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Date: Wed, 24 Jun 2020 13:31:43 -0700
From: Sami Tolvanen <samitolvanen@...gle.com>
To: Masahiro Yamada <masahiroy@...nel.org>, Will Deacon <will@...nel.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, "Paul E. McKenney" <paulmck@...nel.org>,
Kees Cook <keescook@...omium.org>, Nick Desaulniers <ndesaulniers@...gle.com>,
clang-built-linux@...glegroups.com, kernel-hardening@...ts.openwall.com,
linux-arch@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-pci@...r.kernel.org, x86@...nel.org,
Sami Tolvanen <samitolvanen@...gle.com>
Subject: [PATCH 05/22] kbuild: lto: postpone objtool
With LTO, LLVM bitcode won't be compiled into native code until
modpost_link, or modfinal for modules. This change postpones calls
to objtool until after these steps.
Signed-off-by: Sami Tolvanen <samitolvanen@...gle.com>
---
include/linux/compiler.h | 2 +-
lib/Kconfig.debug | 2 +-
scripts/Makefile.build | 2 ++
scripts/Makefile.modfinal | 15 +++++++++++++++
4 files changed, 19 insertions(+), 2 deletions(-)
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 30827f82ad62..12b115152532 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -120,7 +120,7 @@ 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)
-#ifdef CONFIG_DEBUG_ENTRY
+#if defined(CONFIG_DEBUG_ENTRY) || defined(CONFIG_LTO_CLANG)
/* Begin/end of an instrumentation safe region */
#define instrumentation_begin() ({ \
asm volatile("%c0:\n\t" \
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 9ad9210d70a1..9fdba71c135a 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -399,7 +399,7 @@ config STACK_VALIDATION
config VMLINUX_VALIDATION
bool
- depends on STACK_VALIDATION && DEBUG_ENTRY && !PARAVIRT
+ depends on STACK_VALIDATION && (DEBUG_ENTRY || LTO_CLANG) && !PARAVIRT
default y
config DEBUG_FORCE_WEAK_PER_CPU
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 64e99f4baa5b..82977350f5a6 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -226,6 +226,7 @@ endif # CC_USING_PATCHABLE_FUNCTION_ENTRY
endif # CONFIG_FTRACE_MCOUNT_RECORD
ifdef CONFIG_STACK_VALIDATION
+ifndef CONFIG_LTO_CLANG
ifneq ($(SKIP_STACK_VALIDATION),1)
__objtool_obj := $(objtree)/tools/objtool/objtool
@@ -258,6 +259,7 @@ objtool_obj = $(if $(patsubst y%,, \
$(__objtool_obj))
endif # SKIP_STACK_VALIDATION
+endif # CONFIG_LTO_CLANG
endif # CONFIG_STACK_VALIDATION
# Rebuild all objects when objtool changes, or is enabled/disabled.
diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal
index d168f0cfe67c..9f1df2f1fab5 100644
--- a/scripts/Makefile.modfinal
+++ b/scripts/Makefile.modfinal
@@ -48,6 +48,21 @@ endif # CC_USING_PATCHABLE_FUNCTION_ENTRY
endif # CC_USING_RECORD_MCOUNT
endif # CONFIG_FTRACE_MCOUNT_RECORD
+ifdef CONFIG_STACK_VALIDATION
+ifneq ($(SKIP_STACK_VALIDATION),1)
+cmd_ld_ko_o += \
+ $(objtree)/tools/objtool/objtool \
+ $(if $(CONFIG_UNWINDER_ORC),orc generate,check) \
+ --module \
+ $(if $(CONFIG_FRAME_POINTER),,--no-fp) \
+ $(if $(CONFIG_GCOV_KERNEL),--no-unreachable,) \
+ $(if $(CONFIG_RETPOLINE),--retpoline,) \
+ $(if $(CONFIG_X86_SMAP),--uaccess,) \
+ $(@:.ko=$(prelink-ext).o);
+
+endif # SKIP_STACK_VALIDATION
+endif # CONFIG_STACK_VALIDATION
+
endif # CONFIG_LTO_CLANG
quiet_cmd_ld_ko_o = LD [M] $@
--
2.27.0.212.ge8ba1cc988-goog
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