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linux-user/arm: Use force_sig() to deliver fpa11 emulation SIGFPE 

In the Arm target code, when the fpa11 emulation code tells us we
need to send the guest a SIGFPE, we do this with queue_signal(), but
we are using the wrong si_type, and we aren't setting the _sifields
union members corresponding to either the si_type we are using or the
si_type we should be using.

As the existing comment notes, the kernel code for this calls the old
send_sig() function to deliver the signal.  This eventually results
in the kernel's signal handling code fabricating a siginfo_t with a
SI_KERNEL code and a zero pid and uid.  For QEMU this means we need
to use QEMU_SI_KILL.  We already have a function for that:
force_sig() sets up the whole target_siginfo_t the way we need it.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20210813131809.28655-4-peter.maydell@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
This commit is contained in:
Peter Maydell 2021-08-13 14:18:05 +01:00 committed by Laurent Vivier
parent 1af354120d
commit babe6d5c88
1 changed files with 4 additions and 7 deletions
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11
linux-user/arm/cpu_loop.c
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@ -268,16 +268,13 @@ static bool emulate_arm_fpa11(CPUARMState *env, uint32_t opcode)
ts->fpa.fpsr |= raise & ~enabled;
if (raise & enabled) {
target_siginfo_t info = { };
/*
* The kernel's nwfpe emulator does not pass a real si_code.
* It merely uses send_sig(SIGFPE, current, 1).
* It merely uses send_sig(SIGFPE, current, 1), which results in
* __send_signal() filling out SI_KERNEL with pid and uid 0 (under
* the "SEND_SIG_PRIV" case). That's what our force_sig() does.
*/
info.si_signo = TARGET_SIGFPE;
info.si_code = TARGET_SI_KERNEL;
queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
force_sig(TARGET_SIGFPE);
} else {
env->regs[15] += 4;
}