1/*
2
3 x86 function call convention, 64-bit:
4 -------------------------------------
5  arguments           |  callee-saved      | extra caller-saved | return
6 [callee-clobbered]   |                    | [callee-clobbered] |
7 ---------------------------------------------------------------------------
8 rdi rsi rdx rcx r8-9 | rbx rbp [*] r12-15 | r10-11             | rax, rdx [**]
9
10 ( rsp is obviously invariant across normal function calls. (gcc can 'merge'
11   functions when it sees tail-call optimization possibilities) rflags is
12   clobbered. Leftover arguments are passed over the stack frame.)
13
14 [*]  In the frame-pointers case rbp is fixed to the stack frame.
15
16 [**] for struct return values wider than 64 bits the return convention is a
17      bit more complex: up to 128 bits width we return small structures
18      straight in rax, rdx. For structures larger than that (3 words or
19      larger) the caller puts a pointer to an on-stack return struct
20      [allocated in the caller's stack frame] into the first argument - i.e.
21      into rdi. All other arguments shift up by one in this case.
22      Fortunately this case is rare in the kernel.
23
24For 32-bit we have the following conventions - kernel is built with
25-mregparm=3 and -freg-struct-return:
26
27 x86 function calling convention, 32-bit:
28 ----------------------------------------
29  arguments         | callee-saved        | extra caller-saved | return
30 [callee-clobbered] |                     | [callee-clobbered] |
31 -------------------------------------------------------------------------
32 eax edx ecx        | ebx edi esi ebp [*] | <none>             | eax, edx [**]
33
34 ( here too esp is obviously invariant across normal function calls. eflags
35   is clobbered. Leftover arguments are passed over the stack frame. )
36
37 [*]  In the frame-pointers case ebp is fixed to the stack frame.
38
39 [**] We build with -freg-struct-return, which on 32-bit means similar
40      semantics as on 64-bit: edx can be used for a second return value
41      (i.e. covering integer and structure sizes up to 64 bits) - after that
42      it gets more complex and more expensive: 3-word or larger struct returns
43      get done in the caller's frame and the pointer to the return struct goes
44      into regparm0, i.e. eax - the other arguments shift up and the
45      function's register parameters degenerate to regparm=2 in essence.
46
47*/
48
49#include <asm/dwarf2.h>
50
51#ifdef CONFIG_X86_64
52
53/*
54 * 64-bit system call stack frame layout defines and helpers,
55 * for assembly code:
56 */
57
58/* The layout forms the "struct pt_regs" on the stack: */
59/*
60 * C ABI says these regs are callee-preserved. They aren't saved on kernel entry
61 * unless syscall needs a complete, fully filled "struct pt_regs".
62 */
63#define R15		0*8
64#define R14		1*8
65#define R13		2*8
66#define R12		3*8
67#define RBP		4*8
68#define RBX		5*8
69/* These regs are callee-clobbered. Always saved on kernel entry. */
70#define R11		6*8
71#define R10		7*8
72#define R9		8*8
73#define R8		9*8
74#define RAX		10*8
75#define RCX		11*8
76#define RDX		12*8
77#define RSI		13*8
78#define RDI		14*8
79/*
80 * On syscall entry, this is syscall#. On CPU exception, this is error code.
81 * On hw interrupt, it's IRQ number:
82 */
83#define ORIG_RAX	15*8
84/* Return frame for iretq */
85#define RIP		16*8
86#define CS		17*8
87#define EFLAGS		18*8
88#define RSP		19*8
89#define SS		20*8
90
91#define SIZEOF_PTREGS	21*8
92
93	.macro ALLOC_PT_GPREGS_ON_STACK addskip=0
94	subq	$15*8+\addskip, %rsp
95	CFI_ADJUST_CFA_OFFSET 15*8+\addskip
96	.endm
97
98	.macro SAVE_C_REGS_HELPER offset=0 rax=1 rcx=1 r8910=1 r11=1
99	.if \r11
100	movq_cfi r11, 6*8+\offset
101	.endif
102	.if \r8910
103	movq_cfi r10, 7*8+\offset
104	movq_cfi r9,  8*8+\offset
105	movq_cfi r8,  9*8+\offset
106	.endif
107	.if \rax
108	movq_cfi rax, 10*8+\offset
109	.endif
110	.if \rcx
111	movq_cfi rcx, 11*8+\offset
112	.endif
113	movq_cfi rdx, 12*8+\offset
114	movq_cfi rsi, 13*8+\offset
115	movq_cfi rdi, 14*8+\offset
116	.endm
117	.macro SAVE_C_REGS offset=0
118	SAVE_C_REGS_HELPER \offset, 1, 1, 1, 1
119	.endm
120	.macro SAVE_C_REGS_EXCEPT_RAX_RCX offset=0
121	SAVE_C_REGS_HELPER \offset, 0, 0, 1, 1
122	.endm
123	.macro SAVE_C_REGS_EXCEPT_R891011
124	SAVE_C_REGS_HELPER 0, 1, 1, 0, 0
125	.endm
126	.macro SAVE_C_REGS_EXCEPT_RCX_R891011
127	SAVE_C_REGS_HELPER 0, 1, 0, 0, 0
128	.endm
129	.macro SAVE_C_REGS_EXCEPT_RAX_RCX_R11
130	SAVE_C_REGS_HELPER 0, 0, 0, 1, 0
131	.endm
132
133	.macro SAVE_EXTRA_REGS offset=0
134	movq_cfi r15, 0*8+\offset
135	movq_cfi r14, 1*8+\offset
136	movq_cfi r13, 2*8+\offset
137	movq_cfi r12, 3*8+\offset
138	movq_cfi rbp, 4*8+\offset
139	movq_cfi rbx, 5*8+\offset
140	.endm
141	.macro SAVE_EXTRA_REGS_RBP offset=0
142	movq_cfi rbp, 4*8+\offset
143	.endm
144
145	.macro RESTORE_EXTRA_REGS offset=0
146	movq_cfi_restore 0*8+\offset, r15
147	movq_cfi_restore 1*8+\offset, r14
148	movq_cfi_restore 2*8+\offset, r13
149	movq_cfi_restore 3*8+\offset, r12
150	movq_cfi_restore 4*8+\offset, rbp
151	movq_cfi_restore 5*8+\offset, rbx
152	.endm
153
154	.macro ZERO_EXTRA_REGS
155	xorl	%r15d, %r15d
156	xorl	%r14d, %r14d
157	xorl	%r13d, %r13d
158	xorl	%r12d, %r12d
159	xorl	%ebp, %ebp
160	xorl	%ebx, %ebx
161	.endm
162
163	.macro RESTORE_C_REGS_HELPER rstor_rax=1, rstor_rcx=1, rstor_r11=1, rstor_r8910=1, rstor_rdx=1
164	.if \rstor_r11
165	movq_cfi_restore 6*8, r11
166	.endif
167	.if \rstor_r8910
168	movq_cfi_restore 7*8, r10
169	movq_cfi_restore 8*8, r9
170	movq_cfi_restore 9*8, r8
171	.endif
172	.if \rstor_rax
173	movq_cfi_restore 10*8, rax
174	.endif
175	.if \rstor_rcx
176	movq_cfi_restore 11*8, rcx
177	.endif
178	.if \rstor_rdx
179	movq_cfi_restore 12*8, rdx
180	.endif
181	movq_cfi_restore 13*8, rsi
182	movq_cfi_restore 14*8, rdi
183	.endm
184	.macro RESTORE_C_REGS
185	RESTORE_C_REGS_HELPER 1,1,1,1,1
186	.endm
187	.macro RESTORE_C_REGS_EXCEPT_RAX
188	RESTORE_C_REGS_HELPER 0,1,1,1,1
189	.endm
190	.macro RESTORE_C_REGS_EXCEPT_RCX
191	RESTORE_C_REGS_HELPER 1,0,1,1,1
192	.endm
193	.macro RESTORE_C_REGS_EXCEPT_R11
194	RESTORE_C_REGS_HELPER 1,1,0,1,1
195	.endm
196	.macro RESTORE_C_REGS_EXCEPT_RCX_R11
197	RESTORE_C_REGS_HELPER 1,0,0,1,1
198	.endm
199	.macro RESTORE_RSI_RDI
200	RESTORE_C_REGS_HELPER 0,0,0,0,0
201	.endm
202	.macro RESTORE_RSI_RDI_RDX
203	RESTORE_C_REGS_HELPER 0,0,0,0,1
204	.endm
205
206	.macro REMOVE_PT_GPREGS_FROM_STACK addskip=0
207	addq $15*8+\addskip, %rsp
208	CFI_ADJUST_CFA_OFFSET -(15*8+\addskip)
209	.endm
210
211	.macro icebp
212	.byte 0xf1
213	.endm
214
215#else /* CONFIG_X86_64 */
216
217/*
218 * For 32bit only simplified versions of SAVE_ALL/RESTORE_ALL. These
219 * are different from the entry_32.S versions in not changing the segment
220 * registers. So only suitable for in kernel use, not when transitioning
221 * from or to user space. The resulting stack frame is not a standard
222 * pt_regs frame. The main use case is calling C code from assembler
223 * when all the registers need to be preserved.
224 */
225
226	.macro SAVE_ALL
227	pushl_cfi_reg eax
228	pushl_cfi_reg ebp
229	pushl_cfi_reg edi
230	pushl_cfi_reg esi
231	pushl_cfi_reg edx
232	pushl_cfi_reg ecx
233	pushl_cfi_reg ebx
234	.endm
235
236	.macro RESTORE_ALL
237	popl_cfi_reg ebx
238	popl_cfi_reg ecx
239	popl_cfi_reg edx
240	popl_cfi_reg esi
241	popl_cfi_reg edi
242	popl_cfi_reg ebp
243	popl_cfi_reg eax
244	.endm
245
246#endif /* CONFIG_X86_64 */
247
248