Hello, I see the following build warning after this commit (gcc12): ld: warning: orphan section `.init.orc_unwind' from `arch/arm64/kernel/pi/kaslr_early.pi.o' being placed in section `.init.orc_unwind' ld: warning: orphan section `.init.orc_unwind_ip' from `arch/arm64/kernel/pi/kaslr_early.pi.o' being placed in section `.init.orc_unwind_ip' ... My understanding of the cause is that arch/arm64/kernel/pi has its own Makefile and adds "init" prefix to sections by objcopy: https://github.com/madvenka786/linux/blob/orc_v3/arch/arm64/kernel/pi/Makefile#L25 I assume these files are not relevant for livepatch perspective and so it is safe to exclude these sections by --remove-section or should we care these as well? Regards, Tomohiro > Subject: [RFC PATCH v3 18/22] arm64: Build the kernel with ORC information > > From: "Madhavan T. Venkataraman" <madvenka@xxxxxxxxxxxxxxxxxxx> > > Add code to scripts/Makefile.lib to define objtool options to generate > ORC data for frame pointer validation. > > Define kernel configs: > - to enable dynamic FRAME_POINTER_VALIDATION > - to enable the generation of ORC data using objtool > > When these configs are enabled, objtool is invoked on relocatable files > during kernel build with the following command: > > objtool --stackval --orc <object-file> > > Objtool creates special sections in the object files: > > .orc_unwind_ip PC array. > .orc_unwind ORC structure table. > .orc_lookup ORC lookup table. > > Change arch/arm64/kernel/vmlinux.lds.S to include ORC_UNWIND_TABLE in > the data section so that the special sections get included there. For > modules, these sections will be added to the kernel during module load. > > In the future, the kernel can use these sections to find the ORC for a > given instruction address. The unwinder can then compute the FP at an > instruction address and validate the actual FP with that. > > Signed-off-by: Madhavan T. Venkataraman <madvenka@xxxxxxxxxxxxxxxxxxx> > --- > arch/arm64/Kconfig | 2 ++ > arch/arm64/Kconfig.debug | 32 > ++++++++++++++++++++++++++++++++ > arch/arm64/include/asm/module.h | 12 +++++++++++- > arch/arm64/kernel/vmlinux.lds.S | 3 +++ > include/linux/objtool.h | 2 ++ > scripts/Makefile | 4 +++- > scripts/Makefile.lib | 9 +++++++++ > tools/include/linux/objtool.h | 2 ++ > 8 files changed, 64 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 505c8a1ccbe0..73c3f30a37c7 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -230,6 +230,8 @@ config ARM64 > select TRACE_IRQFLAGS_SUPPORT > select TRACE_IRQFLAGS_NMI_SUPPORT > select HAVE_SOFTIRQ_ON_OWN_STACK > + select HAVE_STACK_VALIDATION if > FRAME_POINTER_VALIDATION > + select STACK_VALIDATION if HAVE_STACK_VALIDATION > help > ARM 64-bit (AArch64) Linux support. > > diff --git a/arch/arm64/Kconfig.debug b/arch/arm64/Kconfig.debug > index 265c4461031f..a50caabdb18e 100644 > --- a/arch/arm64/Kconfig.debug > +++ b/arch/arm64/Kconfig.debug > @@ -20,4 +20,36 @@ config ARM64_RELOC_TEST > depends on m > tristate "Relocation testing module" > > +config UNWINDER_ORC > + bool "ORC unwinder" > + depends on FRAME_POINTER_VALIDATION > + select HAVE_MOD_ARCH_SPECIFIC > + select OBJTOOL > + help > + This option enables ORC (Oops Rewind Capability) for ARM64. This > + allows the unwinder to look up ORC data for an instruction address > + and compute the frame pointer at that address. The computed frame > + pointer is used to validate the actual frame pointer. > + > +config UNWINDER_FRAME_POINTER > + bool "Frame pointer unwinder" > + depends on FRAME_POINTER_VALIDATION > + select FRAME_POINTER > + help > + ARM64 already uses the frame pointer for unwinding kernel stack > + traces. We need to enable this config to enable STACK_VALIDATION. > + STACK_VALIDATION is needed to get objtool to do static analysis > + of kernel code. > + > +config FRAME_POINTER_VALIDATION > + bool "Dynamic Frame pointer validation" > + select UNWINDER_FRAME_POINTER > + select UNWINDER_ORC > + help > + This invokes objtool on every object file causing it to > + generate ORC data for the object file. ORC data is in a custom > + data format which is a simplified version of the DWARF > + Call Frame Information standard. See UNWINDER_ORC for more > + details. > + > source "drivers/hwtracing/coresight/Kconfig" > diff --git a/arch/arm64/include/asm/module.h > b/arch/arm64/include/asm/module.h > index 18734fed3bdd..4362f44aae61 100644 > --- a/arch/arm64/include/asm/module.h > +++ b/arch/arm64/include/asm/module.h > @@ -6,6 +6,7 @@ > #define __ASM_MODULE_H > > #include <asm-generic/module.h> > +#include <asm/orc_types.h> > > #ifdef CONFIG_ARM64_MODULE_PLTS > struct mod_plt_sec { > @@ -13,15 +14,24 @@ struct mod_plt_sec { > int plt_num_entries; > int plt_max_entries; > }; > +#endif > > +#ifdef CONFIG_HAVE_MOD_ARCH_SPECIFIC > struct mod_arch_specific { > +#ifdef CONFIG_ARM64_MODULE_PLTS > struct mod_plt_sec core; > struct mod_plt_sec init; > > /* for CONFIG_DYNAMIC_FTRACE */ > struct plt_entry *ftrace_trampolines; > -}; > #endif > +#ifdef CONFIG_UNWINDER_ORC > + unsigned int num_orcs; > + int *orc_unwind_ip; > + struct orc_entry *orc_unwind; > +#endif > +}; > +#endif /* CONFIG_HAVE_MOD_ARCH_SPECIFIC */ > > u64 module_emit_plt_entry(struct module *mod, Elf64_Shdr *sechdrs, > void *loc, const Elf64_Rela *rela, > diff --git a/arch/arm64/kernel/vmlinux.lds.S > b/arch/arm64/kernel/vmlinux.lds.S > index 45131e354e27..bf7b55ae10ee 100644 > --- a/arch/arm64/kernel/vmlinux.lds.S > +++ b/arch/arm64/kernel/vmlinux.lds.S > @@ -61,6 +61,7 @@ > #define RUNTIME_DISCARD_EXIT > > #include <asm-generic/vmlinux.lds.h> > +#include <asm-generic/orc_lookup.h> > #include <asm/cache.h> > #include <asm/kernel-pgtable.h> > #include <asm/kexec.h> > @@ -294,6 +295,8 @@ SECTIONS > __mmuoff_data_end = .; > } > > + ORC_UNWIND_TABLE > + > PECOFF_EDATA_PADDING > __pecoff_data_rawsize = ABSOLUTE(. - __initdata_begin); > _edata = .; > diff --git a/include/linux/objtool.h b/include/linux/objtool.h > index dcbd365944f6..c980522190f7 100644 > --- a/include/linux/objtool.h > +++ b/include/linux/objtool.h > @@ -31,7 +31,9 @@ > > #ifdef CONFIG_OBJTOOL > > +#ifndef CONFIG_ARM64 > #include <asm/asm.h> > +#endif > > #ifndef __ASSEMBLY__ > > diff --git a/scripts/Makefile b/scripts/Makefile > index 1575af84d557..df3e4d90f195 100644 > --- a/scripts/Makefile > +++ b/scripts/Makefile > @@ -23,8 +23,10 @@ HOSTLDLIBS_sign-file = $(shell $(HOSTPKG_CONFIG) > --libs libcrypto 2> /dev/null | > ifdef CONFIG_UNWINDER_ORC > ifeq ($(ARCH),x86_64) > ARCH := x86 > -endif > HOSTCFLAGS_sorttable.o += -I$(srctree)/tools/arch/x86/include > +else > +HOSTCFLAGS_sorttable.o += -I$(srctree)/tools/arch/$(ARCH)/include > +endif > HOSTCFLAGS_sorttable.o += -DUNWINDER_ORC_ENABLED > endif > > diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib > index 3aa384cec76b..d364871a1046 100644 > --- a/scripts/Makefile.lib > +++ b/scripts/Makefile.lib > @@ -252,6 +252,13 @@ ifdef CONFIG_OBJTOOL > > objtool := $(objtree)/tools/objtool/objtool > > +ifdef CONFIG_FRAME_POINTER_VALIDATION > + > +objtool-args-$(CONFIG_STACK_VALIDATION) += > --stackval > +objtool-args-$(CONFIG_UNWINDER_ORC) += --orc > + > +else > + > objtool-args-$(CONFIG_HAVE_JUMP_LABEL_HACK) += > --hacks=jump_label > objtool-args-$(CONFIG_HAVE_NOINSTR_HACK) += --hacks=noinstr > objtool-args-$(CONFIG_X86_KERNEL_IBT) += --ibt > @@ -265,6 +272,8 @@ objtool-args-$(CONFIG_HAVE_STATIC_CALL_INLINE) > += --static-call > objtool-args-$(CONFIG_HAVE_UACCESS_VALIDATION) += > --uaccess > objtool-args-$(CONFIG_GCOV_KERNEL) += > --no-unreachable > > +endif > + > objtool-args = $(objtool-args-y) \ > $(if $(delay-objtool), --link) \ > $(if $(part-of-module), --module) > diff --git a/tools/include/linux/objtool.h b/tools/include/linux/objtool.h > index dcbd365944f6..c980522190f7 100644 > --- a/tools/include/linux/objtool.h > +++ b/tools/include/linux/objtool.h > @@ -31,7 +31,9 @@ > > #ifdef CONFIG_OBJTOOL > > +#ifndef CONFIG_ARM64 > #include <asm/asm.h> > +#endif > > #ifndef __ASSEMBLY__ > > -- > 2.25.1 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
