Commit 9562fd13 authored by Nick Desaulniers's avatar Nick Desaulniers Committed by Linus Torvalds
Browse files

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: default avatarPrasad Sodagudi <psodagud@quicinc.com>
Tested-by: default avatarPrasad Sodagudi <psodagud@quicinc.com>
Signed-off-by: default avatarNick Desaulniers <ndesaulniers@google.com>
Reviewed-by: default avatarNathan Chancellor <nathan@kernel.org>
Cc: <stable@vger.kernel.org>	[5.4+]

Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a3a8833d

kernel/gcov/clang.c

+19 −10
Original line number Diff line number Diff line
@@ -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, &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, 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, &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_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);