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authorLinus Torvalds <torvalds@linux-foundation.org>2020-06-11 18:55:43 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-06-11 18:55:43 -0700
commitb791d1bdf9212d944d749a5c7ff6febdba241771 (patch)
treec207137a4d4f6b5dae3b1ecdf0ffaa357852fa7c /scripts
parent9716e57a0195dae356ae1425df121988abd27131 (diff)
parent1f44328ea24c9de368a3cfe5cc0e110b949afb2e (diff)
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Merge tag 'locking-kcsan-2020-06-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull the Kernel Concurrency Sanitizer from Thomas Gleixner: "The Kernel Concurrency Sanitizer (KCSAN) is a dynamic race detector, which relies on compile-time instrumentation, and uses a watchpoint-based sampling approach to detect races. The feature was under development for quite some time and has already found legitimate bugs. Unfortunately it comes with a limitation, which was only understood late in the development cycle: It requires an up to date CLANG-11 compiler CLANG-11 is not yet released (scheduled for June), but it's the only compiler today which handles the kernel requirements and especially the annotations of functions to exclude them from KCSAN instrumentation correctly. These annotations really need to work so that low level entry code and especially int3 text poke handling can be completely isolated. A detailed discussion of the requirements and compiler issues can be found here: https://lore.kernel.org/lkml/CANpmjNMTsY_8241bS7=XAfqvZHFLrVEkv_uM4aDUWE_kh3Rvbw@mail.gmail.com/ We came to the conclusion that trying to work around compiler limitations and bugs again would end up in a major trainwreck, so requiring a working compiler seemed to be the best choice. For Continous Integration purposes the compiler restriction is manageable and that's where most xxSAN reports come from. For a change this limitation might make GCC people actually look at their bugs. Some issues with CSAN in GCC are 7 years old and one has been 'fixed' 3 years ago with a half baken solution which 'solved' the reported issue but not the underlying problem. The KCSAN developers also ponder to use a GCC plugin to become independent, but that's not something which will show up in a few days. Blocking KCSAN until wide spread compiler support is available is not a really good alternative because the continuous growth of lockless optimizations in the kernel demands proper tooling support" * tag 'locking-kcsan-2020-06-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (76 commits) compiler_types.h, kasan: Use __SANITIZE_ADDRESS__ instead of CONFIG_KASAN to decide inlining compiler.h: Move function attributes to compiler_types.h compiler.h: Avoid nested statement expression in data_race() compiler.h: Remove data_race() and unnecessary checks from {READ,WRITE}_ONCE() kcsan: Update Documentation to change supported compilers kcsan: Remove 'noinline' from __no_kcsan_or_inline kcsan: Pass option tsan-instrument-read-before-write to Clang kcsan: Support distinguishing volatile accesses kcsan: Restrict supported compilers kcsan: Avoid inserting __tsan_func_entry/exit if possible ubsan, kcsan: Don't combine sanitizer with kcov on clang objtool, kcsan: Add kcsan_disable_current() and kcsan_enable_current_nowarn() kcsan: Add __kcsan_{enable,disable}_current() variants checkpatch: Warn about data_race() without comment kcsan: Use GFP_ATOMIC under spin lock Improve KCSAN documentation a bit kcsan: Make reporting aware of KCSAN tests kcsan: Fix function matching in report kcsan: Change data_race() to no longer require marking racing accesses kcsan: Move kcsan_{disable,enable}_current() to kcsan-checks.h ...
Diffstat (limited to 'scripts')
-rw-r--r--scripts/Makefile.kcsan19
-rw-r--r--scripts/Makefile.lib10
-rwxr-xr-xscripts/atomic/gen-atomic-instrumented.sh9
-rwxr-xr-xscripts/atomic/gen-atomic-long.sh3
-rwxr-xr-xscripts/checkpatch.pl8
5 files changed, 44 insertions, 5 deletions
diff --git a/scripts/Makefile.kcsan b/scripts/Makefile.kcsan
new file mode 100644
index 000000000000..bd4da1af5953
--- /dev/null
+++ b/scripts/Makefile.kcsan
@@ -0,0 +1,19 @@
+# SPDX-License-Identifier: GPL-2.0
+ifdef CONFIG_KCSAN
+
+# GCC and Clang accept backend options differently. Do not wrap in cc-option,
+# because Clang accepts "--param" even if it is unused.
+ifdef CONFIG_CC_IS_CLANG
+cc-param = -mllvm -$(1)
+else
+cc-param = --param -$(1)
+endif
+
+# Keep most options here optional, to allow enabling more compilers if absence
+# of some options does not break KCSAN nor causes false positive reports.
+CFLAGS_KCSAN := -fsanitize=thread \
+ $(call cc-option,$(call cc-param,tsan-instrument-func-entry-exit=0) -fno-optimize-sibling-calls) \
+ $(call cc-option,$(call cc-param,tsan-instrument-read-before-write=1)) \
+ $(call cc-param,tsan-distinguish-volatile=1)
+
+endif # CONFIG_KCSAN
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 127f2a7e3ced..e3f047692aeb 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -152,6 +152,16 @@ _c_flags += $(if $(patsubst n%,, \
$(CFLAGS_KCOV))
endif
+#
+# Enable KCSAN flags except some files or directories we don't want to check
+# (depends on variables KCSAN_SANITIZE_obj.o, KCSAN_SANITIZE)
+#
+ifeq ($(CONFIG_KCSAN),y)
+_c_flags += $(if $(patsubst n%,, \
+ $(KCSAN_SANITIZE_$(basetarget).o)$(KCSAN_SANITIZE)y), \
+ $(CFLAGS_KCSAN))
+endif
+
# $(srctree)/$(src) for including checkin headers from generated source files
# $(objtree)/$(obj) for including generated headers from checkin source files
ifeq ($(KBUILD_EXTMOD),)
diff --git a/scripts/atomic/gen-atomic-instrumented.sh b/scripts/atomic/gen-atomic-instrumented.sh
index e09812372b17..6afadf73da17 100755
--- a/scripts/atomic/gen-atomic-instrumented.sh
+++ b/scripts/atomic/gen-atomic-instrumented.sh
@@ -20,7 +20,7 @@ gen_param_check()
# We don't write to constant parameters
[ ${type#c} != ${type} ] && rw="read"
- printf "\tkasan_check_${rw}(${name}, sizeof(*${name}));\n"
+ printf "\tinstrument_atomic_${rw}(${name}, sizeof(*${name}));\n"
}
#gen_param_check(arg...)
@@ -84,7 +84,7 @@ gen_proto_order_variant()
[ ! -z "${guard}" ] && printf "#if ${guard}\n"
cat <<EOF
-static inline ${ret}
+static __always_inline ${ret}
${atomicname}(${params})
{
${checks}
@@ -107,7 +107,7 @@ cat <<EOF
#define ${xchg}(ptr, ...) \\
({ \\
typeof(ptr) __ai_ptr = (ptr); \\
- kasan_check_write(__ai_ptr, ${mult}sizeof(*__ai_ptr)); \\
+ instrument_atomic_write(__ai_ptr, ${mult}sizeof(*__ai_ptr)); \\
arch_${xchg}(__ai_ptr, __VA_ARGS__); \\
})
EOF
@@ -147,7 +147,8 @@ cat << EOF
#define _ASM_GENERIC_ATOMIC_INSTRUMENTED_H
#include <linux/build_bug.h>
-#include <linux/kasan-checks.h>
+#include <linux/compiler.h>
+#include <linux/instrumented.h>
EOF
diff --git a/scripts/atomic/gen-atomic-long.sh b/scripts/atomic/gen-atomic-long.sh
index c240a7231b2e..e318d3f92e53 100755
--- a/scripts/atomic/gen-atomic-long.sh
+++ b/scripts/atomic/gen-atomic-long.sh
@@ -46,7 +46,7 @@ gen_proto_order_variant()
local retstmt="$(gen_ret_stmt "${meta}")"
cat <<EOF
-static inline ${ret}
+static __always_inline ${ret}
atomic_long_${name}(${params})
{
${retstmt}${atomic}_${name}(${argscast});
@@ -64,6 +64,7 @@ cat << EOF
#ifndef _ASM_GENERIC_ATOMIC_LONG_H
#define _ASM_GENERIC_ATOMIC_LONG_H
+#include <linux/compiler.h>
#include <asm/types.h>
#ifdef CONFIG_64BIT
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index e23c912548f5..4c820607540b 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -5945,6 +5945,14 @@ sub process {
}
}
+# check for data_race without a comment.
+ if ($line =~ /\bdata_race\s*\(/) {
+ if (!ctx_has_comment($first_line, $linenr)) {
+ WARN("DATA_RACE",
+ "data_race without comment\n" . $herecurr);
+ }
+ }
+
# check for smp_read_barrier_depends and read_barrier_depends
if (!$file && $line =~ /\b(smp_|)read_barrier_depends\s*\(/) {
WARN("READ_BARRIER_DEPENDS",