1 /* 64 bit S/390-specific implementation of profiling support. 2 Copyright (C) 2001-2022 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 /* How profiling works on 64 bit S/390: 22 On the start of each function _mcount is called with the address of a 23 data word in %r1 (initialized to 0, used for counting). The compiler 24 with the option -p generates code of the form: 25 26 STM 6,15,24(15) 27 BRAS 13,.LTN0_0 28 .LT0_0: 29 .LC13: .long .LP0 30 .data 31 .align 4 32 .LP0: .long 0 33 .text 34 # function profiler 35 stg 14,8(15) 36 lg 1,.LC13-.LT0_0(13) 37 brasl 14,_mcount 38 lg 14,8(15) 39 40 The _mcount implementation now has to call __mcount_internal with the 41 address of .LP0 as first parameter and the return address as second 42 parameter. &.LP0 was loaded to %r1 and the return address is in %r14. 43 _mcount may not modify any register. 44 45 Alternatively, at the start of each function __fentry__ is called using a 46 single 47 48 # function profiler 49 brasl 0,__fentry__ 50 51 instruction. In this case %r0 points to the callee, and %r14 points to the 52 caller. These values need to be passed to __mcount_internal using the same 53 sequence as for _mcount, so the code below is shared between both functions. 54 The only major difference is that __fentry__ cannot return through %r0, in 55 which the return address is located, because br instruction is a no-op with 56 this register. Therefore %r1, which is clobbered by the PLT anyway, is 57 used. */ 58 59 #define xglue(x, y) x ## y 60 #define glue(x, y) xglue(x, y) 61 62 .globl C_SYMBOL_NAME(MCOUNT_SYMBOL) 63 .type C_SYMBOL_NAME(MCOUNT_SYMBOL), @function 64 cfi_startproc 65 .align ALIGNARG(4) 66 C_LABEL(MCOUNT_SYMBOL) 67 cfi_return_column (glue(r, MCOUNT_CALLEE_REG)) 68 /* Save the caller-clobbered registers. */ 69 aghi %r15,-224 70 cfi_adjust_cfa_offset (224) 71 /* binutils 2.28+: .cfi_val_offset r15, -160 */ 72 .cfi_escape \ 73 /* DW_CFA_val_offset */ 0x14, \ 74 /* r15 */ 0x0f, \ 75 /* scaled offset */ 0x14 76 stmg %r14,%r5,160(%r15) 77 cfi_offset (r14, -224) 78 cfi_offset (r0, -224+16) 79 lg %r2,MCOUNT_CALLER_OFF(%r15) # callers address = 1st param 80 lgr %r3,glue(%r, MCOUNT_CALLEE_REG) # callees address = 2nd param 81 82 #ifdef PIC 83 brasl %r14,__mcount_internal@PLT 84 #else 85 brasl %r14,__mcount_internal 86 #endif 87 88 /* Pop the saved registers. Please note that `mcount' has no 89 return value. */ 90 lmg %r14,%r5,160(%r15) 91 aghi %r15,224 92 cfi_adjust_cfa_offset (-224) 93 #if MCOUNT_RETURN_REG != MCOUNT_CALLEE_REG 94 lgr glue(%r, MCOUNT_RETURN_REG),glue(%r, MCOUNT_CALLEE_REG) 95 #endif 96 br glue(%r, MCOUNT_RETURN_REG) 97 cfi_endproc 98 ASM_SIZE_DIRECTIVE(C_SYMBOL_NAME(MCOUNT_SYMBOL)) 99