gcc: backport a fix for out-of-line atomics on aarch64

(From OE-Core rev: ce99eb6b042cb36f5c07461fff7f49719550a955)

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

2 files changed, 67 insertions, 0 deletions

diff --git a/meta/recipes-devtools/gcc/gcc-10.1.inc b/meta/recipes-devtools/gcc/gcc-10.1.inc
index 5f310301b0..e8b0c61aae 100644
--- a/meta/recipes-devtools/gcc/gcc-10.1.inc
+++ b/meta/recipes-devtools/gcc/gcc-10.1.inc
@@ -70,6 +70,7 @@ SRC_URI = "\
            file://0002-aarch64-Introduce-SLS-mitigation-for-RET-and-BR-inst.patch \
            file://0003-aarch64-Mitigate-SLS-for-BLR-instruction.patch \
            file://pr96130.patch \
+           file://0001-aarch64-Fix-up-__aarch64_cas16_acq_rel-fallback.patch \
 "
 SRC_URI[sha256sum] = "b6898a23844b656f1b68691c5c012036c2e694ac4b53a8918d4712ad876e7ea2"
 
diff --git a/meta/recipes-devtools/gcc/gcc-10.1/0001-aarch64-Fix-up-__aarch64_cas16_acq_rel-fallback.patch b/meta/recipes-devtools/gcc/gcc-10.1/0001-aarch64-Fix-up-__aarch64_cas16_acq_rel-fallback.patch
new file mode 100644
index 0000000000..c060accd99
--- /dev/null
+++ b/meta/recipes-devtools/gcc/gcc-10.1/0001-aarch64-Fix-up-__aarch64_cas16_acq_rel-fallback.patch
@@ -0,0 +1,66 @@
+Upstream-Status: Backport
+Signed-off-by: Ross Burton <ross.burton@arm.com>
+
+From fd2ec4542fd2975e6d3f2f1c1a2639945a84f9e1 Mon Sep 17 00:00:00 2001
+From: Jakub Jelinek <jakub@redhat.com>
+Date: Mon, 3 Aug 2020 22:55:28 +0200
+Subject: [PATCH] aarch64: Fix up __aarch64_cas16_acq_rel fallback
+
+As mentioned in the PR, the fallback path when LSE is unavailable writes
+incorrect registers to the memory if the previous content compares equal
+to x0, x1 - it writes copy of x0, x1 from the start of function, but it
+should write x2, x3.
+
+2020-08-03  Jakub Jelinek  <jakub@redhat.com>
+
+        PR target/96402
+        * config/aarch64/lse.S (__aarch64_cas16_acq_rel): Use x2, x3 instead
+        of x(tmp0), x(tmp1) in STXP arguments.
+
+        * gcc.target/aarch64/pr96402.c: New test.
+
+(cherry picked from commit 90b43856fdff7d96d93d22970eca8a86c56e0ddc)
+---
+ gcc/testsuite/gcc.target/aarch64/pr96402.c | 16 ++++++++++++++++
+ libgcc/config/aarch64/lse.S                |  2 +-
+ 2 files changed, 17 insertions(+), 1 deletion(-)
+ create mode 100644 gcc/testsuite/gcc.target/aarch64/pr96402.c
+
+diff --git a/gcc/testsuite/gcc.target/aarch64/pr96402.c b/gcc/testsuite/gcc.target/aarch64/pr96402.c
+new file mode 100644
+index 00000000000..fa2dddfac15
+--- /dev/null
++++ b/gcc/testsuite/gcc.target/aarch64/pr96402.c
+@@ -0,0 +1,16 @@
++/* PR target/96402 */
++/* { dg-do run { target int128 } } */
++/* { dg-options "-moutline-atomics" } */
++
++int
++main ()
++{
++  __int128 a = 0;
++  __sync_val_compare_and_swap (&a, (__int128) 0, (__int128) 1);
++  if (a != 1)
++    __builtin_abort ();
++  __sync_val_compare_and_swap (&a, (__int128) 1, (((__int128) 0xdeadbeeffeedbac1ULL) << 64) | 0xabadcafe00c0ffeeULL);
++  if (a != ((((__int128) 0xdeadbeeffeedbac1ULL) << 64) | 0xabadcafe00c0ffeeULL))
++    __builtin_abort ();
++  return 0;
++}
+diff --git a/libgcc/config/aarch64/lse.S b/libgcc/config/aarch64/lse.S
+index 64691c601c1..c8fbfbce4fd 100644
+--- a/libgcc/config/aarch64/lse.S
++++ b/libgcc/config/aarch64/lse.S
+@@ -203,7 +203,7 @@ STARTFN     NAME(cas)
+        cmp             x0, x(tmp0)
+        ccmp            x1, x(tmp1), #0, eq
+        bne             1f
+-       STXP            w(tmp2), x(tmp0), x(tmp1), [x4]
++       STXP            w(tmp2), x2, x3, [x4]
+        cbnz            w(tmp2), 0b
+ 1:     ret
+ 
+-- 
+2.26.2
+