Faster gdb memory access #380
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Instead of remapping the page to allow the kernel to access a process' memory, simply set the SUM bit. This makes it no longer an error for the kernel to access userspace. Keep setting the `W` bit when we poke, to allow for updating program memory with breakpoints. Signed-off-by: Sean Cross <sean@xobs.io>
Instead of always doing bytewise accesses, support 2- and 4-byte access. Additionally, recognize when multiple 4-byte reads are required. Note that an additional optimization may be made here in the future to prevent having to check every address, but this is left for a future optimization. Signed-off-by: Sean Cross <sean@xobs.io>
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It seems to be faster, and it's rock solid! Set a break point, stepped for 20-30 instructions....set the breakpoint again, called the server, saw the system break there, continued another few times, did register dumps, thread info, etc. Great work! |
bunnie
approved these changes
May 12, 2023
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Great! Was this with or without no-ack? I'm curious if this doesn't fix no-ack mode as well. |
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This is the command line I used to test: |
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This improves GDB memory access times by coalescing 2-, 4-, and multi-byte reads and writes. This should improve access times considerably.
This is done through two methods:
This should improve memory access speeds considerably. Would you mind trying this on real hardware?