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: sta...@vger.kernel.org #5.4+ Reported-by: Prasad Sodagudi <psoda...@quicinc.com> Tested-by: Prasad Sodagudi <psoda...@quicinc.com> Signed-off-by: Nick Desaulniers <ndesaulni...@google.com> Reviewed-by: Nathan Chancellor <nat...@kernel.org> --- Changes V1 -> V2: * Carried Nathan's reviewed-by tag. * Rebased on mainline, as per Andrew. * Left off patch 2/2 from the series https://lore.kernel.org/lkml/20210407185456.41943-1-ndesaulni...@google.com/ I assume that dropping support for clang-10+GCOV will be held separately for -next for 5.13, while this will be sent for 5.12? kernel/gcov/clang.c | 29 +++++++++++++++++++---------- 1 file changed, 19 insertions(+), 10 deletions(-) diff --git a/kernel/gcov/clang.c b/kernel/gcov/clang.c index 8743150db2ac..c466c7fbdece 100644 --- a/kernel/gcov/clang.c +++ b/kernel/gcov/clang.c @@ -70,7 +70,9 @@ struct gcov_fn_info { u32 ident; u32 checksum; +#if CONFIG_CLANG_VERSION < 110000 u8 use_extra_checksum; +#endif u32 cfg_checksum; u32 num_counters; @@ -145,10 +147,8 @@ 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) +void llvm_gcda_emit_function(u32 ident, u32 func_checksum, u32 cfg_checksum) { struct gcov_fn_info *info = kzalloc(sizeof(*info), GFP_KERNEL); @@ -158,12 +158,11 @@ void llvm_gcda_emit_function(u32 ident, u32 func_checksum, 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 +EXPORT_SYMBOL(llvm_gcda_emit_function); void llvm_gcda_emit_arcs(u32 num_counters, u64 *counters) { @@ -293,11 +292,16 @@ 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); } @@ -529,17 +533,22 @@ static 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); base-commit: 3fb4f979b4fa1f92a02b538ae86e725b73e703d0 -- 2.31.1.295.g9ea45b61b8-goog
