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binutils-gdb/include/elf/ppc64.h
Alan Modra f378ab099d PPC64_OPT_LOCALENTRY 
ELFv2 functions with localentry:0 are those with a single entry point,
ie. global entry == local entry, and that have no requirement on r2 or
r12, and guarantee r2 is unchanged on return.  Such an external
function can be called via the PLT without saving r2 or restoring it
on return, avoiding a common load-hit-store for small functions.   The
optimization is attractive.  The TOC pointer load-hit-store is a major
reason why calls to small functions that need no register saves, or
with shrink-wrap, no register saves on a fast path, are slow on
powerpc64le.

To be safe, this optimization needs ld.so support to check that the
run-time matches link-time function implementation.  If a function
in a shared library with st_other localentry non-zero is called
without saving and restoring r2, r2 will be trashed on return, leading
to segfaults.  For that reason the optimization does not happen for
weak functions since a weak definition is a fairly solid hint that the
function will likely be overridden.  I'm also not enabling the
optimization by default unless glibc-2.26 is detected, which should
have the ld.so checks implemented.

bfd/
	* elf64-ppc.c (struct ppc_link_hash_table): Add has_plt_localentry0.
	(ppc64_elf_merge_symbol_attribute): Merge localentry bits from
	dynamic objects.
	(is_elfv2_localentry0): New function.
	(ppc64_elf_tls_setup): Default params->plt_localentry0.
	(plt_stub_size): Adjust size for tls_get_addr_opt stub.
	(build_tls_get_addr_stub): Use a simpler stub when r2 is not saved.
	(ppc64_elf_size_stubs): Leave stub_type as ppc_stub_plt_call for
	optimized localentry:0 stubs.
	(ppc64_elf_build_stubs): Save r2 in ELFv2 __glink_PLTresolve.
	(ppc64_elf_relocate_section): Leave nop unchanged for optimized
	localentry:0 stubs.
	(ppc64_elf_finish_dynamic_sections): Set PPC64_OPT_LOCALENTRY in
	DT_PPC64_OPT.
	* elf64-ppc.h (struct ppc64_elf_params): Add plt_localentry0.
include/
	* elf/ppc64.h (PPC64_OPT_LOCALENTRY): Define.
ld/
	* emultempl/ppc64elf.em (params): Init plt_localentry0 field.
	(enum ppc64_opt): New, replacing OPTION_* defines.  Add
	OPTION_PLT_LOCALENTRY, and OPTION_NO_PLT_LOCALENTRY.
	(PARSE_AND_LIST_*): Support --plt-localentry and --no-plt-localentry.
	* testsuite/ld-powerpc/elfv2so.d: Update.
	* testsuite/ld-powerpc/powerpc.exp (TLS opt 5): Use --no-plt-localentry.
	* testsuite/ld-powerpc/tlsopt5.d: Update.
2017-06-01 22:47:32 +09:30

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/* PPC64 ELF support for BFD.
Copyright (C) 2003-2017 Free Software Foundation, Inc.
This file is part of BFD, the Binary File Descriptor library.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
MA 02110-1301, USA. */
#ifndef _ELF_PPC64_H
#define _ELF_PPC64_H
#include "elf/reloc-macros.h"
/* Relocations. */
START_RELOC_NUMBERS (elf_ppc64_reloc_type)
RELOC_NUMBER (R_PPC64_NONE, 0)
RELOC_NUMBER (R_PPC64_ADDR32, 1)
RELOC_NUMBER (R_PPC64_ADDR24, 2)
RELOC_NUMBER (R_PPC64_ADDR16, 3)
RELOC_NUMBER (R_PPC64_ADDR16_LO, 4)
RELOC_NUMBER (R_PPC64_ADDR16_HI, 5)
RELOC_NUMBER (R_PPC64_ADDR16_HA, 6)
RELOC_NUMBER (R_PPC64_ADDR14, 7)
RELOC_NUMBER (R_PPC64_ADDR14_BRTAKEN, 8)
RELOC_NUMBER (R_PPC64_ADDR14_BRNTAKEN, 9)
RELOC_NUMBER (R_PPC64_REL24, 10)
RELOC_NUMBER (R_PPC64_REL14, 11)
RELOC_NUMBER (R_PPC64_REL14_BRTAKEN, 12)
RELOC_NUMBER (R_PPC64_REL14_BRNTAKEN, 13)
RELOC_NUMBER (R_PPC64_GOT16, 14)
RELOC_NUMBER (R_PPC64_GOT16_LO, 15)
RELOC_NUMBER (R_PPC64_GOT16_HI, 16)
RELOC_NUMBER (R_PPC64_GOT16_HA, 17)
/* 18 unused. 32-bit reloc is R_PPC_PLTREL24. */
RELOC_NUMBER (R_PPC64_COPY, 19)
RELOC_NUMBER (R_PPC64_GLOB_DAT, 20)
RELOC_NUMBER (R_PPC64_JMP_SLOT, 21)
RELOC_NUMBER (R_PPC64_RELATIVE, 22)
/* 23 unused. 32-bit reloc is R_PPC_LOCAL24PC. */
RELOC_NUMBER (R_PPC64_UADDR32, 24)
RELOC_NUMBER (R_PPC64_UADDR16, 25)
RELOC_NUMBER (R_PPC64_REL32, 26)
RELOC_NUMBER (R_PPC64_PLT32, 27)
RELOC_NUMBER (R_PPC64_PLTREL32, 28)
RELOC_NUMBER (R_PPC64_PLT16_LO, 29)
RELOC_NUMBER (R_PPC64_PLT16_HI, 30)
RELOC_NUMBER (R_PPC64_PLT16_HA, 31)
/* 32 unused. 32-bit reloc is R_PPC_SDAREL16. */
RELOC_NUMBER (R_PPC64_SECTOFF, 33)
RELOC_NUMBER (R_PPC64_SECTOFF_LO, 34)
RELOC_NUMBER (R_PPC64_SECTOFF_HI, 35)
RELOC_NUMBER (R_PPC64_SECTOFF_HA, 36)
RELOC_NUMBER (R_PPC64_REL30, 37)
RELOC_NUMBER (R_PPC64_ADDR64, 38)
RELOC_NUMBER (R_PPC64_ADDR16_HIGHER, 39)
RELOC_NUMBER (R_PPC64_ADDR16_HIGHERA, 40)
RELOC_NUMBER (R_PPC64_ADDR16_HIGHEST, 41)
RELOC_NUMBER (R_PPC64_ADDR16_HIGHESTA, 42)
RELOC_NUMBER (R_PPC64_UADDR64, 43)
RELOC_NUMBER (R_PPC64_REL64, 44)
RELOC_NUMBER (R_PPC64_PLT64, 45)
RELOC_NUMBER (R_PPC64_PLTREL64, 46)
RELOC_NUMBER (R_PPC64_TOC16, 47)
RELOC_NUMBER (R_PPC64_TOC16_LO, 48)
RELOC_NUMBER (R_PPC64_TOC16_HI, 49)
RELOC_NUMBER (R_PPC64_TOC16_HA, 50)
RELOC_NUMBER (R_PPC64_TOC, 51)
RELOC_NUMBER (R_PPC64_PLTGOT16, 52)
RELOC_NUMBER (R_PPC64_PLTGOT16_LO, 53)
RELOC_NUMBER (R_PPC64_PLTGOT16_HI, 54)
RELOC_NUMBER (R_PPC64_PLTGOT16_HA, 55)
/* The following relocs were added in the 64-bit PowerPC ELF ABI
revision 1.2. */
RELOC_NUMBER (R_PPC64_ADDR16_DS, 56)
RELOC_NUMBER (R_PPC64_ADDR16_LO_DS, 57)
RELOC_NUMBER (R_PPC64_GOT16_DS, 58)
RELOC_NUMBER (R_PPC64_GOT16_LO_DS, 59)
RELOC_NUMBER (R_PPC64_PLT16_LO_DS, 60)
RELOC_NUMBER (R_PPC64_SECTOFF_DS, 61)
RELOC_NUMBER (R_PPC64_SECTOFF_LO_DS, 62)
RELOC_NUMBER (R_PPC64_TOC16_DS, 63)
RELOC_NUMBER (R_PPC64_TOC16_LO_DS, 64)
RELOC_NUMBER (R_PPC64_PLTGOT16_DS, 65)
RELOC_NUMBER (R_PPC64_PLTGOT16_LO_DS, 66)
/* Relocs added to support TLS. PowerPC64 ELF ABI revision 1.5. */
RELOC_NUMBER (R_PPC64_TLS, 67)
RELOC_NUMBER (R_PPC64_DTPMOD64, 68)
RELOC_NUMBER (R_PPC64_TPREL16, 69)
RELOC_NUMBER (R_PPC64_TPREL16_LO, 70)
RELOC_NUMBER (R_PPC64_TPREL16_HI, 71)
RELOC_NUMBER (R_PPC64_TPREL16_HA, 72)
RELOC_NUMBER (R_PPC64_TPREL64, 73)
RELOC_NUMBER (R_PPC64_DTPREL16, 74)
RELOC_NUMBER (R_PPC64_DTPREL16_LO, 75)
RELOC_NUMBER (R_PPC64_DTPREL16_HI, 76)
RELOC_NUMBER (R_PPC64_DTPREL16_HA, 77)
RELOC_NUMBER (R_PPC64_DTPREL64, 78)
RELOC_NUMBER (R_PPC64_GOT_TLSGD16, 79)
RELOC_NUMBER (R_PPC64_GOT_TLSGD16_LO, 80)
RELOC_NUMBER (R_PPC64_GOT_TLSGD16_HI, 81)
RELOC_NUMBER (R_PPC64_GOT_TLSGD16_HA, 82)
RELOC_NUMBER (R_PPC64_GOT_TLSLD16, 83)
RELOC_NUMBER (R_PPC64_GOT_TLSLD16_LO, 84)
RELOC_NUMBER (R_PPC64_GOT_TLSLD16_HI, 85)
RELOC_NUMBER (R_PPC64_GOT_TLSLD16_HA, 86)
RELOC_NUMBER (R_PPC64_GOT_TPREL16_DS, 87)
RELOC_NUMBER (R_PPC64_GOT_TPREL16_LO_DS, 88)
RELOC_NUMBER (R_PPC64_GOT_TPREL16_HI, 89)
RELOC_NUMBER (R_PPC64_GOT_TPREL16_HA, 90)
RELOC_NUMBER (R_PPC64_GOT_DTPREL16_DS, 91)
RELOC_NUMBER (R_PPC64_GOT_DTPREL16_LO_DS, 92)
RELOC_NUMBER (R_PPC64_GOT_DTPREL16_HI, 93)
RELOC_NUMBER (R_PPC64_GOT_DTPREL16_HA, 94)
RELOC_NUMBER (R_PPC64_TPREL16_DS, 95)
RELOC_NUMBER (R_PPC64_TPREL16_LO_DS, 96)
RELOC_NUMBER (R_PPC64_TPREL16_HIGHER, 97)
RELOC_NUMBER (R_PPC64_TPREL16_HIGHERA, 98)
RELOC_NUMBER (R_PPC64_TPREL16_HIGHEST, 99)
RELOC_NUMBER (R_PPC64_TPREL16_HIGHESTA, 100)
RELOC_NUMBER (R_PPC64_DTPREL16_DS, 101)
RELOC_NUMBER (R_PPC64_DTPREL16_LO_DS, 102)
RELOC_NUMBER (R_PPC64_DTPREL16_HIGHER, 103)
RELOC_NUMBER (R_PPC64_DTPREL16_HIGHERA, 104)
RELOC_NUMBER (R_PPC64_DTPREL16_HIGHEST, 105)
RELOC_NUMBER (R_PPC64_DTPREL16_HIGHESTA, 106)
RELOC_NUMBER (R_PPC64_TLSGD, 107)
RELOC_NUMBER (R_PPC64_TLSLD, 108)
RELOC_NUMBER (R_PPC64_TOCSAVE, 109)
/* Added when HA and HI relocs were changed to report overflows. */
RELOC_NUMBER (R_PPC64_ADDR16_HIGH, 110)
RELOC_NUMBER (R_PPC64_ADDR16_HIGHA, 111)
RELOC_NUMBER (R_PPC64_TPREL16_HIGH, 112)
RELOC_NUMBER (R_PPC64_TPREL16_HIGHA, 113)
RELOC_NUMBER (R_PPC64_DTPREL16_HIGH, 114)
RELOC_NUMBER (R_PPC64_DTPREL16_HIGHA, 115)
/* Added for ELFv2. */
RELOC_NUMBER (R_PPC64_REL24_NOTOC, 116)
RELOC_NUMBER (R_PPC64_ADDR64_LOCAL, 117)
RELOC_NUMBER (R_PPC64_ENTRY, 118)
#ifndef RELOC_MACROS_GEN_FUNC
/* Relocation only used internally by ld. If you need to use these
reloc numbers, you can change them to some other unused value
without affecting the ABI. They will never appear in object files. */
RELOC_NUMBER (R_PPC64_LO_DS_OPT, 128)
/* Reloc only used internally by gas. As above, value is unimportant. */
RELOC_NUMBER (R_PPC64_16DX_HA, 129)
#endif
/* Power9 split rel16 for addpcis. */
RELOC_NUMBER (R_PPC64_REL16DX_HA, 246)
/* Support STT_GNU_IFUNC plt calls. */
RELOC_NUMBER (R_PPC64_JMP_IREL, 247)
RELOC_NUMBER (R_PPC64_IRELATIVE, 248)
/* These are GNU extensions used in PIC code sequences. */
RELOC_NUMBER (R_PPC64_REL16, 249)
RELOC_NUMBER (R_PPC64_REL16_LO, 250)
RELOC_NUMBER (R_PPC64_REL16_HI, 251)
RELOC_NUMBER (R_PPC64_REL16_HA, 252)
/* These are GNU extensions to enable C++ vtable garbage collection. */
RELOC_NUMBER (R_PPC64_GNU_VTINHERIT, 253)
RELOC_NUMBER (R_PPC64_GNU_VTENTRY, 254)
END_RELOC_NUMBERS (R_PPC64_max)
#define IS_PPC64_TLS_RELOC(R) \
(((R) >= R_PPC64_TLS && (R) <= R_PPC64_DTPREL16_HIGHESTA) \
|| ((R) >= R_PPC64_TPREL16_HIGH && (R) <= R_PPC64_DTPREL16_HIGHA))
/* e_flags bits specifying ABI.
1 for original function descriptor using ABI,
2 for revised ABI without function descriptors,
0 for unspecified or not using any features affected by the differences. */
#define EF_PPC64_ABI 3
/* The ELFv2 ABI uses three bits in the symbol st_other field of a
function definition to specify the number of instructions between a
function's global entry point and local entry point.
The global entry point is used when it is necessary to set up the
toc pointer (r2) for the function. Callers must enter the global
entry point with r12 set to the global entry point address. On
return from the function, r2 may have a different value to that
which it had on entry.
The local entry point is used when r2 is known to already be valid
for the function. There is no requirement on r12 when using the
local entry point, and on return r2 will contain the same value as
at entry.
A value of zero in these bits means that the function has a single
entry point with no requirement on r12 or r2, and that on return r2
will contain the same value as at entry.
Values of one and seven are reserved. */
#define STO_PPC64_LOCAL_BIT 5
#define STO_PPC64_LOCAL_MASK (7 << STO_PPC64_LOCAL_BIT)
// 3 bit other field to bytes.
static inline unsigned int
ppc64_decode_local_entry(unsigned int other)
{
return ((1 << other) >> 2) << 2;
}
// bytes to field value.
static inline unsigned int
ppc64_encode_local_entry(unsigned int val)
{
return (val >= 4 * 4
? (val >= 8 * 4
? (val >= 16 * 4 ? 6 : 5)
: 4)
: (val >= 2 * 4
? 3
: (val >= 1 * 4 ? 2 : 0)));
}
/* st_other to number of bytes. */
#define PPC64_LOCAL_ENTRY_OFFSET(other) \
ppc64_decode_local_entry (((other) & STO_PPC64_LOCAL_MASK) \
>> STO_PPC64_LOCAL_BIT)
/* number of bytes to st_other. */
#define PPC64_SET_LOCAL_ENTRY_OFFSET(val) \
ppc64_encode_local_entry (val) << STO_PPC64_LOCAL_BIT
/* Specify the start of the .glink section. */
#define DT_PPC64_GLINK DT_LOPROC
/* Specify the start and size of the .opd section. */
#define DT_PPC64_OPD (DT_LOPROC + 1)
#define DT_PPC64_OPDSZ (DT_LOPROC + 2)
/* Specify whether various optimisations are possible. */
#define DT_PPC64_OPT (DT_LOPROC + 3)
#define PPC64_OPT_TLS 1
#define PPC64_OPT_MULTI_TOC 2
#define PPC64_OPT_LOCALENTRY 4
#endif /* _ELF_PPC64_H */
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