[PATCH v2 2/2] gcov: clang: drop support for clang-10 and older

[Nick Desaulniers <ndesaulniers@google.com>]

LLVM changed the expected function signatures for llvm_gcda_start_file()
and llvm_gcda_emit_function() in the clang-11 release. Drop the older
implementations and require folks to upgrade their compiler if they're
interested in GCOV support.

Link: https://reviews.llvm.org/rGcdd683b516d147925212724b09ec6fb792a40041
Link: https://reviews.llvm.org/rG13a633b438b6500ecad9e4f936ebadf3411d0f44
Suggested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
For an easier time reviewing this series, reviewers may want to apply
these patches, then check the overall diff with `git diff origin/HEAD`.

 kernel/gcov/Kconfig |  1 +
 kernel/gcov/clang.c | 85 ---------------------------------------------
 2 files changed, 1 insertion(+), 85 deletions(-)

diff --git a/kernel/gcov/Kconfig b/kernel/gcov/Kconfig
index f62de2dea8a3..58f87a3092f3 100644
--- a/kernel/gcov/Kconfig
+++ b/kernel/gcov/Kconfig
@@ -4,6 +4,7 @@ menu "GCOV-based kernel profiling"
 config GCOV_KERNEL
 	bool "Enable gcov-based kernel profiling"
 	depends on DEBUG_FS
+	depends on !CC_IS_CLANG || CLANG_VERSION >= 110000
 	select CONSTRUCTORS
 	default n
 	help
diff --git a/kernel/gcov/clang.c b/kernel/gcov/clang.c
index 8743150db2ac..14de5644b5cc 100644
--- a/kernel/gcov/clang.c
+++ b/kernel/gcov/clang.c
@@ -75,9 +75,6 @@ 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;
@@ -107,16 +104,6 @@ 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)
-{
-	current_info->filename = orig_filename;
-	memcpy(&current_info->version, version, sizeof(current_info->version));
-	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;
@@ -124,29 +111,7 @@ void llvm_gcda_start_file(const char *orig_filename, u32 version, u32 checksum)
 	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)
-{
-	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;
-	if (function_name)
-		info->function_name = kstrdup(function_name, GFP_KERNEL);
-
-	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)
 {
@@ -163,7 +128,6 @@ void llvm_gcda_emit_function(u32 ident, u32 func_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)
 {
@@ -326,7 +290,6 @@ 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 */
@@ -335,47 +298,15 @@ static struct gcov_fn_info *gcov_fn_info_dup(struct gcov_fn_info *fn)
 	if (!fn_dup)
 		return NULL;
 	INIT_LIST_HEAD(&fn_dup->head);
-
-	fn_dup->function_name = kstrdup(fn->function_name, GFP_KERNEL);
-	if (!fn_dup->function_name)
-		goto err_name;
-
-	cv_size = fn->num_counters * sizeof(fn->counters[0]);
-	fn_dup->counters = vmalloc(cv_size);
-	if (!fn_dup->counters)
-		goto err_counters;
-	memcpy(fn_dup->counters, fn->counters, cv_size);
-
-	return fn_dup;
-
-err_counters:
-	kfree(fn_dup->function_name);
-err_name:
-	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
@@ -416,21 +347,6 @@ 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;
-
-	list_for_each_entry_safe(fn, tmp, &info->functions, head) {
-		kfree(fn->function_name);
-		vfree(fn->counters);
-		list_del(&fn->head);
-		kfree(fn);
-	}
-	kfree(info->filename);
-	kfree(info);
-}
-#else
 void gcov_info_free(struct gcov_info *info)
 {
 	struct gcov_fn_info *fn, *tmp;
@@ -443,7 +359,6 @@ void gcov_info_free(struct gcov_info *info)
 	kfree(info->filename);
 	kfree(info);
 }
-#endif
 
 #define ITER_STRIDE	PAGE_SIZE
 
-- 
2.31.0.rc2.261.g7f71774620-goog