arm: 0.954
kernel: 0.840
semantic: 0.780
device: 0.738
ppc: 0.719
architecture: 0.705
socket: 0.693
performance: 0.686
network: 0.620
vnc: 0.608
permissions: 0.603
debug: 0.567
peripherals: 0.545
files: 0.544
PID: 0.543
graphic: 0.542
register: 0.538
user-level: 0.532
boot: 0.517
risc-v: 0.517
TCG: 0.468
mistranslation: 0.452
x86: 0.429
hypervisor: 0.423
virtual: 0.421
VMM: 0.416
i386: 0.409
KVM: 0.343
assembly: 0.245

qemu-system-arm exits when cortex-m4 floating point used and irq occurs

qemu-system-arm exits with 

"...Secure UsageFault with CFSR.NOCP because NSACR.CP10 prevents stacking FP regs
...taking pending nonsecure exception 3
Taking exception 7 [Breakpoint]
qemu: fatal: Lockup: can't escalate 3 to HardFault (current priority -1)" 

when emulating Cortex-m4, executing at least 1 floating point instruction, and then an irq (e.g. sys tick) occurring.

CPACR.CP10 and CPACR.CP11 are set to 0x3 respectively prior to executing the fp instructions.

NOTE: NSACR does not appear to be a cortex m4 register.

Attached is a simplified elf to repro the issue.

The qemu command line is: "qemu-system-arm --gdb tcp::1234 -cpu cortex-m4 -machine lm3s6965evb -nographic -semihosting-config enable=on,target=native -kernel QemuExitWhenUsingFPAndIRQOccurs.elf -d int"



I think this patch should fix this bug:

https://<email address hidden>/


I confirm that this fixes the issue above.

Thank you for your help! It is much appreciated.

Now fixed in git master; will be in the imminent 4.1 release.


https://git.qemu.org/?p=qemu.git;a=commitdiff;h=02ac2f7f613b47f6a5b3