[PATCH] iommu/generic_pt: disable GCOV for iommu_amdv1.o

[Konstantin Khorenko <khorenko@virtuozzo.com>]

With -fprofile-update=atomic in global CFLAGS_GCOV, GCC cannot
constant-fold FIELD_PREP() expressions inside deeply inlined page table
walker functions.  GCC creates .constprop clones of the inline level
functions, which get their own GCOV instrumentation that prevents
constant evaluation of compile-time checks.

__no_profile cannot be used here because the entire call chain is
__always_inline functions generated by PT_MAKE_LEVELS() macro, and GCC's
constprop cloning creates new profiled function bodies that bypass the
attribute.

Disable GCOV for iommu_amdv1.o to allow BUILD_BUG_ON / FIELD_PREP
compile-time checks to succeed.

Signed-off-by: Konstantin Khorenko <khorenko@virtuozzo.com>
---
 drivers/iommu/generic_pt/fmt/Makefile | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/iommu/generic_pt/fmt/Makefile b/drivers/iommu/generic_pt/fmt/Makefile
index 976b49ec97dc..0305f7fb9e35 100644
--- a/drivers/iommu/generic_pt/fmt/Makefile
+++ b/drivers/iommu/generic_pt/fmt/Makefile
@@ -1,5 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 
+GCOV_PROFILE_iommu_amdv1.o := n
+
 iommu_pt_fmt-$(CONFIG_IOMMU_PT_AMDV1) += amdv1
 iommu_pt_fmt-$(CONFIG_IOMMUFD_TEST) += mock
 
-- 
2.43.5