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| | 'Retpoline' mitigation technique for Spectre (branch target injection)
[CVE-2017-5715]:
https://security.googleblog.com/2018/01/more-details-about-mitigations-for-cpu_4.html
https://support.google.com/faqs/answer/7625886
https://spectreattack.com/
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-5715
Patch copied from the 'retpoline-regnames' branch of upstream source repository
(please keep an eye for new branches or updates for existing branches):
http://git.infradead.org/users/dwmw2/gcc-retpoline.git
From ca658cd57c02a81327ec09474e24f0688ac1a190 Mon Sep 17 00:00:00 2001
From: hjl <hjl@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Mon, 6 Nov 2017 23:04:15 +0000
Subject: [PATCH 02/10] i386: Use reference of struct ix86_frame to avoid copy
When there is no need to make a copy of ix86_frame, we can use reference
of struct ix86_frame to avoid copy.
Tested on x86-64.
Backport from mainline
* config/i386/i386.c (ix86_can_use_return_insn_p): Use reference
of struct ix86_frame.
(ix86_initial_elimination_offset): Likewise.
(ix86_expand_split_stack_prologue): Likewise.
---
gcc/config/i386/i386.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 813337242d8..397ef7cac26 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -11843,8 +11843,6 @@ symbolic_reference_mentioned_p (rtx op)
bool
ix86_can_use_return_insn_p (void)
{
- struct ix86_frame frame;
-
/* Don't use `ret' instruction in interrupt handler. */
if (! reload_completed
|| frame_pointer_needed
@@ -11857,7 +11855,7 @@ ix86_can_use_return_insn_p (void)
return 0;
ix86_compute_frame_layout ();
- frame = cfun->machine->frame;
+ struct ix86_frame &frame = cfun->machine->frame;
return (frame.stack_pointer_offset == UNITS_PER_WORD
&& (frame.nregs + frame.nsseregs) == 0);
}
@@ -12344,7 +12342,7 @@ HOST_WIDE_INT
ix86_initial_elimination_offset (int from, int to)
{
ix86_compute_frame_layout ();
- struct ix86_frame frame = cfun->machine->frame;
+ struct ix86_frame &frame = cfun->machine->frame;
if (from == ARG_POINTER_REGNUM && to == HARD_FRAME_POINTER_REGNUM)
return frame.hard_frame_pointer_offset;
@@ -14860,7 +14858,6 @@ static GTY(()) rtx split_stack_fn_large;
void
ix86_expand_split_stack_prologue (void)
{
- struct ix86_frame frame;
HOST_WIDE_INT allocate;
unsigned HOST_WIDE_INT args_size;
rtx_code_label *label;
@@ -14873,7 +14870,7 @@ ix86_expand_split_stack_prologue (void)
ix86_finalize_stack_realign_flags ();
ix86_compute_frame_layout ();
- frame = cfun->machine->frame;
+ struct ix86_frame &frame = cfun->machine->frame;
allocate = frame.stack_pointer_offset - INCOMING_FRAME_SP_OFFSET;
/* This is the label we will branch to if we have enough stack
--
2.15.1
|