This patchset fixes https://gitlab.com/qemu-project/qemu/-/issues/613 which is a bug where we weren't setting FPSCR.LTPSIZE correctly out of reset for the user-mode emulator. The effect is that when using an M-profile CPU with the low-overhead-branch or MVE extensions (ie the Cortex-M55) with the linux-user QEMU the 'LE' instruction would take a UserFault and MVE instructions would be incorrectly predicated.
This is the result of some over-exuberant ifdeffery in the arm_cpu_reset() function. Patch 1 fixes that so that most of the M-profile-specific reset handling is not ifdeffed, and when we're in user mode we specifically set the FPU state up cleanly. Patches 2 and 3 are just follow-on tidyup. Christophe, if you are in a position to test this series with: M55 (has Security, MVE and LOB) M33 (has Security extension but not MVE/LOB) M7 or M4 (no Security, but does have FPU) that would be ideal. I don't really have much in the way of test cases for usermode to hand, so it's possible that I forgot something in the init of the FPU state that might break one of those combinations. (It does fix the test case attached to the bug report.) thanks -- PMM Peter Maydell (3): target/arm: Don't skip M-profile reset entirely in user mode target/arm: Always clear exclusive monitor on reset target/arm: Consolidate ifdef blocks in reset target/arm/cpu.c | 39 ++++++++++++++++++++++++++++----------- 1 file changed, 28 insertions(+), 11 deletions(-) -- 2.20.1