diff options
Diffstat (limited to 'sysdeps/s390/s390-64/s390x-mcount.h')
| -rw-r--r-- | sysdeps/s390/s390-64/s390x-mcount.h | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/sysdeps/s390/s390-64/s390x-mcount.h b/sysdeps/s390/s390-64/s390x-mcount.h new file mode 100644 index 0000000000..f936149447 --- /dev/null +++ b/sysdeps/s390/s390-64/s390x-mcount.h @@ -0,0 +1,99 @@ +/* 64 bit S/390-specific implementation of profiling support. + Copyright (C) 2001-2018 Free Software Foundation, Inc. + Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com) + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library 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 + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +#include <sysdep.h> + +/* How profiling works on 64 bit S/390: + On the start of each function _mcount is called with the address of a + data word in %r1 (initialized to 0, used for counting). The compiler + with the option -p generates code of the form: + + STM 6,15,24(15) + BRAS 13,.LTN0_0 + .LT0_0: + .LC13: .long .LP0 + .data + .align 4 + .LP0: .long 0 + .text + # function profiler + stg 14,8(15) + lg 1,.LC13-.LT0_0(13) + brasl 14,_mcount + lg 14,8(15) + + The _mcount implementation now has to call __mcount_internal with the + address of .LP0 as first parameter and the return address as second + parameter. &.LP0 was loaded to %r1 and the return address is in %r14. + _mcount may not modify any register. + + Alternatively, at the start of each function __fentry__ is called using a + single + + # function profiler + brasl 0,__fentry__ + + instruction. In this case %r0 points to the callee, and %r14 points to the + caller. These values need to be passed to __mcount_internal using the same + sequence as for _mcount, so the code below is shared between both functions. + The only major difference is that __fentry__ cannot return through %r0, in + which the return address is located, because br instruction is a no-op with + this register. Therefore %r1, which is clobbered by the PLT anyway, is + used. */ + +#define xglue(x, y) x ## y +#define glue(x, y) xglue(x, y) + + .globl C_SYMBOL_NAME(MCOUNT_SYMBOL) + .type C_SYMBOL_NAME(MCOUNT_SYMBOL), @function + cfi_startproc + .align ALIGNARG(4) +C_LABEL(MCOUNT_SYMBOL) + cfi_return_column (glue(r, MCOUNT_CALLEE_REG)) + /* Save the caller-clobbered registers. */ + aghi %r15,-224 + cfi_adjust_cfa_offset (224) + /* binutils 2.28+: .cfi_val_offset r15, -160 */ + .cfi_escape \ + /* DW_CFA_val_offset */ 0x14, \ + /* r15 */ 0x0f, \ + /* scaled offset */ 0x14 + stmg %r14,%r5,160(%r15) + cfi_offset (r14, -224) + cfi_offset (r0, -224+16) + lg %r2,MCOUNT_CALLER_OFF(%r15) # callers address = 1st param + lgr %r3,glue(%r, MCOUNT_CALLEE_REG) # callees address = 2nd param + +#ifdef PIC + brasl %r14,__mcount_internal@PLT +#else + brasl %r14,__mcount_internal +#endif + + /* Pop the saved registers. Please note that `mcount' has no + return value. */ + lmg %r14,%r5,160(%r15) + aghi %r15,224 + cfi_adjust_cfa_offset (-224) +#if MCOUNT_RETURN_REG != MCOUNT_CALLEE_REG + lgr glue(%r, MCOUNT_RETURN_REG),glue(%r, MCOUNT_CALLEE_REG) +#endif + br glue(%r, MCOUNT_RETURN_REG) + cfi_endproc + ASM_SIZE_DIRECTIVE(C_SYMBOL_NAME(MCOUNT_SYMBOL)) |