Date: Tue, 10 Nov 2020 19:15:14 +0000 (UTC) From: Brooks Davis <brooks@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r367577 - in head: share/mk sys/conf tools/build/options Message-ID: <202011101915.0AAJFEWf059408@repo.freebsd.org>
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Author: brooks Date: Tue Nov 10 19:15:13 2020 New Revision: 367577 URL: https://svnweb.freebsd.org/changeset/base/367577 Log: Support initializing stack variables on function entry There are two options: - WITH_INIT_ALL_ZERO: Zero all variables on the stack. - WITH_INIT_ALL_PATTERN: Initialize variables with well-defined patterns. The exact pattern are a compiler implementation detail and vary by type. They are somewhat documented in the LLVM commit message: https://reviews.llvm.org/rL349442 I've used WITH_INIT_ALL_* to match Microsoft's InitAll feature rather than naming them after the LLVM specific compiler flags. In a range of consumer products, options like these are used in both debug and production builds with debugs builds using patterns (intended to provoke crashes on use of uninitialized values) and production using zeros (deemed more likely to lead to harmless misbehavior or NULL-pointer dereferences). Reviewed by: emaste Obtained from: CheriBSD Sponsored by: DARPA Differential Revision: https://reviews.freebsd.org/D27131 Added: head/tools/build/options/WITH_INIT_ALL_PATTERN (contents, props changed) head/tools/build/options/WITH_INIT_ALL_ZERO (contents, props changed) Modified: head/share/mk/bsd.compiler.mk head/share/mk/bsd.lib.mk head/share/mk/bsd.opts.mk head/share/mk/bsd.prog.mk head/sys/conf/kern.mk Modified: head/share/mk/bsd.compiler.mk ============================================================================== --- head/share/mk/bsd.compiler.mk Tue Nov 10 19:09:35 2020 (r367576) +++ head/share/mk/bsd.compiler.mk Tue Nov 10 19:15:13 2020 (r367577) @@ -24,6 +24,7 @@ # - c++11: supports full (or nearly full) C++11 programming environment. # - retpoline: supports the retpoline speculative execution vulnerability # mitigation. +# - init-all: supports stack variable initialization. # # These variables with an X_ prefix will also be provided if XCC is set. # @@ -214,7 +215,7 @@ ${X_}COMPILER_FEATURES= c++11 c++14 ${X_}COMPILER_FEATURES+= c++17 .endif .if ${${X_}COMPILER_TYPE} == "clang" -${X_}COMPILER_FEATURES+= retpoline +${X_}COMPILER_FEATURES+= retpoline init-all .endif .else Modified: head/share/mk/bsd.lib.mk ============================================================================== --- head/share/mk/bsd.lib.mk Tue Nov 10 19:09:35 2020 (r367576) +++ head/share/mk/bsd.lib.mk Tue Nov 10 19:15:13 2020 (r367577) @@ -85,6 +85,25 @@ LDFLAGS+= -Wl,-zretpolineplt .endif .endif +# Initialize stack variables on function entry +.if ${MK_INIT_ALL_ZERO} == "yes" +.if ${COMPILER_FEATURES:Minit-all} +CFLAGS+= -ftrivial-auto-var-init=zero \ + -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang +CXXFLAGS+= -ftrivial-auto-var-init=zero \ + -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang +.else +.warning InitAll (zeros) requested but not support by compiler +.endif +.elif ${MK_INIT_ALL_PATTERN} == "yes" +.if ${COMPILER_FEATURES:Minit-all} +CFLAGS+= -ftrivial-auto-var-init=pattern +CXXFLAGS+= -ftrivial-auto-var-init=pattern +.else +.warning InitAll (pattern) requested but not support by compiler +.endif +.endif + .if ${MK_DEBUG_FILES} != "no" && empty(DEBUG_FLAGS:M-g) && \ empty(DEBUG_FLAGS:M-gdwarf*) CFLAGS+= ${DEBUG_FILES_CFLAGS} Modified: head/share/mk/bsd.opts.mk ============================================================================== --- head/share/mk/bsd.opts.mk Tue Nov 10 19:09:35 2020 (r367576) +++ head/share/mk/bsd.opts.mk Tue Nov 10 19:15:13 2020 (r367577) @@ -71,6 +71,8 @@ __DEFAULT_NO_OPTIONS = \ BIND_NOW \ CCACHE_BUILD \ CTF \ + INIT_ALL_PATTERN \ + INIT_ALL_ZERO \ INSTALL_AS_USER \ PIE \ RETPOLINE \ @@ -84,6 +86,10 @@ __DEFAULT_DEPENDENT_OPTIONS = \ .include <bsd.mkopt.mk> + +.if ${MK_INIT_ALL_PATTERN} == "yes" && ${MK_INIT_ALL_ZERO} == "yes" +.error WITH_INIT_ALL_PATTERN and WITH_INIT_ALL_ZERO are mutually exclusive. +.endif # # Supported NO_* options (if defined, MK_* will be forced to "no", Modified: head/share/mk/bsd.prog.mk ============================================================================== --- head/share/mk/bsd.prog.mk Tue Nov 10 19:09:35 2020 (r367576) +++ head/share/mk/bsd.prog.mk Tue Nov 10 19:15:13 2020 (r367577) @@ -60,6 +60,25 @@ LDFLAGS+= -Wl,-zretpolineplt .endif .endif +# Initialize stack variables on function entry +.if ${MK_INIT_ALL_ZERO} == "yes" +.if ${COMPILER_FEATURES:Minit-all} +CFLAGS+= -ftrivial-auto-var-init=zero \ + -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang +CXXFLAGS+= -ftrivial-auto-var-init=zero \ + -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang +.else +.warning InitAll (zeros) requested but not support by compiler +.endif +.elif ${MK_INIT_ALL_PATTERN} == "yes" +.if ${COMPILER_FEATURES:Minit-all} +CFLAGS+= -ftrivial-auto-var-init=pattern +CXXFLAGS+= -ftrivial-auto-var-init=pattern +.else +.warning InitAll (pattern) requested but not support by compiler +.endif +.endif + .if ${MACHINE_CPUARCH} == "riscv" && ${LINKER_FEATURES:Mriscv-relaxations} == "" CFLAGS += -mno-relax .endif Modified: head/sys/conf/kern.mk ============================================================================== --- head/sys/conf/kern.mk Tue Nov 10 19:09:35 2020 (r367576) +++ head/sys/conf/kern.mk Tue Nov 10 19:15:13 2020 (r367577) @@ -228,6 +228,24 @@ CFLAGS+= -mretpoline .endif # +# Initialize stack variables on function entry +# +.if ${MK_INIT_ALL_ZERO} == "yes" +.if ${COMPILER_FEATURES:Minit-all} +CFLAGS+= -ftrivial-auto-var-init=zero \ + -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang +.else +.warning InitAll (zeros) requested but not support by compiler +.endif +.elif ${MK_INIT_ALL_PATTERN} == "yes" +.if ${COMPILER_FEATURES:Minit-all} +CFLAGS+= -ftrivial-auto-var-init=pattern +.else +.warning InitAll (pattern) requested but not support by compiler +.endif +.endif + +# # Add -gdwarf-2 when compiling -g. The default starting in clang v3.4 # and gcc 4.8 is to generate DWARF version 4. However, our tools don't # cope well with DWARF 4, so force it to genereate DWARF2, which they Added: head/tools/build/options/WITH_INIT_ALL_PATTERN ============================================================================== --- /dev/null 00:00:00 1970 (empty, because file is newly added) +++ head/tools/build/options/WITH_INIT_ALL_PATTERN Tue Nov 10 19:15:13 2020 (r367577) @@ -0,0 +1,5 @@ +.\" $FreeBSD$ +Set to build the base system or kernel with stack variables initialized to +.Pq compiler defined +debugging patterns on function entry. +This option requires the clang compiler. Added: head/tools/build/options/WITH_INIT_ALL_ZERO ============================================================================== --- /dev/null 00:00:00 1970 (empty, because file is newly added) +++ head/tools/build/options/WITH_INIT_ALL_ZERO Tue Nov 10 19:15:13 2020 (r367577) @@ -0,0 +1,4 @@ +.\" $FreeBSD$ +Set to build the base system or kernel with stack variables initialized +to zero on function entry. +This option requires that the clang compiler be used.
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