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319cbbf633
Fix a commit cc25c8b4c1 ("New pthread rwlock that is more scalable.")
regression and prevent uncontrolled stack space usage from happening
when a 5-, 6- or 7-argument syscall wrapper is placed in a loop.
The cause of the problem is the use of `alloca' in regular MIPS/Linux
wrappers to force the use of the frame pointer register in any function
using one or more of these wrappers. Using the frame pointer register
is required so as not to break frame unwinding as the the stack pointer
is lowered within the inline asm used by these wrappers to make room for
the stack arguments, which 5-, 6- and 7-argument syscalls use with the
o32 ABI.
The regular MIPS/Linux wrappers are macros however, expanded inline, and
stack allocations made with `alloca' are not discarded until the return
of the function they are made in. Consequently if called in a loop,
then virtual memory is wasted, and if the loop goes through enough
iterations, then ultimately available memory can get exhausted causing
the program to crash.
Address the issue by replacing the inline code with standalone assembly
functions, which rely on the compiler arranging syscall arguments
according to the o32 function calling convention, which MIPS/Linux
syscalls also use, except for the syscall number passed and the error
flag returned. This way there is no need to fiddle with the stack
pointer anymore and all that has to be handled in the new standalone
functions is the special handling of the syscall number and the error
flag.
Redirect 5-, 6- or 7-argument MIPS16/Linux syscall wrappers to these new
functions as well, so as to avoid an unnecessary double call the
existing wrappers would cause with the new arrangement.
[BZ #21956]
* sysdeps/unix/sysv/linux/mips/mips32/mips16/Makefile
[subdir = misc] (sysdep_routines): Remove `mips16-syscall5',
`mips16-syscall6' and `mips16-syscall7'.
(CFLAGS-mips16-syscall5.c, CFLAGS-mips16-syscall6.c)
(CFLAGS-mips16-syscall7.c): Remove.
* sysdeps/unix/sysv/linux/mips/mips32/mips16/Versions (libc):
Remove `__mips16_syscall5', `__mips16_syscall6' and
`__mips16_syscall7'.
* sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall0.c
(__mips16_syscall0): Rename `__mips16_syscall_return' to
`__mips_syscall_return'.
* sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall1.c
(__mips16_syscall1): Likewise.
* sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall2.c
(__mips16_syscall2): Likewise.
* sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall3.c
(__mips16_syscall3): Likewise.
* sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall4.c
(__mips16_syscall4): Likewise.
* sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall5.c:
Remove.
* sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall6.c:
Remove.
* sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall7.c:
Remove.
* sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall.h
(__mips16_syscall5): Expand to `__mips_syscall5' rather than
`__mips16_syscall5'. Remove prototype.
(__mips16_syscall6): Expand to `__mips_syscall6' rather than
`__mips16_syscall6'. Remove prototype.
(__mips16_syscall7): Expand to `__mips_syscall7' rather than
`__mips16_syscall7'. Remove prototype.
(__nomips16, __mips16_syscall_return): Move to...
* sysdeps/unix/sysv/linux/mips/mips32/sysdep.h
(__nomips16, __mips_syscall_return): ... here.
[__mips16] (INTERNAL_SYSCALL_NCS): Rename
`__mips16_syscall_return' to `__mips_syscall_return'.
[__mips16] (INTERNAL_SYSCALL_MIPS16): Pass `number' to
`internal_syscall##nr'.
[!__mips16] (INTERNAL_SYSCALL): Pass `SYS_ify (name)' to
`internal_syscall##nr'.
(FORCE_FRAME_POINTER): Remove.
(__mips_syscall5): New prototype.
(internal_syscall5): Rewrite to call `__mips_syscall5'.
(__mips_syscall6): New prototype.
(internal_syscall6): Rewrite to call `__mips_syscall6'.
(__mips_syscall7): New prototype.
(internal_syscall7): Rewrite to call `__mips_syscall7'.
* sysdeps/unix/sysv/linux/mips/mips32/mips-syscall5.S: New file.
* sysdeps/unix/sysv/linux/mips/mips32/mips-syscall6.S: New file.
* sysdeps/unix/sysv/linux/mips/mips32/mips-syscall7.S: New file.
* sysdeps/unix/sysv/linux/mips/mips32/Makefile [subdir = misc]
(sysdep_routines): Add libc-do-syscall.
* sysdeps/unix/sysv/linux/mips/mips32/Versions (libc): Add
`__mips_syscall5', `__mips_syscall6' and `__mips_syscall7'.
374 lines
12 KiB
C
374 lines
12 KiB
C
/* Copyright (C) 2000-2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library. If not, see
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<http://www.gnu.org/licenses/>. */
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#ifndef _LINUX_MIPS_MIPS32_SYSDEP_H
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#define _LINUX_MIPS_MIPS32_SYSDEP_H 1
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/* There is some commonality. */
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#include <sysdeps/unix/sysv/linux/sysdep.h>
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#include <sysdeps/unix/mips/mips32/sysdep.h>
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#include <tls.h>
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/* In order to get __set_errno() definition in INLINE_SYSCALL. */
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#ifndef __ASSEMBLER__
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#include <errno.h>
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#endif
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/* For Linux we can use the system call table in the header file
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/usr/include/asm/unistd.h
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of the kernel. But these symbols do not follow the SYS_* syntax
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so we have to redefine the `SYS_ify' macro here. */
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#undef SYS_ify
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#define SYS_ify(syscall_name) __NR_##syscall_name
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#ifdef __ASSEMBLER__
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/* We don't want the label for the error handler to be visible in the symbol
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table when we define it here. */
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#ifdef __PIC__
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# define SYSCALL_ERROR_LABEL 99b
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#endif
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#else /* ! __ASSEMBLER__ */
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/* Define a macro which expands into the inline wrapper code for a system
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call. */
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#undef INLINE_SYSCALL
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#define INLINE_SYSCALL(name, nr, args...) \
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({ INTERNAL_SYSCALL_DECL (_sc_err); \
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long result_var = INTERNAL_SYSCALL (name, _sc_err, nr, args); \
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if ( INTERNAL_SYSCALL_ERROR_P (result_var, _sc_err) ) \
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{ \
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__set_errno (INTERNAL_SYSCALL_ERRNO (result_var, _sc_err)); \
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result_var = -1L; \
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} \
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result_var; })
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#undef INTERNAL_SYSCALL_DECL
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#define INTERNAL_SYSCALL_DECL(err) long err __attribute__ ((unused))
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#undef INTERNAL_SYSCALL_ERROR_P
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#define INTERNAL_SYSCALL_ERROR_P(val, err) ((void) (val), (long) (err))
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#undef INTERNAL_SYSCALL_ERRNO
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#define INTERNAL_SYSCALL_ERRNO(val, err) ((void) (err), val)
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/* Note that the original Linux syscall restart convention required the
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instruction immediately preceding SYSCALL to initialize $v0 with the
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syscall number. Then if a restart triggered, $v0 would have been
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clobbered by the syscall interrupted, and needed to be reinititalized.
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The kernel would decrement the PC by 4 before switching back to the
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user mode so that $v0 had been reloaded before SYSCALL was executed
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again. This implied the place $v0 was loaded from must have been
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preserved across a syscall, e.g. an immediate, static register, stack
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slot, etc.
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The convention was relaxed in Linux with a change applied to the kernel
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GIT repository as commit 96187fb0bc30cd7919759d371d810e928048249d, that
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first appeared in the 2.6.36 release. Since then the kernel has had
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code that reloads $v0 upon syscall restart and resumes right at the
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SYSCALL instruction, so no special arrangement is needed anymore.
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For backwards compatibility with existing kernel binaries we support
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the old convention by choosing the instruction preceding SYSCALL
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carefully. This also means we have to force a 32-bit encoding of the
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microMIPS MOVE instruction if one is used. */
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#ifdef __mips_micromips
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# define MOVE32 "move32"
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#else
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# define MOVE32 "move"
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#endif
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#undef INTERNAL_SYSCALL
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#undef INTERNAL_SYSCALL_NCS
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#define __nomips16 __attribute__ ((nomips16))
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union __mips_syscall_return
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{
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long long val;
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struct
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{
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long v0;
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long v1;
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}
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reg;
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};
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#ifdef __mips16
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/* There's no MIPS16 syscall instruction, so we go through out-of-line
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standard MIPS wrappers. These do use inline snippets below though,
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through INTERNAL_SYSCALL_MIPS16. Spilling the syscall number to
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memory gives the best code in that case, avoiding the need to save
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and restore a static register. */
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# include <mips16-syscall.h>
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# define INTERNAL_SYSCALL(name, err, nr, args...) \
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INTERNAL_SYSCALL_NCS (SYS_ify (name), err, nr, args)
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# define INTERNAL_SYSCALL_NCS(number, err, nr, args...) \
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({ \
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union __mips_syscall_return _sc_ret; \
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_sc_ret.val = __mips16_syscall##nr (args, number); \
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err = _sc_ret.reg.v1; \
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_sc_ret.reg.v0; \
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})
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# define INTERNAL_SYSCALL_MIPS16(number, err, nr, args...) \
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internal_syscall##nr ("lw\t%0, %2\n\t", \
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"R" (number), \
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number, err, args)
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#else /* !__mips16 */
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# define INTERNAL_SYSCALL(name, err, nr, args...) \
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internal_syscall##nr ("li\t%0, %2\t\t\t# " #name "\n\t", \
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"IK" (SYS_ify (name)), \
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SYS_ify (name), err, args)
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# define INTERNAL_SYSCALL_NCS(number, err, nr, args...) \
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internal_syscall##nr (MOVE32 "\t%0, %2\n\t", \
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"r" (__s0), \
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number, err, args)
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#endif /* !__mips16 */
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#define internal_syscall0(v0_init, input, number, err, dummy...) \
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({ \
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long _sys_result; \
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\
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{ \
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register long __s0 asm ("$16") __attribute__ ((unused)) \
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= (number); \
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register long __v0 asm ("$2"); \
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register long __a3 asm ("$7"); \
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__asm__ volatile ( \
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".set\tnoreorder\n\t" \
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v0_init \
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"syscall\n\t" \
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".set reorder" \
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: "=r" (__v0), "=r" (__a3) \
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: input \
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: __SYSCALL_CLOBBERS); \
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err = __a3; \
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_sys_result = __v0; \
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} \
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_sys_result; \
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})
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#define internal_syscall1(v0_init, input, number, err, arg1) \
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({ \
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long _sys_result; \
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\
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{ \
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register long __s0 asm ("$16") __attribute__ ((unused)) \
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= (number); \
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register long __v0 asm ("$2"); \
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register long __a0 asm ("$4") = (long) (arg1); \
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register long __a3 asm ("$7"); \
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__asm__ volatile ( \
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".set\tnoreorder\n\t" \
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v0_init \
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"syscall\n\t" \
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".set reorder" \
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: "=r" (__v0), "=r" (__a3) \
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: input, "r" (__a0) \
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: __SYSCALL_CLOBBERS); \
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err = __a3; \
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_sys_result = __v0; \
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} \
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_sys_result; \
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})
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#define internal_syscall2(v0_init, input, number, err, arg1, arg2) \
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({ \
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long _sys_result; \
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\
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{ \
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register long __s0 asm ("$16") __attribute__ ((unused)) \
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= (number); \
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register long __v0 asm ("$2"); \
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register long __a0 asm ("$4") = (long) (arg1); \
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register long __a1 asm ("$5") = (long) (arg2); \
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register long __a3 asm ("$7"); \
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__asm__ volatile ( \
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".set\tnoreorder\n\t" \
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v0_init \
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"syscall\n\t" \
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".set\treorder" \
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: "=r" (__v0), "=r" (__a3) \
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: input, "r" (__a0), "r" (__a1) \
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: __SYSCALL_CLOBBERS); \
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err = __a3; \
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_sys_result = __v0; \
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} \
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_sys_result; \
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})
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#define internal_syscall3(v0_init, input, number, err, \
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arg1, arg2, arg3) \
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({ \
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long _sys_result; \
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\
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{ \
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register long __s0 asm ("$16") __attribute__ ((unused)) \
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= (number); \
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register long __v0 asm ("$2"); \
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register long __a0 asm ("$4") = (long) (arg1); \
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register long __a1 asm ("$5") = (long) (arg2); \
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register long __a2 asm ("$6") = (long) (arg3); \
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register long __a3 asm ("$7"); \
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__asm__ volatile ( \
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".set\tnoreorder\n\t" \
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v0_init \
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"syscall\n\t" \
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".set\treorder" \
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: "=r" (__v0), "=r" (__a3) \
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: input, "r" (__a0), "r" (__a1), "r" (__a2) \
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: __SYSCALL_CLOBBERS); \
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err = __a3; \
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_sys_result = __v0; \
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} \
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_sys_result; \
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})
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#define internal_syscall4(v0_init, input, number, err, \
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arg1, arg2, arg3, arg4) \
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({ \
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long _sys_result; \
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\
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{ \
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register long __s0 asm ("$16") __attribute__ ((unused)) \
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= (number); \
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register long __v0 asm ("$2"); \
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register long __a0 asm ("$4") = (long) (arg1); \
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register long __a1 asm ("$5") = (long) (arg2); \
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register long __a2 asm ("$6") = (long) (arg3); \
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register long __a3 asm ("$7") = (long) (arg4); \
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__asm__ volatile ( \
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".set\tnoreorder\n\t" \
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v0_init \
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"syscall\n\t" \
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".set\treorder" \
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: "=r" (__v0), "+r" (__a3) \
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: input, "r" (__a0), "r" (__a1), "r" (__a2) \
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: __SYSCALL_CLOBBERS); \
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err = __a3; \
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_sys_result = __v0; \
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} \
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_sys_result; \
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})
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/* Standalone MIPS wrappers used for 5, 6, and 7 argument syscalls,
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which require stack arguments. We rely on the compiler arranging
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wrapper's arguments according to the MIPS o32 function calling
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convention, which is reused by syscalls, except for the syscall
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number passed and the error flag returned (taken care of in the
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wrapper called). This relieves us from relying on non-guaranteed
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compiler specifics required for the stack arguments to be pushed,
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which would be the case if these syscalls were inlined. */
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long long __nomips16 __mips_syscall5 (long arg1, long arg2, long arg3,
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long arg4, long arg5,
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long number);
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libc_hidden_proto (__mips_syscall5, nomips16)
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#define internal_syscall5(v0_init, input, number, err, \
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arg1, arg2, arg3, arg4, arg5) \
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({ \
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union __mips_syscall_return _sc_ret; \
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_sc_ret.val = __mips_syscall5 ((long) (arg1), \
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(long) (arg2), \
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(long) (arg3), \
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(long) (arg4), \
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(long) (arg5), \
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(long) (number)); \
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err = _sc_ret.reg.v1; \
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_sc_ret.reg.v0; \
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})
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long long __nomips16 __mips_syscall6 (long arg1, long arg2, long arg3,
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long arg4, long arg5, long arg6,
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long number);
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libc_hidden_proto (__mips_syscall6, nomips16)
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#define internal_syscall6(v0_init, input, number, err, \
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arg1, arg2, arg3, arg4, arg5, arg6) \
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({ \
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union __mips_syscall_return _sc_ret; \
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_sc_ret.val = __mips_syscall6 ((long) (arg1), \
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(long) (arg2), \
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(long) (arg3), \
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(long) (arg4), \
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(long) (arg5), \
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(long) (arg6), \
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(long) (number)); \
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err = _sc_ret.reg.v1; \
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_sc_ret.reg.v0; \
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})
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long long __nomips16 __mips_syscall7 (long arg1, long arg2, long arg3,
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long arg4, long arg5, long arg6,
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long arg7,
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long number);
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libc_hidden_proto (__mips_syscall7, nomips16)
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#define internal_syscall7(v0_init, input, number, err, \
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arg1, arg2, arg3, arg4, arg5, arg6, arg7) \
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({ \
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union __mips_syscall_return _sc_ret; \
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_sc_ret.val = __mips_syscall7 ((long) (arg1), \
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(long) (arg2), \
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(long) (arg3), \
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(long) (arg4), \
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(long) (arg5), \
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(long) (arg6), \
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(long) (arg7), \
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(long) (number)); \
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err = _sc_ret.reg.v1; \
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_sc_ret.reg.v0; \
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})
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#define __SYSCALL_CLOBBERS "$1", "$3", "$8", "$9", "$10", "$11", "$12", "$13", \
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"$14", "$15", "$24", "$25", "hi", "lo", "memory"
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/* Standard MIPS syscalls have an error flag, and return a positive errno
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when the error flag is set. Emulate this behaviour for vsyscalls so that
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the INTERNAL_SYSCALL_{ERROR_P,ERRNO} macros work correctly. */
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#define INTERNAL_VSYSCALL_CALL(funcptr, err, nr, args...) \
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({ \
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long _ret = funcptr (args); \
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err = ((unsigned long) (_ret) >= (unsigned long) -4095L); \
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if (err) \
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_ret = -_ret; \
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_ret; \
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})
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/* List of system calls which are supported as vsyscalls. */
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#define HAVE_CLOCK_GETTIME_VSYSCALL 1
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#define HAVE_GETTIMEOFDAY_VSYSCALL 1
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#endif /* __ASSEMBLER__ */
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/* Pointer mangling is not yet supported for MIPS. */
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#define PTR_MANGLE(var) (void) (var)
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#define PTR_DEMANGLE(var) (void) (var)
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#endif /* linux/mips/mips32/sysdep.h */
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