On Wed, Apr 07, 2021 at 11:54:55AM -0700, Nick Desaulniers wrote:
LLVM changed the expected function signature for llvm_gcda_emit_function() in the clang-11 release. Users of clang-11 or newer may have noticed their kernels producing invalid coverage information:
$ llvm-cov gcov -a -c -u -f -b <input>.gcda -- gcno=<input>.gcno 1 <func>: checksum mismatch, \ (<lineno chksum A>, <cfg chksum B>) != (<lineno chksum A>, <cfg chksum C>) 2 Invalid .gcda File! ...
Fix up the function signatures so calling this function interprets its parameters correctly and computes the correct cfg checksum. In particular, in clang-11, the additional checksum is no longer optional.
Link: https://reviews.llvm.org/rG25544ce2df0daa4304c07e64b9c8b0f7df60c11d Cc: stable@vger.kernel.org #5.4+ Reported-by: Prasad Sodagudi psodagud@quicinc.com Tested-by: Prasad Sodagudi psodagud@quicinc.com Signed-off-by: Nick Desaulniers ndesaulniers@google.com
Reviewed-by: Nathan Chancellor nathan@kernel.org
kernel/gcov/clang.c | 38 +++++++++++++++++++++++++++++++++----- 1 file changed, 33 insertions(+), 5 deletions(-)
diff --git a/kernel/gcov/clang.c b/kernel/gcov/clang.c index d41f5ecda9db..1747204541bf 100644 --- a/kernel/gcov/clang.c +++ b/kernel/gcov/clang.c @@ -69,7 +69,9 @@ struct gcov_fn_info { u32 ident; u32 checksum; +#if CONFIG_CLANG_VERSION < 110000 u8 use_extra_checksum; +#endif u32 cfg_checksum; u32 num_counters; @@ -111,6 +113,7 @@ void llvm_gcda_start_file(const char *orig_filename, u32 version, u32 checksum) } EXPORT_SYMBOL(llvm_gcda_start_file); +#if CONFIG_CLANG_VERSION < 110000 void llvm_gcda_emit_function(u32 ident, u32 func_checksum, u8 use_extra_checksum, u32 cfg_checksum) { @@ -126,6 +129,21 @@ void llvm_gcda_emit_function(u32 ident, u32 func_checksum, info->cfg_checksum = cfg_checksum; list_add_tail(&info->head, ¤t_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);
- if (!info)
return;- INIT_LIST_HEAD(&info->head);
- info->ident = ident;
- info->checksum = func_checksum;
- info->cfg_checksum = cfg_checksum;
- list_add_tail(&info->head, ¤t_info->functions);
+} +#endif EXPORT_SYMBOL(llvm_gcda_emit_function); void llvm_gcda_emit_arcs(u32 num_counters, u64 *counters) @@ -256,11 +274,16 @@ 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); } @@ -378,17 +401,22 @@ size_t convert_to_gcda(char *buffer, struct gcov_info *info) list_for_each_entry(fi_ptr, &info->functions, head) { u32 i;
u32 len = 2;if (fi_ptr->use_extra_checksum)len++;pos += store_gcov_u32(buffer, pos, GCOV_TAG_FUNCTION);
pos += store_gcov_u32(buffer, pos, len);+#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); -- 2.31.1.295.g9ea45b61b8-goog