On Thu, 16 Dec 2021 at 17:44, Philippe Mathieu-Daudé <f4...@amsat.org> wrote: > > Cc'ing qemu-arm developers. > > On 12/16/21 18:31, abhijeet inamdar wrote: > > Hi, > > > > I was running my .elf file on my custom machine(CM3) and was hit with > > this error when debugging and had the required -d flags and single stepping. > > > > IN: Hal_MemFault > > 0x7004e794: 4770 bx lr > > > > Trace 0: 0x7f4faa471100 [00000000/7004e794/0x312000c1] Hal_MemFault > > R00=7004938d R01=00000000 R02=7004938c R03=ffffffff > > R04=7005e410 R05=10020000 R06=e000eda0 R07=00000000 > > R08=00000010 R09=1003f8e0 R10=e000ed94 R11=00000000 > > R12=ffffffff R13=1003dbe0 R14=fffffff9 R15=7004e794 > > XPSR=01000003 ---- T handler > > Taking exception 8 [QEMU v7M exception exit] > > Exception return: magic PC fffffff9 previous exception 3 > > M profile return from interrupt with misaligned PC is UNPREDICTABLE on v7M > > ...successful exception return > > DRBAR[6]: 0xa0000000 misaligned to DRSR region size, mask = 0x3fffffff > > Taking exception 3 [Prefetch Abort] > > ...with CFSR.IACCVIOL > > ...taking pending nonsecure exception 3
The logging here tells you what happened: * we are in an exception handler * we do the bx lr to magic value which is M-profile's exception-return * ...but there's something wrong with the return address we pull off the stack, because it's not an aligned value (its least significant bit is set) * moreover, it's an address that corresponds to an MPU region that has been misprogrammed (the DRBAR value isn't right); the MPU treats such regions as not matching * and so we take an instruction access fault So you have two problems: (1) the PC value on the stack that you're trying to return to is wrong (2) you're programming the MPU wrong You need to investigate and fix both. -- PMM
