On Fri, Aug 23, 2024 at 2:24 PM Will Deacon <will@xxxxxxxxxx> wrote: > > On Tue, Aug 20, 2024 at 05:13:58PM +0200, Alice Ryhl wrote: > > 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: > > > > 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. > > I'm not sure I follow why this will get really complicated. Isn't it as > straightforward as the diff below, or did I miss something? Hmm. I tried this but I wasn't able to enable Rust with this setup. Even though the deps of RUSTC_SUPPORTS_ARM64 are ok, it doesn't seem to be enabled and I can't find it in menuconfig. I think we need to have a `select RUSTC_SUPPORTS_ARM64` somewhere. Alice > --->8 > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index a2f8ff354ca6..2f5702cb9dac 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -231,7 +231,7 @@ config ARM64 > select HAVE_FUNCTION_ARG_ACCESS_API > select MMU_GATHER_RCU_TABLE_FREE > select HAVE_RSEQ > - select HAVE_RUST if CPU_LITTLE_ENDIAN > + select HAVE_RUST if RUSTC_SUPPORTS_ARM64 > select HAVE_STACKPROTECTOR > select HAVE_SYSCALL_TRACEPOINTS > select HAVE_KPROBES > @@ -265,6 +265,11 @@ config ARM64 > help > ARM 64-bit (AArch64) Linux support. > > +config RUSTC_SUPPORTS_ARM64 > + bool > + depends on CPU_LITTLE_ENDIAN > + depends on !SHADOW_CALL_STACK || RUSTC_VERSION >= 108000 && UNWIND_PATCH_PAC_INTO_SC > + > config CLANG_SUPPORTS_DYNAMIC_FTRACE_WITH_ARGS > def_bool CC_IS_CLANG > # https://github.com/ClangBuiltLinux/linux/issues/1507 > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > index 0f3cd7c3a436..93858dbfefc0 100644 > --- a/arch/riscv/Kconfig > +++ b/arch/riscv/Kconfig > @@ -172,7 +172,7 @@ config RISCV > select HAVE_REGS_AND_STACK_ACCESS_API > select HAVE_RETHOOK if !XIP_KERNEL > select HAVE_RSEQ > - select HAVE_RUST if 64BIT > + select HAVE_RUST if 64BIT && !SHADOW_CALL_STACK > select HAVE_SAMPLE_FTRACE_DIRECT > select HAVE_SAMPLE_FTRACE_DIRECT_MULTI > select HAVE_STACKPROTECTOR > diff --git a/init/Kconfig b/init/Kconfig > index 5783a0b87517..3ada33b1d681 100644 > --- a/init/Kconfig > +++ b/init/Kconfig > @@ -1902,7 +1902,6 @@ config RUST > depends on !MODVERSIONS > depends on !GCC_PLUGINS > depends on !RANDSTRUCT > - depends on !SHADOW_CALL_STACK > depends on !DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE > help > Enables Rust support in the kernel. >
