1/* Assembler macros for x86.
2 Copyright (C) 2017-2026 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#ifndef _X86_SYSDEP_H
20#define _X86_SYSDEP_H 1
21
22#include <sysdeps/generic/sysdep.h>
23
24/* The extended state feature IDs in the state component bitmap. */
25#define X86_XSTATE_X87_ID 0
26#define X86_XSTATE_SSE_ID 1
27#define X86_XSTATE_AVX_ID 2
28#define X86_XSTATE_BNDREGS_ID 3
29#define X86_XSTATE_BNDCFG_ID 4
30#define X86_XSTATE_K_ID 5
31#define X86_XSTATE_ZMM_H_ID 6
32#define X86_XSTATE_ZMM_ID 7
33#define X86_XSTATE_PKRU_ID 9
34#define X86_XSTATE_TILECFG_ID 17
35#define X86_XSTATE_TILEDATA_ID 18
36#define X86_XSTATE_APX_F_ID 19
37
38#ifdef __x86_64__
39/* Offset for fxsave/xsave area used by _dl_runtime_resolve. Also need
40 space to preserve RCX, RDX, RSI, RDI, R8, R9 and RAX. It must be
41 aligned to 16 bytes for fxsave and 64 bytes for xsave. It is non-zero
42 because MOV, instead of PUSH, is used to save registers onto stack.
43
44 +==================+<- stack frame start aligned at 8 or 16 bytes
45 | |<- paddings for stack realignment of 64 bytes
46 |------------------|<- xsave buffer end aligned at 64 bytes
47 | |<-
48 | |<-
49 | |<-
50 |------------------|<- xsave buffer start at STATE_SAVE_OFFSET(%rsp)
51 | |<- 8-byte padding for 64-byte alignment
52 | |<- R9
53 | |<- R8
54 | |<- RDI
55 | |<- RSI
56 | |<- RDX
57 | |<- RCX
58 | |<- RAX
59 +==================+<- RSP aligned at 64 bytes
60
61 */
62# define STATE_SAVE_OFFSET (8 * 7 + 8)
63
64/* _dl_tlsdesc_dynamic preserves RDI, RSI and RBX before realigning
65 stack. After realigning stack, it saves RCX, RDX, R8, R9, R10 and
66 R11. Allocate space for RDI, RSI and RBX to avoid clobbering saved
67 RDI, RSI and RBX values on stack by xsave.
68
69 +==================+<- stack frame start aligned at 8 or 16 bytes
70 | |<- RDI saved in the red zone
71 | |<- RSI saved in the red zone
72 | |<- RBX saved in the red zone
73 | |<- paddings for stack realignment of 64 bytes
74 |------------------|<- xsave buffer end aligned at 64 bytes
75 | |<-
76 | |<-
77 | |<-
78 |------------------|<- xsave buffer start at STATE_SAVE_OFFSET(%rsp)
79 | |<- 8-byte padding for 64-byte alignment
80 | |<- 8-byte padding for 64-byte alignment
81 | |<- R11
82 | |<- R10
83 | |<- R9
84 | |<- R8
85 | |<- RDX
86 | |<- RCX
87 +==================+<- RSP aligned at 64 bytes
88
89 Define the total register save area size for all integer registers by
90 adding 24 to STATE_SAVE_OFFSET since RDI, RSI and RBX are saved onto
91 stack without adjusting stack pointer first, using the red-zone. */
92# define TLSDESC_CALL_REGISTER_SAVE_AREA (STATE_SAVE_OFFSET + 24)
93
94/* Save SSE, AVX, AVX512, mask, bound and APX registers. Bound and APX
95 registers are mutually exclusive. */
96# define STATE_SAVE_MASK \
97 ((1 << X86_XSTATE_SSE_ID) \
98 | (1 << X86_XSTATE_AVX_ID) \
99 | (1 << X86_XSTATE_BNDREGS_ID) \
100 | (1 << X86_XSTATE_K_ID) \
101 | (1 << X86_XSTATE_ZMM_H_ID) \
102 | (1 << X86_XSTATE_ZMM_ID) \
103 | (1 << X86_XSTATE_APX_F_ID))
104
105/* The maximum supported xstate ID. */
106# define X86_XSTATE_MAX_ID X86_XSTATE_APX_F_ID
107
108/* AMX state mask. */
109# define AMX_STATE_SAVE_MASK \
110 ((1 << X86_XSTATE_TILECFG_ID) | (1 << X86_XSTATE_TILEDATA_ID))
111
112/* States to be included in xsave_state_full_size. */
113# define FULL_STATE_SAVE_MASK \
114 (STATE_SAVE_MASK | AMX_STATE_SAVE_MASK)
115#else
116/* Offset for fxsave/xsave area used by _dl_tlsdesc_dynamic. Since i386
117 uses PUSH to save registers onto stack, use 0 here. */
118# define STATE_SAVE_OFFSET 0
119# define TLSDESC_CALL_REGISTER_SAVE_AREA 0
120
121/* Save SSE, AVX, AXV512, mask and bound registers. */
122# define STATE_SAVE_MASK \
123 ((1 << X86_XSTATE_SSE_ID) \
124 | (1 << X86_XSTATE_AVX_ID) \
125 | (1 << X86_XSTATE_BNDREGS_ID) \
126 | (1 << X86_XSTATE_K_ID) \
127 | (1 << X86_XSTATE_ZMM_H_ID))
128
129/* The maximum supported xstate ID. */
130# define X86_XSTATE_MAX_ID X86_XSTATE_ZMM_H_ID
131
132/* States to be included in xsave_state_size. */
133# define FULL_STATE_SAVE_MASK STATE_SAVE_MASK
134#endif
135
136/* States which should be saved for TLSDESC_CALL and TLS_DESC_CALL.
137 Compiler assumes that all registers, including AMX and x87 FPU
138 stack registers, are unchanged after CALL, except for EFLAGS and
139 RAX/EAX. */
140#define TLSDESC_CALL_STATE_SAVE_MASK \
141 (FULL_STATE_SAVE_MASK | (1 << X86_XSTATE_X87_ID))
142
143/* Constants for bits in __x86_string_control: */
144
145/* Avoid short distance REP MOVSB. */
146#define X86_STRING_CONTROL_AVOID_SHORT_DISTANCE_REP_MOVSB (1 << 0)
147
148#ifdef __ASSEMBLER__
149
150/* Syntactic details of assembler. */
151
152/* ELF uses byte-counts for .align, most others use log2 of count of bytes. */
153#define ALIGNARG(log2) 1<<log2
154#define ASM_SIZE_DIRECTIVE(name) .size name,.-name;
155
156/* Common entry 16 byte aligns. */
157#define ENTRY(name) ENTRY_P2ALIGN (name, 4)
158
159#undef END
160#define END(name) \
161 cfi_endproc; \
162 ASM_SIZE_DIRECTIVE(name)
163
164#define ENTRY_CHK(name) ENTRY (name)
165#define END_CHK(name) END (name)
166
167/* Since C identifiers are not normally prefixed with an underscore
168 on this system, the asm identifier `syscall_error' intrudes on the
169 C name space. Make sure we use an innocuous name. */
170#define syscall_error __syscall_error
171#define mcount _mcount
172
173#undef PSEUDO_END
174#define PSEUDO_END(name) \
175 END (name)
176
177/* Local label name for asm code. */
178#ifndef L
179/* ELF-like local names start with `.L'. */
180# define LOCAL_LABEL(name) .L##name
181# define L(name) LOCAL_LABEL(name)
182#endif
183
184#define atom_text_section .section ".text.atom", "ax"
185
186#ifndef DL_STACK_ALIGNMENT
187/* Due to GCC bug:
188
189 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58066
190
191 __tls_get_addr may be called with 8-byte/4-byte stack alignment.
192 Although this bug has been fixed in GCC 4.9.4, 5.3 and 6, we can't
193 assume that stack will be always aligned at 16 bytes. */
194# ifdef __x86_64__
195# define DL_STACK_ALIGNMENT 8
196# define MINIMUM_ALIGNMENT 16
197# else
198# define DL_STACK_ALIGNMENT 4
199# endif
200#endif
201
202/* True if _dl_runtime_resolve/_dl_tlsdesc_dynamic should align stack for
203 STATE_SAVE or align stack to MINIMUM_ALIGNMENT bytes before calling
204 _dl_fixup/__tls_get_addr. */
205#define DL_RUNTIME_RESOLVE_REALIGN_STACK \
206 (STATE_SAVE_ALIGNMENT > DL_STACK_ALIGNMENT \
207 || MINIMUM_ALIGNMENT > DL_STACK_ALIGNMENT)
208
209#endif /* __ASSEMBLER__ */
210
211#endif /* _X86_SYSDEP_H */