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'.
General purpose registers in mcontext_t structure
are 8 bytes long for both MIPS32/MIPS64.
get/set/make/swap context implementations for MIPS O32
incorrectly assume that general purpose registers
in this structure are 4 bytes long.
This patch is fixing that.
Tested for MIPS O32 LE and BE.
Compared objdump of modified functions for mips n32 and mips n64.
[BZ #21548]
* sysdeps/unix/sysv/linux/mips/getcontext.S: Define MCONTEXT_SZGREG as
8 and use it when copying general purpose registers.
* sysdeps/unix/sysv/linux/mips/makecontext.S: Likewise.
* sysdeps/unix/sysv/linux/mips/mips32/Makefile: Include new test for
mips o32.
* sysdeps/unix/sysv/linux/mips/mips32/bug-getcontext-mips-gp.c: Added
new test for mips o32.
* sysdeps/unix/sysv/linux/mips/setcontext.S: Define MCONTEXT_SZGREG as
8 and use it when copying general purpose registers.
* sysdeps/unix/sysv/linux/mips/swapcontext.S: Likewise.
MIPS o32 struct stat has the wrong type of st_rdev. This patch XFAILs
that test in the conformtest expectations for this case (the bug
should not be closed without an actual fix, however).
Tested with build-many-glibcs.py.
[BZ #21278]
* sysdeps/unix/sysv/linux/mips/mips32/Makefile
[$(subdir) = conform] (conformtest-xfail-conds): Update comment.
* conform/data/sys/stat.h-data (stat.st_rdev): XFAIL for
mips-o32-linux.
As noted in bug 17786, MIPS o32 struct stat has the wrong type of
st_dev. This patch XFAILs that test in the conformtest expectations
for this case (the test still fails after the patch because there's
also a similar issue for st_rdev that needs reporting and XFAILing
separately, and the bug should not be closed without an actual fix,
not just XFAILing).
Tested for mips with build-many-glibcs.py.
[BZ #17786]
* sysdeps/unix/sysv/linux/mips/mips32/Makefile: New file.
* conform/data/sys/stat.h-data (stat.st_dev): XFAIL for
mips-o32-linux.
