diff mbox series

[v2,1/2] gcov: fix clang-11+ support

Message ID 20210312224132.3413602-2-ndesaulniers@google.com
State New
Headers show
Series [v2,1/2] gcov: fix clang-11+ support | expand

Commit Message

Nick Desaulniers March 12, 2021, 10:41 p.m. UTC 
LLVM changed the expected function signatures for llvm_gcda_start_file()
and llvm_gcda_emit_function() in the clang-11 release. Users of clang-11
or newer may have noticed their kernels failing to boot due to a panic
when enabling CONFIG_GCOV_KERNEL=y +CONFIG_GCOV_PROFILE_ALL=y.  Fix up
the function signatures so calling these functions doesn't panic the
kernel.

Link: https://reviews.llvm.org/rGcdd683b516d147925212724b09ec6fb792a40041
Link: https://reviews.llvm.org/rG13a633b438b6500ecad9e4f936ebadf3411d0f44
Cc: stable@vger.kernel.org # 5.4
Reported-by: Prasad Sodagudi <psodagud@quicinc.com>
Suggested-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Fangrui Song <maskray@google.com>

Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>

Tested-by: Nathan Chancellor <nathan@kernel.org>

---
Changes V1 -> V2:
* Use CONFIG_CLANG_VERSION instead of __clang_major__.
* Pick up and retain Suggested-by, Tested-by, and Reviewed-by tags.
* Drop note from commit message about `git blame`; I did what was
  sugguested in V1, but it still looks to git like I wrote those
  functions. Oh well.

 kernel/gcov/clang.c | 69 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)


base-commit: f78d76e72a4671ea52d12752d92077788b4f5d50
-- 
2.31.0.rc2.261.g7f71774620-goog

Comments

Peter Oberparleiter March 15, 2021, 1:51 p.m. UTC | #1 
On 12.03.2021 23:41, Nick Desaulniers wrote:
> LLVM changed the expected function signatures for llvm_gcda_start_file()

> and llvm_gcda_emit_function() in the clang-11 release. Users of clang-11

> or newer may have noticed their kernels failing to boot due to a panic

> when enabling CONFIG_GCOV_KERNEL=y +CONFIG_GCOV_PROFILE_ALL=y.  Fix up

> the function signatures so calling these functions doesn't panic the

> kernel.

> 

> Link: https://reviews.llvm.org/rGcdd683b516d147925212724b09ec6fb792a40041

> Link: https://reviews.llvm.org/rG13a633b438b6500ecad9e4f936ebadf3411d0f44

> Cc: stable@vger.kernel.org # 5.4

> Reported-by: Prasad Sodagudi <psodagud@quicinc.com>

> Suggested-by: Nathan Chancellor <nathan@kernel.org>

> Reviewed-by: Fangrui Song <maskray@google.com>

> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>

> Tested-by: Nathan Chancellor <nathan@kernel.org>


Looks good to me (minus the code duplication - but that's IMO acceptable
since it's cleaned up again with patch 2).

Acked-by: Peter Oberparleiter <oberpar@linux.ibm.com>


That said, I'm currently thinking of adding a compile time check that
performs a dry-run gcov_info => gcda conversion in user space to detect
these kind of issues before kernels fail unpredictably [1]. I'm
confident that this could work for the GCC gcov kernel code, not sure
about the Clang version though. But if it's possible I guess it would
make sense to extend this to include the Clang code as well.

Note that this check wouldn't work for cross-compiles since the build
machine must be able to run code for the target machine.

[1]
https://lore.kernel.org/lkml/1c7a49e7-0e27-561b-a2f9-d42a83dc4c29@linux.ibm.com/


Regards,
  Peter

-- 
Peter Oberparleiter
Linux on Z Development - IBM Germany
Nathan Chancellor March 15, 2021, 6:13 p.m. UTC | #2 
On Fri, Mar 12, 2021 at 02:41:31PM -0800, Nick Desaulniers wrote:
> LLVM changed the expected function signatures for llvm_gcda_start_file()

> and llvm_gcda_emit_function() in the clang-11 release. Users of clang-11

> or newer may have noticed their kernels failing to boot due to a panic

> when enabling CONFIG_GCOV_KERNEL=y +CONFIG_GCOV_PROFILE_ALL=y.  Fix up

> the function signatures so calling these functions doesn't panic the

> kernel.

> 

> Link: https://reviews.llvm.org/rGcdd683b516d147925212724b09ec6fb792a40041

> Link: https://reviews.llvm.org/rG13a633b438b6500ecad9e4f936ebadf3411d0f44

> Cc: stable@vger.kernel.org # 5.4

> Reported-by: Prasad Sodagudi <psodagud@quicinc.com>

> Suggested-by: Nathan Chancellor <nathan@kernel.org>

> Reviewed-by: Fangrui Song <maskray@google.com>

> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>

> Tested-by: Nathan Chancellor <nathan@kernel.org>


Reviewed-by: Nathan Chancellor <nathan@kernel.org>


> ---

> Changes V1 -> V2:

> * Use CONFIG_CLANG_VERSION instead of __clang_major__.

> * Pick up and retain Suggested-by, Tested-by, and Reviewed-by tags.

> * Drop note from commit message about `git blame`; I did what was

>   sugguested in V1, but it still looks to git like I wrote those

>   functions. Oh well.

> 

>  kernel/gcov/clang.c | 69 +++++++++++++++++++++++++++++++++++++++++++++

>  1 file changed, 69 insertions(+)

> 

> diff --git a/kernel/gcov/clang.c b/kernel/gcov/clang.c

> index c94b820a1b62..8743150db2ac 100644

> --- a/kernel/gcov/clang.c

> +++ b/kernel/gcov/clang.c

> @@ -75,7 +75,9 @@ struct gcov_fn_info {

>  

>  	u32 num_counters;

>  	u64 *counters;

> +#if CONFIG_CLANG_VERSION < 110000

>  	const char *function_name;

> +#endif

>  };

>  

>  static struct gcov_info *current_info;

> @@ -105,6 +107,7 @@ void llvm_gcov_init(llvm_gcov_callback writeout, llvm_gcov_callback flush)

>  }

>  EXPORT_SYMBOL(llvm_gcov_init);

>  

> +#if CONFIG_CLANG_VERSION < 110000

>  void llvm_gcda_start_file(const char *orig_filename, const char version[4],

>  		u32 checksum)

>  {

> @@ -113,7 +116,17 @@ void llvm_gcda_start_file(const char *orig_filename, const char version[4],

>  	current_info->checksum = checksum;

>  }

>  EXPORT_SYMBOL(llvm_gcda_start_file);

> +#else

> +void llvm_gcda_start_file(const char *orig_filename, u32 version, u32 checksum)

> +{

> +	current_info->filename = orig_filename;

> +	current_info->version = version;

> +	current_info->checksum = checksum;

> +}

> +EXPORT_SYMBOL(llvm_gcda_start_file);

> +#endif

>  

> +#if CONFIG_CLANG_VERSION < 110000

>  void llvm_gcda_emit_function(u32 ident, const char *function_name,

>  		u32 func_checksum, u8 use_extra_checksum, u32 cfg_checksum)

>  {

> @@ -133,6 +146,24 @@ void llvm_gcda_emit_function(u32 ident, const char *function_name,

>  	list_add_tail(&info->head, &current_info->functions);

>  }

>  EXPORT_SYMBOL(llvm_gcda_emit_function);

> +#else

> +void llvm_gcda_emit_function(u32 ident, u32 func_checksum,

> +		u8 use_extra_checksum, u32 cfg_checksum)

> +{

> +	struct gcov_fn_info *info = kzalloc(sizeof(*info), GFP_KERNEL);

> +

> +	if (!info)

> +		return;

> +

> +	INIT_LIST_HEAD(&info->head);

> +	info->ident = ident;

> +	info->checksum = func_checksum;

> +	info->use_extra_checksum = use_extra_checksum;

> +	info->cfg_checksum = cfg_checksum;

> +	list_add_tail(&info->head, &current_info->functions);

> +}

> +EXPORT_SYMBOL(llvm_gcda_emit_function);

> +#endif

>  

>  void llvm_gcda_emit_arcs(u32 num_counters, u64 *counters)

>  {

> @@ -295,6 +326,7 @@ void gcov_info_add(struct gcov_info *dst, struct gcov_info *src)

>  	}

>  }

>  

> +#if CONFIG_CLANG_VERSION < 110000

>  static struct gcov_fn_info *gcov_fn_info_dup(struct gcov_fn_info *fn)

>  {

>  	size_t cv_size; /* counter values size */

> @@ -322,6 +354,28 @@ static struct gcov_fn_info *gcov_fn_info_dup(struct gcov_fn_info *fn)

>  	kfree(fn_dup);

>  	return NULL;

>  }

> +#else

> +static struct gcov_fn_info *gcov_fn_info_dup(struct gcov_fn_info *fn)

> +{

> +	size_t cv_size; /* counter values size */

> +	struct gcov_fn_info *fn_dup = kmemdup(fn, sizeof(*fn),

> +			GFP_KERNEL);

> +	if (!fn_dup)

> +		return NULL;

> +	INIT_LIST_HEAD(&fn_dup->head);

> +

> +	cv_size = fn->num_counters * sizeof(fn->counters[0]);

> +	fn_dup->counters = vmalloc(cv_size);

> +	if (!fn_dup->counters) {

> +		kfree(fn_dup);

> +		return NULL;

> +	}

> +

> +	memcpy(fn_dup->counters, fn->counters, cv_size);

> +

> +	return fn_dup;

> +}

> +#endif

>  

>  /**

>   * gcov_info_dup - duplicate profiling data set

> @@ -362,6 +416,7 @@ struct gcov_info *gcov_info_dup(struct gcov_info *info)

>   * gcov_info_free - release memory for profiling data set duplicate

>   * @info: profiling data set duplicate to free

>   */

> +#if CONFIG_CLANG_VERSION < 110000

>  void gcov_info_free(struct gcov_info *info)

>  {

>  	struct gcov_fn_info *fn, *tmp;

> @@ -375,6 +430,20 @@ void gcov_info_free(struct gcov_info *info)

>  	kfree(info->filename);

>  	kfree(info);

>  }

> +#else

> +void gcov_info_free(struct gcov_info *info)

> +{

> +	struct gcov_fn_info *fn, *tmp;

> +

> +	list_for_each_entry_safe(fn, tmp, &info->functions, head) {

> +		vfree(fn->counters);

> +		list_del(&fn->head);

> +		kfree(fn);

> +	}

> +	kfree(info->filename);

> +	kfree(info);

> +}

> +#endif

>  

>  #define ITER_STRIDE	PAGE_SIZE

>  

> 

> base-commit: f78d76e72a4671ea52d12752d92077788b4f5d50

> -- 

> 2.31.0.rc2.261.g7f71774620-goog

>
diff mbox series

Patch

diff --git a/kernel/gcov/clang.c b/kernel/gcov/clang.c
index c94b820a1b62..8743150db2ac 100644
--- a/kernel/gcov/clang.c
+++ b/kernel/gcov/clang.c
@@ -75,7 +75,9 @@  struct gcov_fn_info {
 
 	u32 num_counters;
 	u64 *counters;
+#if CONFIG_CLANG_VERSION < 110000
 	const char *function_name;
+#endif
 };
 
 static struct gcov_info *current_info;
@@ -105,6 +107,7 @@  void llvm_gcov_init(llvm_gcov_callback writeout, llvm_gcov_callback flush)
 }
 EXPORT_SYMBOL(llvm_gcov_init);
 
+#if CONFIG_CLANG_VERSION < 110000
 void llvm_gcda_start_file(const char *orig_filename, const char version[4],
 		u32 checksum)
 {
@@ -113,7 +116,17 @@  void llvm_gcda_start_file(const char *orig_filename, const char version[4],
 	current_info->checksum = checksum;
 }
 EXPORT_SYMBOL(llvm_gcda_start_file);
+#else
+void llvm_gcda_start_file(const char *orig_filename, u32 version, u32 checksum)
+{
+	current_info->filename = orig_filename;
+	current_info->version = version;
+	current_info->checksum = checksum;
+}
+EXPORT_SYMBOL(llvm_gcda_start_file);
+#endif
 
+#if CONFIG_CLANG_VERSION < 110000
 void llvm_gcda_emit_function(u32 ident, const char *function_name,
 		u32 func_checksum, u8 use_extra_checksum, u32 cfg_checksum)
 {
@@ -133,6 +146,24 @@  void llvm_gcda_emit_function(u32 ident, const char *function_name,
 	list_add_tail(&info->head, &current_info->functions);
 }
 EXPORT_SYMBOL(llvm_gcda_emit_function);
+#else
+void llvm_gcda_emit_function(u32 ident, u32 func_checksum,
+		u8 use_extra_checksum, u32 cfg_checksum)
+{
+	struct gcov_fn_info *info = kzalloc(sizeof(*info), GFP_KERNEL);
+
+	if (!info)
+		return;
+
+	INIT_LIST_HEAD(&info->head);
+	info->ident = ident;
+	info->checksum = func_checksum;
+	info->use_extra_checksum = use_extra_checksum;
+	info->cfg_checksum = cfg_checksum;
+	list_add_tail(&info->head, &current_info->functions);
+}
+EXPORT_SYMBOL(llvm_gcda_emit_function);
+#endif
 
 void llvm_gcda_emit_arcs(u32 num_counters, u64 *counters)
 {
@@ -295,6 +326,7 @@  void gcov_info_add(struct gcov_info *dst, struct gcov_info *src)
 	}
 }
 
+#if CONFIG_CLANG_VERSION < 110000
 static struct gcov_fn_info *gcov_fn_info_dup(struct gcov_fn_info *fn)
 {
 	size_t cv_size; /* counter values size */
@@ -322,6 +354,28 @@  static struct gcov_fn_info *gcov_fn_info_dup(struct gcov_fn_info *fn)
 	kfree(fn_dup);
 	return NULL;
 }
+#else
+static struct gcov_fn_info *gcov_fn_info_dup(struct gcov_fn_info *fn)
+{
+	size_t cv_size; /* counter values size */
+	struct gcov_fn_info *fn_dup = kmemdup(fn, sizeof(*fn),
+			GFP_KERNEL);
+	if (!fn_dup)
+		return NULL;
+	INIT_LIST_HEAD(&fn_dup->head);
+
+	cv_size = fn->num_counters * sizeof(fn->counters[0]);
+	fn_dup->counters = vmalloc(cv_size);
+	if (!fn_dup->counters) {
+		kfree(fn_dup);
+		return NULL;
+	}
+
+	memcpy(fn_dup->counters, fn->counters, cv_size);
+
+	return fn_dup;
+}
+#endif
 
 /**
  * gcov_info_dup - duplicate profiling data set
@@ -362,6 +416,7 @@  struct gcov_info *gcov_info_dup(struct gcov_info *info)
  * gcov_info_free - release memory for profiling data set duplicate
  * @info: profiling data set duplicate to free
  */
+#if CONFIG_CLANG_VERSION < 110000
 void gcov_info_free(struct gcov_info *info)
 {
 	struct gcov_fn_info *fn, *tmp;
@@ -375,6 +430,20 @@  void gcov_info_free(struct gcov_info *info)
 	kfree(info->filename);
 	kfree(info);
 }
+#else
+void gcov_info_free(struct gcov_info *info)
+{
+	struct gcov_fn_info *fn, *tmp;
+
+	list_for_each_entry_safe(fn, tmp, &info->functions, head) {
+		vfree(fn->counters);
+		list_del(&fn->head);
+		kfree(fn);
+	}
+	kfree(info->filename);
+	kfree(info);
+}
+#endif
 
 #define ITER_STRIDE	PAGE_SIZE