From: Sami Tolvanen samitolvanen@google.com
[ Upstream commit 9520a2b3f0b5e182f73410e45b9b92ea51d9b828 ]
With CONFIG_GENDWARFKSYMS, __gendwarfksyms_ptr variables are added to the kernel in EXPORT_SYMBOL() to ensure DWARF type information is available for exported symbols in the TUs where they're actually exported. These symbols are dropped when linking vmlinux, but dangling references to them remain in DWARF.
With CONFIG_DEBUG_INFO_BTF enabled on X86, pahole versions after commit 47dcb534e253 ("btf_encoder: Stop indexing symbols for VARs") and before commit 9810758003ce ("btf_encoder: Verify 0 address DWARF variables are in ELF section") place these symbols in the .data..percpu section, which results in an "Invalid offset" error in btf_datasec_check_meta() during boot, as all the variables are at zero offset and have non-zero size. If CONFIG_DEBUG_INFO_BTF_MODULES is enabled, this also results in a failure to load modules with:
failed to validate module [$module] BTF: -22
As the issue occurs in pahole v1.28 and the fix was merged after v1.29 was released, require pahole <v1.28 or >v1.29 when GENDWARFKSYMS is enabled with DEBUG_INFO_BTF on X86.
Reported-by: Paolo Pisati paolo.pisati@canonical.com Signed-off-by: Sami Tolvanen samitolvanen@google.com Signed-off-by: Masahiro Yamada masahiroy@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/module/Kconfig | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/kernel/module/Kconfig b/kernel/module/Kconfig index d7762ef5949a2..39278737bb68f 100644 --- a/kernel/module/Kconfig +++ b/kernel/module/Kconfig @@ -192,6 +192,11 @@ config GENDWARFKSYMS depends on !DEBUG_INFO_REDUCED && !DEBUG_INFO_SPLIT # Requires ELF object files. depends on !LTO + # To avoid conflicts with the discarded __gendwarfksyms_ptr symbols on + # X86, requires pahole before commit 47dcb534e253 ("btf_encoder: Stop + # indexing symbols for VARs") or after commit 9810758003ce ("btf_encoder: + # Verify 0 address DWARF variables are in ELF section"). + depends on !X86 || !DEBUG_INFO_BTF || PAHOLE_VERSION < 128 || PAHOLE_VERSION > 129 help Calculate symbol versions from DWARF debugging information using gendwarfksyms. Requires DEBUG_INFO to be enabled.