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Re: libsanitizer merge from upstream r175042
On Thu, Feb 14, 2013 at 03:55:47PM +0400, Konstantin Serebryany wrote:
> The patch seems to work on a simple test. Let me digest it.
> I am trying to understand if there are problems with it other than the
> added complexity (which is what I don't like the most).
Yes, it is some added complexity, but not too much, and something that can
be tested regularly that it works.
> -Wl,-Ttext-segment=0x3600000000 does not work with binutils-gold.
> gold understands -Wl,-Ttext=0x3600000000, but bfd ld doesn't.
> Do you know any flag supported by both?
-Wl,-Ttext is unfortunately something different, at least for
the bfd linker. -Ttext-segment aligns the base of the whole shared library,
if you look at start of the linker script for -shared:
/* Read-only sections, merged into text segment: */
. = SEGMENT_START("text-segment", 0) + SIZEOF_HEADERS;
.note.gnu.build-id : { *(.note.gnu.build-id) }
.hash : { *(.hash) }
.gnu.hash : { *(.gnu.hash) }
.dynsym : { *(.dynsym) }
.dynstr : { *(.dynstr) }
.gnu.version : { *(.gnu.version) }
.gnu.version_d : { *(.gnu.version_d) }
.gnu.version_r : { *(.gnu.version_r) }
...
.rela.plt :
{
*(.rela.plt)
*(.rela.iplt)
}
.init :
{
KEEP (*(.init))
}
.plt : { *(.plt) *(.iplt) }
.text :
{
*(.text.unlikely .text.*_unlikely)
*(.text.exit .text.exit.*)
-Ttext-segment chooses the base at which ELF headers will reside.
-Ttext aligns the .text section's start to that, so most likely the shared
library won't even link, because .init section will be many GBs appart from
.text section.
CCing Ian, if gold has any way to do something similar.
As I said, the alternative is to link the library normally, and run
prelink -r 0x3600000000 libtest.so on the shared library afterwards if prelink is
installed, and make sure you install it on your linux/x86-64 test boxes.
Jakub