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, 4 deletions

diff --git a/gcc-4.6/gcc/config/i386/i386.c b/gcc-4.6/gcc/config/i386/i386.c
index b99d31150..6e7eb6183 100644
--- a/gcc-4.6/gcc/config/i386/i386.c
+++ b/gcc-4.6/gcc/config/i386/i386.c
@@ -2369,6 +2369,9 @@ static int ix86_regparm;
 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_add3) (rtx, rtx, rtx);
 static rtx (*ix86_gen_sub3) (rtx, rtx, rtx);
@@ -4360,6 +4363,22 @@ ix86_option_override_internal (bool main_args_p)
 	}
       free (token);
     }
+
+  /* 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;
+    }
 }
 
 /* Return TRUE if VAL is passed in register with 256bit AVX modes.  */
diff --git a/gcc-4.6/gcc/config/i386/i386.h b/gcc-4.6/gcc/config/i386/i386.h
index 678071f27..d7714f7e4 100644
--- a/gcc-4.6/gcc/config/i386/i386.h
+++ b/gcc-4.6/gcc/config/i386/i386.h
@@ -2378,6 +2378,12 @@ extern void debug_dispatch_window (int);
 #define CLZ_DEFINED_VALUE_AT_ZERO(MODE, VALUE) \
 	((VALUE) = GET_MODE_BITSIZE (MODE), TARGET_BMI)
 
+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:
diff --git a/gcc-4.6/gcc/config/i386/i386.md b/gcc-4.6/gcc/config/i386/i386.md
index b1d7e5eba..dcc2a21b2 100644
--- a/gcc-4.6/gcc/config/i386/i386.md
+++ b/gcc-4.6/gcc/config/i386/i386.md
@@ -17955,7 +17955,7 @@
 (define_expand "stack_protect_set"
   [(match_operand 0 "memory_operand" "")
    (match_operand 1 "memory_operand" "")]
-  ""
+  "ix86_stack_protector_guard == SSP_TLS"
 {
   rtx (*insn)(rtx, rtx);
 
@@ -17979,7 +17979,7 @@
 	(unspec:P [(match_operand:P 1 "memory_operand" "m")] UNSPEC_SP_SET))
    (set (match_scratch:P 2 "=&r") (const_int 0))
    (clobber (reg:CC FLAGS_REG))]
-  ""
+  "ix86_stack_protector_guard == SSP_TLS"
   "mov{<imodesuffix>}\t{%1, %2|%2, %1}\;mov{<imodesuffix>}\t{%2, %0|%0, %2}\;xor{l}\t%k2, %k2"
   [(set_attr "type" "multi")])
 
@@ -17997,7 +17997,7 @@
   [(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);
 
@@ -18027,7 +18027,7 @@
 		     (match_operand:P 2 "memory_operand" "m")]
 		    UNSPEC_SP_TEST))
    (clobber (match_scratch:P 3 "=&r"))]
-  ""
+  "ix86_stack_protector_guard == SSP_TLS"
   "mov{<imodesuffix>}\t{%1, %3|%3, %1}\;xor{<imodesuffix>}\t{%2, %3|%3, %2}"
   [(set_attr "type" "multi")])
 
diff --git a/gcc-4.6/gcc/config/i386/i386.opt b/gcc-4.6/gcc/config/i386/i386.opt
index 9deba3e01..3f0e3f718 100644
--- a/gcc-4.6/gcc/config/i386/i386.opt
+++ b/gcc-4.6/gcc/config/i386/i386.opt
@@ -435,3 +435,7 @@ Split 32-byte AVX unaligned load
 mavx256-split-unaligned-store
 Target Report Mask(AVX256_SPLIT_UNALIGNED_STORE) Save
 Split 32-byte AVX unaligned store
+
+mstack-protector-guard=
+Target RejectNegative Joined Var(ix86_stack_protector_guard_string)
+Use given stack-protector guard