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Bug 1481727 - Fix an elfhack corner case after bug 1423822. r=froydnj

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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.
This commit is contained in:
Mike Hommey
2018-08-08 17:37:17 +09:00
parent bf099f3123
commit 33ed0cd9df
1 changed files with 4 additions and 1 deletions
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5
build/unix/elfhack/elfhack.cpp
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@@ -1079,8 +1079,11 @@ int do_relocation_section(Elf *elf, unsigned int rel_type, unsigned int rel_type
relhackcode->insertBefore(first_executable);
// Don't try further if we can't gain from the relocation section size change.
// We account for the fact we're going to split the PT_LOAD before the injected
// code section, so the overhead of the page alignment for section needs to be
// accounted for.
size_t align = first_executable->getSegmentByType(PT_LOAD)->getAlign();
size_t new_size = relhack->getSize() + relhackcode->getSize();
size_t new_size = relhack->getSize() + relhackcode->getSize() + relhackcode->getAddr() & (align - 1);
if (!force && (new_size >= old_size || old_size - new_size < align)) {
fprintf(stderr, "No gain. Skipping\n");
return -1;