[PATCH v3] gcov: clang: drop support for clang-10 and older

From: Nick Desaulniers
Date: Tue Apr 13 2021 - 14:31:29 EST


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
Link: https://lkml.kernel.org/r/20210312224132.3413602-3-ndesaulniers@xxxxxxxxxx
Signed-off-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Suggested-by: Nathan Chancellor <nathan@xxxxxxxxxx>
Acked-by: Peter Oberparleiter <oberpar@xxxxxxxxxxxxx>
Reviewed-by: Nathan Chancellor <nathan@xxxxxxxxxx>
Reviewed-by: Fangrui Song <maskray@xxxxxxxxxx>
Cc: Prasad Sodagudi <psodagud@xxxxxxxxxxx>
Cc: Johannes Berg <johannes.berg@xxxxxxxxx>
---
This patch is
https://lore.kernel.org/lkml/20210412214210.6e1ecca9cdc5.I24459763acf0591d5e6b31c7e3a59890d802f79c@changeid/
and
https://lore.kernel.org/lkml/20210312224132.3413602-3-ndesaulniers@xxxxxxxxxx/
rolled into one, then rebased on linux-next with
https://lore.kernel.org/lkml/20210412214210.6e1ecca9cdc5.I24459763acf0591d5e6b31c7e3a59890d802f79c@changeid/
applied. I merged the Reviewed-by and Acked-by tags. It was
simpler to drop v1
https://www.spinics.net/lists/mm-commits/msg154861.html in order to land
commit 9562fd132985 ("gcov: re-fix clang-11+ support").

kernel/gcov/Kconfig | 1 +
kernel/gcov/clang.c | 103 --------------------------------------------
2 files changed, 1 insertion(+), 103 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 d43ffd0c5ddb..cbb0bed958ab 100644
--- a/kernel/gcov/clang.c
+++ b/kernel/gcov/clang.c
@@ -69,16 +69,10 @@ struct gcov_fn_info {

u32 ident;
u32 checksum;
-#if CONFIG_CLANG_VERSION < 110000
- u8 use_extra_checksum;
-#endif
u32 cfg_checksum;

u32 num_counters;
u64 *counters;
-#if CONFIG_CLANG_VERSION < 110000
- const char *function_name;
-#endif
};

static struct gcov_info *current_info;
@@ -108,16 +102,6 @@ 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;
@@ -125,28 +109,7 @@ 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);
-}
-#else
void llvm_gcda_emit_function(u32 ident, u32 func_checksum, u32 cfg_checksum)
{
struct gcov_fn_info *info = kzalloc(sizeof(*info), GFP_KERNEL);
@@ -160,7 +123,6 @@ void llvm_gcda_emit_function(u32 ident, u32 func_checksum, u32 cfg_checksum)
info->cfg_checksum = cfg_checksum;
list_add_tail(&info->head, &current_info->functions);
}
-#endif
EXPORT_SYMBOL(llvm_gcda_emit_function);

void llvm_gcda_emit_arcs(u32 num_counters, u64 *counters)
@@ -291,16 +253,8 @@ int gcov_info_is_compatible(struct gcov_info *info1, struct gcov_info *info2)
!list_is_last(&fn_ptr2->head, &info2->functions)) {
if (fn_ptr1->checksum != fn_ptr2->checksum)
return false;
-#if CONFIG_CLANG_VERSION < 110000
- if (fn_ptr1->use_extra_checksum != fn_ptr2->use_extra_checksum)
- return false;
- if (fn_ptr1->use_extra_checksum &&
- fn_ptr1->cfg_checksum != fn_ptr2->cfg_checksum)
- return false;
-#else
if (fn_ptr1->cfg_checksum != fn_ptr2->cfg_checksum)
return false;
-#endif
fn_ptr1 = list_next_entry(fn_ptr1, head);
fn_ptr2 = list_next_entry(fn_ptr2, head);
}
@@ -329,35 +283,6 @@ 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 */
- struct gcov_fn_info *fn_dup = kmemdup(fn, sizeof(*fn), GFP_KERNEL);
-
- 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 = kvmalloc(cv_size, GFP_KERNEL);
- 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 */
@@ -378,7 +303,6 @@ static struct gcov_fn_info *gcov_fn_info_dup(struct gcov_fn_info *fn)

return fn_dup;
}
-#endif

/**
* gcov_info_dup - duplicate profiling data set
@@ -419,21 +343,6 @@ 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;
@@ -446,7 +355,6 @@ void gcov_info_free(struct gcov_info *info)
kfree(info->filename);
kfree(info);
}
-#endif

/**
* convert_to_gcda - convert profiling data set to gcda file format
@@ -469,21 +377,10 @@ size_t convert_to_gcda(char *buffer, struct gcov_info *info)
u32 i;

pos += store_gcov_u32(buffer, pos, GCOV_TAG_FUNCTION);
-#if CONFIG_CLANG_VERSION < 110000
- pos += store_gcov_u32(buffer, pos,
- fi_ptr->use_extra_checksum ? 3 : 2);
-#else
pos += store_gcov_u32(buffer, pos, 3);
-#endif
pos += store_gcov_u32(buffer, pos, fi_ptr->ident);
pos += store_gcov_u32(buffer, pos, fi_ptr->checksum);
-#if CONFIG_CLANG_VERSION < 110000
- if (fi_ptr->use_extra_checksum)
- pos += store_gcov_u32(buffer, pos, fi_ptr->cfg_checksum);
-#else
pos += store_gcov_u32(buffer, pos, fi_ptr->cfg_checksum);
-#endif
-
pos += store_gcov_u32(buffer, pos, GCOV_TAG_COUNTER_BASE);
pos += store_gcov_u32(buffer, pos, fi_ptr->num_counters * 2);
for (i = 0; i < fi_ptr->num_counters; i++)
--
2.31.1.295.g9ea45b61b8-goog