forked from OSchip/llvm-project
88fdce5be6
Addresses on AArch64 can have top byte tags, memory tags and pointer authentication signatures in the upper bits. While testing memory tagging I found that memory read couldn't read a range if the two addresses had different tags. The same could apply to signed pointers given the right circumstance. (lldb) memory read mte_buf_alt_tag mte_buf+16 error: end address (0x900fffff7ff8010) must be greater than the start address (0xa00fffff7ff8000). Or it would try to read a lot more memory than expected. (lldb) memory read mte_buf mte_buf_alt_tag+16 error: Normally, 'memory read' will not read over 1024 bytes of data. error: Please use --force to override this restriction just once. error: or set target.max-memory-read-size if you will often need a larger limit. Fix this by removing non address bits before we calculate the read range. A test is added for AArch64 Linux that confirms this by using the top byte ignore feature. This means that if you do read with a tagged pointer the output does not include those tags. This is potentially confusing but I think overall it's better that we don't pretend that we're reading memory from a range that the process is unable to map. (lldb) p ptr1 (char *) $4 = 0x3400fffffffff140 "\x80\xf1\xff\xff\xff\xff" (lldb) p ptr2 (char *) $5 = 0x5600fffffffff140 "\x80\xf1\xff\xff\xff\xff" (lldb) memory read ptr1 ptr2+16 0xfffffffff140: 80 f1 ff ff ff ff 00 00 38 70 bc f7 ff ff 00 00 ........8p...... Reviewed By: omjavaid, danielkiss Differential Revision: https://reviews.llvm.org/D103626 |
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