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Re: [PATCH v5] [BZ #21956] MIPS/o32: Fix internal_syscall5/6/7
On 24/08/2017 10:26, Maciej W. Rozycki wrote:
> From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
>
> Fix a commit cc25c8b4c119 ("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.
>
> 2017-08-24 Adhemerval Zanella <adhemerval.zanella@linaro.org>
> Aurelien Jarno <aurelien@aurel32.net>
> Maciej W. Rozycki <macro@imgtec.com>
>
> [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'.
Patch LGTM, thanks for following this up.
>
> ---
> On Mon, 21 Aug 2017, Adhemerval Zanella wrote:
>
>>> 2. I exported `__mips_syscall?' wrappers from `libc.so' rather than making
>>> them hidden. This is also consistent with `__mips16_syscall?' wrappers
>>> and reduces code duplication of doubtful benefit -- it could be that
>>> some calls, if internal, could be subject to the JALR->BAL
>>> optimisation, however only those that are in range and only in regular
>>> MIPS code, for a minimal execution time saving on some processors only.
>>> Exporting these entries makes the maintenance effort much easier
>>> though, as we don't have to track and record their use in the
>>> individual subdirectories in Makefile.
>>
>> In this case we can still have internal hidden calls for libc with the cost
>> of code duplication by using hiden alias with:
>>
>> libc_hidden_proto (__mips_syscall{5,6,7}, nomips16)
>>
>> And with the pairing
>>
>> libc_hidden_def (__mips_syscall{5,6,7});
>>
>> On implementation.
>
> Thanks for the hint. Actually that does not cause code duplication.
>
> I actually considered making hidden aliases available for use within
> libc.so as a possible future improvement, but didn't realise it would be
> as simple to arrange with the symbols defined in standalone assembly
> code rather than C. This results in 61 BAL instructions replacing JALR
> ones in my regular MIPS libc.so build.
Nice improvement.
>
>>> Index: glibc/sysdeps/unix/sysv/linux/mips/mips32/mips-syscall5.S
>>> ===================================================================
>>> --- /dev/null 1970-01-01 00:00:00.000000000 +0000
>>> +++ glibc/sysdeps/unix/sysv/linux/mips/mips32/mips-syscall5.S 2017-08-20 03:02:13.583854495 +0100
>>> @@ -0,0 +1,33 @@
>>
>> One line comment to describe this file.
>
> I pinched the terse comment used across the existing MIPS16 wrappers
> (with s/MIPS16/MIPS/ applied); I hope this is good enough as otherwise the
> code should be self-explanatory.
I think it is good enough.
>
>>> @@ -262,110 +275,65 @@
>>> _sys_result; \
>>> })
>>>
>>> -/* We need to use a frame pointer for the functions in which we
>>> - adjust $sp around the syscall, or debug information and unwind
>>> - information will be $sp relative and thus wrong during the syscall. As
>>> - of GCC 4.7, this is sufficient. */
>>> -#define FORCE_FRAME_POINTER \
>>> - void *volatile __fp_force __attribute__ ((unused)) = alloca (4)
>>> +/* Out-of-line standard MIPS wrappers used for 5, 6, and 7 argument
>>> + syscalls, which require stack arguments. */
>>
>> I think it is worth to add a comment why we are using out-of-line wrappers
>> for syscalls with 5, 6, and 7 arguments.
>
> Good point, let me know if what I came up with is comprehensive enough.
>
> This update has passed regular MIPS and MIPS16 o32 regression testing,
> with no regressions. OK to apply?
Ok from my side.
>
> NB while looking at it I've noticed we do not pass any `-O' optimisation
> flag to the GCC driver while building .S files. That in turn means no GAS
> branch optimisation is enabled and consequently branch delay slots are not
> scheduled in `reorder' code by the assembler (the MIPS/GCC `asm' spec has
> this `%{noasmopt:-O0; O0|fno-delayed-branch:-O1; O*:-O2; :-O1}'), causing
> delay slots wasted with a NOP where a preceding instruction could be moved
> instead and save some code space. It can be easily observed by comparing
> code in the compiler-generated MIPS16 wrappers vs the new standalone
> assembly regular MIPS (and microMIPS) wrappers.
>
> Was this a deliberate choice made sometime to have greater control over
> code produced or just an accidental oversight?
I am not sure if it was deliberate, but my guess it is not really an issue
for most architectures since afaik any '-O' optimization flag along with
.S files usually does not turn any extra flags (SUBTARGET_ASM_SPEC seems
to be define only in a handful architectures on gcc).
For MIPS I think we can set ASFLAGS to O1 since it should enable the
required optimization, unless there is an specific gas option to enable
it (which I couldn't find). Another option would be to filter out CFLAGS
and extract the optimization level used for ASFLAGS, but I think for this
specific issue it should extra non required complexity.
Another thing I noticed is another possible optimization for size would
to use ".set push", ".set noreorder", and ".set pop" instead of current
code as below.
Using GCC 6.2.1 and binutils 2.27 I noted building for mips16 (using
a strip libc.so for both):
- base:
section size
.text 966480
.eh_frame_hdr 8764
.eh_frame 36628
.pdr 97568
- patched:
section size
.text 966160
.eh_frame_hdr 8732
.eh_frame 36492
.pdr 97440
Not that much, but still a gain. Using O1 (as below) shows some more
slight gains:
section size
.text 966096
.eh_frame_hdr 8732
.eh_frame 36492
.pdr 97440
---
diff --git a/sysdeps/mips/Makefile b/sysdeps/mips/Makefile
index 7c1d779..1130015 100644
--- a/sysdeps/mips/Makefile
+++ b/sysdeps/mips/Makefile
@@ -83,3 +83,9 @@ $(objpfx)tst-mode-switch-2: $(shared-thread-library)
endif
endif
endif
+
+# Enable delay branch optimization
+ASFLAGS-.o += -O1
+ASFLAGS-.os += -O1
+ASFLAGS-.op += -O1
+ASFLAGS-.oS += -O2
---
diff --git a/sysdeps/unix/sysv/linux/mips/mips32/sysdep.h b/sysdeps/unix/sysv/linux/mips/mips32/sysdep.h
index dadfa18..96867de 100644
--- a/sysdeps/unix/sysv/linux/mips/mips32/sysdep.h
+++ b/sysdeps/unix/sysv/linux/mips/mips32/sysdep.h
@@ -159,10 +159,11 @@ union __mips_syscall_return
register long __v0 asm ("$2"); \
register long __a3 asm ("$7"); \
__asm__ volatile ( \
- ".set\tnoreorder\n\t" \
+ ".set push\n\t" \
+ ".set noreorder\n\t" \
v0_init \
"syscall\n\t" \
- ".set reorder" \
+ ".set pop" \
: "=r" (__v0), "=r" (__a3) \
: input \
: __SYSCALL_CLOBBERS); \
@@ -183,10 +184,11 @@ union __mips_syscall_return
register long __a0 asm ("$4") = (long) (arg1); \
register long __a3 asm ("$7"); \
__asm__ volatile ( \
- ".set\tnoreorder\n\t" \
+ ".set push\n\t" \
+ ".set noreorder\n\t" \
v0_init \
"syscall\n\t" \
- ".set reorder" \
+ ".set pop" \
: "=r" (__v0), "=r" (__a3) \
: input, "r" (__a0) \
: __SYSCALL_CLOBBERS); \
@@ -208,10 +210,11 @@ union __mips_syscall_return
register long __a1 asm ("$5") = (long) (arg2); \
register long __a3 asm ("$7"); \
__asm__ volatile ( \
- ".set\tnoreorder\n\t" \
+ ".set push\n\t" \
+ ".set noreorder\n\t" \
v0_init \
"syscall\n\t" \
- ".set\treorder" \
+ ".set pop" \
: "=r" (__v0), "=r" (__a3) \
: input, "r" (__a0), "r" (__a1) \
: __SYSCALL_CLOBBERS); \
@@ -235,10 +238,11 @@ union __mips_syscall_return
register long __a2 asm ("$6") = (long) (arg3); \
register long __a3 asm ("$7"); \
__asm__ volatile ( \
- ".set\tnoreorder\n\t" \
+ ".set push\n\t" \
+ ".set noreorder\n\t" \
v0_init \
"syscall\n\t" \
- ".set\treorder" \
+ ".set pop" \
: "=r" (__v0), "=r" (__a3) \
: input, "r" (__a0), "r" (__a1), "r" (__a2) \
: __SYSCALL_CLOBBERS); \
@@ -262,10 +266,11 @@ union __mips_syscall_return
register long __a2 asm ("$6") = (long) (arg3); \
register long __a3 asm ("$7") = (long) (arg4); \
__asm__ volatile ( \
- ".set\tnoreorder\n\t" \
+ ".set push\n\t" \
+ ".set noreorder\n\t" \
v0_init \
"syscall\n\t" \
- ".set\treorder" \
+ ".set pop" \
: "=r" (__v0), "+r" (__a3) \
: input, "r" (__a0), "r" (__a1), "r" (__a2) \
: __SYSCALL_CLOBBERS); \
>
> Maciej
>
> ---
> sysdeps/unix/sysv/linux/mips/mips32/Makefile | 4
> sysdeps/unix/sysv/linux/mips/mips32/Versions | 3
> sysdeps/unix/sysv/linux/mips/mips32/mips-syscall5.S | 35 ++
> sysdeps/unix/sysv/linux/mips/mips32/mips-syscall6.S | 35 ++
> sysdeps/unix/sysv/linux/mips/mips32/mips-syscall7.S | 35 ++
> sysdeps/unix/sysv/linux/mips/mips32/mips16/Makefile | 6
> sysdeps/unix/sysv/linux/mips/mips32/mips16/Versions | 2
> sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall.h | 44 --
> sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall0.c | 3
> sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall1.c | 3
> sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall2.c | 3
> sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall3.c | 3
> sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall4.c | 3
> sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall5.c | 33 --
> sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall6.c | 33 --
> sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall7.c | 33 --
> sysdeps/unix/sysv/linux/mips/mips32/sysdep.h | 163 ++++-------
> 17 files changed, 201 insertions(+), 240 deletions(-)
>
> glibc-aurelien-mips-o32-syscall.diff
> Index: glibc/sysdeps/unix/sysv/linux/mips/mips32/Makefile
> ===================================================================
> --- glibc.orig/sysdeps/unix/sysv/linux/mips/mips32/Makefile 2017-08-20 21:30:35.093821957 +0100
> +++ glibc/sysdeps/unix/sysv/linux/mips/mips32/Makefile 2017-08-22 20:33:16.504589387 +0100
> @@ -3,6 +3,10 @@ ifeq ($(subdir),conform)
> conformtest-xfail-conds += mips-o32-linux
> endif
>
> +ifeq ($(subdir),misc)
> +sysdep_routines += mips-syscall5 mips-syscall6 mips-syscall7
> +endif
> +
> ifeq ($(subdir),stdlib)
> tests += bug-getcontext-mips-gp
> endif
> Index: glibc/sysdeps/unix/sysv/linux/mips/mips32/Versions
> ===================================================================
> --- glibc.orig/sysdeps/unix/sysv/linux/mips/mips32/Versions 2017-08-20 21:30:35.142707136 +0100
> +++ glibc/sysdeps/unix/sysv/linux/mips/mips32/Versions 2017-08-22 20:33:16.571894966 +0100
> @@ -3,4 +3,7 @@ libc {
> getrlimit64;
> setrlimit64;
> }
> + GLIBC_PRIVATE {
> + __mips_syscall5; __mips_syscall6; __mips_syscall7;
> + }
> }
> Index: glibc/sysdeps/unix/sysv/linux/mips/mips32/mips-syscall5.S
> ===================================================================
> --- /dev/null 1970-01-01 00:00:00.000000000 +0000
> +++ glibc/sysdeps/unix/sysv/linux/mips/mips32/mips-syscall5.S 2017-08-22 20:47:54.745857965 +0100
> @@ -0,0 +1,35 @@
> +/* MIPS syscall wrappers.
> + Copyright (C) 2017 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>
> +#include <sys/asm.h>
> +
> + .text
> + .set nomips16
> +
> +/* long long __mips_syscall5 (long arg1, long arg2, long arg3, long arg4,
> + long arg5,
> + long number) */
> +
> +ENTRY(__mips_syscall5)
> + lw v0, 20(sp)
> + syscall
> + move v1, a3
> + jr ra
> +END(__mips_syscall5)
> +libc_hidden_def (__mips_syscall5)
> Index: glibc/sysdeps/unix/sysv/linux/mips/mips32/mips-syscall6.S
> ===================================================================
> --- /dev/null 1970-01-01 00:00:00.000000000 +0000
> +++ glibc/sysdeps/unix/sysv/linux/mips/mips32/mips-syscall6.S 2017-08-22 20:47:47.596264940 +0100
> @@ -0,0 +1,35 @@
> +/* MIPS syscall wrappers.
> + Copyright (C) 2017 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>
> +#include <sys/asm.h>
> +
> + .text
> + .set nomips16
> +
> +/* long long __mips_syscall6 (long arg1, long arg2, long arg3, long arg4,
> + long arg5, long arg6,
> + long number) */
> +
> +ENTRY(__mips_syscall6)
> + lw v0, 24(sp)
> + syscall
> + move v1, a3
> + jr ra
> +END(__mips_syscall6)
> +libc_hidden_def (__mips_syscall6)
> Index: glibc/sysdeps/unix/sysv/linux/mips/mips32/mips-syscall7.S
> ===================================================================
> --- /dev/null 1970-01-01 00:00:00.000000000 +0000
> +++ glibc/sysdeps/unix/sysv/linux/mips/mips32/mips-syscall7.S 2017-08-22 20:47:25.781928113 +0100
> @@ -0,0 +1,35 @@
> +/* MIPS syscall wrappers.
> + Copyright (C) 2017 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>
> +#include <sys/asm.h>
> +
> + .text
> + .set nomips16
> +
> +/* long long __mips_syscall7 (long arg1, long arg2, long arg3, long arg4,
> + long arg5, long arg6, long arg7,
> + long number) */
> +
> +ENTRY(__mips_syscall7)
> + lw v0, 28(sp)
> + syscall
> + move v1, a3
> + jr ra
> +END(__mips_syscall7)
> +libc_hidden_def (__mips_syscall7)
> Index: glibc/sysdeps/unix/sysv/linux/mips/mips32/mips16/Makefile
> ===================================================================
> --- glibc.orig/sysdeps/unix/sysv/linux/mips/mips32/mips16/Makefile 2017-08-20 21:30:35.448096086 +0100
> +++ glibc/sysdeps/unix/sysv/linux/mips/mips32/mips16/Makefile 2017-08-22 20:33:16.687468562 +0100
> @@ -1,13 +1,9 @@
> ifeq ($(subdir),misc)
> sysdep_routines += mips16-syscall0 mips16-syscall1 mips16-syscall2
> -sysdep_routines += mips16-syscall3 mips16-syscall4 mips16-syscall5
> -sysdep_routines += mips16-syscall6 mips16-syscall7
> +sysdep_routines += mips16-syscall3 mips16-syscall4
> CFLAGS-mips16-syscall0.c += -fexceptions
> CFLAGS-mips16-syscall1.c += -fexceptions
> CFLAGS-mips16-syscall2.c += -fexceptions
> CFLAGS-mips16-syscall3.c += -fexceptions
> CFLAGS-mips16-syscall4.c += -fexceptions
> -CFLAGS-mips16-syscall5.c += -fexceptions
> -CFLAGS-mips16-syscall6.c += -fexceptions
> -CFLAGS-mips16-syscall7.c += -fexceptions
> endif
> Index: glibc/sysdeps/unix/sysv/linux/mips/mips32/mips16/Versions
> ===================================================================
> --- glibc.orig/sysdeps/unix/sysv/linux/mips/mips32/mips16/Versions 2017-08-20 21:30:35.487709423 +0100
> +++ glibc/sysdeps/unix/sysv/linux/mips/mips32/mips16/Versions 2017-08-22 20:33:16.719930829 +0100
> @@ -1,6 +1,6 @@
> libc {
> GLIBC_PRIVATE {
> __mips16_syscall0; __mips16_syscall1; __mips16_syscall2; __mips16_syscall3;
> - __mips16_syscall4; __mips16_syscall5; __mips16_syscall6; __mips16_syscall7;
> + __mips16_syscall4;
> }
> }
> Index: glibc/sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall.h
> ===================================================================
> --- glibc.orig/sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall.h 2017-08-20 21:30:35.540283348 +0100
> +++ glibc/sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall.h 2017-08-22 20:33:16.732035716 +0100
> @@ -19,19 +19,6 @@
> #ifndef MIPS16_SYSCALL_H
> #define MIPS16_SYSCALL_H 1
>
> -#define __nomips16 __attribute__ ((nomips16))
> -
> -union __mips16_syscall_return
> - {
> - long long val;
> - struct
> - {
> - long v0;
> - long v1;
> - }
> - reg;
> - };
> -
> long long __nomips16 __mips16_syscall0 (long number);
> #define __mips16_syscall0(dummy, number) \
> __mips16_syscall0 ((long) (number))
> @@ -61,29 +48,22 @@ long long __nomips16 __mips16_syscall4 (
> (long) (a3), \
> (long) (number))
>
> -long long __nomips16 __mips16_syscall5 (long a0, long a1, long a2, long a3,
> - long a4,
> - long number);
> +/* The remaining ones use regular MIPS wrappers. */
> +
> #define __mips16_syscall5(a0, a1, a2, a3, a4, number) \
> - __mips16_syscall5 ((long) (a0), (long) (a1), (long) (a2), \
> - (long) (a3), (long) (a4), \
> - (long) (number))
> + __mips_syscall5 ((long) (a0), (long) (a1), (long) (a2), \
> + (long) (a3), (long) (a4), \
> + (long) (number))
>
> -long long __nomips16 __mips16_syscall6 (long a0, long a1, long a2, long a3,
> - long a4, long a5,
> - long number);
> #define __mips16_syscall6(a0, a1, a2, a3, a4, a5, number) \
> - __mips16_syscall6 ((long) (a0), (long) (a1), (long) (a2), \
> - (long) (a3), (long) (a4), (long) (a5), \
> - (long) (number))
> + __mips_syscall6 ((long) (a0), (long) (a1), (long) (a2), \
> + (long) (a3), (long) (a4), (long) (a5), \
> + (long) (number))
>
> -long long __nomips16 __mips16_syscall7 (long a0, long a1, long a2, long a3,
> - long a4, long a5, long a6,
> - long number);
> #define __mips16_syscall7(a0, a1, a2, a3, a4, a5, a6, number) \
> - __mips16_syscall7 ((long) (a0), (long) (a1), (long) (a2), \
> - (long) (a3), (long) (a4), (long) (a5), \
> - (long) (a6), \
> - (long) (number))
> + __mips_syscall7 ((long) (a0), (long) (a1), (long) (a2), \
> + (long) (a3), (long) (a4), (long) (a5), \
> + (long) (a6), \
> + (long) (number))
>
> #endif
> Index: glibc/sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall0.c
> ===================================================================
> --- glibc.orig/sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall0.c 2017-08-20 21:30:35.557630985 +0100
> +++ glibc/sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall0.c 2017-08-22 20:33:16.741195496 +0100
> @@ -17,14 +17,13 @@
> <http://www.gnu.org/licenses/>. */
>
> #include <sysdep.h>
> -#include <mips16-syscall.h>
>
> #undef __mips16_syscall0
>
> long long __nomips16
> __mips16_syscall0 (long number)
> {
> - union __mips16_syscall_return ret;
> + union __mips_syscall_return ret;
> ret.reg.v0 = INTERNAL_SYSCALL_MIPS16 (number, ret.reg.v1, 0);
> return ret.val;
> }
> Index: glibc/sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall1.c
> ===================================================================
> --- glibc.orig/sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall1.c 2017-08-20 21:30:35.658293922 +0100
> +++ glibc/sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall1.c 2017-08-22 20:33:16.758455153 +0100
> @@ -17,7 +17,6 @@
> <http://www.gnu.org/licenses/>. */
>
> #include <sysdep.h>
> -#include <mips16-syscall.h>
>
> #undef __mips16_syscall1
>
> @@ -25,7 +24,7 @@ long long __nomips16
> __mips16_syscall1 (long a0,
> long number)
> {
> - union __mips16_syscall_return ret;
> + union __mips_syscall_return ret;
> ret.reg.v0 = INTERNAL_SYSCALL_MIPS16 (number, ret.reg.v1, 1,
> a0);
> return ret.val;
> Index: glibc/sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall2.c
> ===================================================================
> --- glibc.orig/sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall2.c 2017-08-20 21:30:35.769000365 +0100
> +++ glibc/sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall2.c 2017-08-22 20:33:16.768703866 +0100
> @@ -17,7 +17,6 @@
> <http://www.gnu.org/licenses/>. */
>
> #include <sysdep.h>
> -#include <mips16-syscall.h>
>
> #undef __mips16_syscall2
>
> @@ -25,7 +24,7 @@ long long __nomips16
> __mips16_syscall2 (long a0, long a1,
> long number)
> {
> - union __mips16_syscall_return ret;
> + union __mips_syscall_return ret;
> ret.reg.v0 = INTERNAL_SYSCALL_MIPS16 (number, ret.reg.v1, 2,
> a0, a1);
> return ret.val;
> Index: glibc/sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall3.c
> ===================================================================
> --- glibc.orig/sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall3.c 2017-08-20 21:30:35.796726756 +0100
> +++ glibc/sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall3.c 2017-08-22 20:33:16.779819073 +0100
> @@ -17,7 +17,6 @@
> <http://www.gnu.org/licenses/>. */
>
> #include <sysdep.h>
> -#include <mips16-syscall.h>
>
> #undef __mips16_syscall3
>
> @@ -25,7 +24,7 @@ long long __nomips16
> __mips16_syscall3 (long a0, long a1, long a2,
> long number)
> {
> - union __mips16_syscall_return ret;
> + union __mips_syscall_return ret;
> ret.reg.v0 = INTERNAL_SYSCALL_MIPS16 (number, ret.reg.v1, 3,
> a0, a1, a2);
> return ret.val;
> Index: glibc/sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall4.c
> ===================================================================
> --- glibc.orig/sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall4.c 2017-08-20 21:30:35.819263979 +0100
> +++ glibc/sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall4.c 2017-08-22 20:33:16.794914009 +0100
> @@ -17,7 +17,6 @@
> <http://www.gnu.org/licenses/>. */
>
> #include <sysdep.h>
> -#include <mips16-syscall.h>
>
> #undef __mips16_syscall4
>
> @@ -25,7 +24,7 @@ long long __nomips16
> __mips16_syscall4 (long a0, long a1, long a2, long a3,
> long number)
> {
> - union __mips16_syscall_return ret;
> + union __mips_syscall_return ret;
> ret.reg.v0 = INTERNAL_SYSCALL_MIPS16 (number, ret.reg.v1, 4,
> a0, a1, a2, a3);
> return ret.val;
> Index: glibc/sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall5.c
> ===================================================================
> --- glibc.orig/sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall5.c 2017-08-20 21:30:35.822296212 +0100
> +++ /dev/null 1970-01-01 00:00:00.000000000 +0000
> @@ -1,33 +0,0 @@
> -/* MIPS16 syscall wrappers.
> - Copyright (C) 2013-2017 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>
> -#include <mips16-syscall.h>
> -
> -#undef __mips16_syscall5
> -
> -long long __nomips16
> -__mips16_syscall5 (long a0, long a1, long a2, long a3,
> - long a4,
> - long number)
> -{
> - union __mips16_syscall_return ret;
> - ret.reg.v0 = INTERNAL_SYSCALL_MIPS16 (number, ret.reg.v1, 5,
> - a0, a1, a2, a3, a4);
> - return ret.val;
> -}
> Index: glibc/sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall6.c
> ===================================================================
> --- glibc.orig/sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall6.c 2017-08-20 21:30:35.838512882 +0100
> +++ /dev/null 1970-01-01 00:00:00.000000000 +0000
> @@ -1,33 +0,0 @@
> -/* MIPS16 syscall wrappers.
> - Copyright (C) 2013-2017 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>
> -#include <mips16-syscall.h>
> -
> -#undef __mips16_syscall6
> -
> -long long __nomips16
> -__mips16_syscall6 (long a0, long a1, long a2, long a3,
> - long a4, long a5,
> - long number)
> -{
> - union __mips16_syscall_return ret;
> - ret.reg.v0 = INTERNAL_SYSCALL_MIPS16 (number, ret.reg.v1, 6,
> - a0, a1, a2, a3, a4, a5);
> - return ret.val;
> -}
> Index: glibc/sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall7.c
> ===================================================================
> --- glibc.orig/sysdeps/unix/sysv/linux/mips/mips32/mips16/mips16-syscall7.c 2017-08-20 21:30:35.846816836 +0100
> +++ /dev/null 1970-01-01 00:00:00.000000000 +0000
> @@ -1,33 +0,0 @@
> -/* MIPS16 syscall wrappers.
> - Copyright (C) 2013-2017 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>
> -#include <mips16-syscall.h>
> -
> -#undef __mips16_syscall7
> -
> -long long __nomips16
> -__mips16_syscall7 (long a0, long a1, long a2, long a3,
> - long a4, long a5, long a6,
> - long number)
> -{
> - union __mips16_syscall_return ret;
> - ret.reg.v0 = INTERNAL_SYSCALL_MIPS16 (number, ret.reg.v1, 7,
> - a0, a1, a2, a3, a4, a5, a6);
> - return ret.val;
> -}
> Index: glibc/sysdeps/unix/sysv/linux/mips/mips32/sysdep.h
> ===================================================================
> --- glibc.orig/sysdeps/unix/sysv/linux/mips/mips32/sysdep.h 2017-08-20 21:30:35.944796826 +0100
> +++ glibc/sysdeps/unix/sysv/linux/mips/mips32/sysdep.h 2017-08-22 23:13:25.010701782 +0100
> @@ -98,6 +98,19 @@
> #undef INTERNAL_SYSCALL
> #undef INTERNAL_SYSCALL_NCS
>
> +#define __nomips16 __attribute__ ((nomips16))
> +
> +union __mips_syscall_return
> + {
> + long long val;
> + struct
> + {
> + long v0;
> + long v1;
> + }
> + reg;
> + };
> +
> #ifdef __mips16
> /* There's no MIPS16 syscall instruction, so we go through out-of-line
> standard MIPS wrappers. These do use inline snippets below though,
> @@ -112,7 +125,7 @@
>
> # define INTERNAL_SYSCALL_NCS(number, err, nr, args...) \
> ({ \
> - union __mips16_syscall_return _sc_ret; \
> + union __mips_syscall_return _sc_ret; \
> _sc_ret.val = __mips16_syscall##nr (args, number); \
> err = _sc_ret.reg.v1; \
> _sc_ret.reg.v0; \
> @@ -121,13 +134,13 @@
> # define INTERNAL_SYSCALL_MIPS16(number, err, nr, args...) \
> internal_syscall##nr ("lw\t%0, %2\n\t", \
> "R" (number), \
> - 0, err, args)
> + number, err, args)
>
> #else /* !__mips16 */
> # define INTERNAL_SYSCALL(name, err, nr, args...) \
> internal_syscall##nr ("li\t%0, %2\t\t\t# " #name "\n\t", \
> "IK" (SYS_ify (name)), \
> - 0, err, args)
> + SYS_ify (name), err, args)
>
> # define INTERNAL_SYSCALL_NCS(number, err, nr, args...) \
> internal_syscall##nr (MOVE32 "\t%0, %2\n\t", \
> @@ -262,110 +275,74 @@
> _sys_result; \
> })
>
> -/* We need to use a frame pointer for the functions in which we
> - adjust $sp around the syscall, or debug information and unwind
> - information will be $sp relative and thus wrong during the syscall. As
> - of GCC 4.7, this is sufficient. */
> -#define FORCE_FRAME_POINTER \
> - void *volatile __fp_force __attribute__ ((unused)) = alloca (4)
> +/* Standalone MIPS wrappers used for 5, 6, and 7 argument syscalls,
> + which require stack arguments. We rely on the compiler arranging
> + wrapper's arguments according to the MIPS o32 function calling
> + convention, which is reused by syscalls, except for the syscall
> + number passed and the error flag returned (taken care of in the
> + wrapper called). This relieves us from relying on non-guaranteed
> + compiler specifics required for the stack arguments to be pushed,
> + which would be the case if these syscalls were inlined. */
> +
> +long long __nomips16 __mips_syscall5 (long arg1, long arg2, long arg3,
> + long arg4, long arg5,
> + long number);
> +libc_hidden_proto (__mips_syscall5, nomips16)
>
> #define internal_syscall5(v0_init, input, number, err, \
> arg1, arg2, arg3, arg4, arg5) \
> ({ \
> - long _sys_result; \
> - \
> - FORCE_FRAME_POINTER; \
> - { \
> - register long __s0 asm ("$16") __attribute__ ((unused)) \
> - = (number); \
> - register long __v0 asm ("$2"); \
> - register long __a0 asm ("$4") = (long) (arg1); \
> - register long __a1 asm ("$5") = (long) (arg2); \
> - register long __a2 asm ("$6") = (long) (arg3); \
> - register long __a3 asm ("$7") = (long) (arg4); \
> - __asm__ volatile ( \
> - ".set\tnoreorder\n\t" \
> - "subu\t$29, 32\n\t" \
> - "sw\t%6, 16($29)\n\t" \
> - v0_init \
> - "syscall\n\t" \
> - "addiu\t$29, 32\n\t" \
> - ".set\treorder" \
> - : "=r" (__v0), "+r" (__a3) \
> - : input, "r" (__a0), "r" (__a1), "r" (__a2), \
> - "r" ((long) (arg5)) \
> - : __SYSCALL_CLOBBERS); \
> - err = __a3; \
> - _sys_result = __v0; \
> - } \
> - _sys_result; \
> + union __mips_syscall_return _sc_ret; \
> + _sc_ret.val = __mips_syscall5 ((long) (arg1), \
> + (long) (arg2), \
> + (long) (arg3), \
> + (long) (arg4), \
> + (long) (arg5), \
> + (long) (number)); \
> + err = _sc_ret.reg.v1; \
> + _sc_ret.reg.v0; \
> })
>
> +long long __nomips16 __mips_syscall6 (long arg1, long arg2, long arg3,
> + long arg4, long arg5, long arg6,
> + long number);
> +libc_hidden_proto (__mips_syscall6, nomips16)
> +
> #define internal_syscall6(v0_init, input, number, err, \
> arg1, arg2, arg3, arg4, arg5, arg6) \
> ({ \
> - long _sys_result; \
> - \
> - FORCE_FRAME_POINTER; \
> - { \
> - register long __s0 asm ("$16") __attribute__ ((unused)) \
> - = (number); \
> - register long __v0 asm ("$2"); \
> - register long __a0 asm ("$4") = (long) (arg1); \
> - register long __a1 asm ("$5") = (long) (arg2); \
> - register long __a2 asm ("$6") = (long) (arg3); \
> - register long __a3 asm ("$7") = (long) (arg4); \
> - __asm__ volatile ( \
> - ".set\tnoreorder\n\t" \
> - "subu\t$29, 32\n\t" \
> - "sw\t%6, 16($29)\n\t" \
> - "sw\t%7, 20($29)\n\t" \
> - v0_init \
> - "syscall\n\t" \
> - "addiu\t$29, 32\n\t" \
> - ".set\treorder" \
> - : "=r" (__v0), "+r" (__a3) \
> - : input, "r" (__a0), "r" (__a1), "r" (__a2), \
> - "r" ((long) (arg5)), "r" ((long) (arg6)) \
> - : __SYSCALL_CLOBBERS); \
> - err = __a3; \
> - _sys_result = __v0; \
> - } \
> - _sys_result; \
> + union __mips_syscall_return _sc_ret; \
> + _sc_ret.val = __mips_syscall6 ((long) (arg1), \
> + (long) (arg2), \
> + (long) (arg3), \
> + (long) (arg4), \
> + (long) (arg5), \
> + (long) (arg6), \
> + (long) (number)); \
> + err = _sc_ret.reg.v1; \
> + _sc_ret.reg.v0; \
> })
>
> +long long __nomips16 __mips_syscall7 (long arg1, long arg2, long arg3,
> + long arg4, long arg5, long arg6,
> + long arg7,
> + long number);
> +libc_hidden_proto (__mips_syscall7, nomips16)
> +
> #define internal_syscall7(v0_init, input, number, err, \
> arg1, arg2, arg3, arg4, arg5, arg6, arg7) \
> ({ \
> - long _sys_result; \
> - \
> - FORCE_FRAME_POINTER; \
> - { \
> - register long __s0 asm ("$16") __attribute__ ((unused)) \
> - = (number); \
> - register long __v0 asm ("$2"); \
> - register long __a0 asm ("$4") = (long) (arg1); \
> - register long __a1 asm ("$5") = (long) (arg2); \
> - register long __a2 asm ("$6") = (long) (arg3); \
> - register long __a3 asm ("$7") = (long) (arg4); \
> - __asm__ volatile ( \
> - ".set\tnoreorder\n\t" \
> - "subu\t$29, 32\n\t" \
> - "sw\t%6, 16($29)\n\t" \
> - "sw\t%7, 20($29)\n\t" \
> - "sw\t%8, 24($29)\n\t" \
> - v0_init \
> - "syscall\n\t" \
> - "addiu\t$29, 32\n\t" \
> - ".set\treorder" \
> - : "=r" (__v0), "+r" (__a3) \
> - : input, "r" (__a0), "r" (__a1), "r" (__a2), \
> - "r" ((long) (arg5)), "r" ((long) (arg6)), "r" ((long) (arg7)) \
> - : __SYSCALL_CLOBBERS); \
> - err = __a3; \
> - _sys_result = __v0; \
> - } \
> - _sys_result; \
> + union __mips_syscall_return _sc_ret; \
> + _sc_ret.val = __mips_syscall7 ((long) (arg1), \
> + (long) (arg2), \
> + (long) (arg3), \
> + (long) (arg4), \
> + (long) (arg5), \
> + (long) (arg6), \
> + (long) (arg7), \
> + (long) (number)); \
> + err = _sc_ret.reg.v1; \
> + _sc_ret.reg.v0; \
> })
>
> #define __SYSCALL_CLOBBERS "$1", "$3", "$8", "$9", "$10", "$11", "$12", "$13", \
>