| Message ID | 20210305202124.3768527-1-samitolvanen@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: arm64: Don't use cbz/adr with external symbols | expand |
On Fri, Mar 05, 2021 at 12:21:24PM -0800, Sami Tolvanen wrote: > allmodconfig + CONFIG_LTO_CLANG_THIN=y fails to build due to following > linker errors: > > ld.lld: error: irqbypass.c:(function __guest_enter: .text+0x21CC): > relocation R_AARCH64_CONDBR19 out of range: 2031220 is not in > [-1048576, 1048575]; references hyp_panic > >>> defined in vmlinux.o > > ld.lld: error: irqbypass.c:(function __guest_enter: .text+0x21E0): > relocation R_AARCH64_ADR_PREL_LO21 out of range: 2031200 is not in > [-1048576, 1048575]; references hyp_panic > >>> defined in vmlinux.o > > This is because with LTO, the compiler ends up placing hyp_panic() > more than 1MB away from __guest_enter(). Use an unconditional branch > and adr_l instead to fix the issue. > > Link: https://github.com/ClangBuiltLinux/linux/issues/1317 > Reported-by: Nathan Chancellor <nathan@kernel.org> > Suggested-by: Marc Zyngier <maz@kernel.org> > Suggested-by: Ard Biesheuvel <ardb@kernel.org> > Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Reviewed-by: Kees Cook <keescook@chromium.org>
On Fri, Mar 05, 2021 at 12:21:24PM -0800, Sami Tolvanen wrote: > allmodconfig + CONFIG_LTO_CLANG_THIN=y fails to build due to following > linker errors: > > ld.lld: error: irqbypass.c:(function __guest_enter: .text+0x21CC): > relocation R_AARCH64_CONDBR19 out of range: 2031220 is not in > [-1048576, 1048575]; references hyp_panic > >>> defined in vmlinux.o > > ld.lld: error: irqbypass.c:(function __guest_enter: .text+0x21E0): > relocation R_AARCH64_ADR_PREL_LO21 out of range: 2031200 is not in > [-1048576, 1048575]; references hyp_panic > >>> defined in vmlinux.o > > This is because with LTO, the compiler ends up placing hyp_panic() > more than 1MB away from __guest_enter(). Use an unconditional branch > and adr_l instead to fix the issue. > > Link: https://github.com/ClangBuiltLinux/linux/issues/1317 > Reported-by: Nathan Chancellor <nathan@kernel.org> > Suggested-by: Marc Zyngier <maz@kernel.org> > Suggested-by: Ard Biesheuvel <ardb@kernel.org> > Signed-off-by: Sami Tolvanen <samitolvanen@google.com> I booted an kernel with this patch in it on my Raspberry Pi 4 and booted a kernel under KVM without any issues. Tested-by: Nathan Chancellor <nathan@kernel.org> > --- > arch/arm64/kvm/hyp/entry.S | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S > index b0afad7a99c6..c62265951467 100644 > --- a/arch/arm64/kvm/hyp/entry.S > +++ b/arch/arm64/kvm/hyp/entry.S > @@ -85,8 +85,10 @@ SYM_INNER_LABEL(__guest_exit_panic, SYM_L_GLOBAL) > > // If the hyp context is loaded, go straight to hyp_panic > get_loaded_vcpu x0, x1 > - cbz x0, hyp_panic > + cbnz x0, 1f > + b hyp_panic > > +1: > // The hyp context is saved so make sure it is restored to allow > // hyp_panic to run at hyp and, subsequently, panic to run in the host. > // This makes use of __guest_exit to avoid duplication but sets the > @@ -94,7 +96,7 @@ SYM_INNER_LABEL(__guest_exit_panic, SYM_L_GLOBAL) > // current state is saved to the guest context but it will only be > // accurate if the guest had been completely restored. > adr_this_cpu x0, kvm_hyp_ctxt, x1 > - adr x1, hyp_panic > + adr_l x1, hyp_panic > str x1, [x0, #CPU_XREG_OFFSET(30)] > > get_vcpu_ptr x1, x0 > > base-commit: 280d542f6ffac0e6d65dc267f92191d509b13b64 > -- > 2.30.1.766.gb4fecdf3b7-goog > > _______________________________________________ > kvmarm mailing list > kvmarm@lists.cs.columbia.edu > https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
On Fri, Mar 05, 2021 at 12:21:24PM -0800, Sami Tolvanen wrote: > allmodconfig + CONFIG_LTO_CLANG_THIN=y fails to build due to following > linker errors: > > ld.lld: error: irqbypass.c:(function __guest_enter: .text+0x21CC): > relocation R_AARCH64_CONDBR19 out of range: 2031220 is not in > [-1048576, 1048575]; references hyp_panic > >>> defined in vmlinux.o > > ld.lld: error: irqbypass.c:(function __guest_enter: .text+0x21E0): > relocation R_AARCH64_ADR_PREL_LO21 out of range: 2031200 is not in > [-1048576, 1048575]; references hyp_panic > >>> defined in vmlinux.o > > This is because with LTO, the compiler ends up placing hyp_panic() > more than 1MB away from __guest_enter(). Use an unconditional branch > and adr_l instead to fix the issue. > > Link: https://github.com/ClangBuiltLinux/linux/issues/1317 > Reported-by: Nathan Chancellor <nathan@kernel.org> > Suggested-by: Marc Zyngier <maz@kernel.org> > Suggested-by: Ard Biesheuvel <ardb@kernel.org> > Signed-off-by: Sami Tolvanen <samitolvanen@google.com> > --- > arch/arm64/kvm/hyp/entry.S | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) Acked-by: Will Deacon <will@kernel.org> Will
On Fri, 5 Mar 2021 12:21:24 -0800, Sami Tolvanen wrote: > allmodconfig + CONFIG_LTO_CLANG_THIN=y fails to build due to following > linker errors: > > ld.lld: error: irqbypass.c:(function __guest_enter: .text+0x21CC): > relocation R_AARCH64_CONDBR19 out of range: 2031220 is not in > [-1048576, 1048575]; references hyp_panic > >>> defined in vmlinux.o > > [...] Applied to next, thanks! [1/1] KVM: arm64: Don't use cbz/adr with external symbols commit: dbaee836d60a8e1b03e7d53a37893235662ba124 Cheers, M.
diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S index b0afad7a99c6..c62265951467 100644 --- a/arch/arm64/kvm/hyp/entry.S +++ b/arch/arm64/kvm/hyp/entry.S @@ -85,8 +85,10 @@ SYM_INNER_LABEL(__guest_exit_panic, SYM_L_GLOBAL) // If the hyp context is loaded, go straight to hyp_panic get_loaded_vcpu x0, x1 - cbz x0, hyp_panic + cbnz x0, 1f + b hyp_panic +1: // The hyp context is saved so make sure it is restored to allow // hyp_panic to run at hyp and, subsequently, panic to run in the host. // This makes use of __guest_exit to avoid duplication but sets the @@ -94,7 +96,7 @@ SYM_INNER_LABEL(__guest_exit_panic, SYM_L_GLOBAL) // current state is saved to the guest context but it will only be // accurate if the guest had been completely restored. adr_this_cpu x0, kvm_hyp_ctxt, x1 - adr x1, hyp_panic + adr_l x1, hyp_panic str x1, [x0, #CPU_XREG_OFFSET(30)] get_vcpu_ptr x1, x0