glibc/sysdeps/unix/sysv/linux/i386/libc-do-syscall.S

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Support six-argument syscalls from C for 32-bit x86, use generic lowlevellock-futex.h (bug 18138). This patch follows the approach outlined in <https://sourceware.org/ml/libc-alpha/2015-03/msg00656.html> to support six-argument syscalls from INTERNAL_SYSCALL for 32-bit x86, making them call a function __libc_do_syscall that takes the syscall number and three syscall arguments in the registers in which the kernel expects them, along with a pointer to a structure containing the other three arguments. In turn, this allows the generic lowlevellock-futex.h to be used on 32-bit x86, so supporting lll_futex_timed_wait_bitset (and so allowing FUTEX_CLOCK_REALTIME to be used in various cases, so fixing bug 18138 for 32-bit x86 and leaving hppa as the only architecture missing lll_futex_timed_wait_bitset). The change to lowlevellock.h's definition of SYS_futex is because the generic lowlevelloc-futex.h ends up bringing in bits/syscall.h which defines SYS_futex to __NR_futex, so resulting in redefinition errors. The revised definition in lowlevellock.h is in line with what the x86_64 version does. __libc_do_syscall is only needed in libpthread at present (meaning nothing special needs to be done to make it shared-only in most libraries containing it, static in libc only, as on ARM). Tested for 32-bit x86, with the glibc testsuite and with the test in bug 18138. The failures seen FAIL: nptl/tst-cleanupx4 FAIL: rt/tst-cpuclock2 are pre-existing. [BZ #18138] * sysdeps/unix/sysv/linux/i386/sysdep.h (struct libc_do_syscall_args): New structure. (INTERNAL_SYSCALL_MAIN_0): New macro. (INTERNAL_SYSCALL_MAIN_1): Likewise. (INTERNAL_SYSCALL_MAIN_2): Likewise. (INTERNAL_SYSCALL_MAIN_3): Likewise. (INTERNAL_SYSCALL_MAIN_4): Likewise. (INTERNAL_SYSCALL_MAIN_5): Likewise. (INTERNAL_SYSCALL_MAIN_6): Likewise. Call __libc_do_syscall. (INTERNAL_SYSCALL): Define to use INTERNAL_SYSCALL_MAIN_##nr. Replace conditional definitions by conditional definitions of .... (INTERNAL_SYSCALL_MAIN_INLINE): ... this. New macro. * sysdeps/unix/sysv/linux/i386/libc-do-syscall.S: New file. * sysdeps/unix/sysv/linux/i386/Makefile [$(subdir) = nptl] (libpthread-sysdep_routines): Add libc-do-syscall. * sysdeps/unix/sysv/linux/i386/lowlevellock-futex.h: Remove file. * sysdeps/unix/sysv/linux/i386/lowlevellock.h (SYS_futex): Define to __NR_futex not 240.
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/* Out-of-line syscall stub for six-argument syscalls from C.
Copyright (C) 2015 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
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>
#ifndef OPTIMIZE_FOR_GCC_5
Optimize i386 syscall inlining for GCC 5 Since GCC 5 and above can properly spill %ebx when needed, we can inline syscalls with 6 arguments if GCC 5 or above is used to compile glibc. This patch rewrites INTERNAL_SYSCALL macros and skips __libc_do_syscall for GCC 5. For sysdeps/unix/sysv/linux/i386/brk.c, with -O2 -march=i686 -mtune=generic, GCC 5.2 now generates: <__brk>: 0: push %ebx 1: mov $0x2d,%eax 6: mov 0x8(%esp),%ebx a: call b <__brk+0xb> b: R_386_PC32 __x86.get_pc_thunk.dx f: add $0x2,%edx 11: R_386_GOTPC _GLOBAL_OFFSET_TABLE_ 15: call *%gs:0x10 1c: mov 0x0(%edx),%edx 1e: R_386_GOT32 __curbrk 22: cmp %eax,%ebx 24: mov %eax,(%edx) 26: ja 30 <__brk+0x30> 28: xor %eax,%eax 2a: pop %ebx 2b: ret instead of <__brk>: 0: push %ebx 1: mov 0x8(%esp),%ecx 5: call 6 <__brk+0x6> 6: R_386_PC32 __x86.get_pc_thunk.bx a: add $0x2,%ebx c: R_386_GOTPC _GLOBAL_OFFSET_TABLE_ 10: xchg %ecx,%ebx 12: mov $0x2d,%eax 17: call *%gs:0x10 1e: xchg %ecx,%ebx 20: mov %eax,%edx 22: mov 0x0(%ebx),%eax 24: R_386_GOT32 __curbrk 28: mov %edx,(%eax) 2a: xor %eax,%eax 2c: cmp %edx,%ecx 2e: ja 38 <__brk+0x38> 30: pop %ebx 31: ret The new one is shorter by 2 instructions. * sysdeps/unix/sysv/linux/i386/libc-do-syscall.S (__libc_do_syscall): Defined only if !__GNUC_PREREQ (5,0). * sysdeps/unix/sysv/linux/i386/sysdep.h: Define assembler macros only if !__GNUC_PREREQ (5,0). (INTERNAL_SYSCALL_MAIN_6): Optimize for GCC 5. (INTERNAL_SYSCALL_MAIN_INLINE): Likewise. (INTERNAL_SYSCALL_NCS): Likewise. (LOADREGS_0): New macro for GCC 5. (ASMARGS_0): Likewise. (LOADREGS_1): Likewise. (ASMARGS_1): Likewise. (LOADREGS_2): Likewise. (ASMARGS_2): Likewise. (LOADREGS_3): Likewise. (ASMARGS_3): Likewise. (LOADREGS_4): Likewise. (ASMARGS_4): Likewise. (LOADREGS_5): Likewise. (ASMARGS_5): Likewise. (LOADREGS_6): Likewise. (ASMARGS_6): Likewise.
2015-10-15 12:23:42 +00:00
Support six-argument syscalls from C for 32-bit x86, use generic lowlevellock-futex.h (bug 18138). This patch follows the approach outlined in <https://sourceware.org/ml/libc-alpha/2015-03/msg00656.html> to support six-argument syscalls from INTERNAL_SYSCALL for 32-bit x86, making them call a function __libc_do_syscall that takes the syscall number and three syscall arguments in the registers in which the kernel expects them, along with a pointer to a structure containing the other three arguments. In turn, this allows the generic lowlevellock-futex.h to be used on 32-bit x86, so supporting lll_futex_timed_wait_bitset (and so allowing FUTEX_CLOCK_REALTIME to be used in various cases, so fixing bug 18138 for 32-bit x86 and leaving hppa as the only architecture missing lll_futex_timed_wait_bitset). The change to lowlevellock.h's definition of SYS_futex is because the generic lowlevelloc-futex.h ends up bringing in bits/syscall.h which defines SYS_futex to __NR_futex, so resulting in redefinition errors. The revised definition in lowlevellock.h is in line with what the x86_64 version does. __libc_do_syscall is only needed in libpthread at present (meaning nothing special needs to be done to make it shared-only in most libraries containing it, static in libc only, as on ARM). Tested for 32-bit x86, with the glibc testsuite and with the test in bug 18138. The failures seen FAIL: nptl/tst-cleanupx4 FAIL: rt/tst-cpuclock2 are pre-existing. [BZ #18138] * sysdeps/unix/sysv/linux/i386/sysdep.h (struct libc_do_syscall_args): New structure. (INTERNAL_SYSCALL_MAIN_0): New macro. (INTERNAL_SYSCALL_MAIN_1): Likewise. (INTERNAL_SYSCALL_MAIN_2): Likewise. (INTERNAL_SYSCALL_MAIN_3): Likewise. (INTERNAL_SYSCALL_MAIN_4): Likewise. (INTERNAL_SYSCALL_MAIN_5): Likewise. (INTERNAL_SYSCALL_MAIN_6): Likewise. Call __libc_do_syscall. (INTERNAL_SYSCALL): Define to use INTERNAL_SYSCALL_MAIN_##nr. Replace conditional definitions by conditional definitions of .... (INTERNAL_SYSCALL_MAIN_INLINE): ... this. New macro. * sysdeps/unix/sysv/linux/i386/libc-do-syscall.S: New file. * sysdeps/unix/sysv/linux/i386/Makefile [$(subdir) = nptl] (libpthread-sysdep_routines): Add libc-do-syscall. * sysdeps/unix/sysv/linux/i386/lowlevellock-futex.h: Remove file. * sysdeps/unix/sysv/linux/i386/lowlevellock.h (SYS_futex): Define to __NR_futex not 240.
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/* %eax, %ecx, %edx and %esi contain the values expected by the kernel.
%edi points to a structure with the values of %ebx, %edi and %ebp. */
.hidden __libc_do_syscall
ENTRY (__libc_do_syscall)
pushl %ebx
cfi_adjust_cfa_offset (4)
cfi_rel_offset (ebx, 0)
pushl %edi
cfi_adjust_cfa_offset (4)
cfi_rel_offset (edi, 0)
pushl %ebp
cfi_adjust_cfa_offset (4)
cfi_rel_offset (ebp, 0)
movl 0(%edi), %ebx
movl 8(%edi), %ebp
movl 4(%edi), %edi
ENTER_KERNEL
popl %ebp
cfi_adjust_cfa_offset (-4)
cfi_restore (ebp)
popl %edi
cfi_adjust_cfa_offset (-4)
cfi_restore (edi)
popl %ebx
cfi_adjust_cfa_offset (-4)
cfi_restore (ebx)
ret
END (__libc_do_syscall)
Optimize i386 syscall inlining for GCC 5 Since GCC 5 and above can properly spill %ebx when needed, we can inline syscalls with 6 arguments if GCC 5 or above is used to compile glibc. This patch rewrites INTERNAL_SYSCALL macros and skips __libc_do_syscall for GCC 5. For sysdeps/unix/sysv/linux/i386/brk.c, with -O2 -march=i686 -mtune=generic, GCC 5.2 now generates: <__brk>: 0: push %ebx 1: mov $0x2d,%eax 6: mov 0x8(%esp),%ebx a: call b <__brk+0xb> b: R_386_PC32 __x86.get_pc_thunk.dx f: add $0x2,%edx 11: R_386_GOTPC _GLOBAL_OFFSET_TABLE_ 15: call *%gs:0x10 1c: mov 0x0(%edx),%edx 1e: R_386_GOT32 __curbrk 22: cmp %eax,%ebx 24: mov %eax,(%edx) 26: ja 30 <__brk+0x30> 28: xor %eax,%eax 2a: pop %ebx 2b: ret instead of <__brk>: 0: push %ebx 1: mov 0x8(%esp),%ecx 5: call 6 <__brk+0x6> 6: R_386_PC32 __x86.get_pc_thunk.bx a: add $0x2,%ebx c: R_386_GOTPC _GLOBAL_OFFSET_TABLE_ 10: xchg %ecx,%ebx 12: mov $0x2d,%eax 17: call *%gs:0x10 1e: xchg %ecx,%ebx 20: mov %eax,%edx 22: mov 0x0(%ebx),%eax 24: R_386_GOT32 __curbrk 28: mov %edx,(%eax) 2a: xor %eax,%eax 2c: cmp %edx,%ecx 2e: ja 38 <__brk+0x38> 30: pop %ebx 31: ret The new one is shorter by 2 instructions. * sysdeps/unix/sysv/linux/i386/libc-do-syscall.S (__libc_do_syscall): Defined only if !__GNUC_PREREQ (5,0). * sysdeps/unix/sysv/linux/i386/sysdep.h: Define assembler macros only if !__GNUC_PREREQ (5,0). (INTERNAL_SYSCALL_MAIN_6): Optimize for GCC 5. (INTERNAL_SYSCALL_MAIN_INLINE): Likewise. (INTERNAL_SYSCALL_NCS): Likewise. (LOADREGS_0): New macro for GCC 5. (ASMARGS_0): Likewise. (LOADREGS_1): Likewise. (ASMARGS_1): Likewise. (LOADREGS_2): Likewise. (ASMARGS_2): Likewise. (LOADREGS_3): Likewise. (ASMARGS_3): Likewise. (LOADREGS_4): Likewise. (ASMARGS_4): Likewise. (LOADREGS_5): Likewise. (ASMARGS_5): Likewise. (LOADREGS_6): Likewise. (ASMARGS_6): Likewise.
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#endif