[PATCH] D133099: [LLD][COFF] Add load config checks to warn if incorrect for CFGuard

[Martin Storsjö via Phabricator via llvm-commits]

mstorsjo added a comment.

This looks like a good idea IMO! Especially the check for the basic condition that `_load_config_used` must exist if this flag is enabled; I was surprised to see that you don't get any diagnostics for this combination today.

Other than that, the rest of the checks are certainly useful when implementing these things. (I didn't check all the details of what is verified.) On the other hand, since LLD is quite focused on performance, LLD omits pedantic checks of all inputs where it's relevant for performance (i.e. it's considered ok to not handle corrupted inputs cleanly) - but these checks shouldn't really have any performance impact I think, so they could be considered fine in that aspect.



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Comment at: lld/COFF/Writer.cpp:2123
+  uint8_t *symBuf = secBuf + (b->getRVA() - sec->getRVA());
+  if (!isAligned(Align(config->is64() ? 8 : 4), b->getRVA()))
+    warn("'_load_config_used' may be misaligned (RVA is 0x" +
----------------
Do you think it would be worthwhile to check that the section chunk itself also has got the right alignment? Since even if the section doesn't flag the right required alignment, we can accidentally end up on a correctly aligned RVA anyway.


Repository:
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https://reviews.llvm.org/D133099