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From: Sergey Fedorov <serge.fdrv@gmail.com>
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Date: Wed, 2 Sep 2015 19:53:21 +0300
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Subject: Re: [Qemu-devel] ARM softmmu breakpoint misbehavior
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: QEMU Developers <qemu-devel@nongnu.org>

On 28.08.2015 22:21, Peter Maydell wrote:
> The watchpoint code has a chance of cpu_resume_from_signal
> doing the right thing, because we really did have the
> code to do the load/store. However I have a feeling this
> won't interact properly with the fact that ARM needs
> BP_STOP_BEFORE_ACCESS on its watchpoints (unlike x86, which
> is where I was looking at when I wrote the ARM wp handling
> code.) So we may well be broken there as well in the
> case where check_watchpoints() returns false.

You are right. The same problem with watchpoints. Here is a small test
for this:

    .text
    .global _start
_start:
    adr     x0, wp
    msr     dbgwvr0_el1, x0
    mov     x0, #1
    orr     x0, x0, #(3 << 3)
    orr     x0, x0, #(0xff << 5)
    msr     dbgwcr0_el1, x0
    ldr     x0, wp
    wfi
    b       .

    .data
    .balign 64
wp:
    .quad   0