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author | Ilya Leoshkevich <iii@linux.ibm.com> | 2018-08-10 09:07:44 +0200 |
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committer | Stefan Liebler <stli@linux.ibm.com> | 2018-08-10 09:07:44 +0200 |
commit | 71c01af52fdf643abe3946f934693a55887a8ead (patch) | |
tree | 3ffe528dc1f7a56facab84d857f458f42d208655 /sysdeps/s390 | |
parent | 8d997d2253e742546db2b27c8ee56edbbe4c906c (diff) | |
download | glibc-71c01af52fdf643abe3946f934693a55887a8ead.tar glibc-71c01af52fdf643abe3946f934693a55887a8ead.tar.gz glibc-71c01af52fdf643abe3946f934693a55887a8ead.tar.bz2 glibc-71c01af52fdf643abe3946f934693a55887a8ead.zip |
S390: Implement 64-bit __fentry__
* Since __fentry__ is almost the same as _mcount, reuse the code by
#including it twice with different #defines around.
* Remove LA usages - they are needed in 31-bit mode to clear the top
bit, but in 64-bit they appear to do nothing.
* Add CFI rule for the nonstandard return register. This rule applies
to the current function (binutils generates a new CIE - see
gas/dw2gencfi.c:select_cie_for_fde()), so it is not necessary to put
__fentry__ into a new file.
* Fix CFI offset for %r14.
* Add CFI rule for %r0.
* Fix unwound value of %r15 being off by 244 bytes.
* Unwinding in __fentry__@plt does not work, no plan to fix it - it
would require asking linker to generate CFI for return address in
%r0. From functional perspective keeping it broken is fine, since
the callee did not have a chance to do anything yet. From
convenience perspective it would be possible to enhance GDB in the
future to treat __fentry__@plt in a special way.
* Fix whitespace.
* Fix offsets in comments, which were copied from 32-bit code.
* 32-bit version will not be implemented, since it's not compatible
with the corresponding PLT stubs: they assume %r12 points to GOT,
which is not the case for gcc-emitted __fentry__ stub, which runs
before the prolog.
This patch adds the runtime support in glibc for the -mfentry
gcc feature introduced in [1] and [2].
[1] https://gcc.gnu.org/ml/gcc-patches/2018-07/msg00784.html
[2] https://gcc.gnu.org/ml/gcc-patches/2018-07/msg00912.html
ChangeLog:
* sysdeps/s390/s390-64/Versions (__fentry__): Add.
* sysdeps/s390/s390-64/s390x-mcount.S: Move the common
code to s390x-mcount.h and #include it.
* sysdeps/s390/s390-64/s390x-mcount.h: New file.
* sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
(__fentry__): Add.
Diffstat (limited to 'sysdeps/s390')
-rw-r--r-- | sysdeps/s390/s390-64/Versions | 5 | ||||
-rw-r--r-- | sysdeps/s390/s390-64/s390x-mcount.S | 77 | ||||
-rw-r--r-- | sysdeps/s390/s390-64/s390x-mcount.h | 99 |
3 files changed, 124 insertions, 57 deletions
diff --git a/sysdeps/s390/s390-64/Versions b/sysdeps/s390/s390-64/Versions new file mode 100644 index 0000000000..ec1d68313d --- /dev/null +++ b/sysdeps/s390/s390-64/Versions @@ -0,0 +1,5 @@ +libc { + GLIBC_2.29 { + __fentry__; + } +} diff --git a/sysdeps/s390/s390-64/s390x-mcount.S b/sysdeps/s390/s390-64/s390x-mcount.S index c6b5d65e17..6c1271032b 100644 --- a/sysdeps/s390/s390-64/s390x-mcount.S +++ b/sysdeps/s390/s390-64/s390x-mcount.S @@ -1,6 +1,5 @@ /* 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) + Copyright (C) 2018 Free Software Foundation, Inc. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or @@ -17,61 +16,25 @@ 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 14,4(15) - lg 1,.LC13-.LT0_0(13) - brasl 14,_mcount - lg 14,4(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. */ - - .globl C_SYMBOL_NAME(_mcount) - .type C_SYMBOL_NAME(_mcount), @function - cfi_startproc - .align ALIGNARG(4) -C_LABEL(_mcount) - /* Save the caller-clobbered registers. */ - aghi %r15,-224 - cfi_adjust_cfa_offset (224) - stmg %r14,%r5,160(%r15) - cfi_offset (r14, 0) - cfi_offset (r15, 8) - lg %r2,232(%r15) # callers address = first parameter - la %r2,0(%r2) # clear bit 0 - la %r3,0(%r14) # callees address = second parameter - -#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) - br %r14 - cfi_endproc - ASM_SIZE_DIRECTIVE(C_SYMBOL_NAME(_mcount)) +#define MCOUNT_SYMBOL _mcount +#define MCOUNT_CALLER_OFF 232 /* Pushed by the _mcount stub. */ +#define MCOUNT_CALLEE_REG 14 /* Normal calling convention. */ +#define MCOUNT_RETURN_REG 14 +#include "s390x-mcount.h" +#undef MCOUNT_SYMBOL +#undef MCOUNT_CALLER_OFF +#undef MCOUNT_CALLEE_REG +#undef MCOUNT_RETURN_REG + +#define MCOUNT_SYMBOL __fentry__ +#define MCOUNT_CALLER_OFF 160 /* Saved %r14. */ +#define MCOUNT_CALLEE_REG 0 /* __fentry__ calling convention. */ +#define MCOUNT_RETURN_REG 1 /* Cannot return via %r0. */ +#include "s390x-mcount.h" +#undef MCOUNT_SYMBOL +#undef MCOUNT_CALLER_OFF +#undef MCOUNT_CALLEE_REG +#undef MCOUNT_RETURN_REG #undef mcount weak_alias (_mcount, mcount) 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)) |