On Tue, Aug 20, 2024 at 4:35 PM Will Deacon <will@xxxxxxxxxx> wrote: > > On Tue, Aug 06, 2024 at 10:01:44AM +0000, Alice Ryhl wrote: > > This patch adds all of the flags that are needed to support the shadow > > call stack (SCS) sanitizer with Rust, and updates Kconfig to allow > > configurations that work. > > Minor nit, but some folks have allergic reactions to "This patch". > See: > > https://docs.kernel.org/process/submitting-patches.html#describe-your-changes > > I think the commit message is much better now, though, so thank you for > adding so much more detail for v5. If you end up respinning anyway, you > could move this all to the imperative. Ah, yeah, I keep forgetting about this. I'll change it to imperative if I send another version. > > Makefile | 1 + > > arch/arm64/Makefile | 3 +++ > > init/Kconfig | 2 +- > > 3 files changed, 5 insertions(+), 1 deletion(-) > > > > diff --git a/Makefile b/Makefile > > index 44c02a6f60a1..eb01a26d8354 100644 > > --- a/Makefile > > +++ b/Makefile > > @@ -927,6 +927,7 @@ ifdef CONFIG_SHADOW_CALL_STACK > > ifndef CONFIG_DYNAMIC_SCS > > CC_FLAGS_SCS := -fsanitize=shadow-call-stack > > KBUILD_CFLAGS += $(CC_FLAGS_SCS) > > +KBUILD_RUSTFLAGS += -Zsanitizer=shadow-call-stack > > endif > > export CC_FLAGS_SCS > > endif > > diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile > > index f6bc3da1ef11..b058c4803efb 100644 > > --- a/arch/arm64/Makefile > > +++ b/arch/arm64/Makefile > > @@ -57,9 +57,11 @@ KBUILD_AFLAGS += $(call cc-option,-mabi=lp64) > > ifneq ($(CONFIG_UNWIND_TABLES),y) > > KBUILD_CFLAGS += -fno-asynchronous-unwind-tables -fno-unwind-tables > > KBUILD_AFLAGS += -fno-asynchronous-unwind-tables -fno-unwind-tables > > +KBUILD_RUSTFLAGS += -Cforce-unwind-tables=n > > else > > KBUILD_CFLAGS += -fasynchronous-unwind-tables > > KBUILD_AFLAGS += -fasynchronous-unwind-tables > > +KBUILD_RUSTFLAGS += -Cforce-unwind-tables=y -Zuse-sync-unwind=n > > endif > > > > ifeq ($(CONFIG_STACKPROTECTOR_PER_TASK),y) > > @@ -114,6 +116,7 @@ endif > > > > ifeq ($(CONFIG_SHADOW_CALL_STACK), y) > > KBUILD_CFLAGS += -ffixed-x18 > > +KBUILD_RUSTFLAGS += -Zfixed-x18 > > endif > > > > ifeq ($(CONFIG_CPU_BIG_ENDIAN), y) > > diff --git a/init/Kconfig b/init/Kconfig > > index fe76c5d0a72e..d857f6f90885 100644 > > --- a/init/Kconfig > > +++ b/init/Kconfig > > @@ -1909,7 +1909,7 @@ config RUST > > depends on !MODVERSIONS > > depends on !GCC_PLUGINS > > depends on !RANDSTRUCT > > - depends on !SHADOW_CALL_STACK > > + depends on !SHADOW_CALL_STACK || RUSTC_VERSION >= 108000 && UNWIND_PATCH_PAC_INTO_SCS > > Sorry, I didn't spot this in v4, but since UNWIND_PATCH_PAC_INTO_SCS is > specific to arm64 and the only other architecture selecting > ARCH_SUPPORTS_SHADOW_CALL_STACK is riscv, I can't help but feel it would > be cleaner to move this logic into the arch code selecting HAVE_RUST. > > That is, it's up to the architecture to make sure that it has whatever > it needs for SCS to work with Rust if it claims to support Rust. > > What do you think? The `select RUST if ...` is going to get really complicated if we apply that rule in general. Having options here allows us to split them across several `depends on` clauses. I'm not sure it will even work, I had issues with cyclic Kconfig errors previously. I also don't think it's unreasonable for the architecture to say it supports both options when it really does support both; they are just mutually exclusive. I also think there is value in having all of the options that Rust doesn't work with in one place. So I'd like to keep it as-is. Alice
