From patchwork Thu Sep 16 14:03:20 2010
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Subject: Fix libffi x86-64 < 8 bytes last stack argument issue (PR
 libffi/45677)
Date: Thu, 16 Sep 2010 04:03:20 -0000
From: Jakub Jelinek <jakub@redhat.com>
X-Patchwork-Id: 64977
Message-Id: <20100916140320.GR1269@tyan-ft48-01.lab.bos.redhat.com>
To: Anthony Green <green@redhat.com>, Tom Tromey <tromey@redhat.com>
Cc: gcc-patches@gcc.gnu.org

Hi!

GCC assumes the callee owns the whole stack slot word instead of just
the first 8/16/32 bits of it when the last argument is 8/16/32 bit.
unix64.S puts a saved copy of flags right after the last byte of the
arguments block, so when it was not a multiple of 8 bytes, GCC could happily
clobber the saved copy of flags after it.
Fixed thusly, tested on x86_64-linux, ok to commit?

2010-09-16  Jakub Jelinek  <jakub@redhat.com>

	PR libffi/45677
	* src/x86/ffi64.c (ffi_prep_cif_machdep): Ensure cif->bytes is
	a multiple of 8.
	* testsuite/libffi.call/many2.c: New test.


	Jakub


--- libffi/src/x86/ffi64.c.jj	2010-08-11 21:08:14.000000000 +0200
+++ libffi/src/x86/ffi64.c	2010-09-16 15:34:57.000000000 +0200
@@ -378,7 +378,7 @@ ffi_prep_cif_machdep (ffi_cif *cif)
 	  if (align < 8)
 	    align = 8;
 
-	  bytes = ALIGN(bytes, align);
+	  bytes = ALIGN (bytes, align);
 	  bytes += cif->arg_types[i]->size;
 	}
       else
@@ -390,7 +390,7 @@ ffi_prep_cif_machdep (ffi_cif *cif)
   if (ssecount)
     flags |= 1 << 11;
   cif->flags = flags;
-  cif->bytes = bytes;
+  cif->bytes = ALIGN (bytes, 8);
 
   return FFI_OK;
 }
--- libffi/testsuite/libffi.call/many2.c.jj	2010-09-16 15:01:08.000000000 +0200
+++ libffi/testsuite/libffi.call/many2.c	2010-09-16 15:28:57.000000000 +0200
@@ -0,0 +1,54 @@
+/* Area:        ffi_call
+   Purpose:     Check uint8_t arguments.
+   Limitations: none.
+   PR:          PR45677.
+   Originator:  Dan Witte <dwitte@gmail.com> 20100916  */
+
+/* { dg-do run } */
+
+#include "ffitest.h"
+
+#define NARGS 7
+
+typedef unsigned char u8;
+
+__attribute__((noinline)) uint8_t
+foo (uint8_t a, uint8_t b, uint8_t c, uint8_t d,
+     uint8_t e, uint8_t f, uint8_t g)
+{
+  return a + b + c + d + e + f + g;
+}
+
+uint8_t
+bar (uint8_t a, uint8_t b, uint8_t c, uint8_t d,
+     uint8_t e, uint8_t f, uint8_t g)
+{
+  return foo (a, b, c, d, e, f, g);
+}
+
+int
+main (void)
+{
+  ffi_type *ffitypes[NARGS];
+  int i;
+  ffi_cif cif;
+  ffi_arg result = 0;
+  uint8_t args[NARGS];
+  void *argptrs[NARGS];
+
+  for (i = 0; i < NARGS; ++i)
+    ffitypes[i] = &ffi_type_uint8;
+
+  CHECK (ffi_prep_cif (&cif, FFI_DEFAULT_ABI, NARGS,
+		       &ffi_type_uint8, ffitypes) == FFI_OK);
+
+  for (i = 0; i < NARGS; ++i)
+    {
+      args[i] = i;
+      argptrs[i] = &args[i];
+    }
+  ffi_call (&cif, FFI_FN (bar), &result, argptrs);
+
+  CHECK (result == 21);
+  return 0;
+}