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RE: [PATCH][GCC][AArch64] Validate and set default parameters for stack-clash. [Patch (3/3)]


Hi All,

This is an updated patch which applies the same style changes as requested in patch 5/6.

Ok for trunk?

Thanks,
Tamar

gcc/
2018-08-07  Tamar Christina  <tamar.christina@arm.com>

	* common/config/aarch64/aarch64-common.c (TARGET_OPTION_DEFAULT_PARAM,
	aarch64_option_default_param):	New.
	(params.h): Include.
	(TARGET_OPTION_VALIDATE_PARAM, aarch64_option_validate_param): New.
	* config/aarch64/aarch64.c (aarch64_override_options_internal): Simplify
	stack-clash protection validation code.

> -----Original Message-----
> From: Tamar Christina
> Sent: Friday, July 13, 2018 17:36
> To: Tamar Christina <Tamar.Christina@arm.com>; gcc-patches@gcc.gnu.org
> Cc: nd <nd@arm.com>; James Greenhalgh <James.Greenhalgh@arm.com>;
> Richard Earnshaw <Richard.Earnshaw@arm.com>; Marcus Shawcroft
> <Marcus.Shawcroft@arm.com>
> Subject: RE: [PATCH][GCC][AArch64] Validate and set default parameters for
> stack-clash. [Patch (3/3)]
> 
> Hi All,
> 
> I am sending an updated patch which takes into account a case where the set
> parameter value would not be safe to call.
> 
> No change in the cover letter.
> 
> Regards,
> Tamar
> 
> > -----Original Message-----
> > From: Tamar Christina <tamar.christina@arm.com>
> > Sent: Wednesday, July 11, 2018 12:25
> > To: gcc-patches@gcc.gnu.org
> > Cc: nd <nd@arm.com>; James Greenhalgh <James.Greenhalgh@arm.com>;
> > Richard Earnshaw <Richard.Earnshaw@arm.com>; Marcus Shawcroft
> > <Marcus.Shawcroft@arm.com>
> > Subject: [PATCH][GCC][AArch64] Validate and set default parameters for
> > stack-clash. [Patch (3/3)]
> >
> > Hi All,
> >
> > This patch defines the default parameters and validation for the
> > aarch64 stack clash probing interval and guard sizes.  It cleans up
> > the previous implementation and insures that at no point the
> > invalidate arguments are present in the pipeline for AArch64.
> > Currently they are only corrected once
> > cc1 initalizes the back-end.
> >
> > The default for AArch64 is 64 KB for both of these and we only support
> > 4 KB and 64 KB probes.  We also enforce that any value you set here
> > for the parameters must be in sync.
> >
> > If an invalid value is specified an error will be generated and
> > compilation aborted.
> >
> > Bootstrapped Regtested on aarch64-none-linux-gnu and no issues.
> > Target was tested with stack clash on and off by default.
> >
> > Ok for trunk?
> >
> > Thanks,
> > Tamar
> >
> > gcc/
> > 2018-07-11  Tamar Christina  <tamar.christina@arm.com>
> >
> > 	* common/config/aarch64/aarch64-common.c
> > (TARGET_OPTION_DEFAULT_PARAM,
> > 	aarch64_option_default_param):	New.
> > 	(params.h): Include.
> > 	(TARGET_OPTION_VALIDATE_PARAM,
> > aarch64_option_validate_param): New.
> > 	* config/aarch64/aarch64.c (aarch64_override_options_internal):
> > Simplify
> > 	stack-clash protection validation code.
> >
> > --
diff --git a/gcc/common/config/aarch64/aarch64-common.c b/gcc/common/config/aarch64/aarch64-common.c
index 292fb818705d4650113da59a6d88cf2aa7c9e57d..97d7770190b8388ba277db96c07609f7b6f46817 100644
--- a/gcc/common/config/aarch64/aarch64-common.c
+++ b/gcc/common/config/aarch64/aarch64-common.c
@@ -30,6 +30,7 @@
 #include "opts.h"
 #include "flags.h"
 #include "diagnostic.h"
+#include "params.h"
 
 #ifdef  TARGET_BIG_ENDIAN_DEFAULT
 #undef  TARGET_DEFAULT_TARGET_FLAGS
@@ -41,6 +42,10 @@
 
 #undef	TARGET_OPTION_OPTIMIZATION_TABLE
 #define TARGET_OPTION_OPTIMIZATION_TABLE aarch_option_optimization_table
+#undef TARGET_OPTION_DEFAULT_PARAMS
+#define TARGET_OPTION_DEFAULT_PARAMS aarch64_option_default_params
+#undef TARGET_OPTION_VALIDATE_PARAM
+#define TARGET_OPTION_VALIDATE_PARAM aarch64_option_validate_param
 
 /* Set default optimization options.  */
 static const struct default_options aarch_option_optimization_table[] =
@@ -60,6 +65,49 @@ static const struct default_options aarch_option_optimization_table[] =
     { OPT_LEVELS_NONE, 0, NULL, 0 }
   };
 
+/* Implement target validation TARGET_OPTION_DEFAULT_PARAM.  */
+
+static bool
+aarch64_option_validate_param (const int value, const int param)
+{
+  /* Check that both parameters are the same.  */
+  if (param == (int) PARAM_STACK_CLASH_PROTECTION_GUARD_SIZE)
+    {
+      if (value != 12 && value != 16)
+	{
+	  error ("only values 12 (4 KB) and 16 (64 KB) are supported for guard "
+		 "size.  Given value %d (%llu KB) is out of range.",
+		 value, (1ULL << value) / 1024ULL);
+	  return false;
+	}
+    }
+
+  return true;
+}
+
+/* Implement TARGET_OPTION_DEFAULT_PARAMS.  */
+
+static void
+aarch64_option_default_params (void)
+{
+  /* We assume the guard page is 64k.  */
+  int index = (int) PARAM_STACK_CLASH_PROTECTION_GUARD_SIZE;
+  set_default_param_value (PARAM_STACK_CLASH_PROTECTION_GUARD_SIZE,
+			   DEFAULT_STK_CLASH_GUARD_SIZE == 0
+			     ? 16 : DEFAULT_STK_CLASH_GUARD_SIZE);
+
+  int guard_size
+    = default_param_value (PARAM_STACK_CLASH_PROTECTION_GUARD_SIZE);
+
+  /* Set the interval parameter to be the same as the guard size.  This way the
+     mid-end code does the right thing for us.  */
+  set_default_param_value (PARAM_STACK_CLASH_PROTECTION_PROBE_INTERVAL,
+			   guard_size);
+
+  /* Validate the options.  */
+  aarch64_option_validate_param (guard_size, index);
+}
+
 /* Implement TARGET_HANDLE_OPTION.
    This function handles the target specific options for CPU/target selection.
 
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 31948dc67c8ae1e879a3d3f1ca8cb96e975afc30..ed85093a1e5a9126f2498b2aecc369f054839e0c 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -10938,10 +10938,6 @@ aarch64_override_options_internal (struct gcc_options *opts)
 
   /* Validate the guard size.  */
   int guard_size = PARAM_VALUE (PARAM_STACK_CLASH_PROTECTION_GUARD_SIZE);
-  if (guard_size != 12 && guard_size != 16)
-    error ("only values 12 (4 KB) and 16 (64 KB) are supported for guard "
-	   "size.  Given value %d (%llu KB) is out of range.",
-	   guard_size, (1ULL << guard_size) / 1024ULL);
 
   /* Enforce that interval is the same size as size so the mid-end does the
      right thing.  */


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