| Message ID | 1531043982-13325-1-git-send-email-yamada.masahiro@socionext.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sun, Jul 08, 2018 at 06:59:42PM +0900, Masahiro Yamada wrote: > Currently, users are allowed to enable STACK_VALIDATION regardless > of the compiler capability. The top-level Makefile warns or breaks > the build if it turns out that the host compiler cannot link libelf. > > Move the libelf test to Kconfig so that users can enable the feature > only when the host compiler can build the objtool. The ugly check > in the Makefile will go away. > > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Thanks for cleaning this up! > I am sure about this patch only from the build system point of view. > > Please review this from x86 and objtool point of view. > > In my understanding: > > - UNWINDER_ORC _requires_ objtool, > so I added 'depends on STACK_VALIDATION'. > ('select' would end up with unmet depenency) Correct. > - RETPOLINE _wants_ objtool, so I added 'imply' Yeah, I think this is fine. Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
2018-07-10 4:21 GMT+09:00 Josh Poimboeuf <jpoimboe@redhat.com>: > On Sun, Jul 08, 2018 at 06:59:42PM +0900, Masahiro Yamada wrote: >> Currently, users are allowed to enable STACK_VALIDATION regardless >> of the compiler capability. The top-level Makefile warns or breaks >> the build if it turns out that the host compiler cannot link libelf. >> >> Move the libelf test to Kconfig so that users can enable the feature >> only when the host compiler can build the objtool. The ugly check >> in the Makefile will go away. >> >> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> > > Thanks for cleaning this up! > >> I am sure about this patch only from the build system point of view. >> >> Please review this from x86 and objtool point of view. >> >> In my understanding: >> >> - UNWINDER_ORC _requires_ objtool, >> so I added 'depends on STACK_VALIDATION'. >> ('select' would end up with unmet depenency) > > Correct. > >> - RETPOLINE _wants_ objtool, so I added 'imply' > > Yeah, I think this is fine. > > Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Thanks for your review! I have one question. The package information is contained in the warning/error message. Is it better to keep this? If so, I will send v2 to move the information to the help, like this: config STACK_VALIDATION bool "Compile-time stack metadata validation" depends on HAVE_STACK_VALIDATION depends on $(success,echo "int main() {}" | $(HOSTCC) -xc -o /dev/null -lelf -) 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. + To enable this, the host compiler needs to be able to link libelf. + If it is missing, please install libelf-dev, libelf-devel or + elfutils-libelf-devel. For more information, see tools/objtool/Documentation/stack-validation.txt.
diff --git a/Makefile b/Makefile index d15ac32..f724349 100644 --- a/Makefile +++ b/Makefile @@ -927,19 +927,7 @@ endif export mod_sign_cmd ifdef CONFIG_STACK_VALIDATION - has_libelf := $(call try-run,\ - echo "int main() {}" | $(HOSTCC) -xc -o /dev/null -lelf -,1,0) - ifeq ($(has_libelf),1) - objtool_target := tools/objtool FORCE - else - ifdef CONFIG_UNWINDER_ORC - $(error "Cannot generate ORC metadata for CONFIG_UNWINDER_ORC=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel") - else - $(warning "Cannot use CONFIG_STACK_VALIDATION=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel") - endif - SKIP_STACK_VALIDATION := 1 - export SKIP_STACK_VALIDATION - endif + objtool_target := tools/objtool endif diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index f1dbb4e..c1ded99 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -434,7 +434,7 @@ config GOLDFISH config RETPOLINE bool "Avoid speculative indirect branches in kernel" default y - select STACK_VALIDATION if HAVE_STACK_VALIDATION + imply STACK_VALIDATION help Compile kernel with the retpoline compiler options to guard against kernel-to-user data leaks by avoiding speculative indirect diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug index c6dd1d9..4713b3c 100644 --- a/arch/x86/Kconfig.debug +++ b/arch/x86/Kconfig.debug @@ -364,7 +364,7 @@ choice config UNWINDER_ORC bool "ORC unwinder" depends on X86_64 - select STACK_VALIDATION + depends on STACK_VALIDATION ---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/lib/Kconfig.debug b/lib/Kconfig.debug index 8838d11..07eb744 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -364,7 +364,7 @@ config FRAME_POINTER config STACK_VALIDATION bool "Compile-time stack metadata validation" depends on HAVE_STACK_VALIDATION - default n + depends on $(success,echo "int main() {}" | $(HOSTCC) -xc -o /dev/null -lelf -) help Add compile-time checks to validate stack metadata, including frame pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure diff --git a/scripts/Makefile.build b/scripts/Makefile.build index e7889f4..154205b 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -243,7 +243,6 @@ endif # -record-mcount endif # CONFIG_FTRACE_MCOUNT_RECORD ifdef CONFIG_STACK_VALIDATION -ifneq ($(SKIP_STACK_VALIDATION),1) __objtool_obj := $(objtree)/tools/objtool/objtool @@ -282,7 +281,6 @@ objtool_obj = $(if $(patsubst y%,, \ $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \ $(__objtool_obj)) -endif # SKIP_STACK_VALIDATION endif # CONFIG_STACK_VALIDATION # Rebuild all objects when objtool changes, or is enabled/disabled.
Currently, users are allowed to enable STACK_VALIDATION regardless of the compiler capability. The top-level Makefile warns or breaks the build if it turns out that the host compiler cannot link libelf. Move the libelf test to Kconfig so that users can enable the feature only when the host compiler can build the objtool. The ugly check in the Makefile will go away. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> --- I am sure about this patch only from the build system point of view. Please review this from x86 and objtool point of view. In my understanding: - UNWINDER_ORC _requires_ objtool, so I added 'depends on STACK_VALIDATION'. ('select' would end up with unmet depenency) - RETPORINE _wants_ objtool, so I added 'imply' Please correct me if I am wrong. Makefile | 14 +------------- arch/x86/Kconfig | 2 +- arch/x86/Kconfig.debug | 2 +- lib/Kconfig.debug | 2 +- scripts/Makefile.build | 2 -- 5 files changed, 4 insertions(+), 18 deletions(-)