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Fri, 23 Aug 2019 18:25:09 +0000 (UTC) Received: from [10.36.116.24] (ovpn-116-24.ams2.redhat.com [10.36.116.24]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1A56D1001938; Fri, 23 Aug 2019 18:25:06 +0000 (UTC) To: Richard Henderson , qemu-devel@nongnu.org References: <20190823100741.9621-1-david@redhat.com> <20190823100741.9621-9-david@redhat.com> <8df7d599-bc35-621e-c5d9-ac8554cba512@redhat.com> From: David Hildenbrand Openpgp: preference=signencrypt Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwX4EEwECACgFAljj9eoCGwMFCQlmAYAGCwkI BwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEE3eEPcA/4Na5IIP/3T/FIQMxIfNzZshIq687qgG 8UbspuE/YSUDdv7r5szYTK6KPTlqN8NAcSfheywbuYD9A4ZeSBWD3/NAVUdrCaRP2IvFyELj xoMvfJccbq45BxzgEspg/bVahNbyuBpLBVjVWwRtFCUEXkyazksSv8pdTMAs9IucChvFmmq3 jJ2vlaz9lYt/lxN246fIVceckPMiUveimngvXZw21VOAhfQ+/sofXF8JCFv2mFcBDoa7eYob s0FLpmqFaeNRHAlzMWgSsP80qx5nWWEvRLdKWi533N2vC/EyunN3HcBwVrXH4hxRBMco3jvM m8VKLKao9wKj82qSivUnkPIwsAGNPdFoPbgghCQiBjBe6A75Z2xHFrzo7t1jg7nQfIyNC7ez MZBJ59sqA9EDMEJPlLNIeJmqslXPjmMFnE7Mby/+335WJYDulsRybN+W5rLT5aMvhC6x6POK z55fMNKrMASCzBJum2Fwjf/VnuGRYkhKCqqZ8gJ3OvmR50tInDV2jZ1DQgc3i550T5JDpToh dPBxZocIhzg+MBSRDXcJmHOx/7nQm3iQ6iLuwmXsRC6f5FbFefk9EjuTKcLMvBsEx+2DEx0E UnmJ4hVg7u1PQ+2Oy+Lh/opK/BDiqlQ8Pz2jiXv5xkECvr/3Sv59hlOCZMOaiLTTjtOIU7Tq 7ut6OL64oAq+zsFNBFXLn5EBEADn1959INH2cwYJv0tsxf5MUCghCj/CA/lc/LMthqQ773ga uB9mN+F1rE9cyyXb6jyOGn+GUjMbnq1o121Vm0+neKHUCBtHyseBfDXHA6m4B3mUTWo13nid 0e4AM71r0DS8+KYh6zvweLX/LL5kQS9GQeT+QNroXcC1NzWbitts6TZ+IrPOwT1hfB4WNC+X 2n4AzDqp3+ILiVST2DT4VBc11Gz6jijpC/KI5Al8ZDhRwG47LUiuQmt3yqrmN63V9wzaPhC+ xbwIsNZlLUvuRnmBPkTJwwrFRZvwu5GPHNndBjVpAfaSTOfppyKBTccu2AXJXWAE1Xjh6GOC 8mlFjZwLxWFqdPHR1n2aPVgoiTLk34LR/bXO+e0GpzFXT7enwyvFFFyAS0Nk1q/7EChPcbRb hJqEBpRNZemxmg55zC3GLvgLKd5A09MOM2BrMea+l0FUR+PuTenh2YmnmLRTro6eZ/qYwWkC u8FFIw4pT0OUDMyLgi+GI1aMpVogTZJ70FgV0pUAlpmrzk/bLbRkF3TwgucpyPtcpmQtTkWS gDS50QG9DR/1As3LLLcNkwJBZzBG6PWbvcOyrwMQUF1nl4SSPV0LLH63+BrrHasfJzxKXzqg rW28CTAE2x8qi7e/6M/+XXhrsMYG+uaViM7n2je3qKe7ofum3s4vq7oFCPsOgwARAQABwsFl BBgBAgAPBQJVy5+RAhsMBQkJZgGAAAoJEE3eEPcA/4NagOsP/jPoIBb/iXVbM+fmSHOjEshl KMwEl/m5iLj3iHnHPVLBUWrXPdS7iQijJA/VLxjnFknhaS60hkUNWexDMxVVP/6lbOrs4bDZ NEWDMktAeqJaFtxackPszlcpRVkAs6Msn9tu8hlvB517pyUgvuD7ZS9gGOMmYwFQDyytpepo YApVV00P0u3AaE0Cj/o71STqGJKZxcVhPaZ+LR+UCBZOyKfEyq+ZN311VpOJZ1IvTExf+S/5 lqnciDtbO3I4Wq0ArLX1gs1q1XlXLaVaA3yVqeC8E7kOchDNinD3hJS4OX0e1gdsx/e6COvy qNg5aL5n0Kl4fcVqM0LdIhsubVs4eiNCa5XMSYpXmVi3HAuFyg9dN+x8thSwI836FoMASwOl C7tHsTjnSGufB+D7F7ZBT61BffNBBIm1KdMxcxqLUVXpBQHHlGkbwI+3Ye+nE6HmZH7IwLwV W+Ajl7oYF+jeKaH4DZFtgLYGLtZ1LDwKPjX7VAsa4Yx7S5+EBAaZGxK510MjIx6SGrZWBrrV TEvdV00F2MnQoeXKzD7O4WFbL55hhyGgfWTHwZ457iN9SgYi1JLPqWkZB0JRXIEtjd4JEQcx +8Umfre0Xt4713VxMygW0PnQt5aSQdMD58jHFxTk092mU+yIHj5LeYgvwSgZN4airXk5yRXl SE+xAvmumFBY Organization: Red Hat GmbH Message-ID: Date: Fri, 23 Aug 2019 20:25:06 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.68]); Fri, 23 Aug 2019 18:25:10 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH v1 8/9] exec.c: Factor out core logic of check_watchpoint() X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Thomas Huth , Cornelia Huck , Eduardo Habkost , Aleksandar Rikalo , Riku Voipio , qemu-s390x@nongnu.org, Aleksandar Markovic , Paolo Bonzini , Aurelien Jarno , Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 23.08.19 18:09, Richard Henderson wrote: > On 8/23/19 4:27 AM, David Hildenbrand wrote: >> On 23.08.19 12:07, David Hildenbrand wrote: >>> We want to perform the same checks in probe_write() to trigger a cpu >>> exit before doing any modifications. We'll have to pass a PC. >>> >>> Signed-off-by: David Hildenbrand >>> --- >>> exec.c | 23 +++++++++++++++++------ >>> include/hw/core/cpu.h | 2 ++ >>> 2 files changed, 19 insertions(+), 6 deletions(-) >>> >>> diff --git a/exec.c b/exec.c >>> index 1df966d17a..d233a4250b 100644 >>> --- a/exec.c >>> +++ b/exec.c >>> @@ -2810,12 +2810,10 @@ static const MemoryRegionOps notdirty_mem_ops = { >>> }, >>> }; >>> >>> -/* Generate a debug exception if a watchpoint has been hit. */ >>> -static void check_watchpoint(int offset, int len, MemTxAttrs attrs, int flags) >>> +void cpu_check_watchpoint(CPUState *cpu, vaddr vaddr, int len, >>> + MemTxAttrs attrs, int flags, uintptr_t ra) >>> { >>> - CPUState *cpu = current_cpu; >>> CPUClass *cc = CPU_GET_CLASS(cpu); >>> - target_ulong vaddr; >>> CPUWatchpoint *wp; >>> >>> assert(tcg_enabled()); >>> @@ -2826,7 +2824,7 @@ static void check_watchpoint(int offset, int len, MemTxAttrs attrs, int flags) >>> cpu_interrupt(cpu, CPU_INTERRUPT_DEBUG); >>> return; >>> } >>> - vaddr = (cpu->mem_io_vaddr & TARGET_PAGE_MASK) + offset; >>> + >>> vaddr = cc->adjust_watchpoint_address(cpu, vaddr, len); >>> QTAILQ_FOREACH(wp, &cpu->watchpoints, entry) { >>> if (cpu_watchpoint_address_matches(wp, vaddr, len) >>> @@ -2851,11 +2849,14 @@ static void check_watchpoint(int offset, int len, MemTxAttrs attrs, int flags) >>> if (wp->flags & BP_STOP_BEFORE_ACCESS) { >>> cpu->exception_index = EXCP_DEBUG; >>> mmap_unlock(); >>> - cpu_loop_exit(cpu); >>> + cpu_loop_exit_restore(cpu, ra); >>> } else { >>> /* Force execution of one insn next time. */ >>> cpu->cflags_next_tb = 1 | curr_cflags(); >>> mmap_unlock(); >>> + if (ra) { >>> + cpu_restore_state(cpu, ra, true); >>> + } >>> cpu_loop_exit_noexc(cpu); >>> } >>> } >>> @@ -2865,6 +2866,16 @@ static void check_watchpoint(int offset, int len, MemTxAttrs attrs, int flags) >>> } >>> } >>> >>> +/* Generate a debug exception if a watchpoint has been hit. */ >>> +static void check_watchpoint(int offset, int len, MemTxAttrs attrs, int flags) >>> +{ >>> + CPUState *cpu = current_cpu; >>> + vaddr vaddr; >>> + >>> + vaddr = (cpu->mem_io_vaddr & TARGET_PAGE_MASK) + offset; >>> + cpu_check_watchpoint(cpu, vaddr, len, attrs, flags, 0); >>> +} >>> + >>> /* Watchpoint access routines. Watchpoints are inserted using TLB tricks, >>> so these check for a hit then pass through to the normal out-of-line >>> phys routines. */ >>> diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h >>> index 77fca95a40..3a2d76b32c 100644 >>> --- a/include/hw/core/cpu.h >>> +++ b/include/hw/core/cpu.h >>> @@ -1070,6 +1070,8 @@ static inline bool cpu_breakpoint_test(CPUState *cpu, vaddr pc, int mask) >>> return false; >>> } >>> >>> +void cpu_check_watchpoint(CPUState *cpu, vaddr vaddr, int len, >>> + MemTxAttrs attrs, int flags, uintptr_t ra); >>> int cpu_watchpoint_insert(CPUState *cpu, vaddr addr, vaddr len, >>> int flags, CPUWatchpoint **watchpoint); >>> int cpu_watchpoint_remove(CPUState *cpu, vaddr addr, >>> >> >> As we will have bigger accesses with probe_write(), we should do >> >> diff --git a/exec.c b/exec.c >> index d233a4250b..4f8cc62a5f 100644 >> --- a/exec.c >> +++ b/exec.c >> @@ -2834,7 +2834,7 @@ void cpu_check_watchpoint(CPUState *cpu, vaddr >> vaddr, int len, >> } else { >> wp->flags |= BP_WATCHPOINT_HIT_WRITE; >> } >> - wp->hitaddr = vaddr; >> + wp->hitaddr = MAX(vaddr, wp->vaddr); >> wp->hitattrs = attrs; >> if (!cpu->watchpoint_hit) { >> if (wp->flags & BP_CPU && >> >> I guess, to make sure we actually indicate the watchpoint. > > Yes, that looks right. > > As for your changes to use cpu_loop_exit_restore... Those are so right that I > didn't even recognize how wrong this code is when I was looking through it the > other day. Watchpoints must not actually be working at all at the moment, really. We keep finding surprises ... guess we payed the wrong area of QEMU src code a visit :) > > I suspect that we need to use a page flag for this and not use I/O memory at > all. Or convert to read/write_with_attrs and use magic MemTxResult values, but > that seems sketchier than page flags. Either way is the only way that we can > get access to the host return address so that we can unwind and return to the > main loop. I wonder if we can pass through the RA from the callers somehow. But I have to admit, how the whole MemOps (+MemTX) stuff is fits together is not yet 100% clear to me. > > But this is a good step, in the right direction. We'll fix the rest later. > > With the MAX, > Reviewed-by: Richard Henderson > Thanks! I'll fixup the smaller things and resend next week. I already have another set of patches (e.g., probe_read() and return void* from probe_write() lying around). The s390x part is still in the works. -- Thanks, David / dhildenb