File stack-protect-kernel.patch of Package gcc41

2006-07-27  Arjan van de Ven <arjan@linux.intel.com>
 
 	* config/i386/i386.md (stack_tls_protect_set_di) Use %gs rather than
 	%fs for -mcmodel=kernel.
 	(stack_tls_protect_test_di): Likewise.
 
 	* gcc.target/i386/stack-prot-kernel.c: New test.
 
Index: gcc/config/i386/i386.md
===================================================================
--- gcc/config/i386/i386.md.orig	2009-11-20 13:41:13.000000000 +0100
+++ gcc/config/i386/i386.md	2009-11-20 13:42:16.000000000 +0100
@@ -20709,7 +20709,15 @@
    (set (match_scratch:DI 2 "=&r") (const_int 0))
    (clobber (reg:CC FLAGS_REG))]
   "TARGET_64BIT"
-  "mov{q}\t{%%fs:%P1, %2|%2, QWORD PTR %%fs:%P1}\;mov{q}\t{%2, %0|%0, %2}\;xor{l}\t%k2, %k2"
+  {
+     /* The kernel uses a different segment register for performance reasons; a
+        system call would not have to trash the userspace segment register,
+        which would be expensive */
+     if (ix86_cmodel != CM_KERNEL)
+        return "mov{q}\t{%%fs:%P1, %2|%2, QWORD PTR %%fs:%P1}\;mov{q}\t{%2, %0|%0, %2}\;xor{l}\t%k2, %k2";
+     else
+        return "mov{q}\t{%%gs:%P1, %2|%2, QWORD PTR %%gs:%P1}\;mov{q}\t{%2, %0|%0, %2}\;xor{l}\t%k2, %k2";
+  }
   [(set_attr "type" "multi")])
 
 (define_expand "stack_protect_test"
@@ -20777,7 +20785,15 @@
 		    UNSPEC_SP_TLS_TEST))
    (clobber (match_scratch:DI 3 "=r"))]
   "TARGET_64BIT"
-  "mov{q}\t{%1, %3|%3, %1}\;xor{q}\t{%%fs:%P2, %3|%3, QWORD PTR %%fs:%P2}"
+  {
+     /* The kernel uses a different segment register for performance reasons; a
+        system call would not have to trash the userspace segment register,
+        which would be expensive */
+     if (ix86_cmodel != CM_KERNEL)
+        return "mov{q}\t{%1, %3|%3, %1}\;xor{q}\t{%%fs:%P2, %3|%3, QWORD PTR %%fs:%P2}";
+     else
+        return "mov{q}\t{%1, %3|%3, %1}\;xor{q}\t{%%gs:%P2, %3|%3, QWORD PTR %%gs:%P2}";
+  }
   [(set_attr "type" "multi")])
 
 (include "sse.md")
Index: gcc/testsuite/gcc.target/i386/stack-prot-kernel.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ gcc/testsuite/gcc.target/i386/stack-prot-kernel.c	2009-11-20 13:42:16.000000000 +0100
@@ -0,0 +1,12 @@
+/* { dg-do compile { target lp64 } } */
+/* { dg-options "-O2 -fstack-protector-all -mcmodel=kernel" } */
+
+void test1 (int x)
+{
+  char p[40];
+  int i;
+  for (i=0; i<40; i++)
+	p[i] = x;
+}
+
+/* { dg-final { scan-assembler-not "%fs" } } */