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

[KD]

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"

[Peter Maydell (pmaydell)]

I think this patch should fix this bug:

https://<email address hidden>/

[KD (buckfobb)]

I confirm that this fixes the issue above.

Thank you for your help! It is much appreciated.

[Peter Maydell (pmaydell)]

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

[Thomas Huth (th-huth)]

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