[PATCH 0/3] aarch64: Update ld.so for vector abi

[rth at twiddle dot net]

From: Richard Henderson <richard.henderson@linaro.org>

There is a new calling convention defined for vectorized functions [1].

This is similar to what has happened for x86_64, where the original ABI
did not pass or preserve full vector contents, but then a new ABI is
defined that does.

There was an old patch for [BZ #15128] that saves full AdvSIMD registers
along _dl_runtime_resolve, but failed to do so for _dl_runtime_profile.
In the chatter for the BZ [2], Markus Shawcroft mentions that it should
save and restore d0-d7, which is indeed correct fro the original ABI.
It is not clear from the BZ why q0-q7 are saved instead.

That said, the new abi for AdvSIMD does use q0-q7.
When SVE is enabled, we need to save even more: z0-z7 plus p0-p3.

This fixes a number of minor issues with _dl_runtime_resolve itself,
and more major issues with _dl_runtime_profile before copying those
routines and making the modifications required for SVE.

I have *not* attempted to extend the <bits/link.h> interface for
the new ABI.  This should be done with more discussion on list.
I have instead simply saved and restored registers as the abi
requires, so that the actual callee gets the correct data.

I have lightly tested this under QEMU, in that the new sve paths
pass the same glibc tests as the old paths.


r~


[1] http://infocenter.arm.com/help/topic/com.arm.doc.ecm0665628/abi_sve_aapcs64_100986_0000_00_en.pdf
[2] https://sourceware.org/bugzilla/show_bug.cgi?id=15128#c11

Richard Henderson (3):
  aarch64: Clean up _dl_runtime_resolve
  aarch64: Clean up _dl_runtime_profile
  aarch64: Save and restore SVE registers in ld.so

 sysdeps/aarch64/dl-machine.h    |  13 +-
 sysdeps/aarch64/dl-trampoline.S | 531 +++++++++++++++++++++++++-------
 2 files changed, 438 insertions(+), 106 deletions(-)

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2.17.1