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>
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>
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>
The man page states:
> Note that older kernels which do not recognize the MAP_FIXED_NOREPLACE
> flag will typically (upon detecting a collision with a preexisting
> mapping) fall back to a “non-MAP_FIXED” type of behavior: they will
> return an address that is different from the requested address.
> Therefore, backward-compatible software should check the returned
> address against the requested address.
https://man7.org/linux/man-pages/man2/mmap.2.html
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-Id: <20230802071754.14876-3-akihiko.odaki@daynix.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Passing MAP_FIXED_NOREPLACE to host will fail for reserved_va because
the address space is reserved with mmap. Replace it with MAP_FIXED
in that case.
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-Id: <20230802071754.14876-2-akihiko.odaki@daynix.com>
[rth: Expand inline commentary.]
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Set V bit for hwcap if misa is set.
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1793
Signed-off-by: Nathan Egge <negge@xiph.org>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Tested-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Message-Id: <20230803131424.40744-1-negge@xiph.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Commit 7f4f0d9ea8 ("linux-user/arm: Implement __kernel_cmpxchg with host
atomics") switched to use qatomic_cmpxchg() to swap a word with the memory
content, but missed to endianess-swap the oldval and newval values when
emulating an armeb CPU, which expects words to be stored in big endian in
the guest memory.
The bug can be verified with qemu >= v7.0 on any little-endian host, when
starting the armeb binary of the upx program, which just hangs without
this patch.
Cc: qemu-stable@nongnu.org
Signed-off-by: Helge Deller <deller@gmx.de>
Reported-by: "Markus F.X.J. Oberhumer" <markus@oberhumer.com>
Reported-by: John Reiser <jreiser@BitWagon.com>
Closes: https://github.com/upx/upx/issues/687
Message-Id: <ZMQVnqY+F+5sTNFd@p100>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This reverts commit 518f32221a.
It is causing similar segfaults at least on aarch64, ppc64el
and s390x. Let's revert this one for now and analyze what's
going on later.
Reopens: https://bugs.debian.org/1040981
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Commit 86f04735ac ("linux-user: Fix brk() to release pages") introduced
the possibility for userspace applications to reduce memory footprint by
calling brk() with a lower address and as such free up memory, the same
way as the Linux kernel allows on physical machines.
This change introduced some failures for applications with errors like
- accesing bytes above the brk heap address on the same page,
- freeing memory below the initial brk address,
and introduced a behaviour which isn't done by the kernel (e.g. zeroing
memory above brk).
This patch series fixes those issues and has been tested with existing
programs (e.g. upx).
Additionally one patch fixes running static armhf executables (e.g. fstype)
which was broken since qemu-8.0.
Changes in v2:
- dropped patch to revert d28b3c90cf ("linux-user: Make sure initial brk(0)
is page-aligned")
- rephrased some commit messages
- fixed Cc email addresses, added new ones
- added R-b tags
Helge
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Merge tag 'linux-user-brk-fixes-pull-request' of https://github.com/hdeller/qemu-hppa into staging
linux-user: brk() syscall fixes and armhf static binary fix
Commit 86f04735ac ("linux-user: Fix brk() to release pages") introduced
the possibility for userspace applications to reduce memory footprint by
calling brk() with a lower address and as such free up memory, the same
way as the Linux kernel allows on physical machines.
This change introduced some failures for applications with errors like
- accesing bytes above the brk heap address on the same page,
- freeing memory below the initial brk address,
and introduced a behaviour which isn't done by the kernel (e.g. zeroing
memory above brk).
This patch series fixes those issues and has been tested with existing
programs (e.g. upx).
Additionally one patch fixes running static armhf executables (e.g. fstype)
which was broken since qemu-8.0.
Changes in v2:
- dropped patch to revert d28b3c90cf ("linux-user: Make sure initial brk(0)
is page-aligned")
- rephrased some commit messages
- fixed Cc email addresses, added new ones
- added R-b tags
Helge
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# gpg: Signature made Wed 19 Jul 2023 16:52:19 BST
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# gpg: aka "Helge Deller <deller@kernel.org>" [unknown]
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg: There is no indication that the signature belongs to the owner.
# Primary key fingerprint: 4544 8228 2CD9 10DB EF3D 25F8 3E5F 3D04 A7A2 4603
# Subkey fingerprint: BCE9 123E 1AD2 9F07 C049 BBDE F712 B510 A23A 0F5F
* tag 'linux-user-brk-fixes-pull-request' of https://github.com/hdeller/qemu-hppa:
linux-user: Fix qemu-arm to run static armhf binaries
linux-user: Fix strace output for old_mmap
linux-user: Fix signed math overflow in brk() syscall
linux-user: Prohibit brk() to to shrink below initial heap address
linux-user: Fix qemu brk() to not zero bytes on current page
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
qemu-user crashes immediately when running static binaries on the armhf
architecture. The problem is the memory layout where the executable is
loaded before the interpreter library, in which case the reserved brk
region clashes with the interpreter code and is released before qemu
tries to start the program.
At load time qemu calculates a brk value for interpreter and executable
each. The fix is to choose the higher one of both.
Signed-off-by: Helge Deller <deller@gmx.de>
Cc: Andreas Schwab <schwab@suse.de>
Cc: qemu-stable@nongnu.org
Reported-by: Venkata.Pyla@toshiba-tsip.com
Closes: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1040981
The old_mmap syscall (e.g. on i386) hands over the parameters in
a struct. Adjust the strace output to print the correct values.
Signed-off-by: Helge Deller <deller@gmx.de>
Reported-by: John Reiser <jreiser@BitWagon.com>
Closes: https://gitlab.com/qemu-project/qemu/-/issues/1760
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
elf_hwcap_str() takes a bit number, but compares it for equality with
the HWCAP_S390_* masks. This causes /proc/cpuinfo to display incorrect
hwcaps.
Fix by introducing the HWCAP_S390_NR_* constants and using them in
elf_hwcap_str() instead of the HWCAP_S390_*. While at it, add the
missing nnpa, pcimio and sie hwcaps from the latest kernel.
Output before:
features : esan3 zarch stfle msa
Output after:
features : esan3 zarch stfle msa ldisp eimm etf3eh highgprs vx vxe
Fixes: e19807bee3 ("linux-user/elfload: Introduce elf_hwcap_str() on s390x")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-Id: <20230627151356.273259-1-iii@linux.ibm.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>
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
Since commit fbd3c4cff6 ("linux-user/arm: Mark the commpage
executable") executing bare-metal (linked with rdimon.specs)
cortex-M code fails as:
$ qemu-arm -cpu cortex-m3 ~/hello.exe.m3
qemu-arm: ../../accel/tcg/user-exec.c:492: page_set_flags: Assertion `last <= GUEST_ADDR_MAX' failed.
Aborted (core dumped)
Commit 4f5c67f8df ("linux-user/arm: Take more care allocating
commpage") already took care of not allocating a commpage for
M-profile CPUs, however it had to be reverted as commit 6cda41daa2.
Re-introduce the M-profile fix from commit 4f5c67f8df.
Fixes: fbd3c4cff6 ("linux-user/arm: Mark the commpage executable")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1755
Reported-by: Christophe Lyon <christophe.lyon@linaro.org>
Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Anton Johansson <anjo@rev.ng>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230711153408.68389-1-philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@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>
The trivial length 0 check can be moved up, simplifying some
of the other cases. The end < start test is handled by
guest_range_valid_untagged.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230707204054.8792-27-richard.henderson@linaro.org>
Use page_check_range instead, which uses the interval tree
instead of checking each page individually.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230707204054.8792-26-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>
All of the guest to host page adjustment is handled by
mmap_reserve_or_unmap; there is no need to duplicate that.
There are no failure modes for munmap after alignment and
guest address range have been validated.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230707204054.8792-23-richard.henderson@linaro.org>
If !reserved_va, munmap instead and assert success.
Update all callers.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230707204054.8792-22-richard.henderson@linaro.org>
Use 'last' variables instead of 'end' variables; be careful
about avoiding overflow. Assert that the mmap succeeded.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230707204054.8792-21-richard.henderson@linaro.org>
Complete the transition within the mmap functions to a formulation
that does not overflow at the end of the address space.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20230707204054.8792-20-richard.henderson@linaro.org>
Use the interval tree to find empty space, rather than
probing each page in turn.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230707204054.8792-19-richard.henderson@linaro.org>
Use 'last' variables instead of 'end' variables.
Always zero MAP_ANONYMOUS fragments, which we previously
failed to do if they were not writable; early exit in case
we allocate a new page from the kernel, known zeros.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230707204054.8792-16-richard.henderson@linaro.org>
Use 'last' variables instead of 'end' variables.
When host page size > guest page size, detect when
adjacent host pages have the same protection and
merge that expanded host range into fewer syscalls.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230707204054.8792-15-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>
Split out from validate_prot_to_pageflags, as there is not
one single host_prot for the entire range. We need to adjust
prot for every host page that overlaps multiple guest pages.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230707204054.8792-13-richard.henderson@linaro.org>
