Please find submitted a patch for ARM memory barriers. This patch is against qemu-2.12-rc2 but I do believe it should apply for anything from 2.11.x to current.
I found with qemu 2.11.x or newer that I would get an illegal instruction error running some Intel binaries on my ARM chromebook. On investigation, I found it was quitting on memory barriers.
qemu instruction:
mb $0x31
was translating as:
0x604050cc: 5bf07ff5 blpl #0x600250a8
After patch it gives:
0x604050cc: f57ff05b dmb ish
In short, I found INSN_DMB_ISH (memory barrier for ARMv7) appeared to be correct based on online docs, but due to some endian-related shenanigans it had to be byte-swapped to suit qemu; it appears INSN_DMB_MCR (memory barrier for ARMv6) also should be byte swapped (and this patch does so). I have not checked for correctness of aarch64's barrier instruction.
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Please find submitted a patch for getdents (this system call stands for "get directory entries", it is passed a file descriptor pointing to a directory and returns a struct with info on the entries in that directory.) This patch is against qemu-2.10 series but continues to apply cleanly on current as of April 15 2018. If you are running a 32-bit binary on 64-bit target current qemu will convert he getdents struct, but it will NOT in the case of 64-bit binary on 32-bit host. (In my case, I had android SDK's "aapt" for x86-64 error out on 32-bit ARM without this patch, and run fine with it.) This patch simply replaces a "#if TARGET_ABI_BITS == 32 && HOST_LONG_BITS == 64" with "#if TARGET_ABI_BITS != HOST_LONG_BITS".
Thanks!
arm-mb.patch