This field is write-only. Use only the function-local
variable within load_elf_image.
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Most binaries don't actually depend on more than page alignment,
but any binary can request it. Not honoring this was a bug.
This became obvious when gdb reported
Failed to read a valid object file image from memory
when examining some vdso which are marked as needing more
than page alignment.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Running qemu-i386 on a system running with SELinux in enforcing mode
(more precisely: s390x trixie container on Fedora 40) fails with:
qemu-i386: tests/tcg/i386-linux-user/sigreturn-sigmask: Unable to find a guest_base to satisfy all guest address mapping requirements
00000000-ffffffff
The reason is that main() determines mmap_min_addr from
/proc/sys/vm/mmap_min_addr, but SELinux additionally defines
CONFIG_LSM_MMAP_MIN_ADDR, which is normally larger: 32K or 64K, but,
in general, can be anything. There is no portable way to query its
value: /boot/config, /proc/config and /proc/config.gz are distro- and
environment-specific.
Once the identity map fails, the magnitude of guest_base does not
matter, so fix by starting the search from 1M or 1G.
Cc: qemu-stable@nongnu.org
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2598
Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-ID: <20241023002558.34589-1-iii@linux.ibm.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
The commit fd6f7798ac ("linux-user: Use direct syscalls for setuid(),
etc") added direct syscall wrappers for setuid(), setgid(), etc since the
system calls have different semantics than the libc functions.
Add and use the corresponding wrappers for setreuid and setregid which
were missed in that commit.
This fixes the build of the debian package of the uid_wrapper library
(https://cwrap.org/uid_wrapper.html) when running linux-user.
Cc: qemu-stable@nongnu.org
Signed-off-by: Helge Deller <deller@gmx.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-ID: <Zyo2jMKqq8hG8Pkz@p100>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Some applications want to use low priority realtime signals (e.g.,
SIGRTMAX). Currently QEMU cannot map all target realtime signals to
host realtime signals, and chooses to sacrifice the end of the target
realtime signal range.
Allow users to choose how to map target realtime signals to host
realtime signals using the new -t option, the new QEMU_RTSIG_MAP
environment variable, and the new -Drtsig_map=\"...\" meson flag.
To simplify things, the meson flag is not per-target, because the
intended use case is app-specific qemu-user builds.
The mapping is specified using the "tsig hsig count[,...]" syntax.
Target realtime signals [tsig,tsig+count) are mapped to host realtime
signals [hsig,hsig+count). Care is taken to avoid double and
out-of-range mappings.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20241029232211.206766-2-iii@linux.ibm.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
When debugging qemu-user processes using gdbstub, the following warning
appears every time:
warning: BFD: warning: system-supplied DSO at 0x7f8253cc3000 has a corrupt string table index
The reason is that QEMU does not map the VDSO's section headers. The
VDSO's ELF header's e_shoff points to zeros, which GDB fails to parse.
The difference with the kernel's VDSO is that the latter is mapped as a
blob, ignoring program headers - which also don't cover the section
table. QEMU, on the other hand, loads it as an ELF file.
There appears to be no way to place section headers inside a section,
and, therefore, no way to refer to them from a linker script. Also, ld
hardcodes section headers to be non-loadable, see
_bfd_elf_assign_file_positions_for_non_load(). In theory ld could be
enhanced by implementing an "SHDRS" keyword in addition to the existing
"FILEHDR" and "PHDRS".
There are multiple ways to resolve the issue:
- Copy VDSO as a blob in load_elf_vdso(). This would require creating
specialized loader logic, that duplicates parts of load_elf_image().
- Fix up VDSO's PHDR size in load_elf_vdso(). This would require either
duplicating the parsing logic, or adding an ugly parameter to
load_elf_image().
- Fix up VDSO's PHDR size in gen-vdso. This is the simplest solution,
so do it.
There are two tricky parts:
- Byte-swaps need to be done either on local copies, or in-place and
then reverted in the end. To preserve the existing code structure, do
the former for Sym and Dyn, and the latter for Ehdr, Phdr, and Shdr.
- There must be no .bss, which is already the case - but having an
explicit check is helpful to ensure correctness.
To verify this change, I diffed the on-disk and the loaded VDSOs; the
result does not show anything unusual, except for what seems to be an
existing oversight (which should probably be fixed separately):
│ Symbol table '.dynsym' contains 8 entries:
│ Num: Value Size Type Bind Vis Ndx Name
│ - 0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
│ - 6: 0000000000000000 0 OBJECT GLOBAL DEFAULT ABS LINUX_2.6.29
│ + 0: 00007f61075bf000 0 NOTYPE LOCAL DEFAULT UND
│ + 6: 00007f61075bf000 0 OBJECT GLOBAL DEFAULT ABS LINUX_2.6.29
Fixes: 2fa536d107 ("linux-user: Add gen-vdso tool")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20241023202850.55211-1-iii@linux.ibm.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Set the 2-NaN propagation rule explicitly in the float_status words
we use. We wrap this plus the pre-existing setting of the
tininess-before-rounding flag in a new function
arm_set_default_fp_behaviours() to avoid repetition, since we have a
lot of float_status words at this point.
The situation with FPA11 emulation in linux-user is a little odd, and
arguably "correct" behaviour there would be to exactly match a real
Linux kernel's FPA11 emulation. However FPA11 emulation is
essentially dead at this point and so it seems better to continue
with QEMU's current behaviour and leave a comment describing the
situation.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20241025141254.2141506-4-peter.maydell@linaro.org
Add a function for formatting target sigsets. It can be useful for
other syscalls in the future, so put it into the beginning of strace.c.
For simplicity, do not implement the strace's ~[] output syntax.
Add a rt_sigprocmask return handler.
Example outputs:
753914 rt_sigprocmask(SIG_BLOCK,[SIGCHLD SIGTSTP SIGTTIN SIGTTOU],0x00007f80fddfe380,8) = 0 (oldset=[SIGTTOU])
753914 rt_sigprocmask(SIG_SETMASK,[SIGCHLD],NULL,8) = 0
753914 rt_sigprocmask(SIG_BLOCK,NULL,0x00007f80fddff3c0,8) = 0 (oldset=[])
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-ID: <20241022102726.18520-1-iii@linux.ibm.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Since commit 95b9c27c81 ("linux-user: Remove unused handle_vm86_fault")
a bunch of other "static inline" function are now unused, too. Clang
warns about such unused "static inline" functions in .c files, so the
build currently breaks when compiling with "--enable-werror". Remove
the unused functions to get it going again.
Fixes: 95b9c27c81 ("linux-user: Remove unused handle_vm86_fault")
Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Dr. David Alan Gilbert <dave@treblig.org>
Message-ID: <20241011161845.417342-1-thuth@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
