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Subject[PATCH 11/18] objtool: Add CONFIG_OBJTOOL
Date
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>
---
Makefile | 2 +-
arch/Kconfig | 8 ++++++--
arch/x86/Kconfig | 18 ++++++++++-------
arch/x86/Kconfig.debug | 2 +-
arch/x86/include/asm/jump_label.h | 6 +++---
arch/x86/kernel/alternative.c | 6 +++---
include/linux/compiler.h | 6 +++---
include/linux/instrumentation.h | 6 +++---
include/linux/objtool.h | 6 +++---
kernel/trace/Kconfig | 1 +
lib/Kconfig.debug | 20 ++++++++++---------
lib/Kconfig.kcsan | 3 ++-
lib/Kconfig.ubsan | 2 +-
scripts/Makefile.build | 4 ++--
scripts/link-vmlinux.sh | 32 +++++++++++++++++--------------
scripts/package/builddeb | 2 +-
tools/include/linux/objtool.h | 6 +++---
17 files changed, 73 insertions(+), 57 deletions(-)

diff --git a/Makefile b/Makefile
index 29e273d3f8cc..707dfbf643a2 100644
--- a/Makefile
+++ b/Makefile
@@ -1302,7 +1302,7 @@ install: sub_make_done :=
# ---------------------------------------------------------------------------
# Tools

-ifdef CONFIG_STACK_VALIDATION
+ifdef CONFIG_OBJTOOL
prepare: tools/objtool
endif

diff --git a/arch/Kconfig b/arch/Kconfig
index 29b0167c088b..04cdef16db24 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -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
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index b0142e01002e..bce0c23f3550 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -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
diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index d3a6f74a94bd..d872a7522e55 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -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
diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
index 0449b125d27f..3ce0e67c579c 100644
--- a/arch/x86/include/asm/jump_label.h
+++ b/arch/x86/include/asm/jump_label.h
@@ -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 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran
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 @@ static __always_inline bool arch_static_branch(struct static_key * const key, co
return true;
}

-#endif /* STACK_VALIDATION */
+#endif /* CONFIG_OBJTOOL */

static __always_inline bool arch_static_branch_jump(struct static_key * const key, const bool branch)
{
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index d374cb3cf024..3c66073e7645 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -338,7 +338,7 @@ void __init_or_module noinline apply_alternatives(struct alt_instr *start,
}
}

-#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

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 219aa5ddbc73..01ce94b58b42 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -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 { \
diff --git a/include/linux/instrumentation.h b/include/linux/instrumentation.h
index 24359b4a9605..9111a3704072 100644
--- a/include/linux/instrumentation.h
+++ b/include/linux/instrumentation.h
@@ -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 */
diff --git a/include/linux/objtool.h b/include/linux/objtool.h
index 586d35720f13..977d90ba642d 100644
--- a/include/linux/objtool.h
+++ b/include/linux/objtool.h
@@ -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 */
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 2c43e327a619..2956bc277150 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -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
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 075cd25363ac..c0e4e47f3ce3 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -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).
diff --git a/lib/Kconfig.kcsan b/lib/Kconfig.kcsan
index de022445fbba..901c3b509aca 100644
--- a/lib/Kconfig.kcsan
+++ b/lib/Kconfig.kcsan
@@ -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.
diff --git a/lib/Kconfig.ubsan b/lib/Kconfig.ubsan
index f3c57ed51838..c4fe15d38b60 100644
--- a/lib/Kconfig.ubsan
+++ b/lib/Kconfig.ubsan
@@ -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
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index d5e15ae29156..0f73e02b7cf1 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -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),)

diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index 0140bfa32c0c..5101a7fbfaaf 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -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
diff --git a/scripts/package/builddeb b/scripts/package/builddeb
index 91a502bb97e8..67cd420dcf89 100755
--- a/scripts/package/builddeb
+++ b/scripts/package/builddeb
@@ -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

diff --git a/tools/include/linux/objtool.h b/tools/include/linux/objtool.h
index 586d35720f13..977d90ba642d 100644
--- a/tools/include/linux/objtool.h
+++ b/tools/include/linux/objtool.h
@@ -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 */
--
2.34.1
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