Export nova-core's Rust symbols so nova-drm can resolve references to it when loaded as a module.
This is done by generating declarations and EXPORT_SYMBOL_RUST_GPL() calls for Rust symbols referenced by nova-drm, and compiling them into the module as `nova_core_exports.o`. `nova_core_exports.o` declares every Rust symbol as `extern int`. Running `gendwarfksyms` on it would compute CRCs from those placeholder types instead of the real Rust ones, so make MODVERSIONS use this shim only for the export list, and derive CRCs from `nova_core.o`. This patch is intended to be a workaround until the build system supports Rust cross-crate dependencies natively. Signed-off-by: Alexandre Courbot <[email protected]> --- drivers/gpu/Makefile | 40 ++++++++++++++++++++++++++++++- drivers/gpu/nova-core/.gitignore | 1 + drivers/gpu/nova-core/nova_core_exports.c | 15 ++++++++++++ 3 files changed, 55 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/Makefile b/drivers/gpu/Makefile index 45e0941324fb..67d51b7f3f55 100644 --- a/drivers/gpu/Makefile +++ b/drivers/gpu/Makefile @@ -14,7 +14,45 @@ obj-$(CONFIG_TRACE_GPU_MEM) += trace/ # system supports cross-crate dependencies natively. obj-$(CONFIG_NOVA_CORE) += nova-core.o -nova-core-y := nova-core/nova_core.o +nova-core-y := nova-core/nova_core.o nova-core/nova_core_exports.o obj-$(CONFIG_DRM_NOVA) += nova-drm.o nova-drm-y := drm/nova/nova.o + +# Export Rust symbols from nova-core only if nova-drm actually references them. +nova-core-export-deps := $(if $(CONFIG_DRM_NOVA),$(obj)/drm/nova/nova.o) + +rust_needed_exports = \ + { $(if $(strip $(2)),$(NM) -u $(2);,) echo "__DEFINED_RUST_SYMBOLS__"; \ + $(NM) -p --defined-only $(1); } | \ + awk -v fmt='$(3)' ' \ + /^__DEFINED_RUST_SYMBOLS__$$/ { defs = 1; next } \ + !defs { if ($$NF ~ /^_R/) needed[$$NF] = 1; next } \ + defs && $$2 ~ /(T|R|D|B)/ && $$3 ~ /^_R/ && \ + $$3 !~ /_(init|cleanup)_module$$/ && \ + $$3 !~ /__(pfx|cfi|odr_asan)/ && \ + $$3 in needed { printf fmt, $$3 } \ + ' + +quiet_cmd_exports = EXPORTS $@ + cmd_exports = \ + $(call rust_needed_exports,$<,$(nova-core-export-deps),EXPORT_SYMBOL_RUST_GPL(%s);\n) > $@ + +$(obj)/nova-core/exports_nova_core_generated.h: $(obj)/nova-core/nova_core.o $(nova-core-export-deps) FORCE + $(call if_changed,exports) + +targets += nova-core/exports_nova_core_generated.h + +$(obj)/nova-core/nova_core_exports.o: $(obj)/nova-core/exports_nova_core_generated.h +CFLAGS_nova-core/nova_core_exports.o := -I $(objtree)/$(obj)/nova-core + +ifdef CONFIG_MODVERSIONS +# The C export shim declares Rust symbols as `extern int`, so reuse its export +# list but generate symbol CRCs from the Rust object instead of the shim's DWARF. +$(obj)/nova-core/nova_core_exports.o: private cmd_gensymtypes_c = \ + $(call getexportsymbols,\1) | \ + $(objtree)/scripts/gendwarfksyms/gendwarfksyms \ + $(if $(KBUILD_GENDWARFKSYMS_STABLE), --stable) \ + $(if $(KBUILD_SYMTYPES), --symtypes $(@:.o=.symtypes),) \ + $(obj)/nova-core/nova_core.o +endif diff --git a/drivers/gpu/nova-core/.gitignore b/drivers/gpu/nova-core/.gitignore new file mode 100644 index 000000000000..7cc8318c76b1 --- /dev/null +++ b/drivers/gpu/nova-core/.gitignore @@ -0,0 +1 @@ +exports_nova_core_generated.h diff --git a/drivers/gpu/nova-core/nova_core_exports.c b/drivers/gpu/nova-core/nova_core_exports.c new file mode 100644 index 000000000000..6e80ca9792ee --- /dev/null +++ b/drivers/gpu/nova-core/nova_core_exports.c @@ -0,0 +1,15 @@ +// SPDX-License-Identifier: GPL-2.0 +// SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved. + +/* + * Exports Rust symbols from the `nova_core` crate for use by dependent modules. + * + * This is a workaround until the build system supports Rust cross-module + * dependencies natively. + */ + +#include <linux/export.h> + +#define EXPORT_SYMBOL_RUST_GPL(sym) extern int sym; EXPORT_SYMBOL_GPL(sym) + +#include "exports_nova_core_generated.h" -- 2.54.0
