Now that linker_wrapper.o does not use objcopy --prefix-symbols=__dlwrap_
it can reference the _start symbol of the original binary without
colliding with its own __dlwrap__start symbol, which means
host_bionic_inject is no longer necessary.
Test: build and run host bionic binary
Change-Id: I1752efa39fa73a092fab039771bf59c99b7b5974
The only symbol that actually needs a prefix to avoid a collision is
_start, and that can be handled with a copy of begin.S that uses a
"#define" to rename _start to __dlwrap__start. Removing the prefixed
symbols will also allow simplifying the host bionic build process by
letting it directly reference the real _start.
Test: build and run host bionic binary
Change-Id: I50be786c16fe04b7f05c14ebfb74f710c7446ed9
This is use by Host Bionic to bootstrap into an embedded copy of the
linker by tweaking the AT_* values before calling in to the linker entry.
Similarly to 9729f35922, get the base
address from AT_PHDR, so that we're not relying on the relative offset
before relocation, which doesn't work with lld (at least with the
standard flags).
To find the offset to the linker code, we can still use an absolute
symbol created by extract_linker (which is currently hardcoded to 0x1000).
Instead of relying on something similar for the linker entry point,
we're now just reading the entry point from the linker's ELF header.
Then we get the address to the real _start function using
host_bionic_inject, which injects the value into a global variable after
the link step is finished. It also uses that opportunity to verify that
the linker is embedded as we expect it to be.
Bug: 31559095
Test: build with host bionic
Change-Id: I9d81ea77c51c079de06905da1ebe421fead1dc3b
The linux kernel requires that the ELF interpreter (runtime linker)
that's referenced by PT_INTERP be either an absolute path, or a relative
path from the current working directory. We'd prefer a relative path
from the binary, similarly to how we handle looking up shared libraries,
but that's not supported.
Instead, extract the LOAD segments from the runtime linker ELF binary
and embed them into each host bionic binary, omitting the PT_INTERP
declaration. The kernel will treat it as a static binary, and we'll use
a special entry point (linker_wrapper) to fix up the arguments passed by
the kernel before jumping to the embedded linker. From the linker's
point of view, it looks like the kernel loaded the linker like normal.
Bug: 31559095
Test: Enable host bionic, build and run libdemangle_test
Change-Id: I1753401ef91eecbf0ae3376faca31eec1c53842b
