The patch titled Subject: gcov: re-fix clang-11+ support has been added to the -mm tree. Its filename is gcov-re-fix-clang-11-support.patch

This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/gcov-re-fix-clang-11-support.patch and later at https://ozlabs.org/~akpm/mmotm/broken-out/gcov-re-fix-clang-11-support.patch

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------------------------------------------------------ From: Nick Desaulniers ndesaulniers@google.com Subject: gcov: re-fix clang-11+ support

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 Link: https://lkml.kernel.org/r/20210408184631.1156669-1-ndesaulniers@google.com 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 Cc: stable@vger.kernel.org [5.4+]

Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

kernel/gcov/clang.c | 29 +++++++++++++++++++---------- 1 file changed, 19 insertions(+), 10 deletions(-)

--- a/kernel/gcov/clang.c~gcov-re-fix-clang-11-support +++ a/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,

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) +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, 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, &current_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_ !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 *buff

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); _

Patches currently in -mm which might be from ndesaulniers@google.com are

gcov-re-fix-clang-11-support.patch gcov-clang-drop-support-for-clang-10-and-older.patch