Add -mstack-protector-guard= to x86 compilers

To choose between "global" (default) and "tls" (new)
for -fstack-protector, -fstack-protector-all, and
-fstack-protector-strong (GCC 4.6+).

Note that this alone doesn't enable any -fstack-protector*

For NDK: The default "global" generates code backward
compatible with older bionic

For AOSP: build may add "-mstack-protector-guard=tls" to
build platform code with new bionic (*1)

Related CL:
  https://android-review.googlesource.com/#/c/45416 (*1)
  https://android-review.googlesource.com/#/c/45784

Change-Id: Iedf5b7ae5148572db2e35f0add93bc3d13511304

4 files changed, 33 insertions, 3 deletions

diff --git a/gcc-4.4.3/gcc/config/i386/i386.c b/gcc-4.4.3/gcc/config/i386/i386.c
index 31ce38a58..2ca822040 100644
--- a/gcc-4.4.3/gcc/config/i386/i386.c
+++ b/gcc-4.4.3/gcc/config/i386/i386.c
@@ -1810,6 +1810,9 @@ extern int ix86_force_align_arg_pointer;
 static const char ix86_force_align_arg_pointer_string[]
   = "force_align_arg_pointer";
 
+/* Stack protector option.  */
+enum stack_protector_guard ix86_stack_protector_guard;
+
 static rtx (*ix86_gen_leave) (void);
 static rtx (*ix86_gen_pop1) (rtx);
 static rtx (*ix86_gen_add3) (rtx, rtx, rtx);
@@ -3435,6 +3438,22 @@ override_options (bool main_args_p)
       flag_stack_check = 0;
       target_flags |= MASK_STACK_PROBE;
     }
+
+  /* Handle stack protector */
+  if (ix86_stack_protector_guard_string != 0)
+    {
+      if (!strcmp (ix86_stack_protector_guard_string, "tls"))
+	ix86_stack_protector_guard = SSP_TLS;
+      else if (!strcmp (ix86_stack_protector_guard_string, "global"))
+	ix86_stack_protector_guard = SSP_GLOBAL;
+      else
+	error ("bad value (%s) for %sstack-protector-guard=%s %s",
+	       ix86_stack_protector_guard, prefix, suffix, sw);
+    }
+  else
+    {
+      ix86_stack_protector_guard = TARGET_HAS_BIONIC? SSP_GLOBAL : SSP_TLS;
+    }
 }
 
 /* Update register usage after having seen the compiler flags.  */
diff --git a/gcc-4.4.3/gcc/config/i386/i386.h b/gcc-4.4.3/gcc/config/i386/i386.h
index d7cb8ac3c..d611fe632 100644
--- a/gcc-4.4.3/gcc/config/i386/i386.h
+++ b/gcc-4.4.3/gcc/config/i386/i386.h
@@ -2517,6 +2517,13 @@ struct machine_function GTY(())
 #undef TARG_COND_NOT_TAKEN_BRANCH_COST
 #define TARG_COND_NOT_TAKEN_BRANCH_COST ix86_cost->cond_not_taken_branch_cost
 
+enum stack_protector_guard {
+  SSP_TLS,      /* per-thread canary at %gs:20 */
+  SSP_GLOBAL,   /* global canary */
+};
+
+extern enum stack_protector_guard ix86_stack_protector_guard;
+
 /*
 Local variables:
 version-control: t
diff --git a/gcc-4.4.3/gcc/config/i386/i386.md b/gcc-4.4.3/gcc/config/i386/i386.md
index 7989c31db..a1d7bcba2 100644
--- a/gcc-4.4.3/gcc/config/i386/i386.md
+++ b/gcc-4.4.3/gcc/config/i386/i386.md
@@ -21926,7 +21926,7 @@
 (define_expand "stack_protect_set"
   [(match_operand 0 "memory_operand" "")
    (match_operand 1 "memory_operand" "")]
-  ""
+  "ix86_stack_protector_guard == SSP_TLS"
 {
 #ifdef TARGET_THREAD_SSP_OFFSET
   if (TARGET_64BIT)
@@ -21949,7 +21949,7 @@
 	(unspec:SI [(match_operand:SI 1 "memory_operand" "m")] UNSPEC_SP_SET))
    (set (match_scratch:SI 2 "=&r") (const_int 0))
    (clobber (reg:CC FLAGS_REG))]
-  ""
+  "ix86_stack_protector_guard == SSP_TLS"
   "mov{l}\t{%1, %2|%2, %1}\;mov{l}\t{%2, %0|%0, %2}\;xor{l}\t%2, %2"
   [(set_attr "type" "multi")])
 
@@ -21992,7 +21992,7 @@
   [(match_operand 0 "memory_operand" "")
    (match_operand 1 "memory_operand" "")
    (match_operand 2 "" "")]
-  ""
+  "ix86_stack_protector_guard == SSP_TLS"
 {
   rtx flags = gen_rtx_REG (CCZmode, FLAGS_REG);
   ix86_compare_op0 = operands[0];
diff --git a/gcc-4.4.3/gcc/config/i386/i386.opt b/gcc-4.4.3/gcc/config/i386/i386.opt
index c2562e48d..880fc98ca 100644
--- a/gcc-4.4.3/gcc/config/i386/i386.opt
+++ b/gcc-4.4.3/gcc/config/i386/i386.opt
@@ -362,3 +362,7 @@ Support PCLMUL built-in functions and code generation
 msse2avx
 Target Report Var(ix86_sse2avx)
 Encode SSE instructions with VEX prefix
+
+mstack-protector-guard=
+Target RejectNegative Joined Var(ix86_stack_protector_guard_string)
+Use given stack-protector guard