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Re: [Qemu-devel] [PATCH 4/6] exec: Factor out cpu_watchpoint_address_mat
From: |
Richard Henderson |
Subject: |
Re: [Qemu-devel] [PATCH 4/6] exec: Factor out cpu_watchpoint_address_matches |
Date: |
Wed, 28 Aug 2019 14:28:32 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 |
On 8/26/19 1:41 AM, David Hildenbrand wrote:
>> - /* Make accesses to pages with watchpoints go via the
>> - watchpoint trap routines. */
>> - QTAILQ_FOREACH(wp, &cpu->watchpoints, entry) {
>> - if (cpu_watchpoint_address_matches(wp, vaddr, TARGET_PAGE_SIZE)) {
>> - /* Avoid trapping reads of pages with a write breakpoint. */
>> - if ((prot & PAGE_WRITE) || (wp->flags & BP_MEM_READ)) {
>> - iotlb = PHYS_SECTION_WATCH + paddr;
>> - *address |= TLB_MMIO;
>> - break;
> In the old code, we were able to break once we found a hit ...
>
>> - }
>> - }
>> + /* Avoid trapping reads of pages with a write breakpoint. */
>> + match = (prot & PAGE_READ ? BP_MEM_READ : 0)
>> + | (prot & PAGE_WRITE ? BP_MEM_WRITE : 0);
>> + flags = cpu_watchpoint_address_matches(cpu, vaddr, TARGET_PAGE_SIZE);
>> + if (flags & match) {
> ... now you cannot break early anymore. Maybe pass in the match to
> cpu_watchpoint_address_matches() ?
Hmm, yes, perhaps.
OTOH, summing a bitmask is a very quick operation. Depending on the total
number of watchpoints, of course...
r~
- [Qemu-devel] [PATCH 0/6] exec: Cleanup watchpoints, Richard Henderson, 2019/08/24
- [Qemu-devel] [PATCH 3/6] cputlb: Fold TLB_RECHECK into TLB_INVALID_MASK, Richard Henderson, 2019/08/24
- [Qemu-devel] [PATCH 5/6] cputlb: Handle watchpoints via TLB_WATCHPOINT, Richard Henderson, 2019/08/24
- [Qemu-devel] [PATCH 6/6] tcg: Check for watchpoints in probe_write(), Richard Henderson, 2019/08/24
- Re: [Qemu-devel] [PATCH 0/6] exec: Cleanup watchpoints, Richard Henderson, 2019/08/28