = { PLT_OLD, 0, 0, 1, 0, 0, 12, 0, 0, 0 };
+ = { PLT_OLD, 0, 0, 0, 1, 0, 0, 12, 0, 0, 0 };
ret = bfd_zmalloc (sizeof (struct ppc_elf_link_hash_table));
if (ret == NULL)
@@ -7167,6 +7168,8 @@ ppc_elf_relax_section (bfd *abfd,
size = 4 * ARRAY_SIZE (stub_entry);
insn_offset = 0;
}
+ if (htab->params->plt_speculation_barrier)
+ size += 8;
stub_rtype = R_PPC_RELAX;
if (tsec == htab->elf.splt
|| tsec == htab->glink)
@@ -7448,6 +7451,26 @@ elf_finish_pointer_linker_section (bfd *input_bfd,
#define PPC_HI(v) (((v) >> 16) & 0xffff)
#define PPC_HA(v) PPC_HI ((v) + 0x8000)
+static inline bfd_byte *
+output_bctr (struct ppc_elf_link_hash_table *htab, bfd *obfd, bfd_byte *p)
+{
+ if (htab->params->plt_speculation_barrier)
+ {
+ bfd_put_32 (obfd, CRSETEQ, p);
+ p += 4;
+ bfd_put_32 (obfd, BEQCTRM, p);
+ p += 4;
+ bfd_put_32 (obfd, B, p);
+ p += 4;
+ }
+ else
+ {
+ bfd_put_32 (obfd, BCTR, p);
+ p += 4;
+ }
+ return p;
+}
+
static void
write_glink_stub (struct elf_link_hash_entry *h, struct plt_entry *ent,
asection *plt_sec, unsigned char *p,
@@ -7515,8 +7538,7 @@ write_glink_stub (struct elf_link_hash_entry *h, struct plt_entry *ent,
p += 4;
bfd_put_32 (output_bfd, MTCTR_11, p);
p += 4;
- bfd_put_32 (output_bfd, BCTR, p);
- p += 4;
+ p = output_bctr (htab, output_bfd, p);
while (p < end)
{
bfd_put_32 (output_bfd, htab->params->ppc476_workaround ? BA : NOP, p);
@@ -8954,6 +8976,7 @@ ppc_elf_relocate_section (bfd *output_bfd,
stub = stub_entry;
size = ARRAY_SIZE (stub_entry);
}
+ --size;
relocation += addend;
if (bfd_link_relocatable (info))
@@ -8978,6 +9001,7 @@ ppc_elf_relocate_section (bfd *output_bfd,
bfd_put_32 (input_bfd, insn, contents + insn_offset);
insn_offset += 4;
}
+ output_bctr (htab, input_bfd, contents + insn_offset);
/* Rewrite the reloc and convert one of the trailing nop
relocs to describe this relocation. */
@@ -10686,8 +10710,7 @@ ppc_elf_finish_dynamic_sections (bfd *output_bfd,
p += 4;
bfd_put_32 (output_bfd, ADD_11_0_11, p);
p += 4;
- bfd_put_32 (output_bfd, BCTR, p);
- p += 4;
+ p = output_bctr (htab, output_bfd, p);
while (p < endp)
{
bfd_put_32 (output_bfd,
diff --git a/bfd/elf32-ppc.h b/bfd/elf32-ppc.h
index f56d027..50b8d92 100644
--- a/bfd/elf32-ppc.h
+++ b/bfd/elf32-ppc.h
@@ -35,6 +35,9 @@ struct ppc_elf_params
/* Set if individual PLT call stubs should be aligned. */
int plt_stub_align;
+ /* Set if PLT call stubs should use a speculative execution barrier. */
+ int plt_speculation_barrier;
+
/* Whether to emit symbols for stubs. */
int emit_stub_syms;
diff --git a/bfd/elf64-ppc.c b/bfd/elf64-ppc.c
index 10d3fe9..efdd81b 100644
--- a/bfd/elf64-ppc.c
+++ b/bfd/elf64-ppc.c
@@ -161,6 +161,10 @@ static bfd_vma opd_entry_value
#define LD_R11_0R11 0xe96b0000 /* ld %r11,xxx+16@l(%r11) */
#define BCTR 0x4e800420 /* bctr */
+#define CRSETEQ 0x4c421242 /* crset 4*%cr0+%eq */
+#define BEQCTRM 0x4dc20420 /* beqctr- */
+#define BEQCTRLM 0x4dc20421 /* beqctrl- */
+
#define ADDI_R11_R11 0x396b0000 /* addi %r11,%r11,off@l */
#define ADDIS_R2_R2 0x3c420000 /* addis %r2,%r2,off@ha */
#define ADDI_R2_R2 0x38420000 /* addi %r2,%r2,off@l */
@@ -189,7 +193,8 @@ static bfd_vma opd_entry_value
/* __glink_PLTresolve stub instructions. We enter with the index in R0. */
#define GLINK_PLTRESOLVE_SIZE(htab) \
- (8u + (htab->opd_abi ? 11 * 4 : 14 * 4))
+ (8u + (htab->opd_abi ? 11 * 4 : 14 * 4) \
+ + (htab->params->plt_speculation_barrier ? 2 * 4 : 0))
/* 0: */
/* .quad plt0-1f */
/* __glink: */
@@ -9881,6 +9886,8 @@ size_global_entry_stubs (struct elf_link_hash_entry *h, void *inf)
unsigned int align_power;
stub_size = 16;
+ if (htab->params->plt_speculation_barrier)
+ stub_size += 8;
stub_off = s->size;
if (htab->params->plt_stub_align >= 0)
align_power = htab->params->plt_stub_align;
@@ -10446,6 +10453,8 @@ plt_stub_size (struct ppc_link_hash_table *htab,
size += 4;
if (PPC_HA (off) != 0)
size += 4;
+ if (htab->params->plt_speculation_barrier)
+ size += 8;
if (htab->opd_abi)
{
size += 4;
@@ -10467,7 +10476,11 @@ plt_stub_size (struct ppc_link_hash_table *htab,
size += 7 * 4;
if (ALWAYS_EMIT_R2SAVE
|| stub_entry->stub_type == ppc_stub_plt_call_r2save)
- size += 6 * 4;
+ {
+ size += 6 * 4;
+ if (htab->params->plt_speculation_barrier)
+ size -= 4;
+ }
}
return size;
}
@@ -10502,6 +10515,26 @@ plt_stub_pad (struct ppc_link_hash_table *htab,
return 0;
}
+static inline bfd_byte *
+output_bctr (struct ppc_link_hash_table *htab, bfd *obfd, bfd_byte *p)
+{
+ if (htab->params->plt_speculation_barrier)
+ {
+ bfd_put_32 (obfd, CRSETEQ, p);
+ p += 4;
+ bfd_put_32 (obfd, BEQCTRM, p);
+ p += 4;
+ bfd_put_32 (obfd, B_DOT, p);
+ p += 4;
+ }
+ else
+ {
+ bfd_put_32 (obfd, BCTR, p);
+ p += 4;
+ }
+ return p;
+}
+
/* Build a .plt call stub. */
static inline bfd_byte *
@@ -10522,6 +10555,7 @@ build_plt_stub (struct ppc_link_hash_table *htab,
if (!ALWAYS_USE_FAKE_DEP
&& plt_load_toc
&& plt_thread_safe
+ && !htab->params->plt_speculation_barrier
&& !((stub_entry->h == htab->tls_get_addr_fd
|| stub_entry->h == htab->tls_get_addr)
&& htab->params->tls_get_addr_opt))
@@ -10676,7 +10710,7 @@ build_plt_stub (struct ppc_link_hash_table *htab,
bfd_put_32 (obfd, B_DOT | (cmp_branch_off & 0x3fffffc), p), p += 4;
}
else
- bfd_put_32 (obfd, BCTR, p), p += 4;
+ p = output_bctr (htab, obfd, p);
return p;
}
@@ -10720,7 +10754,13 @@ build_tls_get_addr_stub (struct ppc_link_hash_table *htab,
if (r != NULL)
r[0].r_offset += 2 * 4;
p = build_plt_stub (htab, stub_entry, p, offset, r);
- bfd_put_32 (obfd, BCTRL, p - 4);
+ if (htab->params->plt_speculation_barrier)
+ {
+ p -= 4;
+ bfd_put_32 (obfd, BEQCTRLM, p - 4);
+ }
+ else
+ bfd_put_32 (obfd, BCTRL, p - 4);
bfd_put_32 (obfd, LD_R2_0R1 + STK_TOC (htab), p), p += 4;
bfd_put_32 (obfd, LD_R11_0R1 + STK_LINKER (htab), p), p += 4;
@@ -11073,8 +11113,7 @@ ppc_build_one_stub (struct bfd_hash_entry *gen_entry, void *in_arg)
p += 4;
bfd_put_32 (htab->params->stub_bfd, MTCTR_R12, p);
p += 4;
- bfd_put_32 (htab->params->stub_bfd, BCTR, p);
- p += 4;
+ p = output_bctr (htab, htab->params->stub_bfd, p);
break;
case ppc_stub_plt_call:
@@ -11407,6 +11446,8 @@ ppc_size_one_stub (struct bfd_hash_entry *gen_entry, void *in_arg)
if (PPC_LO (r2off) != 0)
size += 4;
}
+ if (htab->params->plt_speculation_barrier)
+ size += 8;
}
else if (info->emitrelocations)
{
@@ -13040,7 +13081,7 @@ build_global_entry_stubs (struct elf_link_hash_entry *h, void *inf)
p += 4;
bfd_put_32 (s->owner, MTCTR_R12, p);
p += 4;
- bfd_put_32 (s->owner, BCTR, p);
+ output_bctr (htab, s->owner, p);
break;
}
return TRUE;
@@ -13169,8 +13210,7 @@ ppc64_elf_build_stubs (struct bfd_link_info *info,
bfd_put_32 (htab->glink->owner, LD_R11_0R11 | 8, p);
p += 4;
}
- bfd_put_32 (htab->glink->owner, BCTR, p);
- p += 4;
+ p = output_bctr (htab, htab->glink->owner, p);
BFD_ASSERT (p - htab->glink->contents == GLINK_PLTRESOLVE_SIZE (htab));
/* Build the .glink lazy link call stubs. */
diff --git a/bfd/elf64-ppc.h b/bfd/elf64-ppc.h
index 8fa0140..1faca6e 100644
--- a/bfd/elf64-ppc.h
+++ b/bfd/elf64-ppc.h
@@ -51,6 +51,9 @@ struct ppc64_elf_params
/* Set if PLT call stubs for localentry:0 functions should omit r2 save. */
int plt_localentry0;
+ /* Set if PLT call stubs should use a speculative execution barrier. */
+ int plt_speculation_barrier;
+
/* Whether to canonicalize .opd so that there are no overlapping
.opd entries. */
int non_overlapping_opd;
diff --git a/gold/options.h b/gold/options.h
index b39d5ff..119665d 100644
--- a/gold/options.h
+++ b/gold/options.h
@@ -1108,6 +1108,10 @@ class General_options
N_("(PowerPC64 only) Optimize calls to ELFv2 localentry:0 functions"),
N_("(PowerPC64 only) Don't optimize ELFv2 calls"));
+ DEFINE_bool(plt_speculation_barrier, options::TWO_DASHES, '\0', false,
+ N_("(PowerPC only) PLT call stubs with speculation barrier"),
+ N_("(PowerPC only) PLT call stubs without speculation barrier"));
+
DEFINE_bool(plt_static_chain, options::TWO_DASHES, '\0', false,
N_("(PowerPC64 only) PLT call stubs should load r11"),
N_("(PowerPC64 only) PLT call stubs should not load r11"));
diff --git a/gold/powerpc.cc b/gold/powerpc.cc
index 9ed5b21..5a2a593 100644
--- a/gold/powerpc.cc
+++ b/gold/powerpc.cc
@@ -3781,6 +3781,8 @@ static const uint32_t b = 0x48000000;
static const uint32_t bcl_20_31 = 0x429f0005;
static const uint32_t bctr = 0x4e800420;
static const uint32_t bctrl = 0x4e800421;
+static const uint32_t beqctrm = 0x4dc20420;
+static const uint32_t beqctrlm = 0x4dc20421;
static const uint32_t beqlr = 0x4d820020;
static const uint32_t blr = 0x4e800020;
static const uint32_t bnectr_p4 = 0x4ce20420;
@@ -3790,6 +3792,7 @@ static const uint32_t cmpdi_11_0 = 0x2c2b0000;
static const uint32_t cmpwi_11_0 = 0x2c0b0000;
static const uint32_t cror_15_15_15 = 0x4def7b82;
static const uint32_t cror_31_31_31 = 0x4ffffb82;
+static const uint32_t crseteq = 0x4c421242;
static const uint32_t ld_0_1 = 0xe8010000;
static const uint32_t ld_0_12 = 0xe80c0000;
static const uint32_t ld_2_1 = 0xe8410000;
@@ -4165,6 +4168,24 @@ write_insn(unsigned char* p, uint32_t v)
elfcpp::Swap<32, big_endian>::writeval(p, v);
}
+template<bool big_endian>
+static unsigned char*
+output_bctr(unsigned char* p)
+{
+ if (parameters->options().plt_speculation_barrier())
+ {
+ write_insn<big_endian>(p, crseteq);
+ p += 4;
+ write_insn<big_endian>(p, beqctrm);
+ p += 4;
+ write_insn<big_endian>(p, b);
+ }
+ else
+ write_insn<big_endian>(p, bctr);
+ p += 4;
+ return p;
+}
+
// Stub_table holds information about plt and long branch stubs.
// Stubs are built in an area following some input section determined
// by group_sections(). This input section is converted to a relaxed
@@ -4426,6 +4447,7 @@ class Stub_table : public Output_relaxed_input_section
{
const Symbol* gsym = p->first.sym_;
return (4 * 4
+ + (parameters->options().plt_speculation_barrier() ? 2 * 4 : 0)
+ (this->targ_->is_tls_get_addr_opt(gsym) ? 8 * 4 : 0));
}
@@ -4441,6 +4463,8 @@ class Stub_table : public Output_relaxed_input_section
got_addr += ppcobj->toc_base_offset();
Address off = plt_addr - got_addr;
unsigned int bytes = 4 * 4 + 4 * (ha(off) != 0);
+ if (parameters->options().plt_speculation_barrier())
+ bytes += 2 * 4;
const Symbol* gsym = p->first.sym_;
if (this->targ_->is_tls_get_addr_opt(gsym))
bytes += 13 * 4;
@@ -4471,6 +4495,8 @@ class Stub_table : public Output_relaxed_input_section
if (p->first.dest_ - loc + (1 << 25) < 2 << 25)
return 4;
unsigned int bytes = 16;
+ if (parameters->options().plt_speculation_barrier())
+ bytes += 8;
if (size == 32 && parameters->options().output_is_position_independent())
bytes += 16;
return bytes;
@@ -4924,7 +4950,8 @@ class Output_data_glink : public Output_section_data
{
if (size == 64)
return (8
- + (this->targ_->abiversion() < 2 ? 11 * 4 : 14 * 4));
+ + (this->targ_->abiversion() < 2 ? 11 * 4 : 14 * 4)
+ + (parameters->options().plt_speculation_barrier() ? 2 * 4 : 0));
return 16 * 4;
}
@@ -5001,7 +5028,8 @@ Output_data_glink<size, big_endian>::add_global_entry(const Symbol* gsym)
std::pair<typename Global_entry_stub_entries::iterator, bool> p
= this->global_entry_stubs_.insert(std::make_pair(gsym, off));
if (p.second)
- this->ge_size_ = off + 16;
+ this->ge_size_
+ = off + 16 + (parameters->options().plt_speculation_barrier() ? 8 : 0);
}
template<int size, bool big_endian>
@@ -5190,7 +5218,10 @@ Stub_table<size, big_endian>::do_write(Output_file* of)
= plt_load_toc && this->targ_->plt_thread_safe();
bool use_fake_dep = false;
Address cmp_branch_off = 0;
- if (thread_safe)
+ if (thread_safe
+ && parameters->options().plt_speculation_barrier())
+ use_fake_dep = true;
+ else if (thread_safe)
{
unsigned int pltindex
= ((pltoff - this->targ_->first_plt_entry_offset())
@@ -5238,7 +5269,7 @@ Stub_table<size, big_endian>::do_write(Output_file* of)
+ this->targ_->stk_linker()));
p += 4;
}
- use_fake_dep = thread_safe;
+ use_fake_dep |= thread_safe;
}
if (ha(off) != 0)
{
@@ -5329,7 +5360,14 @@ Stub_table<size, big_endian>::do_write(Output_file* of)
if (!cs->second.localentry0_
&& this->targ_->is_tls_get_addr_opt(gsym))
{
- write_insn<big_endian>(p, bctrl);
+ if (parameters->options().plt_speculation_barrier())
+ {
+ write_insn<big_endian>(p, crseteq);
+ p += 4;
+ write_insn<big_endian>(p, beqctrlm);
+ }
+ else
+ write_insn<big_endian>(p, bctrl);
p += 4;
write_insn<big_endian>(p, ld_2_1 + this->targ_->stk_toc());
p += 4;
@@ -5348,7 +5386,7 @@ Stub_table<size, big_endian>::do_write(Output_file* of)
write_insn<big_endian>(p, b | (cmp_branch_off & 0x3fffffc));
}
else
- write_insn<big_endian>(p, bctr);
+ output_bctr<big_endian>(p);
}
}
@@ -5383,7 +5421,7 @@ Stub_table<size, big_endian>::do_write(Output_file* of)
write_insn<big_endian>(p, ld_12_12 + l(brltoff)), p += 4;
}
write_insn<big_endian>(p, mtctr_12), p += 4;
- write_insn<big_endian>(p, bctr);
+ output_bctr<big_endian>(p);
}
}
}
@@ -5479,7 +5517,7 @@ Stub_table<size, big_endian>::do_write(Output_file* of)
p += 4;
write_insn<big_endian>(p, mtctr_11);
p += 4;
- write_insn<big_endian>(p, bctr);
+ output_bctr<big_endian>(p);
}
}
@@ -5520,7 +5558,7 @@ Stub_table<size, big_endian>::do_write(Output_file* of)
p += 4;
write_insn<big_endian>(p, mtctr_12);
p += 4;
- write_insn<big_endian>(p, bctr);
+ output_bctr<big_endian>(p);
}
}
if (this->need_save_res_)
@@ -5587,7 +5625,7 @@ Output_data_glink<size, big_endian>::do_write(Output_file* of)
write_insn<big_endian>(p, mtctr_12), p += 4;
write_insn<big_endian>(p, ld_11_11 + 8), p += 4;
}
- write_insn<big_endian>(p, bctr), p += 4;
+ p = output_bctr<big_endian>(p);
gold_assert(p == oview + this->pltresolve_size());
// Write lazy link call stubs.
@@ -5643,7 +5681,7 @@ Output_data_glink<size, big_endian>::do_write(Output_file* of)
write_insn<big_endian>(p, addis_12_12 + ha(off)), p += 4;
write_insn<big_endian>(p, ld_12_12 + l(off)), p += 4;
write_insn<big_endian>(p, mtctr_12), p += 4;
- write_insn<big_endian>(p, bctr);
+ output_bctr<big_endian>(p);
}
}
else
@@ -5735,8 +5773,7 @@ Output_data_glink<size, big_endian>::do_write(Output_file* of)
write_insn<big_endian>(p, add_11_0_11);
}
p += 4;
- write_insn<big_endian>(p, bctr);
- p += 4;
+ p = output_bctr<big_endian>(p);
while (p < end_p)
{
write_insn<big_endian>(p, nop);
diff --git a/ld/emultempl/ppc32elf.em b/ld/emultempl/ppc32elf.em
index 70dd5a0..857034d 100644
--- a/ld/emultempl/ppc32elf.em
+++ b/ld/emultempl/ppc32elf.em
@@ -38,7 +38,7 @@ static int notlsopt = 0;
/* Choose the correct place for .got. */
static int old_got = 0;
-static struct ppc_elf_params params = { PLT_UNSET, 0, -1,
+static struct ppc_elf_params params = { PLT_UNSET, 0, 0, -1,
0, 0, 0, 0, 0, 0, 0 };
static void
@@ -246,6 +246,8 @@ enum ppc32_opt
OPTION_NO_TLS_GET_ADDR_OPT,
OPTION_NEW_PLT,
OPTION_OLD_PLT,
+ OPTION_PLT_SPECULATION_BARRIER,
+ OPTION_NO_PLT_SPECULATION_BARRIER,
OPTION_PLT_ALIGN,
OPTION_NO_PLT_ALIGN,
OPTION_OLD_GOT,
@@ -267,6 +269,8 @@ if test -z "$VXWORKS_BASE_EM_FILE" ; then
PARSE_AND_LIST_LONGOPTS=${PARSE_AND_LIST_LONGOPTS}'
{ "secure-plt", no_argument, NULL, OPTION_NEW_PLT },
{ "bss-plt", no_argument, NULL, OPTION_OLD_PLT },
+ { "plt-speculation-barrier", no_argument, NULL, OPTION_PLT_SPECULATION_BARRIER },
+ { "no-plt-speculation-barrier", no_argument, NULL, OPTION_NO_PLT_SPECULATION_BARRIER },
{ "plt-align", no_argument, NULL, OPTION_PLT_ALIGN },
{ "no-plt-align", no_argument, NULL, OPTION_NO_PLT_ALIGN },
{ "sdata-got", no_argument, NULL, OPTION_OLD_GOT },'
@@ -300,6 +304,12 @@ if test -z "$VXWORKS_BASE_EM_FILE" ; then
--bss-plt Force old-style BSS PLT.\n"
));
fprintf (file, _("\
+ --plt-speculation-barrier PLT call stubs with speculation barrier.\n"
+ ));
+ fprintf (file, _("\
+ --no-plt-speculation-barrier PLT call stubs without that barrier.\n"
+ ));
+ fprintf (file, _("\
--plt-align Align PLT call stubs to fit cache lines.\n"
));
fprintf (file, _("\
@@ -350,6 +360,14 @@ PARSE_AND_LIST_ARGS_CASES=${PARSE_AND_LIST_ARGS_CASES}'
params.plt_style = PLT_OLD;
break;
+ case OPTION_PLT_SPECULATION_BARRIER:
+ params.plt_speculation_barrier = 1;
+ break;
+
+ case OPTION_NO_PLT_SPECULATION_BARRIER:
+ params.plt_speculation_barrier = 0;
+ break;
+
case OPTION_PLT_ALIGN:
params.plt_stub_align = 5;
break;
diff --git a/ld/emultempl/ppc64elf.em b/ld/emultempl/ppc64elf.em
index 840bd44..664cfd3 100644
--- a/ld/emultempl/ppc64elf.em
+++ b/ld/emultempl/ppc64elf.em
@@ -38,7 +38,7 @@ static struct ppc64_elf_params params = { NULL,
&ppc_layout_sections_again,
1, -1, 0,
${DEFAULT_PLT_STATIC_CHAIN-0}, -1, 5,
- -1, 0, -1, -1, 0};
+ -1, 0, 0, -1, -1, 0};
/* Fake input file for stubs. */
static lang_input_statement_type *stub_file;
@@ -692,6 +692,8 @@ enum ppc64_opt
OPTION_NO_PLT_STATIC_CHAIN,
OPTION_PLT_THREAD_SAFE,
OPTION_NO_PLT_THREAD_SAFE,
+ OPTION_PLT_SPECULATION_BARRIER,
+ OPTION_NO_PLT_SPECULATION_BARRIER,
OPTION_PLT_ALIGN,
OPTION_NO_PLT_ALIGN,
OPTION_PLT_LOCALENTRY,
@@ -719,6 +721,8 @@ PARSE_AND_LIST_LONGOPTS=${PARSE_AND_LIST_LONGOPTS}'
{ "no-plt-static-chain", no_argument, NULL, OPTION_NO_PLT_STATIC_CHAIN },
{ "plt-thread-safe", no_argument, NULL, OPTION_PLT_THREAD_SAFE },
{ "no-plt-thread-safe", no_argument, NULL, OPTION_NO_PLT_THREAD_SAFE },
+ { "plt-speculation-barrier", no_argument, NULL, OPTION_PLT_SPECULATION_BARRIER },
+ { "no-plt-speculation-barrier", no_argument, NULL, OPTION_NO_PLT_SPECULATION_BARRIER },
{ "plt-align", optional_argument, NULL, OPTION_PLT_ALIGN },
{ "no-plt-align", no_argument, NULL, OPTION_NO_PLT_ALIGN },
{ "plt-localentry", optional_argument, NULL, OPTION_PLT_LOCALENTRY },
@@ -760,7 +764,13 @@ PARSE_AND_LIST_OPTIONS=${PARSE_AND_LIST_OPTIONS}'
--plt-thread-safe PLT call stubs with load-load barrier.\n"
));
fprintf (file, _("\
- --no-plt-thread-safe PLT call stubs without barrier.\n"
+ --no-plt-thread-safe PLT call stubs without that barrier.\n"
+ ));
+ fprintf (file, _("\
+ --plt-speculation-barrier PLT call stubs with speculation barrier.\n"
+ ));
+ fprintf (file, _("\
+ --no-plt-speculation-barrier PLT call stubs without that barrier.\n"
));
fprintf (file, _("\
--plt-align [=<align>] Align PLT call stubs to fit cache lines.\n"
@@ -850,6 +860,14 @@ PARSE_AND_LIST_ARGS_CASES=${PARSE_AND_LIST_ARGS_CASES}'
params.plt_thread_safe = 0;
break;
+ case OPTION_PLT_SPECULATION_BARRIER:
+ params.plt_speculation_barrier = 1;
+ break;
+
+ case OPTION_NO_PLT_SPECULATION_BARRIER:
+ params.plt_speculation_barrier = 0;
+ break;
+
case OPTION_PLT_ALIGN:
if (optarg != NULL)
{
diff --git a/ld/ld.texinfo b/ld/ld.texinfo
index 94d340c..77b4192 100644
--- a/ld/ld.texinfo
+++ b/ld/ld.texinfo
@@ -7635,7 +7635,7 @@ chain since there is never any need to do so on a PLT call.
@kindex --plt-thread-safe
@kindex --no-plt-thread-safe
@item --plt-thread-safe
-@itemx --no-thread-safe
+@itemx --no-plt-thread-safe
With power7's weakly ordered memory model, it is possible when using
lazy binding for ld.so to update a plt entry in one thread and have
another thread see the individual plt entry words update in the wrong
@@ -7646,6 +7646,15 @@ looks for calls to commonly used functions that create threads, and if
seen, adds the necessary barriers. Use these options to change the
default behaviour.
+@cindex PowerPC64 PLT call stub speculative execution barrier
+@kindex --plt-speculation-barrier
+@kindex --no-plt-speculation-barrier
+@item --plt-speculation-barrier
+@itemx --no-plt-speculation-barrier
+Use these options to control whether all indirect branch instructions
+emitted by @code{ld}, such as those in the PLT, have a speculative
+execution barrier to mitigate Spectre variant 2 attacks.
+
@cindex PowerPC64 ELFv2 PLT localentry optimization
@kindex --plt-localentry
@kindex --no-plt-localentry
diff --git a/ld/testsuite/ld-powerpc/elfv2exe.d b/ld/testsuite/ld-powerpc/elfv2exe.d
index 77bf6e2..3788ab7 100644
--- a/ld/testsuite/ld-powerpc/elfv2exe.d
+++ b/ld/testsuite/ld-powerpc/elfv2exe.d
@@ -1,6 +1,6 @@
#source: elfv2.s
#as: -a64
-#ld: -melf64ppc --defsym f2=0x1234 --defsym f3=0x10008888 --defsym f4=0x1200000 --defsym _start=f1
+#ld: -melf64ppc --no-plt-speculation-barrier --defsym f2=0x1234 --defsym f3=0x10008888 --defsym f4=0x1200000 --defsym _start=f1
#objdump: -dr
.*
diff --git a/ld/testsuite/ld-powerpc/elfv2so.d b/ld/testsuite/ld-powerpc/elfv2so.d
index e7cd45c..8284c51 100644
--- a/ld/testsuite/ld-powerpc/elfv2so.d
+++ b/ld/testsuite/ld-powerpc/elfv2so.d
@@ -1,6 +1,6 @@
#source: elfv2.s
#as: -a64
-#ld: -melf64ppc -shared
+#ld: -melf64ppc -shared --no-plt-speculation-barrier
#objdump: -dr
.*
diff --git a/ld/testsuite/ld-powerpc/powerpc.exp b/ld/testsuite/ld-powerpc/powerpc.exp
index 217b443..ead5247 100644
--- a/ld/testsuite/ld-powerpc/powerpc.exp
+++ b/ld/testsuite/ld-powerpc/powerpc.exp
@@ -121,11 +121,11 @@ set ppcelftests {
"tls32"}
{"TLS32 helper shared library" "-shared -melf32ppc tmpdir/tlslib32.o" "" "" {}
{} "libtlslib32.so"}
- {"TLS32 dynamic exec" "-melf32ppc --no-ld-generated-unwind-info --hash-style=sysv tmpdir/tls32.o tmpdir/libtlslib32.so" "" "" {}
+ {"TLS32 dynamic exec" "-melf32ppc --no-plt-align --no-plt-speculation-barrier --no-ld-generated-unwind-info --hash-style=sysv tmpdir/tls32.o tmpdir/libtlslib32.so" "" "" {}
{{readelf -WSsrl tlsexe32.r} {objdump -dr tlsexe32.d}
{objdump -sj.got tlsexe32.g} {objdump -sj.tdata tlsexe32.t}}
"tlsexe32"}
- {"TLS32 shared" "-shared -melf32ppc --no-ld-generated-unwind-info --hash-style=sysv tmpdir/tls32.o" "" "" {}
+ {"TLS32 shared" "-shared -melf32ppc --no-plt-align --no-plt-speculation-barrier --no-ld-generated-unwind-info --hash-style=sysv tmpdir/tls32.o" "" "" {}
{{readelf -WSsrl tlsso32.r} {objdump -dr tlsso32.d}
{objdump -sj.got tlsso32.g} {objdump -sj.tdata tlsso32.t}}
"tls32.so"}
@@ -147,7 +147,7 @@ set ppcelftests {
{"TLS32 DLL" "-shared -melf32ppc --version-script tlsdll.ver" ""
"-a32" {tlsdll_32.s}
{} "tlsdll32.so"}
- {"TLS32 opt 5" "-melf32ppc -shared --gc-sections --secure-plt tmpdir/tlsdll32.so" "" "-a32" {tlsopt5_32.s}
+ {"TLS32 opt 5" "-melf32ppc -shared --gc-sections --secure-plt --no-plt-align --no-plt-speculation-barrier tmpdir/tlsdll32.so" "" "-a32" {tlsopt5_32.s}
{{objdump -dr tlsopt5_32.d}}
"tlsopt5_32"}
{"Shared library with global symbol" "-shared -melf32ppc" "" "-a32" {sdalib.s}
@@ -174,15 +174,15 @@ set ppc64elftests {
{} "libtlslib.so"}
{"TLS helper old shared lib" "-shared -melf64ppc" "" "-a64" {oldtlslib.s}
{} "liboldlib.so"}
- {"TLS dynamic exec" "-melf64ppc --no-plt-align --no-ld-generated-unwind-info --hash-style=sysv tmpdir/tls.o tmpdir/libtlslib.so" "" "" {}
+ {"TLS dynamic exec" "-melf64ppc --no-plt-align --no-plt-speculation-barrier --no-ld-generated-unwind-info --hash-style=sysv tmpdir/tls.o tmpdir/libtlslib.so" "" "" {}
{{readelf -WSsrl tlsexe.r} {objdump -dr tlsexe.d}
{objdump -sj.got tlsexe.g} {objdump -sj.tdata tlsexe.t}}
"tlsexe"}
- {"TLS dynamic old" "-melf64ppc --no-plt-align --no-ld-generated-unwind-info --hash-style=sysv tmpdir/tls.o tmpdir/liboldlib.so" "" "" {}
+ {"TLS dynamic old" "-melf64ppc --no-plt-align --no-plt-speculation-barrier --no-ld-generated-unwind-info --hash-style=sysv tmpdir/tls.o tmpdir/liboldlib.so" "" "" {}
{{readelf -WSsrl tlsexe.r} {objdump -dr tlsexe.d}
{objdump -sj.got tlsexe.g} {objdump -sj.tdata tlsexe.t}}
"tlsexeold"}
- {"TLS shared" "-shared -melf64ppc --no-plt-align --no-ld-generated-unwind-info --hash-style=sysv tmpdir/tls.o" "" "" {}
+ {"TLS shared" "-shared -melf64ppc --no-plt-align --no-plt-speculation-barrier --no-ld-generated-unwind-info --hash-style=sysv tmpdir/tls.o" "" "" {}
{{readelf -WSsrl tlsso.r} {objdump -dr tlsso.d}
{objdump -sj.got tlsso.g} {objdump -sj.tdata tlsso.t}}
"tls.so"}
@@ -190,17 +190,17 @@ set ppc64elftests {
{{objdump -dr tlstoc.d} {objdump -sj.got tlstoc.g}
{objdump -sj.tdata tlstoc.t}}
"tlstoc"}
- {"TLSTOC dynamic exec" "-melf64ppc --no-plt-align --no-ld-generated-unwind-info --hash-style=sysv tmpdir/tlstoc.o tmpdir/libtlslib.so" ""
+ {"TLSTOC dynamic exec" "-melf64ppc --no-plt-align --no-plt-speculation-barrier --no-ld-generated-unwind-info --hash-style=sysv tmpdir/tlstoc.o tmpdir/libtlslib.so" ""
"" {}
{{readelf -WSsrl tlsexetoc.r} {objdump -dr tlsexetoc.d}
{objdump -sj.got tlsexetoc.g} {objdump -sj.tdata tlsexetoc.t}}
"tlsexetoc"}
- {"TLSTOC dynamic old" "-melf64ppc --no-plt-align --no-ld-generated-unwind-info --hash-style=sysv tmpdir/tlstoc.o tmpdir/liboldlib.so" ""
+ {"TLSTOC dynamic old" "-melf64ppc --no-plt-align --no-plt-speculation-barrier --no-ld-generated-unwind-info --hash-style=sysv tmpdir/tlstoc.o tmpdir/liboldlib.so" ""
"" {}
{{readelf -WSsrl tlsexetoc.r} {objdump -dr tlsexetoc.d}
{objdump -sj.got tlsexetoc.g} {objdump -sj.tdata tlsexetoc.t}}
"tlsexetocold"}
- {"TLSTOC shared" "-shared -melf64ppc --no-plt-align --no-ld-generated-unwind-info --hash-style=sysv tmpdir/tlstoc.o" "" "" {}
+ {"TLSTOC shared" "-shared -melf64ppc --no-plt-align --no-plt-speculation-barrier --no-ld-generated-unwind-info --hash-style=sysv tmpdir/tlstoc.o" "" "" {}
{{readelf -WSsrl tlstocso.r} {objdump -dr tlstocso.d}
{objdump -sj.got tlstocso.g} {objdump -sj.tdata tlstocso.t}}
"tlstoc.so"}
@@ -221,7 +221,7 @@ set ppc64elftests {
"tlsopt4"}
{"TLS DLL" "-shared -melf64ppc --version-script tlsdll.ver" "" "-a64" {tlsdll.s}
{} "tlsdll.so"}
- {"TLS opt 5" "-melf64ppc --no-plt-align -shared --gc-sections --no-plt-localentry tmpdir/tlsdll.so" "" "-a64" {tlsopt5.s}
+ {"TLS opt 5" "-melf64ppc --no-plt-align --no-plt-speculation-barrier -shared --gc-sections --no-plt-localentry tmpdir/tlsdll.so" "" "-a64" {tlsopt5.s}
{{objdump -dr tlsopt5.d} {readelf -wf tlsopt5.wf}}
"tlsopt5"}
{"sym@tocbase" "-shared -melf64ppc" "" "-a64" {symtocbase-1.s symtocbase-2.s}
diff --git a/ld/testsuite/ld-powerpc/relbrlt.d b/ld/testsuite/ld-powerpc/relbrlt.d
index 6f3db7d..6178c06 100644
--- a/ld/testsuite/ld-powerpc/relbrlt.d
+++ b/ld/testsuite/ld-powerpc/relbrlt.d
@@ -1,6 +1,6 @@
#source: relbrlt.s
#as: -a64
-#ld: -melf64ppc --no-plt-align --no-ld-generated-unwind-info --emit-relocs
+#ld: -melf64ppc --no-plt-align --no-plt-speculation-barrier --no-ld-generated-unwind-info --emit-relocs
#objdump: -Dr
.*
--
Alan Modra
Australia Development Lab, IBM