This patch exposes Ztso via hwprobe in QEMU's user space emulator.
Signed-off-by: Christoph Müllner <christoph.muellner@vrull.eu>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Message-ID: <20240207122256.902627-3-christoph.muellner@vrull.eu>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Upstream Linux recently added many additional keys to the hwprobe API.
This patch adds support for all of them with the exception of Ztso,
which is currently not supported in QEMU.
Signed-off-by: Christoph Müllner <christoph.muellner@vrull.eu>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Message-ID: <20240207115926.887816-3-christoph.muellner@vrull.eu>
[ Changes by AF:
- Fixup whitespace
]
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Upstream Linux recently added RISC-V Zicboz support to the hwprobe API.
This patch introduces this for QEMU's user space emulator.
Signed-off-by: Christoph Müllner <christoph.muellner@vrull.eu>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Message-ID: <20240207115926.887816-2-christoph.muellner@vrull.eu>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
The upcoming follow-fork-mode child support requires knowing the child
pid. Pass it down.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-Id: <20240219141628.246823-6-iii@linux.ibm.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240305121005.3528075-7-alex.bennee@linaro.org>
A CPU's TaskState is stored in the CPUState's void *opaque field,
accessing which is somewhat awkward due to having to use a cast.
Introduce a wrapper and use it everywhere.
Suggested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Warner Losh <imp@bsdimp.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20240219141628.246823-3-iii@linux.ibm.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240305121005.3528075-4-alex.bennee@linaro.org>
This is the only case in which we expect to have no host memory backing
for a guest memory page, because in general linux user processes cannot
map any pages in the top half of the 64-bit address space.
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2170
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Support for probing the Zicboz block size landed in Linux 6.6, which was
released a few weeks ago. This provides the user-configured block size
when Zicboz is enabled.
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Message-ID: <20231110173716.24423-1-palmer@rivosinc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
p is a generic variable in syscall() and can be used by any syscall
case, so this patch removes the useless local variable declaration for
the following syscalls: TARGET_NR_llistxattr, TARGET_NR_listxattr,
TARGET_NR_setxattr, TARGET_NR_lsetxattr, TARGET_NR_getxattr,
TARGET_NR_lgetxattr, TARGET_NR_removexattr, TARGET_NR_lremovexattr.
Fix following warnings:
.../linux-user/syscall.c:12342:15: warning: declaration of 'p' shadows a previous local [-Wshadow=compatible-local]
12342 | void *p, *b = 0;
| ^
.../linux-user/syscall.c:8975:11: note: shadowed declaration is here
8975 | void *p;
| ^
.../linux-user/syscall.c:12379:19: warning: declaration of 'p' shadows a previous local [-Wshadow=compatible-local]
12379 | void *p, *n, *v = 0;
| ^
.../linux-user/syscall.c:8975:11: note: shadowed declaration is here
8975 | void *p;
| ^
.../linux-user/syscall.c:12424:19: warning: declaration of 'p' shadows a previous local [-Wshadow=compatible-local]
12424 | void *p, *n, *v = 0;
| ^
.../linux-user/syscall.c:8975:11: note: shadowed declaration is here
8975 | void *p;
| ^
.../linux-user/syscall.c:12469:19: warning: declaration of 'p' shadows a previous local [-Wshadow=compatible-local]
12469 | void *p, *n;
| ^
.../linux-user/syscall.c:8975:11: note: shadowed declaration is here
8975 | void *p;
| ^
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Message-ID: <20230925151029.461358-6-laurent@vivier.eu>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
The tcg/tcg.h header is a big bucket, containing stuff related to
the translators and the JIT backend. The places that initialize
tcg or create new threads do not need all of that, so split out
these three functions to a new header.
Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This patch adds the new extensions in
linux 6.5 to the hwprobe syscall.
And fixes RVC check to OR with correct value.
The previous variable contains 0 therefore it
did work.
Signed-off-by: Robbin Ehn <rehn@rivosinc.com>
Acked-by: Richard Henderson <richard.henderson@linaro.org>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <bc82203b72d7efb30f1b4a8f9eb3d94699799dc8.camel@rivosinc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Rename from do_* to target_*. Fix some minor checkpatch errors.
Tested-by: Helge Deller <deller@gmx.de>
Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Warner Losh <imp@bsdimp.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Core dumps produced by gdb's gcore when connected to qemu's gdbstub
lack stack. The reason is that gdb includes only anonymous memory in
core dumps, which is distinguished by a non-0 Anonymous: value.
Consider the mappings with PAGE_ANON fully anonymous, and the mappings
without it fully non-anonymous.
Tested-by: Helge Deller <deller@gmx.de>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
[rth: Update for open_self_maps_* rewrite]
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Replace the by-hand method of region identification with
the official user-exec interface. Cross-check the region
provided to the callback with the interval tree from
read_self_maps().
Tested-by: Helge Deller <deller@gmx.de>
Reviewed-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Use dev_t instead of a string, and ino_t instead of uint64_t.
The latter is likely to be identical on modern systems but is
more type-correct for usage.
Tested-by: Helge Deller <deller@gmx.de>
Reviewed-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Move the various open_cpuinfo functions into new files.
Move the m68k open_hardware function as well.
All other guest architectures get a boilerplate empty file.
Tested-by: Helge Deller <deller@gmx.de>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
In qemu we catch accesses to files like /proc/cpuinfo or /proc/net/route
and return to the guest contents which would be visible on a real system
(instead what the host would show).
This patch fixes a bug, where for example the accesses
cat /proc////cpuinfo
or
cd /proc && cat cpuinfo
will not be recognized by qemu and where qemu will wrongly show
the contents of the host's /proc/cpuinfo file.
Signed-off-by: Helge Deller <deller@gmx.de>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20230803214450.647040-2-deller@gmx.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Rather than using a zero tuple to end the table, use a macro
to apply ARRAY_SIZE and pass that on to the convert functions.
This fixes two bugs in which the conversion functions required
that both the target and host masks be non-zero in order to
continue, rather than require both target and host masks be
zero in order to terminate.
This affected mmap_flags_tbl when the host does not support
all of the flags we wish to convert (e.g. MAP_UNINITIALIZED).
Mapping these flags to zero is good enough, and matches how
the kernel ignores bits that are unknown.
Fixes: 4b840f96 ("linux-user: Populate more bits in mmap_flags_tbl")
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
New function that rejects unsupported map types and flags.
In 4b840f96 we should not have accepted MAP_SHARED_VALIDATE
without actually validating the rest of the flags.
Fixes: 4b840f96 ("linux-user: Populate more bits in mmap_flags_tbl")
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
We will want to be able to search the set of mappings.
For this patch, the two users iterate the tree in order.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
do_brk() minimizes calls into target_mmap() by aligning the address
with host page size, which is potentially larger than the target page
size. However, the current implementation of this optimization has two
bugs:
- The start of brk is rounded up with the host page size while brk
advertises an address aligned with the target page size as the
beginning of brk. This makes the beginning of brk unmapped.
- Content clearing after mapping is flawed. The size to clear is
specified as HOST_PAGE_ALIGN(brk_page) - brk_page, but brk_page is
aligned with the host page size so it is always zero.
This optimization actually has no practical benefit. It makes difference
when brk() is called multiple times with values in a range of the host
page size. However, sophisticated memory allocators try to avoid to
make such frequent brk() calls. For example, glibc 2.37 calls brk() to
shrink the heap only when there is a room more than 128 KiB. It is
rare to have a page size larger than 128 KiB if it happens.
Let's remove the optimization to fix the bugs and make the code simpler.
Fixes: 86f04735ac ("linux-user: Fix brk() to release pages")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1616
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-Id: <20230802071754.14876-7-akihiko.odaki@daynix.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Linux 6.4.7 does nothing when a value smaller than the initial brk is
specified.
Fixes: 86f04735ac ("linux-user: Fix brk() to release pages")
Reviewed-by: Helge Deller <deller@gmx.de>
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-Id: <20230802071754.14876-6-akihiko.odaki@daynix.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
MAP_FIXED_NOREPLACE can ensure the mapped address is fixed without
concerning that the new mapping overwrites something else.
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-Id: <20230802071754.14876-5-akihiko.odaki@daynix.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Later the returned value is compared with -1, and negated errno is not
expected.
Fixes: 00faf08c95 ("linux-user: Don't use MAP_FIXED in do_brk()")
Reviewed-by: Helge Deller <deller@gmx.de>
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-Id: <20230802071754.14876-4-akihiko.odaki@daynix.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Fix the math overflow when calculating the new_malloc_size.
new_host_brk_page and brk_page are unsigned integers. If userspace
reduces the heap, new_host_brk_page is lower than brk_page which results
in a huge positive number (but should actually be negative).
Fix it by adding a proper check and as such make the code more readable.
Signed-off-by: Helge Deller <deller@gmx.de>
Tested-by: "Markus F.X.J. Oberhumer" <markus@oberhumer.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Fixes: 86f04735ac ("linux-user: Fix brk() to release pages")
Cc: qemu-stable@nongnu.org
Buglink: https://github.com/upx/upx/issues/683
Since commit 86f04735ac ("linux-user: Fix brk() to release pages") it's
possible for userspace applications to reduce their memory footprint by
calling brk() with a lower address and free up memory. Before that commit
guest heap memory was never unmapped.
But the Linux kernel prohibits to reduce brk() below the initial memory
address which is set at startup by the set_brk() function in binfmt_elf.c.
Such a range check was missed in commit 86f04735ac.
This patch adds the missing check by storing the initial brk value in
initial_target_brk and verify any new brk addresses against that value.
Tested with the i386 upx binary from
https://github.com/upx/upx/releases/download/v4.0.2/upx-4.0.2-i386_linux.tar.xz
Signed-off-by: Helge Deller <deller@gmx.de>
Tested-by: "Markus F.X.J. Oberhumer" <markus@oberhumer.com>
Fixes: 86f04735ac ("linux-user: Fix brk() to release pages")
Cc: qemu-stable@nongnu.org
Buglink: https://github.com/upx/upx/issues/683
The qemu brk() implementation is too aggressive and cleans remaining bytes
on the current page above the last brk address.
But some existing applications are buggy and read/write bytes above their
current heap address. On a phyiscal machine this does not trigger a
runtime error as long as the access happens on the same page. Additionally
the Linux kernel allocates only full pages and does no zeroing on already
allocated pages, even if the brk address is lowered.
Fix qemu to behave the same way as the kernel does. Do not touch already
allocated pages, and - when running with different page sizes of guest and
host - zero out only those memory areas where the host page size is bigger
than the guest page size.
Signed-off-by: Helge Deller <deller@gmx.de>
Tested-by: "Markus F.X.J. Oberhumer" <markus@oberhumer.com>
Fixes: 86f04735ac ("linux-user: Fix brk() to release pages")
Cc: qemu-stable@nongnu.org
Buglink: https://github.com/upx/upx/issues/683
In the code for TARGET_NR_clock_adjtime, we set the pointer phtx to
the address of the local variable htx. This means it can never be
NULL, but later in the code we check it for NULL anyway. Coverity
complains about this (CID 1507683) because the NULL check comes after
a call to clock_adjtime() that assumes it is non-NULL.
Since phtx is always &htx, and is used only in three places, it's not
really necessary. Remove it, bringing the code structure in to line
with that for TARGET_NR_clock_adjtime64, which already uses a simple
'&htx' when it wants a pointer to 'htx'.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230623144410.1837261-1-peter.maydell@linaro.org
These are types not used anymore anywhere else.
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: <20230511085056.13809-1-quintela@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Replace the 0/-1 result with true/false.
Invert the sense of the test of all callers.
Document the function.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230707204054.8792-25-richard.henderson@linaro.org>
We build with _FILE_OFFSET_BITS=64, so off_t = off64_t = uint64_t.
With an extra cast, this fixes emulation of mmap2, which could
overflow the computation of the full value of offset.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230707204054.8792-14-richard.henderson@linaro.org>
Fix translation of TARGET_MAP_SHARED and TARGET_MAP_PRIVATE,
which are types not single bits. Add TARGET_MAP_SHARED_VALIDATE,
TARGET_MAP_SYNC, TARGET_MAP_NONBLOCK, TARGET_MAP_POPULATE,
TARGET_MAP_FIXED_NOREPLACE, and TARGET_MAP_UNINITIALIZED.
Update strace to match.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230707204054.8792-9-richard.henderson@linaro.org>
The guest address, raddr, should be unsigned, aka abi_ulong.
The host addresses should be cast via *intptr_t not long.
Drop the inline and fix two other whitespace issues.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Anton Johansson <anjo@rev.ng>
Message-Id: <20230626140250.69572-1-richard.henderson@linaro.org>
Support for execveat syscall was implemented in 55bbe4 and is available
since QEMU 8.0.0. It relies on host execveat, which is widely available
on most of Linux kernels today.
However, this change breaks qemu-user self emulation, if "host" qemu
version is less than 8.0.0. Indeed, it does not implement yet execveat.
This strange use case happens with most of distribution today having
binfmt support.
With a concrete failing example:
$ qemu-x86_64-7.2 qemu-x86_64-8.0 /bin/bash -c /bin/ls
/bin/bash: line 1: /bin/ls: Function not implemented
-> not implemented means execve returned ENOSYS
qemu-user-static 7.2 and 8.0 can be conveniently grabbed from debian
packages qemu-user-static* [1].
One usage of this is running wine-arm64 from linux-x64 (details [2]).
This is by updating qemu embedded in docker image that we ran into this
issue.
The solution to update host qemu is not always possible. Either it's
complicated or ask you to recompile it, or simply is not accessible
(GitLab CI, GitHub Actions). Thus, it could be worth to implement execve
without relying on execveat, which is the goal of this patch.
This patch was tested with example presented in this commit message.
[1] http://ftp.us.debian.org/debian/pool/main/q/qemu/
[1] https://www.linaro.org/blog/emulate-windows-on-arm/
Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Message-Id: <20230705121023.973284-1-pierrick.bouvier@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This patch adds the new syscall for the
"RISC-V Hardware Probing Interface"
(https://docs.kernel.org/riscv/hwprobe.html).
Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Robbin Ehn <rehn@rivosinc.com>
Message-Id: <06a4543df2aa6101ca9a48f21a3198064b4f1f87.camel@rivosinc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
The Linux accept4() syscall allows two flags only: SOCK_NONBLOCK and
SOCK_CLOEXEC, and returns -EINVAL if any other bits have been set.
Change the qemu implementation accordingly, which means we can not use
the fcntl_flags_tbl[] translation table which allows too many other
values.
Beside the correction in behaviour, this actually fixes the accept4()
emulation for hppa, mips and alpha targets for which SOCK_NONBLOCK is
different than TARGET_SOCK_NONBLOCK (aka O_NONBLOCK).
The fix can be verified with the testcase of the debian lwt package,
which hangs forever in a read() syscall without this patch.
Signed-off-by: Helge Deller <deller@gmx.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
When running a 32-bit guest on a 64-bit host, fcntl[64](F_GETFL) should
return with the TARGET_O_LARGEFILE flag set, because all 64-bit hosts
support large files unconditionally.
But on 64-bit hosts, O_LARGEFILE has the value 0, so the flag
translation can't be done with the fcntl_flags_tbl[]. Instead add the
TARGET_O_LARGEFILE flag afterwards.
Note that for 64-bit guests the compiler will optimize away this code,
since TARGET_O_LARGEFILE is zero.
Signed-off-by: Helge Deller <deller@gmx.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
/proc/self/smaps is an extension of /proc/self/maps: it provides the
same lines, plus additional information about each range.
GDB uses /proc/self/smaps when available, which means that
generate-core-file tries it first before falling back to
/proc/self/maps. This, in turn, causes it to dump the host mappings,
since /proc/self/smaps is not emulated and is just passed through.
Fix by emulating /proc/self/smaps. Provide true values only for
Size, KernelPageSize, MMUPageSize and VmFlags. Leave all other values
at 0, which is a valid conservative estimate.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230621203627.1808446-4-iii@linux.ibm.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20230630180423.558337-34-alex.bennee@linaro.org>
gdbstub cannot meaningfully handle QEMU_ERESTARTSYS, and it doesn't
need to. Add a parameter to do_guest_openat() that makes it use
openat() instead of safe_openat(), so that it becomes usable from
gdbstub.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230621203627.1808446-3-iii@linux.ibm.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20230630180423.558337-33-alex.bennee@linaro.org>
These functions will be required by the GDB stub in order to provide
the guest view of /proc to GDB.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230621203627.1808446-2-iii@linux.ibm.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20230630180423.558337-32-alex.bennee@linaro.org>
Coverity doesn't like the way we might end up calling getgroups()
with a NULL grouplist pointer. This is fine for the special case
of gidsetsize == 0, but we will also do it if the guest passes
us a negative gidsetsize. (CID 1512465)
Explicitly fail the negative gidsetsize with EINVAL, as the kernel
does. This means we definitely only call the libc getgroups()
with valid parameters. It also brings the getgroups() code in
to line with the setgroups() code.
Possibly Coverity may still complain about getgroups(0, NULL), but
that would be a false positive.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
There are 2 pairs of identical code (with different types)
for TARGET_NR_setgroups & TARGET_NR_setgroups32, and
for TARGET_NR_getgroups & TARGET_NR_getgroups32. Add
comments stating this fact, so that further modifications
are done in two places.
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
