The Arm signal-handling code has some parts ifdeffed with a
TARGET_CONFIG_CPU_32, which is always defined. This is a leftover
from when this code's structure was based on the Linux kernel
signal handling code, where it was intended to support 26-bit
Arm CPUs. The kernel dropped its CONFIG_CPU_32 in kernel commit
4da8b8208eded0ba21e3 in 2009.
QEMU has never had 26-bit CPU support and is unlikely to ever
add it; we certainly aren't going to support 26-bit Linux
binaries via linux-user mode. The ifdef is just unhelpful
noise, so remove it entirely.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200518143014.20689-1-peter.maydell@linaro.org
Using the MSR instruction to write to CPSR.E is deprecated, but it is
required to work from any mode including unprivileged code. We were
incorrectly forbidding usermode code from writing it because
CPSR_USER did not include the CPSR_E bit.
We use CPSR_USER in only three places:
* as the mask of what to allow userspace MSR to write to CPSR
* when deciding what bits a linux-user signal-return should be
able to write from the sigcontext structure
* in target_user_copy_regs() when we set up the initial
registers for the linux-user process
In the first two cases not being able to update CPSR.E is a bug, and
in the third case it doesn't matter because CPSR.E is always 0 there.
So we can fix both bugs by adding CPSR_E to CPSR_USER.
Because the cpsr_write() in restore_sigcontext() is now changing
a CPSR bit which is cached in hflags, we need to add an
arm_rebuild_hflags() call there; the callsite in
target_user_copy_regs() was already rebuilding hflags for other
reasons.
(The recommended way to change CPSR.E is to use the 'SETEND'
instruction, which we do correctly allow from usermode code.)
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200518142801.20503-1-peter.maydell@linaro.org
The FDPIC restorer needs to deal with a function descriptor, hence we
have to extend 'retcode' such that it can hold the instructions needed
to perform this.
The restorer sequence uses the same thumbness as the exception
handler (mainly to support Thumb-only architectures).
Co-Authored-By: Mickaël Guêné <mickael.guene@st.com>
Signed-off-by: Christophe Lyon <christophe.lyon@st.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20180430080404.7323-5-christophe.lyon@st.com>
[lv: moved the change to linux-user/arm/signal.c]
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
