Re: [PATCH 13/13] jump_label,x86: Allow short NOPs

From: Peter Zijlstra
Date: Thu May 06 2021 - 15:51:00 EST

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On Thu, May 06, 2021 at 09:34:05PM +0200, Peter Zijlstra wrote:
> +#ifdef CONFIG_STACK_VALIDATION

Do we want something like this?

---
--- a/Documentation/x86/orc-unwinder.rst
+++ b/Documentation/x86/orc-unwinder.rst
@@ -15,7 +15,7 @@ the ORC unwinder to be much simpler and
The ORC data consists of unwind tables which are generated by objtool.
They contain out-of-band data which is used by the in-kernel ORC
unwinder. Objtool generates the ORC data by first doing compile-time
-stack metadata validation (CONFIG_STACK_VALIDATION). After analyzing
+stack metadata validation (CONFIG_OBJTOOL). After analyzing
all the code paths of a .o file, it determines information about the
stack state at each instruction address in the file and outputs that
information to the .orc_unwind and .orc_unwind_ip sections.
--- a/Makefile
+++ b/Makefile
@@ -1091,12 +1091,12 @@ HOST_LIBELF_LIBS = $(shell pkg-config li
has_libelf = $(call try-run,\
echo "int main() {}" | $(HOSTCC) $(KBUILD_HOSTLDFLAGS) -xc -o /dev/null $(HOST_LIBELF_LIBS) -,1,0)

-ifdef CONFIG_STACK_VALIDATION
+ifdef CONFIG_OBJTOOL
ifeq ($(has_libelf),1)
objtool_target := tools/objtool FORCE
else
- SKIP_STACK_VALIDATION := 1
- export SKIP_STACK_VALIDATION
+ SKIP_OBJTOOL := 1
+ export SKIP_OBJTOOL
endif
endif

@@ -1247,7 +1247,7 @@ asm-generic: uapi-asm-generic

PHONY += prepare-objtool prepare-resolve_btfids
prepare-objtool: $(objtool_target)
-ifeq ($(SKIP_STACK_VALIDATION),1)
+ifeq ($(SKIP_OBJTOOL),1)
ifdef CONFIG_FTRACE_MCOUNT_USE_OBJTOOL
@echo "error: Cannot generate __mcount_loc for CONFIG_DYNAMIC_FTRACE=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
@false
@@ -1256,7 +1256,7 @@ ifdef CONFIG_UNWINDER_ORC
@echo "error: Cannot generate ORC metadata for CONFIG_UNWINDER_ORC=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
@false
else
- @echo "warning: Cannot use CONFIG_STACK_VALIDATION=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
+ @echo "warning: Cannot use CONFIG_OBJTOOL=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
endif
endif

--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -984,7 +984,7 @@ config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LA
depends on MMU
select ARCH_HAS_ELF_RANDOMIZE

-config HAVE_STACK_VALIDATION
+config HAVE_OBJTOOL
bool
help
Architecture supports the 'objtool check' host tool command, which
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -76,7 +76,7 @@ config X86
select ARCH_HAS_FILTER_PGPROT
select ARCH_HAS_FORTIFY_SOURCE
select ARCH_HAS_GCOV_PROFILE_ALL
- select ARCH_HAS_KCOV if X86_64 && STACK_VALIDATION
+ select ARCH_HAS_KCOV if X86_64 && OBJTOOL
select ARCH_HAS_MEM_ENCRYPT
select ARCH_HAS_MEMBARRIER_SYNC_CORE
select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
@@ -181,7 +181,7 @@ 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 OBJTOOL
select HAVE_DEBUG_KMEMLEAK
select HAVE_DMA_CONTIGUOUS
select HAVE_DYNAMIC_FTRACE
@@ -232,13 +232,13 @@ config X86
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 X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && OBJTOOL
select HAVE_FUNCTION_ARG_ACCESS_API
select HAVE_SOFTIRQ_ON_OWN_STACK
select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
- select HAVE_STACK_VALIDATION if X86_64
+ select HAVE_OBJTOOL if X86_64
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
select HAVE_RSEQ
select HAVE_SYSCALL_TRACEPOINTS
@@ -255,7 +255,7 @@ config X86
select RTC_MC146818_LIB
select SPARSE_IRQ
select SRCU
- select STACK_VALIDATION if HAVE_STACK_VALIDATION && (HAVE_STATIC_CALL_INLINE || RETPOLINE)
+ select OBJTOOL if HAVE_OBJTOOL && (HAVE_STATIC_CALL_INLINE || RETPOLINE)
select SYSCTL_EXCEPTION_TRACE
select THREAD_INFO_IN_TASK
select USER_STACKTRACE_SUPPORT
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -240,7 +240,7 @@ 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
--- 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)
{
@@ -48,7 +48,7 @@ static __always_inline bool arch_static_
return true;
}

-#endif /* STACK_VALIDATION */
+#endif /* OBJTOOL */

static __always_inline bool arch_static_branch_jump(struct static_key * const key, const bool branch)
{
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -109,7 +109,7 @@ void ftrace_likely_update(struct ftrace_
#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
--- 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)
+#if defined(CONFIG_DEBUG_ENTRY) && defined(CONFIG_OBJTOOL)

/* Begin/end of an instrumentation safe region */
#define instrumentation_begin() ({ \
--- 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__

@@ -120,7 +120,7 @@ struct unwind_hint {

#endif /* __ASSEMBLY__ */

-#else /* !CONFIG_STACK_VALIDATION */
+#else /* !CONFIG_OBJTOOL */

#ifndef __ASSEMBLY__

@@ -135,6 +135,6 @@ struct unwind_hint {
.endm
#endif

-#endif /* CONFIG_STACK_VALIDATION */
+#endif /* CONFIG_OBJTOOL */

#endif /* _LINUX_OBJTOOL_H */
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -428,9 +428,9 @@ config FRAME_POINTER
larger and slower, but it gives very useful debugging information
in case of kernel bugs. (precise oopses/stacktraces/warnings)

-config STACK_VALIDATION
+config OBJTOOL
bool "Compile-time stack metadata validation"
- depends on HAVE_STACK_VALIDATION
+ depends on HAVE_OBJTOOL
default n
help
Add compile-time checks to validate stack metadata, including frame
@@ -445,7 +445,7 @@ config STACK_VALIDATION

config VMLINUX_VALIDATION
bool
- depends on STACK_VALIDATION && DEBUG_ENTRY && !PARAVIRT
+ depends on OBJTOOL && DEBUG_ENTRY && !PARAVIRT
default y

config VMLINUX_MAP
--- a/lib/Kconfig.ubsan
+++ b/lib/Kconfig.ubsan
@@ -106,7 +106,7 @@ 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
depends on $(cc-option,-fsanitize=unreachable)
help
This option enables -fsanitize=unreachable which checks for control
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -217,9 +217,9 @@ cmd_record_mcount = $(if $(findstring $(
$(sub_cmd_record_mcount))
endif # CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT

-ifdef CONFIG_STACK_VALIDATION
+ifdef CONFIG_OBJTOOL
ifndef CONFIG_LTO_CLANG
-ifneq ($(SKIP_STACK_VALIDATION),1)
+ifneq ($(SKIP_OBJTOOL),1)

__objtool_obj := $(objtree)/tools/objtool/objtool

@@ -233,14 +233,14 @@ objtool_obj = $(if $(patsubst y%,, \
$(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \
$(__objtool_obj))

-endif # SKIP_STACK_VALIDATION
+endif # SKIP_OBJTOOL
endif # CONFIG_LTO_CLANG
-endif # CONFIG_STACK_VALIDATION
+endif # CONFIG_OBJTOOL

# Rebuild all objects when objtool changes, or is enabled/disabled.
objtool_dep = $(objtool_obj) \
$(wildcard include/config/ORC_UNWINDER \
- include/config/STACK_VALIDATION)
+ include/config/OBJTOOL)

ifdef CONFIG_TRIM_UNUSED_KSYMS
cmd_gen_ksymdeps = \
--- a/scripts/Makefile.modfinal
+++ b/scripts/Makefile.modfinal
@@ -38,14 +38,14 @@ prelink-ext := .lto
# ELF processing was skipped earlier because we didn't have native code,
# so let's now process the prelinked binary before we link the module.

-ifdef CONFIG_STACK_VALIDATION
-ifneq ($(SKIP_STACK_VALIDATION),1)
+ifdef CONFIG_OBJTOOL
+ifneq ($(SKIP_OBJTOOL),1)
cmd_ld_ko_o += \
$(objtree)/tools/objtool/objtool $(objtool_args) \
$(@:.ko=$(prelink-ext).o);

-endif # SKIP_STACK_VALIDATION
-endif # CONFIG_STACK_VALIDATION
+endif # SKIP_OBJTOOL
+endif # CONFIG_OBJTOOL

endif # CONFIG_LTO_CLANG

--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -106,7 +106,7 @@ objtool_link()
local objtoolcmd;
local objtoolopt;

- if [ "${CONFIG_LTO_CLANG} ${CONFIG_STACK_VALIDATION}" = "y y" ]; then
+ if [ "${CONFIG_LTO_CLANG} ${CONFIG_OBJTOOL}" = "y y" ]; then
# Don't perform vmlinux validation unless explicitly requested,
# but run objtool on vmlinux.o now that we have an object file.
if [ -n "${CONFIG_UNWINDER_ORC}" ]; then
--- 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

--- 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__

@@ -120,7 +120,7 @@ struct unwind_hint {

#endif /* __ASSEMBLY__ */

-#else /* !CONFIG_STACK_VALIDATION */
+#else /* !CONFIG_OBJTOOL */

#ifndef __ASSEMBLY__

@@ -135,6 +135,6 @@ struct unwind_hint {
.endm
#endif

-#endif /* CONFIG_STACK_VALIDATION */
+#endif /* CONFIG_OBJTOOL */

#endif /* _LINUX_OBJTOOL_H */
--- a/tools/objtool/Documentation/stack-validation.txt
+++ b/tools/objtool/Documentation/stack-validation.txt
@@ -5,7 +5,7 @@ Compile-time stack metadata validation
Overview
--------

-The kernel CONFIG_STACK_VALIDATION option enables a host tool named
+The kernel CONFIG_OBJTOOL option enables a host tool named
objtool which runs at compile time. It has a "check" subcommand which
analyzes every .o file and ensures the validity of its stack metadata.
It enforces a set of rules on asm code and C inline assembly code so
--- a/tools/testing/selftests/wireguard/qemu/debug.config
+++ b/tools/testing/selftests/wireguard/qemu/debug.config
@@ -1,6 +1,6 @@
CONFIG_LOCALVERSION="-debug"
CONFIG_FRAME_POINTER=y
-CONFIG_STACK_VALIDATION=y
+CONFIG_OBJTOOL=y
CONFIG_DEBUG_KERNEL=y
CONFIG_DEBUG_INFO=y
CONFIG_DEBUG_INFO_DWARF4=y

Next message: Bhaumik Bhatt: "[PATCH v4 4/6] ath11k: set register access length for MHI driver"
Previous message: Peter Zijlstra: "[PATCH 06/13] jump_label, x86: Introduce jump_entry_size()"
In reply to: Peter Zijlstra: "[PATCH 13/13] jump_label,x86: Allow short NOPs"
Next in thread: Peter Zijlstra: "[PATCH 10/13] objtool: Decode jump_entry::key addend"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]