1481727 - elfhack corner case after bug 1423822

Status: RESOLVED FIXED

(Firefox Build System :: General, enhancement)

Comment 1

[Mike Hommey [:glandium]]

Attachment: Fix an elfhack corner case after bug 1423822

Bug 1423822 moved the injected code section before the .text section.
When linking with lld, the text section is usually page aligned, and
starting a PT_LOAD. We inject code at the beginning of the PT_LOAD,
which means the PT_LOAD is going to be extended at least a page
downwards. And it means the preceding PT_LOAD can't finish in that same
page, so the overhead of the injected code is needs to account for the
page alignment.

Comment 2

[Nathan Froyd [:froydnj]]

Comment on attachment 8998469 [details] [diff] [review]
Fix an elfhack corner case after bug 1423822

Review of attachment 8998469 [details] [diff] [review]:
-----------------------------------------------------------------

::: build/unix/elfhack/elfhack.cpp
@@ +1085,2 @@
>      size_t align = first_executable->getSegmentByType(PT_LOAD)->getAlign();
> +    size_t new_size = relhack->getSize() + relhackcode->getSize() + relhackcode->getAddr() & (align - 1);

This is a slightly odd expression for dealing with page alignment, but I'm not sure how to make it more clearer, short of expanding the comment quite a bit.

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/068870abe0cc
Fix an elfhack corner case after bug 1423822. r=froydnj

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/b353e89db751
Fix up for bug 1481727, because operator priorities are fucked up in C/C++. r=bustage on a CLOSED TREE

Comment 5

[Mike Hommey [:glandium]]

(In reply to Pulsebot from comment #4)
> Pushed by [e-mail]:
> https://hg.mozilla.org/integration/mozilla-inbound/rev/b353e89db751
> Fix up for bug 1481727, because operator priorities are fucked up in C/C++.
> r=bustage on a CLOSED TREE

Because who would expect a + b & c to mean (a + b) & c?

Comment 6

[Andreea Pavel [:apavel]]

https://hg.mozilla.org/mozilla-central/rev/068870abe0cc
https://hg.mozilla.org/mozilla-central/rev/b353e89db751