1 files changed, 74 insertions, 0 deletions
diff --git a/dev-libs/libffi/files/libffi-3.2.1-ia64-small-struct.patch b/dev-libs/libffi/files/libffi-3.2.1-ia64-small-struct.patch
new file mode 100644
index 000000000000..6e21f3566bc9
--- /dev/null
+++ b/dev-libs/libffi/files/libffi-3.2.1-ia64-small-struct.patch
@@ -0,0 +1,74 @@
+From b58caef7fd620408be9239ac24ea89d5bc84f30b Mon Sep 17 00:00:00 2001
+From: Sergei Trofimovich <slyfox@gentoo.org>
+Date: Sat, 17 Feb 2018 19:00:40 +0000
+Subject: [PATCH 2/2] ia64: fix small struct return
+
+This change fixes libffi.call/struct10.c failure on ia64:
+FAIL: libffi.call/struct10.c -W -Wall -Wno-psabi -O0 execution test
+
+.Lst_small_struct handles returns for structs less than 32 bytes
+(following ia64 return value ABI [1]). Subroutine does roughly the
+following:
+
+```
+    mov [sp+0]  = r8
+    mov [sp+8]  = r9
+    mov [sp+16] = r10
+    mov [sp+24] = r11
+    memcpy(destination, source=sp, 12);
+```
+
+The problem: ia64 ABI guarantees that top 16 bytes of stack are
+scratch space for callee function. Thus it can clobber it. [1]
+says (7.1 Procedure Frames):
+"""
+* Scratch area. This 16-byte region is provided as scratch storage
+  for procedures that are called by the current procedure. Leaf
+  procedures do not need to allocate this region. A procedure may
+  use the 16 bytes at the top of its own frame as scratch memory,
+  but the contents of this area are not preserved by a procedure call.
+"""
+
+In our case 16 top bytes are clobbered by a PLT resolver when memcpy()
+is called for the first time. As a result memcpy implementation reads
+already clobbered data frop top of stack.
+
+The fix is simple: allocate 16 bytes of scrats space prior to memcpy()
+call.
+
+[1]: https://www.intel.com/content/dam/www/public/us/en/documents/guides/itanium-software-runtime-architecture-guide.pdf
+
+Bug: https://bugs.gentoo.org/634190
+Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
+---
+ src/ia64/unix.S | 7 ++++++-
+ 1 file changed, 6 insertions(+), 1 deletion(-)
+
+diff --git a/src/ia64/unix.S b/src/ia64/unix.S
+index 4733377..e2547e0 100644
+--- a/src/ia64/unix.S
++++ b/src/ia64/unix.S
+@@ -175,7 +175,6 @@ ffi_call_unix:
+ 	;;
+ 
+ .Lst_small_struct:
+-	add	sp = -16, sp
+ 	cmp.lt	p6, p0 = 8, in3
+ 	cmp.lt	p7, p0 = 16, in3
+ 	cmp.lt	p8, p0 = 24, in3
+@@ -191,6 +190,12 @@ ffi_call_unix:
+ (p8)	st8	[r18] = r11
+ 	mov	out1 = sp
+ 	mov	out2 = in3
++	;;
++	// ia64 software calling convention requires
++	// top 16 bytes of stack to be scratch space
++	// PLT resolver uses that scratch space at
++	// 'memcpy' symbol reolution time
++	add	sp = -16, sp
+ 	br.call.sptk.many b0 = memcpy#
+ 	;;
+ 	mov	ar.pfs = loc0
+-- 
+2.16.1
+