[PATCH] Add no_sanitize_coverage attribute.

[PATCH] Add no_sanitize_coverage attribute.

[Martin Liška]

Hello.

The patch implements one missing attribute which can be used for per-function
disabling of coverage sanitization.

Patch can bootstrap on x86_64-linux-gnu and survives regression tests.

Ready to be installed?
Thanks,
Martin

gcc/ChangeLog:

	* asan.h (sanitize_coverage_p): New function.
	* doc/extend.texi: Document it.
	* fold-const.c (fold_range_test): Use sanitize_flags_p
	instead of flag_sanitize_coverage.
	(fold_truth_andor): Likewise.
	* sancov.c: Likewise.
	* tree-ssa-ifcombine.c (ifcombine_ifandif): Likewise.

gcc/c-family/ChangeLog:

	* c-attribs.c (handle_no_sanitize_coverage_attribute): New.

gcc/testsuite/ChangeLog:

	* gcc.dg/sancov/attribute.c: New test.
---
  gcc/asan.h                              | 10 ++++++++++
  gcc/c-family/c-attribs.c                | 20 ++++++++++++++++++++
  gcc/doc/extend.texi                     |  6 ++++++
  gcc/fold-const.c                        |  4 ++--
  gcc/sancov.c                            |  4 ++--
  gcc/testsuite/gcc.dg/sancov/attribute.c | 15 +++++++++++++++
  gcc/tree-ssa-ifcombine.c                |  4 +++-
  7 files changed, 58 insertions(+), 5 deletions(-)
  create mode 100644 gcc/testsuite/gcc.dg/sancov/attribute.c

diff --git a/gcc/asan.h b/gcc/asan.h
index f110f1db563..8c0b2baf170 100644
--- a/gcc/asan.h
+++ b/gcc/asan.h
@@ -249,4 +249,14 @@ sanitize_flags_p (unsigned int flag, const_tree fn = current_function_decl)
    return result_flags;
  }
  
+/* Return true when coverage sanitization should happend for FN function.  */
+
+static inline bool
+sanitize_coverage_p (const_tree fn = current_function_decl)
+{
+  return (flag_sanitize_coverage
+	  && lookup_attribute ("no_sanitize_coverage",
+			       DECL_ATTRIBUTES (fn)) == NULL_TREE);
+}
+
  #endif /* TREE_ASAN */
diff --git a/gcc/c-family/c-attribs.c b/gcc/c-family/c-attribs.c
index ccf9e4ccf0b..671b27c3200 100644
--- a/gcc/c-family/c-attribs.c
+++ b/gcc/c-family/c-attribs.c
@@ -62,6 +62,8 @@ static tree handle_no_address_safety_analysis_attribute (tree *, tree, tree,
  							 int, bool *);
  static tree handle_no_sanitize_undefined_attribute (tree *, tree, tree, int,
  						    bool *);
+static tree handle_no_sanitize_coverage_attribute (tree *, tree, tree, int,
+						   bool *);
  static tree handle_asan_odr_indicator_attribute (tree *, tree, tree, int,
  						 bool *);
  static tree handle_stack_protect_attribute (tree *, tree, tree, int, bool *);
@@ -449,6 +451,8 @@ const struct attribute_spec c_common_attribute_table[] =
  			      handle_no_sanitize_thread_attribute, NULL },
    { "no_sanitize_undefined",  0, 0, true, false, false, false,
  			      handle_no_sanitize_undefined_attribute, NULL },
+  { "no_sanitize_coverage",   0, 0, true, false, false, false,
+			      handle_no_sanitize_coverage_attribute, NULL },
    { "asan odr indicator",     0, 0, true, false, false, false,
  			      handle_asan_odr_indicator_attribute, NULL },
    { "warning",		      1, 1, true,  false, false, false,
@@ -1211,6 +1215,22 @@ handle_no_sanitize_undefined_attribute (tree *node, tree name, tree, int,
    return NULL_TREE;
  }
  
+/* Handle a "no_sanitize_coverage" attribute; arguments as in
+   struct attribute_spec.handler.  */
+
+static tree
+handle_no_sanitize_coverage_attribute (tree *node, tree name, tree, int,
+				       bool *no_add_attrs)
+{
+  if (TREE_CODE (*node) != FUNCTION_DECL)
+    {
+      warning (OPT_Wattributes, "%qE attribute ignored", name);
+      *no_add_attrs = true;
+    }
+
+  return NULL_TREE;
+}
+
  /* Handle an "asan odr indicator" attribute; arguments as in
     struct attribute_spec.handler.  */
  
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 826804e6149..3ddeb0dee3a 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -3415,6 +3415,12 @@ The @code{no_sanitize_undefined} attribute on functions is used
  to inform the compiler that it should not check for undefined behavior
  in the function when compiling with the @option{-fsanitize=undefined} option.
  
+@item no_sanitize_coverage
+@cindex @code{no_sanitize_coverage} function attribute
+The @code{no_sanitize_coverage} attribute on functions is used
+to inform the compiler that it should not do coverage-guided
+fuzzing code instrumentation (@option{-fsanitize-coverage}).
+
  @item no_split_stack
  @cindex @code{no_split_stack} function attribute
  @opindex fsplit-stack
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 3be9c15e6b2..d088187a057 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -6016,7 +6016,7 @@ fold_range_test (location_t loc, enum tree_code code, tree type,
      logical_op_non_short_circuit
        = param_logical_op_non_short_circuit;
    if (logical_op_non_short_circuit
-      && !flag_sanitize_coverage
+      && !sanitize_coverage_p ()
        && lhs != 0 && rhs != 0
        && (code == TRUTH_ANDIF_EXPR || code == TRUTH_ORIF_EXPR)
        && operand_equal_p (lhs, rhs, 0))
@@ -9652,7 +9652,7 @@ fold_truth_andor (location_t loc, enum tree_code code, tree type,
      logical_op_non_short_circuit
        = param_logical_op_non_short_circuit;
    if (logical_op_non_short_circuit
-      && !flag_sanitize_coverage
+      && !sanitize_coverage_p ()
        && (code == TRUTH_AND_EXPR
            || code == TRUTH_ANDIF_EXPR
            || code == TRUTH_OR_EXPR
diff --git a/gcc/sancov.c b/gcc/sancov.c
index d656c37cae9..9cfbd425def 100644
--- a/gcc/sancov.c
+++ b/gcc/sancov.c
@@ -313,9 +313,9 @@ public:
      return new pass_sancov<O0> (m_ctxt);
    }
    virtual bool
-  gate (function *)
+  gate (function *fun)
    {
-    return flag_sanitize_coverage && (!O0 || !optimize);
+    return sanitize_coverage_p (fun->decl) && (!O0 || !optimize);
    }
    virtual unsigned int
    execute (function *fun)
diff --git a/gcc/testsuite/gcc.dg/sancov/attribute.c b/gcc/testsuite/gcc.dg/sancov/attribute.c
new file mode 100644
index 00000000000..bf6dbd4bae7
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/sancov/attribute.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-fsanitize-coverage=trace-pc -fdump-tree-optimized" } */
+
+void foo(void)
+{
+}
+
+void
+__attribute__((no_sanitize_coverage))
+bar(void)
+{
+}
+
+
+/* { dg-final { scan-tree-dump-times "__builtin___sanitizer_cov_trace_pc \\(\\)" 1 "optimized" } } */
diff --git a/gcc/tree-ssa-ifcombine.c b/gcc/tree-ssa-ifcombine.c
index 836a12d6b80..f93e04aa4df 100644
--- a/gcc/tree-ssa-ifcombine.c
+++ b/gcc/tree-ssa-ifcombine.c
@@ -40,6 +40,8 @@ along with GCC; see the file COPYING3.  If not see
  #include "gimplify-me.h"
  #include "tree-cfg.h"
  #include "tree-ssa.h"
+#include "attribs.h"
+#include "asan.h"
  
  #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
  #define LOGICAL_OP_NON_SHORT_CIRCUIT \
@@ -567,7 +569,7 @@ ifcombine_ifandif (basic_block inner_cond_bb, bool inner_inv,
  	  if (param_logical_op_non_short_circuit != -1)
  	    logical_op_non_short_circuit
  	      = param_logical_op_non_short_circuit;
-	  if (!logical_op_non_short_circuit || flag_sanitize_coverage)
+	  if (!logical_op_non_short_circuit || sanitize_coverage_p ())
  	    return false;
  	  /* Only do this optimization if the inner bb contains only the conditional. */
  	  if (!gsi_one_before_end_p (gsi_start_nondebug_after_labels_bb (inner_cond_bb)))
-- 
2.31.1

Re: [PATCH] Add no_sanitize_coverage attribute.

[Marco Elver]

On Thu, 20 May 2021 at 10:33, Martin Liška <mliska@suse.cz> wrote:
> Hello.
>
> The patch implements one missing attribute which can be used for per-function
> disabling of coverage sanitization.
>
> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.

Thanks for implementing this so quickly. One thing I just have to
double check, is if this works with always_inline (not instrumented if
inlined into no_sanitize), and inline (not inlined if inline fn is
no_sanitize_coverage). Just like the other no_sanitize* do. The test
doesn't mention them.

Thanks,
-- Marco

> Ready to be installed?
> Thanks,
> Martin
>
> gcc/ChangeLog:
>
>         * asan.h (sanitize_coverage_p): New function.
>         * doc/extend.texi: Document it.
>         * fold-const.c (fold_range_test): Use sanitize_flags_p
>         instead of flag_sanitize_coverage.
>         (fold_truth_andor): Likewise.
>         * sancov.c: Likewise.
>         * tree-ssa-ifcombine.c (ifcombine_ifandif): Likewise.
>
> gcc/c-family/ChangeLog:
>
>         * c-attribs.c (handle_no_sanitize_coverage_attribute): New.
>
> gcc/testsuite/ChangeLog:
>
>         * gcc.dg/sancov/attribute.c: New test.
> ---
>   gcc/asan.h                              | 10 ++++++++++
>   gcc/c-family/c-attribs.c                | 20 ++++++++++++++++++++
>   gcc/doc/extend.texi                     |  6 ++++++
>   gcc/fold-const.c                        |  4 ++--
>   gcc/sancov.c                            |  4 ++--
>   gcc/testsuite/gcc.dg/sancov/attribute.c | 15 +++++++++++++++
>   gcc/tree-ssa-ifcombine.c                |  4 +++-
>   7 files changed, 58 insertions(+), 5 deletions(-)
>   create mode 100644 gcc/testsuite/gcc.dg/sancov/attribute.c
>
> diff --git a/gcc/asan.h b/gcc/asan.h
> index f110f1db563..8c0b2baf170 100644
> --- a/gcc/asan.h
> +++ b/gcc/asan.h
> @@ -249,4 +249,14 @@ sanitize_flags_p (unsigned int flag, const_tree fn = current_function_decl)
>     return result_flags;
>   }
>
> +/* Return true when coverage sanitization should happend for FN function.  */
> +
> +static inline bool
> +sanitize_coverage_p (const_tree fn = current_function_decl)
> +{
> +  return (flag_sanitize_coverage
> +         && lookup_attribute ("no_sanitize_coverage",
> +                              DECL_ATTRIBUTES (fn)) == NULL_TREE);
> +}
> +
>   #endif /* TREE_ASAN */
> diff --git a/gcc/c-family/c-attribs.c b/gcc/c-family/c-attribs.c
> index ccf9e4ccf0b..671b27c3200 100644
> --- a/gcc/c-family/c-attribs.c
> +++ b/gcc/c-family/c-attribs.c
> @@ -62,6 +62,8 @@ static tree handle_no_address_safety_analysis_attribute (tree *, tree, tree,
>                                                          int, bool *);
>   static tree handle_no_sanitize_undefined_attribute (tree *, tree, tree, int,
>                                                     bool *);
> +static tree handle_no_sanitize_coverage_attribute (tree *, tree, tree, int,
> +                                                  bool *);
>   static tree handle_asan_odr_indicator_attribute (tree *, tree, tree, int,
>                                                  bool *);
>   static tree handle_stack_protect_attribute (tree *, tree, tree, int, bool *);
> @@ -449,6 +451,8 @@ const struct attribute_spec c_common_attribute_table[] =
>                               handle_no_sanitize_thread_attribute, NULL },
>     { "no_sanitize_undefined",  0, 0, true, false, false, false,
>                               handle_no_sanitize_undefined_attribute, NULL },
> +  { "no_sanitize_coverage",   0, 0, true, false, false, false,
> +                             handle_no_sanitize_coverage_attribute, NULL },
>     { "asan odr indicator",     0, 0, true, false, false, false,
>                               handle_asan_odr_indicator_attribute, NULL },
>     { "warning",                      1, 1, true,  false, false, false,
> @@ -1211,6 +1215,22 @@ handle_no_sanitize_undefined_attribute (tree *node, tree name, tree, int,
>     return NULL_TREE;
>   }
>
> +/* Handle a "no_sanitize_coverage" attribute; arguments as in
> +   struct attribute_spec.handler.  */
> +
> +static tree
> +handle_no_sanitize_coverage_attribute (tree *node, tree name, tree, int,
> +                                      bool *no_add_attrs)
> +{
> +  if (TREE_CODE (*node) != FUNCTION_DECL)
> +    {
> +      warning (OPT_Wattributes, "%qE attribute ignored", name);
> +      *no_add_attrs = true;
> +    }
> +
> +  return NULL_TREE;
> +}
> +
>   /* Handle an "asan odr indicator" attribute; arguments as in
>      struct attribute_spec.handler.  */
>
> diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
> index 826804e6149..3ddeb0dee3a 100644
> --- a/gcc/doc/extend.texi
> +++ b/gcc/doc/extend.texi
> @@ -3415,6 +3415,12 @@ The @code{no_sanitize_undefined} attribute on functions is used
>   to inform the compiler that it should not check for undefined behavior
>   in the function when compiling with the @option{-fsanitize=undefined} option.
>
> +@item no_sanitize_coverage
> +@cindex @code{no_sanitize_coverage} function attribute
> +The @code{no_sanitize_coverage} attribute on functions is used
> +to inform the compiler that it should not do coverage-guided
> +fuzzing code instrumentation (@option{-fsanitize-coverage}).
> +
>   @item no_split_stack
>   @cindex @code{no_split_stack} function attribute
>   @opindex fsplit-stack
> diff --git a/gcc/fold-const.c b/gcc/fold-const.c
> index 3be9c15e6b2..d088187a057 100644
> --- a/gcc/fold-const.c
> +++ b/gcc/fold-const.c
> @@ -6016,7 +6016,7 @@ fold_range_test (location_t loc, enum tree_code code, tree type,
>       logical_op_non_short_circuit
>         = param_logical_op_non_short_circuit;
>     if (logical_op_non_short_circuit
> -      && !flag_sanitize_coverage
> +      && !sanitize_coverage_p ()
>         && lhs != 0 && rhs != 0
>         && (code == TRUTH_ANDIF_EXPR || code == TRUTH_ORIF_EXPR)
>         && operand_equal_p (lhs, rhs, 0))
> @@ -9652,7 +9652,7 @@ fold_truth_andor (location_t loc, enum tree_code code, tree type,
>       logical_op_non_short_circuit
>         = param_logical_op_non_short_circuit;
>     if (logical_op_non_short_circuit
> -      && !flag_sanitize_coverage
> +      && !sanitize_coverage_p ()
>         && (code == TRUTH_AND_EXPR
>             || code == TRUTH_ANDIF_EXPR
>             || code == TRUTH_OR_EXPR
> diff --git a/gcc/sancov.c b/gcc/sancov.c
> index d656c37cae9..9cfbd425def 100644
> --- a/gcc/sancov.c
> +++ b/gcc/sancov.c
> @@ -313,9 +313,9 @@ public:
>       return new pass_sancov<O0> (m_ctxt);
>     }
>     virtual bool
> -  gate (function *)
> +  gate (function *fun)
>     {
> -    return flag_sanitize_coverage && (!O0 || !optimize);
> +    return sanitize_coverage_p (fun->decl) && (!O0 || !optimize);
>     }
>     virtual unsigned int
>     execute (function *fun)
> diff --git a/gcc/testsuite/gcc.dg/sancov/attribute.c b/gcc/testsuite/gcc.dg/sancov/attribute.c
> new file mode 100644
> index 00000000000..bf6dbd4bae7
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/sancov/attribute.c
> @@ -0,0 +1,15 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fsanitize-coverage=trace-pc -fdump-tree-optimized" } */
> +
> +void foo(void)
> +{
> +}
> +
> +void
> +__attribute__((no_sanitize_coverage))
> +bar(void)
> +{
> +}
> +
> +
> +/* { dg-final { scan-tree-dump-times "__builtin___sanitizer_cov_trace_pc \\(\\)" 1 "optimized" } } */
> diff --git a/gcc/tree-ssa-ifcombine.c b/gcc/tree-ssa-ifcombine.c
> index 836a12d6b80..f93e04aa4df 100644
> --- a/gcc/tree-ssa-ifcombine.c
> +++ b/gcc/tree-ssa-ifcombine.c
> @@ -40,6 +40,8 @@ along with GCC; see the file COPYING3.  If not see
>   #include "gimplify-me.h"
>   #include "tree-cfg.h"
>   #include "tree-ssa.h"
> +#include "attribs.h"
> +#include "asan.h"
>
>   #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
>   #define LOGICAL_OP_NON_SHORT_CIRCUIT \
> @@ -567,7 +569,7 @@ ifcombine_ifandif (basic_block inner_cond_bb, bool inner_inv,
>           if (param_logical_op_non_short_circuit != -1)
>             logical_op_non_short_circuit
>               = param_logical_op_non_short_circuit;
> -         if (!logical_op_non_short_circuit || flag_sanitize_coverage)
> +         if (!logical_op_non_short_circuit || sanitize_coverage_p ())
>             return false;
>           /* Only do this optimization if the inner bb contains only the conditional. */
>           if (!gsi_one_before_end_p (gsi_start_nondebug_after_labels_bb (inner_cond_bb)))
> --
> 2.31.1
>

Re: [PATCH] Add no_sanitize_coverage attribute.

[Martin Liška]

On 5/20/21 10:45 AM, Marco Elver wrote:
> On Thu, 20 May 2021 at 10:33, Martin Liška <mliska@suse.cz> wrote:
>> Hello.
>>
>> The patch implements one missing attribute which can be used for per-function
>> disabling of coverage sanitization.
>>
>> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
> 
> Thanks for implementing this so quickly. One thing I just have to
> double check, is if this works with always_inline (not instrumented if
> inlined into no_sanitize),

No, in this case it's instrumented (if caller has not set the attribute).

> and inline (not inlined if inline fn is
> no_sanitize_coverage).

No again, it's not blocking inlining.

> Just like the other no_sanitize* do. The test doesn't mention them.

It's aligned with similar issue that was discussed some time ago:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94722#c9

Martin

> 
> Thanks,
> -- Marco
> 
>> Ready to be installed?
>> Thanks,
>> Martin
>>
>> gcc/ChangeLog:
>>
>>          * asan.h (sanitize_coverage_p): New function.
>>          * doc/extend.texi: Document it.
>>          * fold-const.c (fold_range_test): Use sanitize_flags_p
>>          instead of flag_sanitize_coverage.
>>          (fold_truth_andor): Likewise.
>>          * sancov.c: Likewise.
>>          * tree-ssa-ifcombine.c (ifcombine_ifandif): Likewise.
>>
>> gcc/c-family/ChangeLog:
>>
>>          * c-attribs.c (handle_no_sanitize_coverage_attribute): New.
>>
>> gcc/testsuite/ChangeLog:
>>
>>          * gcc.dg/sancov/attribute.c: New test.
>> ---
>>    gcc/asan.h                              | 10 ++++++++++
>>    gcc/c-family/c-attribs.c                | 20 ++++++++++++++++++++
>>    gcc/doc/extend.texi                     |  6 ++++++
>>    gcc/fold-const.c                        |  4 ++--
>>    gcc/sancov.c                            |  4 ++--
>>    gcc/testsuite/gcc.dg/sancov/attribute.c | 15 +++++++++++++++
>>    gcc/tree-ssa-ifcombine.c                |  4 +++-
>>    7 files changed, 58 insertions(+), 5 deletions(-)
>>    create mode 100644 gcc/testsuite/gcc.dg/sancov/attribute.c
>>
>> diff --git a/gcc/asan.h b/gcc/asan.h
>> index f110f1db563..8c0b2baf170 100644
>> --- a/gcc/asan.h
>> +++ b/gcc/asan.h
>> @@ -249,4 +249,14 @@ sanitize_flags_p (unsigned int flag, const_tree fn = current_function_decl)
>>      return result_flags;
>>    }
>>
>> +/* Return true when coverage sanitization should happend for FN function.  */
>> +
>> +static inline bool
>> +sanitize_coverage_p (const_tree fn = current_function_decl)
>> +{
>> +  return (flag_sanitize_coverage
>> +         && lookup_attribute ("no_sanitize_coverage",
>> +                              DECL_ATTRIBUTES (fn)) == NULL_TREE);
>> +}
>> +
>>    #endif /* TREE_ASAN */
>> diff --git a/gcc/c-family/c-attribs.c b/gcc/c-family/c-attribs.c
>> index ccf9e4ccf0b..671b27c3200 100644
>> --- a/gcc/c-family/c-attribs.c
>> +++ b/gcc/c-family/c-attribs.c
>> @@ -62,6 +62,8 @@ static tree handle_no_address_safety_analysis_attribute (tree *, tree, tree,
>>                                                           int, bool *);
>>    static tree handle_no_sanitize_undefined_attribute (tree *, tree, tree, int,
>>                                                      bool *);
>> +static tree handle_no_sanitize_coverage_attribute (tree *, tree, tree, int,
>> +                                                  bool *);
>>    static tree handle_asan_odr_indicator_attribute (tree *, tree, tree, int,
>>                                                   bool *);
>>    static tree handle_stack_protect_attribute (tree *, tree, tree, int, bool *);
>> @@ -449,6 +451,8 @@ const struct attribute_spec c_common_attribute_table[] =
>>                                handle_no_sanitize_thread_attribute, NULL },
>>      { "no_sanitize_undefined",  0, 0, true, false, false, false,
>>                                handle_no_sanitize_undefined_attribute, NULL },
>> +  { "no_sanitize_coverage",   0, 0, true, false, false, false,
>> +                             handle_no_sanitize_coverage_attribute, NULL },
>>      { "asan odr indicator",     0, 0, true, false, false, false,
>>                                handle_asan_odr_indicator_attribute, NULL },
>>      { "warning",                      1, 1, true,  false, false, false,
>> @@ -1211,6 +1215,22 @@ handle_no_sanitize_undefined_attribute (tree *node, tree name, tree, int,
>>      return NULL_TREE;
>>    }
>>
>> +/* Handle a "no_sanitize_coverage" attribute; arguments as in
>> +   struct attribute_spec.handler.  */
>> +
>> +static tree
>> +handle_no_sanitize_coverage_attribute (tree *node, tree name, tree, int,
>> +                                      bool *no_add_attrs)
>> +{
>> +  if (TREE_CODE (*node) != FUNCTION_DECL)
>> +    {
>> +      warning (OPT_Wattributes, "%qE attribute ignored", name);
>> +      *no_add_attrs = true;
>> +    }
>> +
>> +  return NULL_TREE;
>> +}
>> +
>>    /* Handle an "asan odr indicator" attribute; arguments as in
>>       struct attribute_spec.handler.  */
>>
>> diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
>> index 826804e6149..3ddeb0dee3a 100644
>> --- a/gcc/doc/extend.texi
>> +++ b/gcc/doc/extend.texi
>> @@ -3415,6 +3415,12 @@ The @code{no_sanitize_undefined} attribute on functions is used
>>    to inform the compiler that it should not check for undefined behavior
>>    in the function when compiling with the @option{-fsanitize=undefined} option.
>>
>> +@item no_sanitize_coverage
>> +@cindex @code{no_sanitize_coverage} function attribute
>> +The @code{no_sanitize_coverage} attribute on functions is used
>> +to inform the compiler that it should not do coverage-guided
>> +fuzzing code instrumentation (@option{-fsanitize-coverage}).
>> +
>>    @item no_split_stack
>>    @cindex @code{no_split_stack} function attribute
>>    @opindex fsplit-stack
>> diff --git a/gcc/fold-const.c b/gcc/fold-const.c
>> index 3be9c15e6b2..d088187a057 100644
>> --- a/gcc/fold-const.c
>> +++ b/gcc/fold-const.c
>> @@ -6016,7 +6016,7 @@ fold_range_test (location_t loc, enum tree_code code, tree type,
>>        logical_op_non_short_circuit
>>          = param_logical_op_non_short_circuit;
>>      if (logical_op_non_short_circuit
>> -      && !flag_sanitize_coverage
>> +      && !sanitize_coverage_p ()
>>          && lhs != 0 && rhs != 0
>>          && (code == TRUTH_ANDIF_EXPR || code == TRUTH_ORIF_EXPR)
>>          && operand_equal_p (lhs, rhs, 0))
>> @@ -9652,7 +9652,7 @@ fold_truth_andor (location_t loc, enum tree_code code, tree type,
>>        logical_op_non_short_circuit
>>          = param_logical_op_non_short_circuit;
>>      if (logical_op_non_short_circuit
>> -      && !flag_sanitize_coverage
>> +      && !sanitize_coverage_p ()
>>          && (code == TRUTH_AND_EXPR
>>              || code == TRUTH_ANDIF_EXPR
>>              || code == TRUTH_OR_EXPR
>> diff --git a/gcc/sancov.c b/gcc/sancov.c
>> index d656c37cae9..9cfbd425def 100644
>> --- a/gcc/sancov.c
>> +++ b/gcc/sancov.c
>> @@ -313,9 +313,9 @@ public:
>>        return new pass_sancov<O0> (m_ctxt);
>>      }
>>      virtual bool
>> -  gate (function *)
>> +  gate (function *fun)
>>      {
>> -    return flag_sanitize_coverage && (!O0 || !optimize);
>> +    return sanitize_coverage_p (fun->decl) && (!O0 || !optimize);
>>      }
>>      virtual unsigned int
>>      execute (function *fun)
>> diff --git a/gcc/testsuite/gcc.dg/sancov/attribute.c b/gcc/testsuite/gcc.dg/sancov/attribute.c
>> new file mode 100644
>> index 00000000000..bf6dbd4bae7
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.dg/sancov/attribute.c
>> @@ -0,0 +1,15 @@
>> +/* { dg-do compile } */
>> +/* { dg-options "-fsanitize-coverage=trace-pc -fdump-tree-optimized" } */
>> +
>> +void foo(void)
>> +{
>> +}
>> +
>> +void
>> +__attribute__((no_sanitize_coverage))
>> +bar(void)
>> +{
>> +}
>> +
>> +
>> +/* { dg-final { scan-tree-dump-times "__builtin___sanitizer_cov_trace_pc \\(\\)" 1 "optimized" } } */
>> diff --git a/gcc/tree-ssa-ifcombine.c b/gcc/tree-ssa-ifcombine.c
>> index 836a12d6b80..f93e04aa4df 100644
>> --- a/gcc/tree-ssa-ifcombine.c
>> +++ b/gcc/tree-ssa-ifcombine.c
>> @@ -40,6 +40,8 @@ along with GCC; see the file COPYING3.  If not see
>>    #include "gimplify-me.h"
>>    #include "tree-cfg.h"
>>    #include "tree-ssa.h"
>> +#include "attribs.h"
>> +#include "asan.h"
>>
>>    #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
>>    #define LOGICAL_OP_NON_SHORT_CIRCUIT \
>> @@ -567,7 +569,7 @@ ifcombine_ifandif (basic_block inner_cond_bb, bool inner_inv,
>>            if (param_logical_op_non_short_circuit != -1)
>>              logical_op_non_short_circuit
>>                = param_logical_op_non_short_circuit;
>> -         if (!logical_op_non_short_circuit || flag_sanitize_coverage)
>> +         if (!logical_op_non_short_circuit || sanitize_coverage_p ())
>>              return false;
>>            /* Only do this optimization if the inner bb contains only the conditional. */
>>            if (!gsi_one_before_end_p (gsi_start_nondebug_after_labels_bb (inner_cond_bb)))
>> --
>> 2.31.1
>>

Re: [PATCH] Add no_sanitize_coverage attribute.

[Marco Elver]

On Thu, 20 May 2021 at 11:08, Martin Liška <mliska@suse.cz> wrote:
> On 5/20/21 10:45 AM, Marco Elver wrote:
> > On Thu, 20 May 2021 at 10:33, Martin Liška <mliska@suse.cz> wrote:
> >> Hello.
> >>
> >> The patch implements one missing attribute which can be used for per-function
> >> disabling of coverage sanitization.
> >>
> >> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
> >
> > Thanks for implementing this so quickly. One thing I just have to
> > double check, is if this works with always_inline (not instrumented if
> > inlined into no_sanitize),
>
> No, in this case it's instrumented (if caller has not set the attribute).

This one I'm not sure of, because in too many places, we assume
always_inline behaves like a macro (see below).

> > and inline (not inlined if inline fn is
> > no_sanitize_coverage).
>
> No again, it's not blocking inlining.

I think that's fine, as long as the inlined code is still instrumented
according to the attribute (which I think is the case based on what
you say above).

I think this came up with other no_sanitize [1] based on what I had
written to you last year [2].

[1] https://gcc.gnu.org/pipermail/gcc-patches/2020-June/547618.html
[2] https://lore.kernel.org/lkml/CANpmjNNRz5OVKb6PE7K6GjfoGbht_ZhyPkNG9aD+KjNDzK7hGg@mail.gmail.com/

> > Just like the other no_sanitize* do. The test doesn't mention them.
>
> It's aligned with similar issue that was discussed some time ago:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94722#c9

That's fair, but keep in mind all -fsanitize are not for use in
production, unlike stack protector. no_sanitize_coverage needs to be
aligned with the behavior of other existing no_sanitize*. Of course,
whether to inline or not I don't mind, as long as no_sanitize means
the code is never instrumented as discussed in [2]. AFAIK, it just so
happens that to achieve that for the other sanitizers, the easiest
option was to not inline "inline no_sanitize*" functions.

But always_inline needs to behave in line with other no_sanitize*,
i.e. if inlined into no_sanitize_coverage, never instrument:
https://lore.kernel.org/lkml/CANpmjNMTsY_8241bS7=XAfqvZHFLrVEkv_uM4aDUWE_kh3Rvbw@mail.gmail.com/
This is also what Clang will do for no_sanitize_coverage.

Thanks,
-- Marco

> Martin
>
> >
> > Thanks,
> > -- Marco
> >
> >> Ready to be installed?
> >> Thanks,
> >> Martin
> >>
> >> gcc/ChangeLog:
> >>
> >>          * asan.h (sanitize_coverage_p): New function.
> >>          * doc/extend.texi: Document it.
> >>          * fold-const.c (fold_range_test): Use sanitize_flags_p
> >>          instead of flag_sanitize_coverage.
> >>          (fold_truth_andor): Likewise.
> >>          * sancov.c: Likewise.
> >>          * tree-ssa-ifcombine.c (ifcombine_ifandif): Likewise.
> >>
> >> gcc/c-family/ChangeLog:
> >>
> >>          * c-attribs.c (handle_no_sanitize_coverage_attribute): New.
> >>
> >> gcc/testsuite/ChangeLog:
> >>
> >>          * gcc.dg/sancov/attribute.c: New test.
> >> ---
> >>    gcc/asan.h                              | 10 ++++++++++
> >>    gcc/c-family/c-attribs.c                | 20 ++++++++++++++++++++
> >>    gcc/doc/extend.texi                     |  6 ++++++
> >>    gcc/fold-const.c                        |  4 ++--
> >>    gcc/sancov.c                            |  4 ++--
> >>    gcc/testsuite/gcc.dg/sancov/attribute.c | 15 +++++++++++++++
> >>    gcc/tree-ssa-ifcombine.c                |  4 +++-
> >>    7 files changed, 58 insertions(+), 5 deletions(-)
> >>    create mode 100644 gcc/testsuite/gcc.dg/sancov/attribute.c
> >>
> >> diff --git a/gcc/asan.h b/gcc/asan.h
> >> index f110f1db563..8c0b2baf170 100644
> >> --- a/gcc/asan.h
> >> +++ b/gcc/asan.h
> >> @@ -249,4 +249,14 @@ sanitize_flags_p (unsigned int flag, const_tree fn = current_function_decl)
> >>      return result_flags;
> >>    }
> >>
> >> +/* Return true when coverage sanitization should happend for FN function.  */
> >> +
> >> +static inline bool
> >> +sanitize_coverage_p (const_tree fn = current_function_decl)
> >> +{
> >> +  return (flag_sanitize_coverage
> >> +         && lookup_attribute ("no_sanitize_coverage",
> >> +                              DECL_ATTRIBUTES (fn)) == NULL_TREE);
> >> +}
> >> +
> >>    #endif /* TREE_ASAN */
> >> diff --git a/gcc/c-family/c-attribs.c b/gcc/c-family/c-attribs.c
> >> index ccf9e4ccf0b..671b27c3200 100644
> >> --- a/gcc/c-family/c-attribs.c
> >> +++ b/gcc/c-family/c-attribs.c
> >> @@ -62,6 +62,8 @@ static tree handle_no_address_safety_analysis_attribute (tree *, tree, tree,
> >>                                                           int, bool *);
> >>    static tree handle_no_sanitize_undefined_attribute (tree *, tree, tree, int,
> >>                                                      bool *);
> >> +static tree handle_no_sanitize_coverage_attribute (tree *, tree, tree, int,
> >> +                                                  bool *);
> >>    static tree handle_asan_odr_indicator_attribute (tree *, tree, tree, int,
> >>                                                   bool *);
> >>    static tree handle_stack_protect_attribute (tree *, tree, tree, int, bool *);
> >> @@ -449,6 +451,8 @@ const struct attribute_spec c_common_attribute_table[] =
> >>                                handle_no_sanitize_thread_attribute, NULL },
> >>      { "no_sanitize_undefined",  0, 0, true, false, false, false,
> >>                                handle_no_sanitize_undefined_attribute, NULL },
> >> +  { "no_sanitize_coverage",   0, 0, true, false, false, false,
> >> +                             handle_no_sanitize_coverage_attribute, NULL },
> >>      { "asan odr indicator",     0, 0, true, false, false, false,
> >>                                handle_asan_odr_indicator_attribute, NULL },
> >>      { "warning",                      1, 1, true,  false, false, false,
> >> @@ -1211,6 +1215,22 @@ handle_no_sanitize_undefined_attribute (tree *node, tree name, tree, int,
> >>      return NULL_TREE;
> >>    }
> >>
> >> +/* Handle a "no_sanitize_coverage" attribute; arguments as in
> >> +   struct attribute_spec.handler.  */
> >> +
> >> +static tree
> >> +handle_no_sanitize_coverage_attribute (tree *node, tree name, tree, int,
> >> +                                      bool *no_add_attrs)
> >> +{
> >> +  if (TREE_CODE (*node) != FUNCTION_DECL)
> >> +    {
> >> +      warning (OPT_Wattributes, "%qE attribute ignored", name);
> >> +      *no_add_attrs = true;
> >> +    }
> >> +
> >> +  return NULL_TREE;
> >> +}
> >> +
> >>    /* Handle an "asan odr indicator" attribute; arguments as in
> >>       struct attribute_spec.handler.  */
> >>
> >> diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
> >> index 826804e6149..3ddeb0dee3a 100644
> >> --- a/gcc/doc/extend.texi
> >> +++ b/gcc/doc/extend.texi
> >> @@ -3415,6 +3415,12 @@ The @code{no_sanitize_undefined} attribute on functions is used
> >>    to inform the compiler that it should not check for undefined behavior
> >>    in the function when compiling with the @option{-fsanitize=undefined} option.
> >>
> >> +@item no_sanitize_coverage
> >> +@cindex @code{no_sanitize_coverage} function attribute
> >> +The @code{no_sanitize_coverage} attribute on functions is used
> >> +to inform the compiler that it should not do coverage-guided
> >> +fuzzing code instrumentation (@option{-fsanitize-coverage}).
> >> +
> >>    @item no_split_stack
> >>    @cindex @code{no_split_stack} function attribute
> >>    @opindex fsplit-stack
> >> diff --git a/gcc/fold-const.c b/gcc/fold-const.c
> >> index 3be9c15e6b2..d088187a057 100644
> >> --- a/gcc/fold-const.c
> >> +++ b/gcc/fold-const.c
> >> @@ -6016,7 +6016,7 @@ fold_range_test (location_t loc, enum tree_code code, tree type,
> >>        logical_op_non_short_circuit
> >>          = param_logical_op_non_short_circuit;
> >>      if (logical_op_non_short_circuit
> >> -      && !flag_sanitize_coverage
> >> +      && !sanitize_coverage_p ()
> >>          && lhs != 0 && rhs != 0
> >>          && (code == TRUTH_ANDIF_EXPR || code == TRUTH_ORIF_EXPR)
> >>          && operand_equal_p (lhs, rhs, 0))
> >> @@ -9652,7 +9652,7 @@ fold_truth_andor (location_t loc, enum tree_code code, tree type,
> >>        logical_op_non_short_circuit
> >>          = param_logical_op_non_short_circuit;
> >>      if (logical_op_non_short_circuit
> >> -      && !flag_sanitize_coverage
> >> +      && !sanitize_coverage_p ()
> >>          && (code == TRUTH_AND_EXPR
> >>              || code == TRUTH_ANDIF_EXPR
> >>              || code == TRUTH_OR_EXPR
> >> diff --git a/gcc/sancov.c b/gcc/sancov.c
> >> index d656c37cae9..9cfbd425def 100644
> >> --- a/gcc/sancov.c
> >> +++ b/gcc/sancov.c
> >> @@ -313,9 +313,9 @@ public:
> >>        return new pass_sancov<O0> (m_ctxt);
> >>      }
> >>      virtual bool
> >> -  gate (function *)
> >> +  gate (function *fun)
> >>      {
> >> -    return flag_sanitize_coverage && (!O0 || !optimize);
> >> +    return sanitize_coverage_p (fun->decl) && (!O0 || !optimize);
> >>      }
> >>      virtual unsigned int
> >>      execute (function *fun)
> >> diff --git a/gcc/testsuite/gcc.dg/sancov/attribute.c b/gcc/testsuite/gcc.dg/sancov/attribute.c
> >> new file mode 100644
> >> index 00000000000..bf6dbd4bae7
> >> --- /dev/null
> >> +++ b/gcc/testsuite/gcc.dg/sancov/attribute.c
> >> @@ -0,0 +1,15 @@
> >> +/* { dg-do compile } */
> >> +/* { dg-options "-fsanitize-coverage=trace-pc -fdump-tree-optimized" } */
> >> +
> >> +void foo(void)
> >> +{
> >> +}
> >> +
> >> +void
> >> +__attribute__((no_sanitize_coverage))
> >> +bar(void)
> >> +{
> >> +}
> >> +
> >> +
> >> +/* { dg-final { scan-tree-dump-times "__builtin___sanitizer_cov_trace_pc \\(\\)" 1 "optimized" } } */
> >> diff --git a/gcc/tree-ssa-ifcombine.c b/gcc/tree-ssa-ifcombine.c
> >> index 836a12d6b80..f93e04aa4df 100644
> >> --- a/gcc/tree-ssa-ifcombine.c
> >> +++ b/gcc/tree-ssa-ifcombine.c
> >> @@ -40,6 +40,8 @@ along with GCC; see the file COPYING3.  If not see
> >>    #include "gimplify-me.h"
> >>    #include "tree-cfg.h"
> >>    #include "tree-ssa.h"
> >> +#include "attribs.h"
> >> +#include "asan.h"
> >>
> >>    #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
> >>    #define LOGICAL_OP_NON_SHORT_CIRCUIT \
> >> @@ -567,7 +569,7 @@ ifcombine_ifandif (basic_block inner_cond_bb, bool inner_inv,
> >>            if (param_logical_op_non_short_circuit != -1)
> >>              logical_op_non_short_circuit
> >>                = param_logical_op_non_short_circuit;
> >> -         if (!logical_op_non_short_circuit || flag_sanitize_coverage)
> >> +         if (!logical_op_non_short_circuit || sanitize_coverage_p ())
> >>              return false;
> >>            /* Only do this optimization if the inner bb contains only the conditional. */
> >>            if (!gsi_one_before_end_p (gsi_start_nondebug_after_labels_bb (inner_cond_bb)))
> >> --
> >> 2.31.1
> >>
>

Re: [PATCH] Add no_sanitize_coverage attribute.

[Martin Liška]

[-- Attachment #1: Type: text/plain, Size: 491 bytes --]

On 5/20/21 12:55 PM, Marco Elver wrote:
> I think this came up with other no_sanitize [1] based on what I had
> written to you last year [2].
> 
> [1]https://gcc.gnu.org/pipermail/gcc-patches/2020-June/547618.html
> [2]https://lore.kernel.org/lkml/CANpmjNNRz5OVKb6PE7K6GjfoGbht_ZhyPkNG9aD+KjNDzK7hGg@mail.gmail.com/

Ah, you're right. I've just updated the patch to address that.

Patch can bootstrap on x86_64-linux-gnu and survives regression tests.

Ready to be installed?
Thanks,
Martin

[-- Attachment #2: 0001-Add-no_sanitize_coverage-attribute.patch --]
[-- Type: text/x-patch, Size: 7696 bytes --]

From b7f9f6c9722e7cb1b81b96ec646cadb5706b1038 Mon Sep 17 00:00:00 2001
From: Martin Liska <mliska@suse.cz>
Date: Thu, 20 May 2021 09:32:29 +0200
Subject: [PATCH] Add no_sanitize_coverage attribute.

gcc/ChangeLog:

	* asan.h (sanitize_coverage_p): New function.
	* doc/extend.texi: Document it.
	* fold-const.c (fold_range_test): Use sanitize_flags_p
	instead of flag_sanitize_coverage.
	(fold_truth_andor): Likewise.
	* sancov.c: Likewise.
	* tree-ssa-ifcombine.c (ifcombine_ifandif): Likewise.
	* ipa-inline.c (sanitize_attrs_match_for_inline_p): Handle
	-fsanitize-coverage when inlining.

gcc/c-family/ChangeLog:

	* c-attribs.c (handle_no_sanitize_coverage_attribute): New.

gcc/testsuite/ChangeLog:

	* gcc.dg/sancov/attribute.c: New test.
---
 gcc/asan.h                              | 10 ++++++++++
 gcc/c-family/c-attribs.c                | 20 ++++++++++++++++++++
 gcc/doc/extend.texi                     |  6 ++++++
 gcc/fold-const.c                        |  4 ++--
 gcc/ipa-inline.c                        |  3 +++
 gcc/sancov.c                            |  4 ++--
 gcc/testsuite/gcc.dg/sancov/attribute.c | 15 +++++++++++++++
 gcc/tree-ssa-ifcombine.c                |  4 +++-
 8 files changed, 61 insertions(+), 5 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/sancov/attribute.c

diff --git a/gcc/asan.h b/gcc/asan.h
index f110f1db563..8c0b2baf170 100644
--- a/gcc/asan.h
+++ b/gcc/asan.h
@@ -249,4 +249,14 @@ sanitize_flags_p (unsigned int flag, const_tree fn = current_function_decl)
   return result_flags;
 }
 
+/* Return true when coverage sanitization should happend for FN function.  */
+
+static inline bool
+sanitize_coverage_p (const_tree fn = current_function_decl)
+{
+  return (flag_sanitize_coverage
+	  && lookup_attribute ("no_sanitize_coverage",
+			       DECL_ATTRIBUTES (fn)) == NULL_TREE);
+}
+
 #endif /* TREE_ASAN */
diff --git a/gcc/c-family/c-attribs.c b/gcc/c-family/c-attribs.c
index ccf9e4ccf0b..671b27c3200 100644
--- a/gcc/c-family/c-attribs.c
+++ b/gcc/c-family/c-attribs.c
@@ -62,6 +62,8 @@ static tree handle_no_address_safety_analysis_attribute (tree *, tree, tree,
 							 int, bool *);
 static tree handle_no_sanitize_undefined_attribute (tree *, tree, tree, int,
 						    bool *);
+static tree handle_no_sanitize_coverage_attribute (tree *, tree, tree, int,
+						   bool *);
 static tree handle_asan_odr_indicator_attribute (tree *, tree, tree, int,
 						 bool *);
 static tree handle_stack_protect_attribute (tree *, tree, tree, int, bool *);
@@ -449,6 +451,8 @@ const struct attribute_spec c_common_attribute_table[] =
 			      handle_no_sanitize_thread_attribute, NULL },
   { "no_sanitize_undefined",  0, 0, true, false, false, false,
 			      handle_no_sanitize_undefined_attribute, NULL },
+  { "no_sanitize_coverage",   0, 0, true, false, false, false,
+			      handle_no_sanitize_coverage_attribute, NULL },
   { "asan odr indicator",     0, 0, true, false, false, false,
 			      handle_asan_odr_indicator_attribute, NULL },
   { "warning",		      1, 1, true,  false, false, false,
@@ -1211,6 +1215,22 @@ handle_no_sanitize_undefined_attribute (tree *node, tree name, tree, int,
   return NULL_TREE;
 }
 
+/* Handle a "no_sanitize_coverage" attribute; arguments as in
+   struct attribute_spec.handler.  */
+
+static tree
+handle_no_sanitize_coverage_attribute (tree *node, tree name, tree, int,
+				       bool *no_add_attrs)
+{
+  if (TREE_CODE (*node) != FUNCTION_DECL)
+    {
+      warning (OPT_Wattributes, "%qE attribute ignored", name);
+      *no_add_attrs = true;
+    }
+
+  return NULL_TREE;
+}
+
 /* Handle an "asan odr indicator" attribute; arguments as in
    struct attribute_spec.handler.  */
 
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 826804e6149..3ddeb0dee3a 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -3415,6 +3415,12 @@ The @code{no_sanitize_undefined} attribute on functions is used
 to inform the compiler that it should not check for undefined behavior
 in the function when compiling with the @option{-fsanitize=undefined} option.
 
+@item no_sanitize_coverage
+@cindex @code{no_sanitize_coverage} function attribute
+The @code{no_sanitize_coverage} attribute on functions is used
+to inform the compiler that it should not do coverage-guided
+fuzzing code instrumentation (@option{-fsanitize-coverage}).
+
 @item no_split_stack
 @cindex @code{no_split_stack} function attribute
 @opindex fsplit-stack
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 3be9c15e6b2..d088187a057 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -6016,7 +6016,7 @@ fold_range_test (location_t loc, enum tree_code code, tree type,
     logical_op_non_short_circuit
       = param_logical_op_non_short_circuit;
   if (logical_op_non_short_circuit
-      && !flag_sanitize_coverage
+      && !sanitize_coverage_p ()
       && lhs != 0 && rhs != 0
       && (code == TRUTH_ANDIF_EXPR || code == TRUTH_ORIF_EXPR)
       && operand_equal_p (lhs, rhs, 0))
@@ -9652,7 +9652,7 @@ fold_truth_andor (location_t loc, enum tree_code code, tree type,
     logical_op_non_short_circuit
       = param_logical_op_non_short_circuit;
   if (logical_op_non_short_circuit
-      && !flag_sanitize_coverage
+      && !sanitize_coverage_p ()
       && (code == TRUTH_AND_EXPR
           || code == TRUTH_ANDIF_EXPR
           || code == TRUTH_OR_EXPR
diff --git a/gcc/ipa-inline.c b/gcc/ipa-inline.c
index f15c4828958..9d896beb2ac 100644
--- a/gcc/ipa-inline.c
+++ b/gcc/ipa-inline.c
@@ -283,6 +283,9 @@ sanitize_attrs_match_for_inline_p (const_tree caller, const_tree callee)
 	!= sanitize_flags_p (codes[i], callee))
       return false;
 
+  if (sanitize_coverage_p (caller) != sanitize_coverage_p (callee))
+    return false;
+
   return true;
 }
 
diff --git a/gcc/sancov.c b/gcc/sancov.c
index d656c37cae9..9cfbd425def 100644
--- a/gcc/sancov.c
+++ b/gcc/sancov.c
@@ -313,9 +313,9 @@ public:
     return new pass_sancov<O0> (m_ctxt);
   }
   virtual bool
-  gate (function *)
+  gate (function *fun)
   {
-    return flag_sanitize_coverage && (!O0 || !optimize);
+    return sanitize_coverage_p (fun->decl) && (!O0 || !optimize);
   }
   virtual unsigned int
   execute (function *fun)
diff --git a/gcc/testsuite/gcc.dg/sancov/attribute.c b/gcc/testsuite/gcc.dg/sancov/attribute.c
new file mode 100644
index 00000000000..bf6dbd4bae7
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/sancov/attribute.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-fsanitize-coverage=trace-pc -fdump-tree-optimized" } */
+
+void foo(void)
+{
+}
+
+void
+__attribute__((no_sanitize_coverage))
+bar(void)
+{
+}
+
+
+/* { dg-final { scan-tree-dump-times "__builtin___sanitizer_cov_trace_pc \\(\\)" 1 "optimized" } } */
diff --git a/gcc/tree-ssa-ifcombine.c b/gcc/tree-ssa-ifcombine.c
index 836a12d6b80..f93e04aa4df 100644
--- a/gcc/tree-ssa-ifcombine.c
+++ b/gcc/tree-ssa-ifcombine.c
@@ -40,6 +40,8 @@ along with GCC; see the file COPYING3.  If not see
 #include "gimplify-me.h"
 #include "tree-cfg.h"
 #include "tree-ssa.h"
+#include "attribs.h"
+#include "asan.h"
 
 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
@@ -567,7 +569,7 @@ ifcombine_ifandif (basic_block inner_cond_bb, bool inner_inv,
 	  if (param_logical_op_non_short_circuit != -1)
 	    logical_op_non_short_circuit
 	      = param_logical_op_non_short_circuit;
-	  if (!logical_op_non_short_circuit || flag_sanitize_coverage)
+	  if (!logical_op_non_short_circuit || sanitize_coverage_p ())
 	    return false;
 	  /* Only do this optimization if the inner bb contains only the conditional. */
 	  if (!gsi_one_before_end_p (gsi_start_nondebug_after_labels_bb (inner_cond_bb)))
-- 
2.31.1

Re: [PATCH] Add no_sanitize_coverage attribute.

[Marco Elver]

On Fri, May 21, 2021 at 10:50AM +0200, Martin Liška wrote:
> On 5/20/21 12:55 PM, Marco Elver wrote:
> > I think this came up with other no_sanitize [1] based on what I had
> > written to you last year [2].
> > 
> > [1]https://gcc.gnu.org/pipermail/gcc-patches/2020-June/547618.html
> > [2]https://lore.kernel.org/lkml/CANpmjNNRz5OVKb6PE7K6GjfoGbht_ZhyPkNG9aD+KjNDzK7hGg@mail.gmail.com/
> 
> Ah, you're right. I've just updated the patch to address that.
> 
> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
> 
> Ready to be installed?

Looks good, I also just built a kernel with the no_sanitize_coverage
attribute (without the objtool nop-workaround) and works as expected.

Not sure if required, but would such an additional test be useful:

---

diff --git a/gcc/testsuite/gcc.dg/sancov/attribute.c b/gcc/testsuite/gcc.dg/sancov/attribute.c
index bf6dbd4bae7..7cfa9134ff1 100644
--- a/gcc/testsuite/gcc.dg/sancov/attribute.c
+++ b/gcc/testsuite/gcc.dg/sancov/attribute.c
@@ -11,5 +11,17 @@ bar(void)
 {
 }
 
+static void inline
+__attribute__((always_inline))
+inline_fn(void)
+{
+}
+
+void
+__attribute__((no_sanitize_coverage))
+baz(void)
+{
+  inline_fn();
+}
 
 /* { dg-final { scan-tree-dump-times "__builtin___sanitizer_cov_trace_pc \\(\\)" 1 "optimized" } } */

---

Otherwise, please go ahead. I assume this is targeting GCC 12?

Thanks,
-- Marco

Re: [PATCH] Add no_sanitize_coverage attribute.

[Martin Liška]

[-- Attachment #1: Type: text/plain, Size: 1621 bytes --]

On 5/21/21 2:39 PM, Marco Elver wrote:
> On Fri, May 21, 2021 at 10:50AM +0200, Martin Liška wrote:
>> On 5/20/21 12:55 PM, Marco Elver wrote:
>>> I think this came up with other no_sanitize [1] based on what I had
>>> written to you last year [2].
>>>
>>> [1]https://gcc.gnu.org/pipermail/gcc-patches/2020-June/547618.html
>>> [2]https://lore.kernel.org/lkml/CANpmjNNRz5OVKb6PE7K6GjfoGbht_ZhyPkNG9aD+KjNDzK7hGg@mail.gmail.com/
>>
>> Ah, you're right. I've just updated the patch to address that.
>>
>> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
>>
>> Ready to be installed?
> 
> Looks good, I also just built a kernel with the no_sanitize_coverage
> attribute (without the objtool nop-workaround) and works as expected.

Good, thanks!

> 
> Not sure if required, but would such an additional test be useful:

Yes, it is, thanks for it.

> 
> ---
> 
> diff --git a/gcc/testsuite/gcc.dg/sancov/attribute.c b/gcc/testsuite/gcc.dg/sancov/attribute.c
> index bf6dbd4bae7..7cfa9134ff1 100644
> --- a/gcc/testsuite/gcc.dg/sancov/attribute.c
> +++ b/gcc/testsuite/gcc.dg/sancov/attribute.c
> @@ -11,5 +11,17 @@ bar(void)
>   {
>   }
>   
> +static void inline
> +__attribute__((always_inline))
> +inline_fn(void)
> +{
> +}
> +
> +void
> +__attribute__((no_sanitize_coverage))
> +baz(void)
> +{
> +  inline_fn();
> +}
>   
>   /* { dg-final { scan-tree-dump-times "__builtin___sanitizer_cov_trace_pc \\(\\)" 1 "optimized" } } */
> 
> ---
> 
> Otherwise, please go ahead. I assume this is targeting GCC 12?

Yep.

There's V3 I'm sending.

Ready for master?
Thanks,
Martin

> 
> Thanks,
> -- Marco
> 


[-- Attachment #2: 0001-Add-no_sanitize_coverage-attribute.patch --]
[-- Type: text/x-patch, Size: 7858 bytes --]

From 15053b32a870cd62641ad62a9e76a78558489f4a Mon Sep 17 00:00:00 2001
From: Martin Liska <mliska@suse.cz>
Date: Thu, 20 May 2021 09:32:29 +0200
Subject: [PATCH] Add no_sanitize_coverage attribute.

gcc/ChangeLog:

	* asan.h (sanitize_coverage_p): New function.
	* doc/extend.texi: Document it.
	* fold-const.c (fold_range_test): Use sanitize_flags_p
	instead of flag_sanitize_coverage.
	(fold_truth_andor): Likewise.
	* sancov.c: Likewise.
	* tree-ssa-ifcombine.c (ifcombine_ifandif): Likewise.
	* ipa-inline.c (sanitize_attrs_match_for_inline_p): Handle
	-fsanitize-coverage when inlining.

gcc/c-family/ChangeLog:

	* c-attribs.c (handle_no_sanitize_coverage_attribute): New.

gcc/testsuite/ChangeLog:

	* gcc.dg/sancov/attribute.c: New test.
---
 gcc/asan.h                              | 10 +++++++++
 gcc/c-family/c-attribs.c                | 20 ++++++++++++++++++
 gcc/doc/extend.texi                     |  6 ++++++
 gcc/fold-const.c                        |  4 ++--
 gcc/ipa-inline.c                        |  3 +++
 gcc/sancov.c                            |  4 ++--
 gcc/testsuite/gcc.dg/sancov/attribute.c | 27 +++++++++++++++++++++++++
 gcc/tree-ssa-ifcombine.c                |  4 +++-
 8 files changed, 73 insertions(+), 5 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/sancov/attribute.c

diff --git a/gcc/asan.h b/gcc/asan.h
index f110f1db563..8c0b2baf170 100644
--- a/gcc/asan.h
+++ b/gcc/asan.h
@@ -249,4 +249,14 @@ sanitize_flags_p (unsigned int flag, const_tree fn = current_function_decl)
   return result_flags;
 }
 
+/* Return true when coverage sanitization should happend for FN function.  */
+
+static inline bool
+sanitize_coverage_p (const_tree fn = current_function_decl)
+{
+  return (flag_sanitize_coverage
+	  && lookup_attribute ("no_sanitize_coverage",
+			       DECL_ATTRIBUTES (fn)) == NULL_TREE);
+}
+
 #endif /* TREE_ASAN */
diff --git a/gcc/c-family/c-attribs.c b/gcc/c-family/c-attribs.c
index ccf9e4ccf0b..671b27c3200 100644
--- a/gcc/c-family/c-attribs.c
+++ b/gcc/c-family/c-attribs.c
@@ -62,6 +62,8 @@ static tree handle_no_address_safety_analysis_attribute (tree *, tree, tree,
 							 int, bool *);
 static tree handle_no_sanitize_undefined_attribute (tree *, tree, tree, int,
 						    bool *);
+static tree handle_no_sanitize_coverage_attribute (tree *, tree, tree, int,
+						   bool *);
 static tree handle_asan_odr_indicator_attribute (tree *, tree, tree, int,
 						 bool *);
 static tree handle_stack_protect_attribute (tree *, tree, tree, int, bool *);
@@ -449,6 +451,8 @@ const struct attribute_spec c_common_attribute_table[] =
 			      handle_no_sanitize_thread_attribute, NULL },
   { "no_sanitize_undefined",  0, 0, true, false, false, false,
 			      handle_no_sanitize_undefined_attribute, NULL },
+  { "no_sanitize_coverage",   0, 0, true, false, false, false,
+			      handle_no_sanitize_coverage_attribute, NULL },
   { "asan odr indicator",     0, 0, true, false, false, false,
 			      handle_asan_odr_indicator_attribute, NULL },
   { "warning",		      1, 1, true,  false, false, false,
@@ -1211,6 +1215,22 @@ handle_no_sanitize_undefined_attribute (tree *node, tree name, tree, int,
   return NULL_TREE;
 }
 
+/* Handle a "no_sanitize_coverage" attribute; arguments as in
+   struct attribute_spec.handler.  */
+
+static tree
+handle_no_sanitize_coverage_attribute (tree *node, tree name, tree, int,
+				       bool *no_add_attrs)
+{
+  if (TREE_CODE (*node) != FUNCTION_DECL)
+    {
+      warning (OPT_Wattributes, "%qE attribute ignored", name);
+      *no_add_attrs = true;
+    }
+
+  return NULL_TREE;
+}
+
 /* Handle an "asan odr indicator" attribute; arguments as in
    struct attribute_spec.handler.  */
 
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 826804e6149..3ddeb0dee3a 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -3415,6 +3415,12 @@ The @code{no_sanitize_undefined} attribute on functions is used
 to inform the compiler that it should not check for undefined behavior
 in the function when compiling with the @option{-fsanitize=undefined} option.
 
+@item no_sanitize_coverage
+@cindex @code{no_sanitize_coverage} function attribute
+The @code{no_sanitize_coverage} attribute on functions is used
+to inform the compiler that it should not do coverage-guided
+fuzzing code instrumentation (@option{-fsanitize-coverage}).
+
 @item no_split_stack
 @cindex @code{no_split_stack} function attribute
 @opindex fsplit-stack
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 3be9c15e6b2..d088187a057 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -6016,7 +6016,7 @@ fold_range_test (location_t loc, enum tree_code code, tree type,
     logical_op_non_short_circuit
       = param_logical_op_non_short_circuit;
   if (logical_op_non_short_circuit
-      && !flag_sanitize_coverage
+      && !sanitize_coverage_p ()
       && lhs != 0 && rhs != 0
       && (code == TRUTH_ANDIF_EXPR || code == TRUTH_ORIF_EXPR)
       && operand_equal_p (lhs, rhs, 0))
@@ -9652,7 +9652,7 @@ fold_truth_andor (location_t loc, enum tree_code code, tree type,
     logical_op_non_short_circuit
       = param_logical_op_non_short_circuit;
   if (logical_op_non_short_circuit
-      && !flag_sanitize_coverage
+      && !sanitize_coverage_p ()
       && (code == TRUTH_AND_EXPR
           || code == TRUTH_ANDIF_EXPR
           || code == TRUTH_OR_EXPR
diff --git a/gcc/ipa-inline.c b/gcc/ipa-inline.c
index f15c4828958..9d896beb2ac 100644
--- a/gcc/ipa-inline.c
+++ b/gcc/ipa-inline.c
@@ -283,6 +283,9 @@ sanitize_attrs_match_for_inline_p (const_tree caller, const_tree callee)
 	!= sanitize_flags_p (codes[i], callee))
       return false;
 
+  if (sanitize_coverage_p (caller) != sanitize_coverage_p (callee))
+    return false;
+
   return true;
 }
 
diff --git a/gcc/sancov.c b/gcc/sancov.c
index d656c37cae9..9cfbd425def 100644
--- a/gcc/sancov.c
+++ b/gcc/sancov.c
@@ -313,9 +313,9 @@ public:
     return new pass_sancov<O0> (m_ctxt);
   }
   virtual bool
-  gate (function *)
+  gate (function *fun)
   {
-    return flag_sanitize_coverage && (!O0 || !optimize);
+    return sanitize_coverage_p (fun->decl) && (!O0 || !optimize);
   }
   virtual unsigned int
   execute (function *fun)
diff --git a/gcc/testsuite/gcc.dg/sancov/attribute.c b/gcc/testsuite/gcc.dg/sancov/attribute.c
new file mode 100644
index 00000000000..7cfa9134ff1
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/sancov/attribute.c
@@ -0,0 +1,27 @@
+/* { dg-do compile } */
+/* { dg-options "-fsanitize-coverage=trace-pc -fdump-tree-optimized" } */
+
+void foo(void)
+{
+}
+
+void
+__attribute__((no_sanitize_coverage))
+bar(void)
+{
+}
+
+static void inline
+__attribute__((always_inline))
+inline_fn(void)
+{
+}
+
+void
+__attribute__((no_sanitize_coverage))
+baz(void)
+{
+  inline_fn();
+}
+
+/* { dg-final { scan-tree-dump-times "__builtin___sanitizer_cov_trace_pc \\(\\)" 1 "optimized" } } */
diff --git a/gcc/tree-ssa-ifcombine.c b/gcc/tree-ssa-ifcombine.c
index 836a12d6b80..f93e04aa4df 100644
--- a/gcc/tree-ssa-ifcombine.c
+++ b/gcc/tree-ssa-ifcombine.c
@@ -40,6 +40,8 @@ along with GCC; see the file COPYING3.  If not see
 #include "gimplify-me.h"
 #include "tree-cfg.h"
 #include "tree-ssa.h"
+#include "attribs.h"
+#include "asan.h"
 
 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
@@ -567,7 +569,7 @@ ifcombine_ifandif (basic_block inner_cond_bb, bool inner_inv,
 	  if (param_logical_op_non_short_circuit != -1)
 	    logical_op_non_short_circuit
 	      = param_logical_op_non_short_circuit;
-	  if (!logical_op_non_short_circuit || flag_sanitize_coverage)
+	  if (!logical_op_non_short_circuit || sanitize_coverage_p ())
 	    return false;
 	  /* Only do this optimization if the inner bb contains only the conditional. */
 	  if (!gsi_one_before_end_p (gsi_start_nondebug_after_labels_bb (inner_cond_bb)))
-- 
2.31.1

Re: [PATCH] Add no_sanitize_coverage attribute.

[Marco Elver]

On Mon, 24 May 2021 at 10:03, Martin Liška <mliska@suse.cz> wrote:
> On 5/21/21 2:39 PM, Marco Elver wrote:
> > On Fri, May 21, 2021 at 10:50AM +0200, Martin Liška wrote:
> >> On 5/20/21 12:55 PM, Marco Elver wrote:
> >>> I think this came up with other no_sanitize [1] based on what I had
> >>> written to you last year [2].
> >>>
> >>> [1]https://gcc.gnu.org/pipermail/gcc-patches/2020-June/547618.html
> >>> [2]https://lore.kernel.org/lkml/CANpmjNNRz5OVKb6PE7K6GjfoGbht_ZhyPkNG9aD+KjNDzK7hGg@mail.gmail.com/
> >>
> >> Ah, you're right. I've just updated the patch to address that.
> >>
> >> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
> >>
> >> Ready to be installed?
> >
> > Looks good, I also just built a kernel with the no_sanitize_coverage
> > attribute (without the objtool nop-workaround) and works as expected.
>
> Good, thanks!
>
> >
> > Not sure if required, but would such an additional test be useful:
>
> Yes, it is, thanks for it.
[...]
> > Otherwise, please go ahead. I assume this is targeting GCC 12?
>
> Yep.
>
> There's V3 I'm sending.
>
> Ready for master?

From my side this looks good. Thank you!

-- Marco

Re: [PATCH] Add no_sanitize_coverage attribute.

[Richard Biener]

On Mon, May 24, 2021 at 10:27 AM Martin Liška <mliska@suse.cz> wrote:
>
> On 5/21/21 2:39 PM, Marco Elver wrote:
> > On Fri, May 21, 2021 at 10:50AM +0200, Martin Liška wrote:
> >> On 5/20/21 12:55 PM, Marco Elver wrote:
> >>> I think this came up with other no_sanitize [1] based on what I had
> >>> written to you last year [2].
> >>>
> >>> [1]https://gcc.gnu.org/pipermail/gcc-patches/2020-June/547618.html
> >>> [2]https://lore.kernel.org/lkml/CANpmjNNRz5OVKb6PE7K6GjfoGbht_ZhyPkNG9aD+KjNDzK7hGg@mail.gmail.com/
> >>
> >> Ah, you're right. I've just updated the patch to address that.
> >>
> >> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
> >>
> >> Ready to be installed?
> >
> > Looks good, I also just built a kernel with the no_sanitize_coverage
> > attribute (without the objtool nop-workaround) and works as expected.
>
> Good, thanks!
>
> >
> > Not sure if required, but would such an additional test be useful:
>
> Yes, it is, thanks for it.
>
> >
> > ---
> >
> > diff --git a/gcc/testsuite/gcc.dg/sancov/attribute.c b/gcc/testsuite/gcc.dg/sancov/attribute.c
> > index bf6dbd4bae7..7cfa9134ff1 100644
> > --- a/gcc/testsuite/gcc.dg/sancov/attribute.c
> > +++ b/gcc/testsuite/gcc.dg/sancov/attribute.c
> > @@ -11,5 +11,17 @@ bar(void)
> >   {
> >   }
> >
> > +static void inline
> > +__attribute__((always_inline))
> > +inline_fn(void)
> > +{
> > +}
> > +
> > +void
> > +__attribute__((no_sanitize_coverage))
> > +baz(void)
> > +{
> > +  inline_fn();
> > +}
> >
> >   /* { dg-final { scan-tree-dump-times "__builtin___sanitizer_cov_trace_pc \\(\\)" 1 "optimized" } } */
> >
> > ---
> >
> > Otherwise, please go ahead. I assume this is targeting GCC 12?
>
> Yep.
>
> There's V3 I'm sending.
>
> Ready for master?

OK.

Thanks,
Richard.

> Thanks,
> Martin
>
> >
> > Thanks,
> > -- Marco
> >
>