On 2021-03-12, 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.
When we drop clang-10 support from the kernel, we should carefully
update the original implementations to try to preserve git blame,
deleting these implementations.
Link: https://reviews.llvm.org/rGcdd683b516d147925212724b09ec6fb792a40041
Link: https://reviews.llvm.org/rG13a633b438b6500ecad9e4f936ebadf3411d0f44
Cc: Fangrui Song <mask...@google.com>
Reported-by: Prasad Sodagudi<psoda...@quicinc.com>
Signed-off-by: Nick Desaulniers <ndesaulni...@google.com>
---
kernel/gcov/clang.c | 69 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 69 insertions(+)
diff --git a/kernel/gcov/clang.c b/kernel/gcov/clang.c
index c94b820a1b62..20e6760ec05d 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 __clang_major__ < 11
const char *function_name;
+#endif
function_name can be unconditionally deleted. It is not used by llvm-cov
gcov. You'll need to delete a few assignments to gcov_info_free but you
can then unify the gcov_fn_info_dup and gcov_info_free implementations.
};
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 __clang_major__ < 11
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
LG. On big-endian systems, clang < 11 emitted .gcno/.gcda files do not
work with llvm-cov gcov < 11. To fix it and make .gcno/.gcda work with
gcc gcov I chose to break compatibility (and make all the breaking
changes like deleting some CC1 options) in a short window. At that time
I was not aware that there is the kernel implementation. Later on I was
CCed on a few https://github.com/ClangBuiltLinux/linux/ gcov issues but
I forgot to mention the interface change.
Now in clang 11 onward, clang --coverage defaults to the gcov 4.8
compatible format. You can specify the CC1 option (internal option,
subject to change) -coverage-version to make it compatible with other
versions' gcov.
-Xclang -coverage-version='407*' => 4.7
-Xclang -coverage-version='704*' => 7.4
-Xclang -coverage-version='B02*' => 10.2 (('B'-'A')*10 = 10)
Reviewed-by: Fangrui Song <mask...@google.com>
+#if __clang_major__ < 11
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, ¤t_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, ¤t_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 __clang_major__ < 11
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 __clang_major__ < 11
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
