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objtool: Add CONFIG_OBJTOOL

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Now that stack validation is an optional feature of objtool, add
CONFIG_OBJTOOL and replace most usages of CONFIG_STACK_VALIDATION with
it.

CONFIG_STACK_VALIDATION can now be considered to be frame-pointer
specific.  CONFIG_UNWINDER_ORC is already inherently valid for live
patching, so no need to "validate" it.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/939bf3d85604b2a126412bf11af6e3bd3b872bcb.1650300597.git.jpoimboe@redhat.com
This commit is contained in:
Josh Poimboeuf 2022-04-18 09:50:36 -07:00 committed by Peter Zijlstra
parent c2bdd61c98
commit 03f16cd020
17 changed files with 73 additions and 57 deletions
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2
Makefile
View File

@ -1302,7 +1302,7 @@ install: sub_make_done :=
# ---------------------------------------------------------------------------
# Tools
ifdef CONFIG_STACK_VALIDATION
ifdef CONFIG_OBJTOOL
prepare: tools/objtool
endif

8
arch/Kconfig
View File

@ -1028,11 +1028,14 @@ config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
depends on MMU
select ARCH_HAS_ELF_RANDOMIZE
config HAVE_OBJTOOL
bool
config HAVE_STACK_VALIDATION
bool
help
Architecture supports the 'objtool check' host tool command, which
performs compile-time stack metadata validation.
Architecture supports objtool compile-time frame pointer rule
validation.
config HAVE_RELIABLE_STACKTRACE
bool
@ -1302,6 +1305,7 @@ config HAVE_STATIC_CALL
config HAVE_STATIC_CALL_INLINE
bool
depends on HAVE_STATIC_CALL
select OBJTOOL
config HAVE_PREEMPT_DYNAMIC
bool

18
arch/x86/Kconfig
View File

@ -188,7 +188,7 @@ config X86
select HAVE_CONTEXT_TRACKING if X86_64
select HAVE_CONTEXT_TRACKING_OFFSTACK if HAVE_CONTEXT_TRACKING
select HAVE_C_RECORDMCOUNT
select HAVE_OBJTOOL_MCOUNT if STACK_VALIDATION
select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
select HAVE_BUILDTIME_MCOUNT_SORT
select HAVE_DEBUG_KMEMLEAK
select HAVE_DMA_CONTIGUOUS
@ -231,6 +231,7 @@ config X86
select HAVE_MOVE_PMD
select HAVE_MOVE_PUD
select HAVE_NMI
select HAVE_OBJTOOL if X86_64
select HAVE_OPTPROBES
select HAVE_PCSPKR_PLATFORM
select HAVE_PERF_EVENTS
@ -239,17 +240,17 @@ config X86
select HAVE_PCI
select HAVE_PERF_REGS
select HAVE_PERF_USER_STACK_DUMP
select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
select HAVE_POSIX_CPU_TIMERS_TASK_WORK
select HAVE_REGS_AND_STACK_ACCESS_API
select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION
select HAVE_FUNCTION_ARG_ACCESS_API
select HAVE_SETUP_PER_CPU_AREA
select HAVE_SOFTIRQ_ON_OWN_STACK
select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
select HAVE_STACK_VALIDATION if X86_64
select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
select HAVE_STATIC_CALL
select HAVE_STATIC_CALL_INLINE if HAVE_STACK_VALIDATION
select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL
select HAVE_PREEMPT_DYNAMIC_CALL
select HAVE_RSEQ
select HAVE_SYSCALL_TRACEPOINTS
@ -268,7 +269,6 @@ config X86
select RTC_MC146818_LIB
select SPARSE_IRQ
select SRCU
select STACK_VALIDATION if HAVE_STACK_VALIDATION && (HAVE_STATIC_CALL_INLINE || RETPOLINE)
select SYSCTL_EXCEPTION_TRACE
select THREAD_INFO_IN_TASK
select TRACE_IRQFLAGS_SUPPORT
@ -459,6 +459,7 @@ config GOLDFISH
config RETPOLINE
bool "Avoid speculative indirect branches in kernel"
select OBJTOOL if HAVE_OBJTOOL
default y
help
Compile kernel with the retpoline compiler options to guard against
@ -472,6 +473,7 @@ config CC_HAS_SLS
config SLS
bool "Mitigate Straight-Line-Speculation"
depends on CC_HAS_SLS && X86_64
select OBJTOOL if HAVE_OBJTOOL
default n
help
Compile the kernel with straight-line-speculation options to guard
@ -1819,6 +1821,7 @@ config ARCH_RANDOM
config X86_SMAP
def_bool y
prompt "Supervisor Mode Access Prevention" if EXPERT
select OBJTOOL if HAVE_OBJTOOL
help
Supervisor Mode Access Prevention (SMAP) is a security
feature in newer Intel processors. There is a small
@ -1855,9 +1858,10 @@ config CC_HAS_IBT
config X86_KERNEL_IBT
prompt "Indirect Branch Tracking"
bool
depends on X86_64 && CC_HAS_IBT && STACK_VALIDATION
depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
# https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
depends on !LD_IS_LLD || LLD_VERSION >= 140000
select OBJTOOL
help
Build the kernel with support for Indirect Branch Tracking, a
hardware support course-grain forward-edge Control Flow Integrity

2
arch/x86/Kconfig.debug
View File

@ -237,7 +237,7 @@ choice
config UNWINDER_ORC
bool "ORC unwinder"
depends on X86_64
select STACK_VALIDATION
select OBJTOOL
help
This option enables the ORC (Oops Rewind Capability) unwinder for
unwinding kernel stack traces. It uses a custom data format which is

6
arch/x86/include/asm/jump_label.h
View File

@ -20,7 +20,7 @@
_ASM_PTR "%c0 + %c1 - .\n\t" \
".popsection \n\t"
#ifdef CONFIG_STACK_VALIDATION
#ifdef CONFIG_OBJTOOL
static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
{
@ -34,7 +34,7 @@ l_yes:
return true;
}
#else
#else /* !CONFIG_OBJTOOL */
static __always_inline bool arch_static_branch(struct static_key * const key, const bool branch)
{
@ -48,7 +48,7 @@ l_yes:
return true;
}
#endif /* STACK_VALIDATION */
#endif /* CONFIG_OBJTOOL */
static __always_inline bool arch_static_branch_jump(struct static_key * const key, const bool branch)
{

6
arch/x86/kernel/alternative.c
View File

@ -338,7 +338,7 @@ next:
}
}
#if defined(CONFIG_RETPOLINE) && defined(CONFIG_STACK_VALIDATION)
#if defined(CONFIG_RETPOLINE) && defined(CONFIG_OBJTOOL)
/*
* CALL/JMP *%\reg
@ -507,11 +507,11 @@ void __init_or_module noinline apply_retpolines(s32 *start, s32 *end)
}
}
#else /* !RETPOLINES || !CONFIG_STACK_VALIDATION */
#else /* !CONFIG_RETPOLINE || !CONFIG_OBJTOOL */
void __init_or_module noinline apply_retpolines(s32 *start, s32 *end) { }
#endif /* CONFIG_RETPOLINE && CONFIG_STACK_VALIDATION */
#endif /* CONFIG_RETPOLINE && CONFIG_OBJTOOL */
#ifdef CONFIG_X86_KERNEL_IBT

6
include/linux/compiler.h
View File

@ -109,7 +109,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
#endif
/* Unreachable code */
#ifdef CONFIG_STACK_VALIDATION
#ifdef CONFIG_OBJTOOL
/*
* These macros help objtool understand GCC code flow for unreachable code.
* The __COUNTER__ based labels are a hack to make each instance of the macros
@ -128,10 +128,10 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
/* Annotate a C jump table to allow objtool to follow the code flow */
#define __annotate_jump_table __section(".rodata..c_jump_table")
#else
#else /* !CONFIG_OBJTOOL */
#define annotate_unreachable()
#define __annotate_jump_table
#endif
#endif /* CONFIG_OBJTOOL */
#ifndef unreachable
# define unreachable() do { \

6
include/linux/instrumentation.h
View File

@ -2,7 +2,7 @@
#ifndef __LINUX_INSTRUMENTATION_H
#define __LINUX_INSTRUMENTATION_H
#if defined(CONFIG_DEBUG_ENTRY) && defined(CONFIG_STACK_VALIDATION)
#ifdef CONFIG_VMLINUX_VALIDATION
#include <linux/stringify.h>
@ -53,9 +53,9 @@
".popsection\n\t" : : "i" (c)); \
})
#define instrumentation_end() __instrumentation_end(__COUNTER__)
#else
#else /* !CONFIG_VMLINUX_VALIDATION */
# define instrumentation_begin() do { } while(0)
# define instrumentation_end() do { } while(0)
#endif
#endif /* CONFIG_VMLINUX_VALIDATION */
#endif /* __LINUX_INSTRUMENTATION_H */

6
include/linux/objtool.h
View File

@ -38,7 +38,7 @@ struct unwind_hint {
#define UNWIND_HINT_TYPE_REGS_PARTIAL 2
#define UNWIND_HINT_TYPE_FUNC 3
#ifdef CONFIG_STACK_VALIDATION
#ifdef CONFIG_OBJTOOL
#ifndef __ASSEMBLY__
@ -157,7 +157,7 @@ struct unwind_hint {
#endif /* __ASSEMBLY__ */
#else /* !CONFIG_STACK_VALIDATION */
#else /* !CONFIG_OBJTOOL */
#ifndef __ASSEMBLY__
@ -179,6 +179,6 @@ struct unwind_hint {
.endm
#endif
#endif /* CONFIG_STACK_VALIDATION */
#endif /* CONFIG_OBJTOOL */
#endif /* _LINUX_OBJTOOL_H */

1
kernel/trace/Kconfig
View File

@ -728,6 +728,7 @@ config FTRACE_MCOUNT_USE_OBJTOOL
depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
depends on !FTRACE_MCOUNT_USE_CC
depends on FTRACE_MCOUNT_RECORD
select OBJTOOL
config FTRACE_MCOUNT_USE_RECORDMCOUNT
def_bool y

20
lib/Kconfig.debug
View File

@ -485,24 +485,25 @@ config FRAME_POINTER
larger and slower, but it gives very useful debugging information
in case of kernel bugs. (precise oopses/stacktraces/warnings)
config OBJTOOL
bool
config STACK_VALIDATION
bool "Compile-time stack metadata validation"
depends on HAVE_STACK_VALIDATION
depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER
select OBJTOOL
default n
help
Add compile-time checks to validate stack metadata, including frame
pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure
that runtime stack traces are more reliable.
This is also a prerequisite for generation of ORC unwind data, which
is needed for CONFIG_UNWINDER_ORC.
Validate frame pointer rules at compile-time. This helps ensure that
runtime stack traces are more reliable.
For more information, see
tools/objtool/Documentation/stack-validation.txt.
config VMLINUX_VALIDATION
bool
depends on STACK_VALIDATION && DEBUG_ENTRY
depends on HAVE_OBJTOOL && DEBUG_ENTRY
select OBJTOOL
default y
config VMLINUX_MAP
@ -2035,10 +2036,11 @@ config KCOV
bool "Code coverage for fuzzing"
depends on ARCH_HAS_KCOV
depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
depends on !ARCH_WANTS_NO_INSTR || STACK_VALIDATION || \
depends on !ARCH_WANTS_NO_INSTR || HAVE_OBJTOOL || \
GCC_VERSION >= 120000 || CLANG_VERSION >= 130000
select DEBUG_FS
select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
select OBJTOOL if HAVE_OBJTOOL
help
KCOV exposes kernel code coverage information in a form suitable
for coverage-guided fuzzing (randomized testing).

3
lib/Kconfig.kcsan
View File

@ -187,7 +187,8 @@ config KCSAN_WEAK_MEMORY
# We can either let objtool nop __tsan_func_{entry,exit}() and builtin
# atomics instrumentation in .noinstr.text, or use a compiler that can
# implement __no_kcsan to really remove all instrumentation.
depends on STACK_VALIDATION || CC_IS_GCC || CLANG_VERSION >= 140000
depends on HAVE_OBJTOOL || CC_IS_GCC || CLANG_VERSION >= 140000
select OBJTOOL if HAVE_OBJTOOL
help
Enable support for modeling a subset of weak memory, which allows
detecting a subset of data races due to missing memory barriers.

2
lib/Kconfig.ubsan
View File

@ -94,7 +94,7 @@ config UBSAN_UNREACHABLE
bool "Perform checking for unreachable code"
# objtool already handles unreachable checking and gets angry about
# seeing UBSan instrumentation located in unreachable places.
depends on !STACK_VALIDATION
depends on !(OBJTOOL && (STACK_VALIDATION || UNWINDER_ORC || X86_SMAP))
depends on $(cc-option,-fsanitize=unreachable)
help
This option enables -fsanitize=unreachable which checks for control

4
scripts/Makefile.build
View File

@ -222,7 +222,7 @@ cmd_record_mcount = $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)),
$(sub_cmd_record_mcount))
endif # CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
ifdef CONFIG_STACK_VALIDATION
ifdef CONFIG_OBJTOOL
objtool := $(objtree)/tools/objtool/objtool
@ -241,7 +241,7 @@ objtool_args = \
cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool_args) $@)
cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$@: $$(wildcard $(objtool))' ; } >> $(dot-target).cmd)
endif # CONFIG_STACK_VALIDATION
endif # CONFIG_OBJTOOL
ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),)

32
scripts/link-vmlinux.sh
View File

@ -108,8 +108,11 @@ objtool_link()
local objtoolcmd;
local objtoolopt;
if is_enabled CONFIG_STACK_VALIDATION && \
( is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT ); then
if ! is_enabled CONFIG_OBJTOOL; then
return;
fi
if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then
# Don't perform vmlinux validation unless explicitly requested,
# but run objtool on vmlinux.o now that we have an object file.
@ -126,10 +129,23 @@ objtool_link()
objtoolopt="${objtoolopt} --orc"
fi
if is_enabled CONFIG_RETPOLINE; then
objtoolopt="${objtoolopt} --retpoline"
fi
if is_enabled CONFIG_SLS; then
objtoolopt="${objtoolopt} --sls"
fi
if is_enabled CONFIG_STACK_VALIDATION; then
objtoolopt="${objtoolopt} --stackval"
fi
if is_enabled CONFIG_X86_SMAP; then
objtoolopt="${objtoolopt} --uaccess"
fi
objtoolopt="${objtoolopt} --lto"
fi
@ -139,18 +155,6 @@ objtool_link()
if [ -n "${objtoolopt}" ]; then
if is_enabled CONFIG_RETPOLINE; then
objtoolopt="${objtoolopt} --retpoline"
fi
if is_enabled CONFIG_SLS; then
objtoolopt="${objtoolopt} --sls"
fi
if is_enabled CONFIG_X86_SMAP; then
objtoolopt="${objtoolopt} --uaccess"
fi
if ! is_enabled CONFIG_FRAME_POINTER; then
objtoolopt="${objtoolopt} --no-fp"
fi

2
scripts/package/builddeb
View File

@ -67,7 +67,7 @@ deploy_kernel_headers () {
) > debian/hdrsrcfiles
{
if is_enabled CONFIG_STACK_VALIDATION; then
if is_enabled CONFIG_OBJTOOL; then
echo tools/objtool/objtool
fi

6
tools/include/linux/objtool.h
View File

@ -38,7 +38,7 @@ struct unwind_hint {
#define UNWIND_HINT_TYPE_REGS_PARTIAL 2
#define UNWIND_HINT_TYPE_FUNC 3
#ifdef CONFIG_STACK_VALIDATION
#ifdef CONFIG_OBJTOOL
#ifndef __ASSEMBLY__
@ -157,7 +157,7 @@ struct unwind_hint {
#endif /* __ASSEMBLY__ */
#else /* !CONFIG_STACK_VALIDATION */
#else /* !CONFIG_OBJTOOL */
#ifndef __ASSEMBLY__
@ -179,6 +179,6 @@ struct unwind_hint {
.endm
#endif
#endif /* CONFIG_STACK_VALIDATION */
#endif /* CONFIG_OBJTOOL */
#endif /* _LINUX_OBJTOOL_H */