1/* S/390-specific implementation of profiling support.
2   Copyright (C) 2000-2022 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#include <sysdep.h>
20
21/*
22 * How profiling works on S/390:
23 * On the start of each function _mcount is called with the address of a
24 * data word in %r1 (initialized to 0, used for counting). The compiler
25 * with the option -p generates code of the form:
26 *
27 *         STM    6,15,24(15)
28 *         BRAS   13,.LTN0_0
29 * .LT0_0:
30 * .LC12:  .long  _mcount
31 * .LC13:  .long  .LP0
32 *         .data
33 *         .align 4
34 * .LP0:   .long  0
35 *         .text
36 * # function profiler
37 *         st     14,4(15)
38 *         l      14,.LC12-.LT0_0(13)
39 *         l      1,.LC13-.LT0_0(13)
40 *         basr   14,14
41 *         l      14,4(15)
42 *
43 * The _mcount implementation now has to call __mcount_internal with the
44 * address of .LP0 as first parameter and the return address as second
45 * parameter. &.LP0 was loaded to %r1 and the return address is in %r14.
46 * _mcount may not modify any register.
47 */
48
49	.globl C_SYMBOL_NAME(_mcount)
50	.type C_SYMBOL_NAME(_mcount), @function
51	cfi_startproc
52	.align ALIGNARG(4)
53C_LABEL(_mcount)
54	/* Save the caller-clobbered registers.  */
55	ahi   %r15,-128
56	cfi_adjust_cfa_offset (128)
57	/* binutils 2.28+: .cfi_val_offset r15, -96 */
58	.cfi_escape \
59		/* DW_CFA_val_offset */ 0x14, \
60		/* r15 */               0x0f, \
61		/* scaled offset */     0x18
62	stm   %r14,%r5,96(%r15)
63	cfi_offset (r14, -128)
64	l     %r2,132(%r15)       # callers address  = first parameter
65	la    %r2,0(%r2)          # clear bit 0
66	la    %r3,0(%r14)         # callees address  = second parameter
67
68#ifdef PIC
69	bras  %r14,0f
70	.long _GLOBAL_OFFSET_TABLE_-.
710:	al    %r14,0(%r14)
72	l     %r14,__mcount_internal@GOT(%r14)
73#else
74	bras  %r14,0f
75	.long __mcount_internal
760:      l     %r14,0(%r14)
77#endif
78	basr  %r14,%r14
79
80	/*
81	 * Pop the saved registers.  Please note that `mcount' has no
82	 * return value.
83	 */
84	lm    %r14,%r5,96(%r15)
85	ahi   %r15,128
86	cfi_adjust_cfa_offset (-128)
87	br    %r14
88	cfi_endproc
89	ASM_SIZE_DIRECTIVE(C_SYMBOL_NAME(_mcount))
90
91#undef mcount
92weak_alias (_mcount, mcount)
93