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i386: Honor I386_USE_SYSENTER for 6-argument Linux system calls

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Introduce an int-80h-based version of __libc_do_syscall and use
it if I386_USE_SYSENTER is defined as 0.

Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
This commit is contained in:
Florian Weimer 2022-05-04 15:37:21 +02:00
parent 6e5c7a1e26
commit 60f0f2130d
3 changed files with 37 additions and 3 deletions
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2
sysdeps/unix/sysv/linux/i386/Makefile
View File

@ -13,7 +13,7 @@ install-bin += lddlibc4
endif
ifeq ($(subdir),io)
sysdep_routines += libc-do-syscall
sysdep_routines += libc-do-syscall libc-do-syscall-int80
endif
ifeq ($(subdir),stdlib)

25
sysdeps/unix/sysv/linux/i386/libc-do-syscall-int80.S Normal file
View File

@ -0,0 +1,25 @@
/* Out-of-line syscall stub for six-argument syscalls from C. For static PIE.
Copyright (C) 2022 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
<https://www.gnu.org/licenses/>. */
#ifndef SHARED
# define I386_USE_SYSENTER 0
# include <sysdep.h>
# define __libc_do_syscall __libc_do_syscall_int80
# include "libc-do-syscall.S"
#endif

13
sysdeps/unix/sysv/linux/i386/sysdep.h
View File

@ -42,6 +42,15 @@
# endif
#endif
#if !I386_USE_SYSENTER && IS_IN (libc) && !defined SHARED
/* Inside static libc, we have two versions. For compilation units
with !I386_USE_SYSENTER, the vDSO entry mechanism cannot be
used. */
# define I386_DO_SYSCALL_STRING "__libc_do_syscall_int80"
#else
# define I386_DO_SYSCALL_STRING "__libc_do_syscall"
#endif
#ifdef __ASSEMBLER__
/* Linux uses a negative return value to indicate syscall errors,
@ -301,7 +310,7 @@ struct libc_do_syscall_args
}; \
asm volatile ( \
"movl %1, %%eax\n\t" \
"call __libc_do_syscall" \
"call " I386_DO_SYSCALL_STRING \
: "=a" (resultvar) \
: "i" (__NR_##name), "c" (arg2), "d" (arg3), "S" (arg4), "D" (&_xv) \
: "memory", "cc")
@ -315,7 +324,7 @@ struct libc_do_syscall_args
}; \
asm volatile ( \
"movl %1, %%eax\n\t" \
"call __libc_do_syscall" \
"call " I386_DO_SYSCALL_STRING \
: "=a" (resultvar) \
: "a" (name), "c" (arg2), "d" (arg3), "S" (arg4), "D" (&_xv) \
: "memory", "cc")