From 3b4c6c6acfd781f34ce6318b1a80a800dd5c11ad Mon Sep 17 00:00:00 2001 From: Song Liu Date: Wed, 13 Oct 2021 00:10:20 -0700 Subject: [PATCH 1/2] create-diff-object: compare section name with kpatch_section_function_name Profile-Guided Optimization (PGO) uses profiling data to help the compiler to evaluate the properties of a function, and thus adds different prefixes to the section/function. For example, with -ffunction-sections, the compiler will prefix some sectiones with .text.unlikely. However, if a function changes from the version in the profiling data, the compiler may ignore the profiling data. This often happens to the patched function when kpatch-build builds the patch. As a result, the original function and the patch function may have different prefix, i.e., one of them has .text, the other has .text.unlikely. To correlate these functions properly, use kpatch_section_function_name() in kpatch_correlate_sections() to find matching sections. Signed-off-by: Song Liu --- kpatch-build/create-diff-object.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/kpatch-build/create-diff-object.c b/kpatch-build/create-diff-object.c index 6a4848a2..c3b37dc3 100644 --- a/kpatch-build/create-diff-object.c +++ b/kpatch-build/create-diff-object.c @@ -957,6 +957,8 @@ static void kpatch_correlate_section(struct section *sec_orig, kpatch_correlate_symbol(sec_orig->sym, sec_patched->sym); } +static char *kpatch_section_function_name(struct section *sec); + static void kpatch_correlate_sections(struct list_head *seclist_orig, struct list_head *seclist_patched) { @@ -966,8 +968,9 @@ static void kpatch_correlate_sections(struct list_head *seclist_orig, if (sec_orig->twin) continue; list_for_each_entry(sec_patched, seclist_patched, list) { - if (kpatch_mangled_strcmp(sec_orig->name, sec_patched->name) || - sec_patched->twin) + if (sec_patched->twin || + kpatch_mangled_strcmp(kpatch_section_function_name(sec_orig), + kpatch_section_function_name(sec_patched))) continue; if (is_special_static(is_rela_section(sec_orig) ? From 6d93e41500959170ca222cd17362a5dcfe2945f6 Mon Sep 17 00:00:00 2001 From: Song Liu Date: Wed, 13 Oct 2021 01:03:55 -0700 Subject: [PATCH 2/2] kpatch-build: add support for clang pgo For clang with Profile-Guided Optimization (PGO), profile data is needed to compile the livepatch properly. Add option -p|--profile-data, which specifies the profile data file. This option is only valid with CONFIG_CC_IS_CLANG and CONFIG_PGO_CLANG. Signed-off-by: Song Liu --- kpatch-build/kpatch-build | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-) diff --git a/kpatch-build/kpatch-build b/kpatch-build/kpatch-build index 3a9902e5..d8bee557 100755 --- a/kpatch-build/kpatch-build +++ b/kpatch-build/kpatch-build @@ -538,9 +538,10 @@ usage() { echo " --skip-cleanup Skip post-build cleanup" >&2 echo " --skip-compiler-check Skip compiler version matching check" >&2 echo " (not recommended)" >&2 + echo " -p, --profile-data specify profile data for PGO (clang only)" >&2 } -options="$(getopt -o ha:r:s:c:v:j:t:n:o:de:R -l "help,archversion:,sourcerpm:,sourcedir:,config:,vmlinux:,jobs:,target:,name:,output:,oot-module:,debug,skip-gcc-check,skip-compiler-check,skip-cleanup,non-replace" -- "$@")" || die "getopt failed" +options="$(getopt -o ha:r:s:c:v:j:t:n:o:de:Rp: -l "help,archversion:,sourcerpm:,sourcedir:,config:,vmlinux:,jobs:,target:,name:,output:,oot-module:,debug,skip-gcc-check,skip-compiler-check,skip-cleanup,non-replace,profile-data" -- "$@")" || die "getopt failed" eval set -- "$options" @@ -617,6 +618,10 @@ while [[ $# -gt 0 ]]; do echo "WARNING: Skipping compiler version matching check (not recommended)" SKIPCOMPILERCHECK=1 ;; + -p|--profile-data) + PROFILE_DATA="$(readlink -f "$2")" + shift + ;; *) [[ "$1" = "--" ]] && shift && continue [[ ! -f "$1" ]] && die "patch file '$1' not found" @@ -835,6 +840,7 @@ CONFIG_JUMP_LABEL=0 CONFIG_MODVERSIONS=0 CONFIG_CC_IS_CLANG=0 CONFIG_LD_IS_LLD=0 +CONFIG_PGO_CLANG=0 if grep -q "CONFIG_LIVEPATCH=y" "$CONFIGFILE" && (kernel_is_rhel || kernel_version_gte 4.9.0); then @@ -869,6 +875,7 @@ grep -q "CONFIG_JUMP_LABEL=y" "$CONFIGFILE" && CONFIG_JUMP_LABEL=1 grep -q "CONFIG_MODVERSIONS=y" "$CONFIGFILE" && CONFIG_MODVERSIONS=1 grep -q "CONFIG_CC_IS_CLANG=y" "$CONFIGFILE" && CONFIG_CC_IS_CLANG=1 grep -q "CONFIG_LD_IS_LLD=y" "$CONFIGFILE" && CONFIG_LD_IS_LLD=1 +grep -q "CONFIG_PGO_CLANG=y" "$CONFIGFILE" && CONFIG_PGO_CLANG=1 # unsupported kernel option checking grep -q "CONFIG_DEBUG_INFO_SPLIT=y" "$CONFIGFILE" && die "kernel option 'CONFIG_DEBUG_INFO_SPLIT' not supported" @@ -891,6 +898,16 @@ fi if [[ "$CONFIG_CC_IS_CLANG" -eq 1 ]]; then echo "WARNING: Clang support is experimental" + if [[ -z "$PROFILE_DATA" ]] && [[ "$CONFIG_PGO_CLANG" -eq 1 ]]; then + die "Please specify profile-data for CONFIG_PGO_CLANG" + fi + if [[ -n "$PROFILE_DATA" ]] && [[ "$CONFIG_PGO_CLANG" -eq 0 ]]; then + echo "WARNING profile-data specified w/o CONFIG_PGO_CLANG, ignore it" + fi +else + if [[ -n "$PROFILE_DATA" ]]; then + die "Only supports profile-data with Clang" + fi fi if [[ "$SKIPCOMPILERCHECK" -eq 0 ]]; then @@ -937,6 +954,9 @@ declare -a MAKEVARS if [ "$CONFIG_CC_IS_CLANG" -eq 1 ]; then MAKEVARS+=("CC=${KPATCH_CC_PREFIX}clang") MAKEVARS+=("HOSTCC=clang") + if [[ "$CONFIG_PGO_CLANG" -eq 1 ]]; then + MAKEVARS+=("CFLAGS_PGO_CLANG=-fprofile-use=$PROFILE_DATA") + fi else MAKEVARS+=("CC=${KPATCH_CC_PREFIX}gcc") fi