Enable FEAT_MOPS on the AArch64 'max' CPU, and add it to
the list of features we implement.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230912140434.1333369-13-peter.maydell@linaro.org
FEAT_HBC (Hinted conditional branches) provides a new instruction
BC.cond, which behaves exactly like the existing B.cond except
that it provides a hint to the branch predictor about the
likely behaviour of the branch.
Since QEMU does not implement branch prediction, we can treat
this identically to B.cond.
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>
Add the code to report the arm32 hwcaps we were previously missing:
ss, ssbs, fphp, asimdhp, asimddp, asimdfhm, asimdbf16, i8mm
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Our lists of Arm 32 and 64 bit hwcap values have lagged behind
the Linux kernel. Update them to include all the bits defined
as of upstream Linux git commit a48fa7efaf1161c1 (in the middle
of the kernel 6.6 dev cycle).
For 64-bit, we don't yet implement any of the features reported via
these hwcap bits. For 32-bit we do in fact already implement them
all; we'll add the code to set them in a subsequent commit.
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>
Some of the names we use for CPU features in linux-user's dummy
/proc/cpuinfo don't match the strings in the real kernel in
arch/arm64/kernel/cpuinfo.c. Specifically, the SME related
features have an underscore in the HWCAP_FOO define name,
but (like the SVE ones) they do not have an underscore in the
string in cpuinfo. Correct the errors.
Fixes: a55b9e7226 ("linux-user: Emulate /proc/cpuinfo on aarch64 and arm")
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>
Signed-off-by: Song Gao <gaosong@loongson.cn>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230914022645.1151356-12-gaosong@loongson.cn>
The code in setup_rt_frame reads two words at haddr, but locks only one.
This patch fixes it to lock both.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Acked-by: Helge Deller <deller@gmx.de>
Cc: qemu-stable@nongnu.org
Signed-off-by: Helge Deller <deller@gmx.de>
qemu-hppa may crash when delivering a signal. It can be demonstrated with
this program. Compile the program with "hppa-linux-gnu-gcc -O2 signal.c"
and run it with "qemu-hppa -one-insn-per-tb a.out". It reports that the
address of the flag is 0xb4 and it crashes when attempting to touch it.
#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
#include <signal.h>
sig_atomic_t flag;
void sig(int n)
{
printf("&flag: %p\n", &flag);
flag = 1;
}
int main(void)
{
struct sigaction sa;
struct itimerval it;
sa.sa_handler = sig;
sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_RESTART;
if (sigaction(SIGALRM, &sa, NULL)) perror("sigaction"), exit(1);
it.it_interval.tv_sec = 0;
it.it_interval.tv_usec = 100;
it.it_value.tv_sec = it.it_interval.tv_sec;
it.it_value.tv_usec = it.it_interval.tv_usec;
if (setitimer(ITIMER_REAL, &it, NULL)) perror("setitimer"), exit(1);
while (1) {
}
}
The reason for the crash is that the signal handling routine doesn't clear
the 'N' flag in the PSW. If the signal interrupts a thread when the 'N'
flag is set, the flag remains set at the beginning of the signal handler
and the first instruction of the signal handler is skipped.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Acked-by: Helge Deller <deller@gmx.de>
Cc: qemu-stable@nongnu.org
Signed-off-by: Helge Deller <deller@gmx.de>
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>
We should not use types dependend on host arch for target_ucontext.
This bug is found when run rv32 applications.
Signed-off-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20230811055438.1945-1-zhiwei_liu@linux.alibaba.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Remove the fixed size shm_regions[] array.
Remove references when other mappings completely remove
or replace a region.
Tested-by: Helge Deller <deller@gmx.de>
Reviewed-by: Helge Deller <deller@gmx.de>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
If the shm region is not mapped at shmaddr, EINVAL.
Do not unmap the region until the syscall succeeds.
Use mmap_reserve_or_unmap to preserve reserved_va semantics.
Tested-by: Helge Deller <deller@gmx.de>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
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>
The start_mmap value is write-only.
Remove the field and the defines that populated it.
Logically, this has been replaced by task_unmapped_base.
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>
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>
PIE executables are usually linked at offset 0 and are
relocated somewhere during load. The hiaddr needs to
be adjusted to keep the brk next to the executable.
Cc: qemu-stable@nongnu.org
Fixes: 1f356e8c01 ("linux-user: Adjust initial brk when interpreter is close to executable")
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>
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>
Add emulation for /proc/cpuinfo for the alpha architecture.
alpha output example:
(alpha-chroot)root@p100:/# cat /proc/cpuinfo
cpu : Alpha
cpu model : ev67
cpu variation : 0
cpu revision : 0
cpu serial number : JA00000000
system type : QEMU
system variation : QEMU_v8.0.92
system revision : 0
system serial number : AY00000000
cycle frequency [Hz] : 250000000
timer frequency [Hz] : 250.00
page size [bytes] : 8192
phys. address bits : 44
max. addr. space # : 255
BogoMIPS : 2500.00
platform string : AlphaServer QEMU user-mode VM
cpus detected : 8
cpus active : 4
cpu active mask : 0000000000000095
L1 Icache : n/a
L1 Dcache : n/a
L2 cache : n/a
L3 cache : n/a
Signed-off-by: Helge Deller <deller@gmx.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230803214450.647040-4-deller@gmx.de>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Add emulation for /proc/cpuinfo for arm architecture.
The output below mimics output as seen on debian porterboxes.
aarch64 output example:
processor : 0
model name : ARMv8 Processor rev 0 (v8l)
BogoMIPS : 100.00
Features : swp half thumb fast_mult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae aes pmull sha1 sha2 crc32
CPU implementer : 0x41
CPU architecture: 8
CPU variant : 0x1
CPU part : 0xd07
CPU revision : 0
arm 32-bit output example:
processor : 0
model name : ARMv7 Processor rev 5 (armv7l)
BogoMIPS : 100.00
Features : swp half thumb fast_mult vfp edsp thumbee neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae
CPU implementer : 0x41
CPU architecture: 7
CPU variant : 0x0f
CPU part : 0xc07
CPU revision : 5
Signed-off-by: Helge Deller <deller@gmx.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230803214450.647040-3-deller@gmx.de>
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>
The vxe2 hwcap is not set for programs running in linux-user, but is
set by a Linux kernel running in softmmu. Add it to the former.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-Id: <20230804233748.218935-2-iii@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>
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>
linux-user: Do not adjust image mapping for host page size
linux-user: Adjust initial brk when interpreter is close to executable
util/selfmap: Rewrite using qemu/interval-tree.h
linux-user: Rewrite probe_guest_base
-----BEGIN PGP SIGNATURE-----
iQFRBAABCgA7FiEEekgeeIaLTbaoWgXAZN846K9+IV8FAmTSrp4dHHJpY2hhcmQu
aGVuZGVyc29uQGxpbmFyby5vcmcACgkQZN846K9+IV9lTQf/W/Tbd6CFnZpVE8Sb
BPrhdmo+x6Jftt1Ha66b/4xnasX7DuVaI1ECDh4CQQKIOh9A4LETx6ue9/UGi4vT
Fe4UrrJcAjt/CPaZhwXniJM9CvEnw1gkl3AgKAtZOBEConuPnkTiSWjySmCt3T4r
EGQxDe0HLpWYavNtvyywak/sEbwOD4hNAunFpJB6PLZ+KEoCDZwtcQdl55kg5bIt
WBMgUSXnWhC45t+26OcSDeHovqxHoA647H10T0y0U6bNVkW0tRW51xCTvHt+iDyR
s8UOCe1Q+w8F18fN68HIWBJ6NCzUts/AmQrWwc/MWiK1z91/ht5mlKAuNYnoZ6jH
htCSEA==
=ERAI
-----END PGP SIGNATURE-----
Merge tag 'pull-lu-20230808' of https://gitlab.com/rth7680/qemu into staging
linux-user: Adjust guest image layout vs reserved_va
linux-user: Do not adjust image mapping for host page size
linux-user: Adjust initial brk when interpreter is close to executable
util/selfmap: Rewrite using qemu/interval-tree.h
linux-user: Rewrite probe_guest_base
# -----BEGIN PGP SIGNATURE-----
#
# iQFRBAABCgA7FiEEekgeeIaLTbaoWgXAZN846K9+IV8FAmTSrp4dHHJpY2hhcmQu
# aGVuZGVyc29uQGxpbmFyby5vcmcACgkQZN846K9+IV9lTQf/W/Tbd6CFnZpVE8Sb
# BPrhdmo+x6Jftt1Ha66b/4xnasX7DuVaI1ECDh4CQQKIOh9A4LETx6ue9/UGi4vT
# Fe4UrrJcAjt/CPaZhwXniJM9CvEnw1gkl3AgKAtZOBEConuPnkTiSWjySmCt3T4r
# EGQxDe0HLpWYavNtvyywak/sEbwOD4hNAunFpJB6PLZ+KEoCDZwtcQdl55kg5bIt
# WBMgUSXnWhC45t+26OcSDeHovqxHoA647H10T0y0U6bNVkW0tRW51xCTvHt+iDyR
# s8UOCe1Q+w8F18fN68HIWBJ6NCzUts/AmQrWwc/MWiK1z91/ht5mlKAuNYnoZ6jH
# htCSEA==
# =ERAI
# -----END PGP SIGNATURE-----
# gpg: Signature made Tue 08 Aug 2023 02:07:42 PM PDT
# gpg: using RSA key 7A481E78868B4DB6A85A05C064DF38E8AF7E215F
# gpg: issuer "richard.henderson@linaro.org"
# gpg: Good signature from "Richard Henderson <richard.henderson@linaro.org>" [ultimate]
* tag 'pull-lu-20230808' of https://gitlab.com/rth7680/qemu:
linux-user: Rewrite non-fixed probe_guest_base
linux-user: Rewrite fixed probe_guest_base
linux-user: Consolidate guest bounds check in probe_guest_base
linux-user: Remove duplicate CPU_LOG_PAGE from probe_guest_base
util/selfmap: Rewrite using qemu/interval-tree.h
linux-user: Use zero_bss for PT_LOAD with no file contents too
linux-user: Do not adjust zero_bss for host page size
linux-user: Do not adjust image mapping for host page size
linux-user: Adjust initial brk when interpreter is close to executable
linux-user: Use elf_et_dyn_base for ET_DYN with interpreter
linux-user: Use MAP_FIXED_NOREPLACE for initial image mmap
linux-user: Define ELF_ET_DYN_BASE in $guest/target_mman.h
linux-user: Define TASK_UNMAPPED_BASE in $guest/target_mman.h
linux-user: Adjust task_unmapped_base for reserved_va
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Use pgb_addr_set to probe for all of the guest addresses,
not just the main executable. Handle the identity map
specially and separately from the search.
If /proc/self/maps is available, utilize the full power
of the interval tree search, rather than a linear search
through the address list.
If /proc/self/maps is not available, increase the skip
between probes so that we do not probe every single page
of the host address space. Choose 1 MiB for 32-bit hosts
(max 4k probes) and 1 GiB for 64-bit hosts (possibly a
large number of probes, but the large step makes it more
likely to find empty space quicker).
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Create a set of subroutines to collect a set of guest addresses,
all of which must be mappable on the host. Use this within the
renamed pgb_fixed subroutine to validate the user's choice of
guest_base specified by the -B command-line option.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
The three sets of checks are identical, logically.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
The proper logging for probe_guest_base is in the main function.
There is no need to duplicate that in the subroutines.
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>
If p_filesz == 0, then vaddr_ef == vaddr. We can reuse the
code in zero_bss rather than incompletely duplicating it in
load_elf_image.
Tested-by: Helge Deller <deller@gmx.de>
Reviewed-by: Helge Deller <deller@gmx.de>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Remove TARGET_ELF_EXEC_PAGESIZE, and 3 other TARGET_ELF_PAGE* macros
based off of that. Rely on target_mmap to handle guest vs host page
size mismatch.
Tested-by: Helge Deller <deller@gmx.de>
Reviewed-by: Helge Deller <deller@gmx.de>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
While we attempt to load a ET_DYN executable far away from
TASK_UNMAPPED_BASE, we are not completely in control of the
address space layout. If the interpreter lands close to
the executable, leaving insufficient heap space, move brk.
Tested-by: Helge Deller <deller@gmx.de>
Signed-off-by: Helge Deller <deller@gmx.de>
[rth: Re-order after ELF_ET_DYN_BASE patch so that we do not
"temporarily break" tsan, and also to minimize the changes required.
Remove image_info.reserve_brk as unused.]
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Follow the lead of the linux kernel in fs/binfmt_elf.c,
in which an ET_DYN executable which uses an interpreter
(usually a PIE executable) is loaded away from where the
interpreter itself will be loaded.
Tested-by: Helge Deller <deller@gmx.de>
Reviewed-by: Helge Deller <deller@gmx.de>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Use this as extra protection for the guest mapping over
any qemu host mappings.
Tested-by: Helge Deller <deller@gmx.de>
Reviewed-by: Helge Deller <deller@gmx.de>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Copy each guest kernel's default value, then bound it
against reserved_va or the host address space.
Tested-by: Helge Deller <deller@gmx.de>
Reviewed-by: Helge Deller <deller@gmx.de>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Provide default values that are as close as possible to the
values used by the guest's kernel.
Tested-by: Helge Deller <deller@gmx.de>
Reviewed-by: Helge Deller <deller@gmx.de>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Ensure that the chosen values for mmap_next_start and
task_unmapped_base are within the guest address space.
Tested-by: Helge Deller <deller@gmx.de>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Alpha and 31-bit s390 lack the assembly fragment to handle signals
occurring at the same time as system calls, so they cannot run
linux-user emulation anymore. Drop the host-signal.h files for
them.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Tested-by: Ilya Leoshkevich <iii@linux.ibm.com>
Tested-by: Michael Tokarev <mjt@tls.msk.ru>
Message-ID: <20230808120303.585509-3-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
x32 uses the same signal handling fragments as x86_64, since host_arch
is set to x86_64 when Meson runs. Remove the unnecessary forwarder and
set the host_arch variable properly in configure.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Tested-by: Ilya Leoshkevich <iii@linux.ibm.com>
Tested-by: Michael Tokarev <mjt@tls.msk.ru>
Message-ID: <20230808120303.585509-2-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The heap starts at "brk" not "start_brk". With this fixed,
image_info.start_brk is unused and may be removed.
Tested-by: Helge Deller <deller@gmx.de>
Reviewed-by: Helge Deller <deller@gmx.de>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
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>
