| Message ID | cover.1706491398.git.dxu@dxuuu.xyz (mailing list archive) |
|---|---|
| Headers | show |
| Series | Annotate kfuncs in .BTF_ids section | expand |
On Sun, Jan 28, 2024 at 06:24:05PM -0700, Daniel Xu wrote: > === Description === > > This is a bpf-treewide change that annotates all kfuncs as such inside > .BTF_ids. This annotation eventually allows us to automatically generate > kfunc prototypes from bpftool. > > We store this metadata inside a yet-unused flags field inside struct > btf_id_set8 (thanks Kumar!). pahole will be taught where to look. > > More details about the full chain of events are available in commit 3's > description. > > The accompanying pahole and bpftool changes can be viewed > here on these "frozen" branches [0][1]. > > [0]: https://github.com/danobi/pahole/tree/kfunc_btf-v3-mailed > [1]: https://github.com/danobi/linux/tree/kfunc_bpftool-mailed > > === Changelog === > > Changes from v3: > * Rebase to bpf-next and add missing annotation on new kfunc Acked-by: Jiri Olsa <jolsa@kernel.org> jirka > > Changes from v2: > * Only WARN() for vmlinux kfuncs > > Changes from v1: > * Move WARN_ON() up a call level > * Also return error when kfunc set is not properly tagged > * Use BTF_KFUNCS_START/END instead of flags > * Rename BTF_SET8_KFUNC to BTF_SET8_KFUNCS > > Daniel Xu (3): > bpf: btf: Support flags for BTF_SET8 sets > bpf: btf: Add BTF_KFUNCS_START/END macro pair > bpf: treewide: Annotate BPF kfuncs in BTF > > Documentation/bpf/kfuncs.rst | 8 +++---- > drivers/hid/bpf/hid_bpf_dispatch.c | 8 +++---- > fs/verity/measure.c | 4 ++-- > include/linux/btf_ids.h | 21 +++++++++++++++---- > kernel/bpf/btf.c | 8 +++++++ > kernel/bpf/cpumask.c | 4 ++-- > kernel/bpf/helpers.c | 8 +++---- > kernel/bpf/map_iter.c | 4 ++-- > kernel/cgroup/rstat.c | 4 ++-- > kernel/trace/bpf_trace.c | 8 +++---- > net/bpf/test_run.c | 8 +++---- > net/core/filter.c | 20 +++++++++--------- > net/core/xdp.c | 4 ++-- > net/ipv4/bpf_tcp_ca.c | 4 ++-- > net/ipv4/fou_bpf.c | 4 ++-- > net/ipv4/tcp_bbr.c | 4 ++-- > net/ipv4/tcp_cubic.c | 4 ++-- > net/ipv4/tcp_dctcp.c | 4 ++-- > net/netfilter/nf_conntrack_bpf.c | 4 ++-- > net/netfilter/nf_nat_bpf.c | 4 ++-- > net/xfrm/xfrm_interface_bpf.c | 4 ++-- > net/xfrm/xfrm_state_bpf.c | 4 ++-- > .../selftests/bpf/bpf_testmod/bpf_testmod.c | 8 +++---- > 23 files changed, 87 insertions(+), 66 deletions(-) > > -- > 2.42.1 >
Hello: This series was applied to bpf/bpf-next.git (master) by Alexei Starovoitov <ast@kernel.org>: On Sun, 28 Jan 2024 18:24:05 -0700 you wrote: > === Description === > > This is a bpf-treewide change that annotates all kfuncs as such inside > .BTF_ids. This annotation eventually allows us to automatically generate > kfunc prototypes from bpftool. > > We store this metadata inside a yet-unused flags field inside struct > btf_id_set8 (thanks Kumar!). pahole will be taught where to look. > > [...] Here is the summary with links: - [bpf-next,v4,1/3] bpf: btf: Support flags for BTF_SET8 sets https://git.kernel.org/bpf/bpf-next/c/79b47344bbc5 - [bpf-next,v4,2/3] bpf: btf: Add BTF_KFUNCS_START/END macro pair https://git.kernel.org/bpf/bpf-next/c/2747e0ee57c2 - [bpf-next,v4,3/3] bpf: treewide: Annotate BPF kfuncs in BTF https://git.kernel.org/bpf/bpf-next/c/6e7769e6419f You are awesome, thank you!
On Sun, Jan 28, 2024 at 06:24:05PM -0700, Daniel Xu wrote: > === Description === > > This is a bpf-treewide change that annotates all kfuncs as such inside > .BTF_ids. This annotation eventually allows us to automatically generate > kfunc prototypes from bpftool. > > We store this metadata inside a yet-unused flags field inside struct > btf_id_set8 (thanks Kumar!). pahole will be taught where to look. > > More details about the full chain of events are available in commit 3's > description. > > The accompanying pahole and bpftool changes can be viewed > here on these "frozen" branches [0][1]. > > [0]: https://github.com/danobi/pahole/tree/kfunc_btf-v3-mailed > [1]: https://github.com/danobi/linux/tree/kfunc_bpftool-mailed I hit a similar issue to [0] on master 943b043aeecc ("selftests/bpf: Fix bench runner SIGSEGV") when cross-compiling on x86_64 (LE) to s390x (BE). I do have CONFIG_DEBUG_INFO_BTF enable and the issue would not trigger if I disabled CONFIG_DEBUG_INFO_BTF (and with the fix mentioned in [0]). What seems to happen is that `tools/resolve_btfids` is ran in the context of the host endianess and if I printk before the WARN_ON: diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index ef380e546952..a9ed7a1a4936 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -8128,6 +8128,7 @@ int register_btf_kfunc_id_set(enum bpf_prog_type prog_type, * WARN() for initcall registrations that do not check errors. */ if (!(kset->set->flags & BTF_SET8_KFUNCS)) { + printk("Flag 0x%08X, expected 0x%08X\n", kset->set->flags, BTF_SET8_KFUNCS); WARN_ON(!kset->owner); return -EINVAL; } the boot logs would show: Flag 0x01000000, expected 0x00000001 The issue did not happen prior to 6f3189f38a3e ("bpf: treewide: Annotate BPF kfuncs in BTF") has only 0 was written before. It seems [1] will be addressing cross-compilation, but it did not fix it as is by just applying on top of master, so probably some of the changes will also need to be ported to `tools/include/linux/btf_ids.h`? A hacky workaround to cross-compilation I have is to apply: diff --git a/tools/bpf/resolve_btfids/Makefile b/tools/bpf/resolve_btfids/Makefile index 4b8079f294f6..b706e7ab066f 100644 --- a/tools/bpf/resolve_btfids/Makefile +++ b/tools/bpf/resolve_btfids/Makefile @@ -22,10 +22,10 @@ HOST_OVERRIDES := AR="$(HOSTAR)" CC="$(HOSTCC)" LD="$(HOSTLD)" ARCH="$(HOSTARCH) CROSS_COMPILE="" EXTRA_CFLAGS="$(HOSTCFLAGS)" RM ?= rm -HOSTCC ?= gcc -HOSTLD ?= ld -HOSTAR ?= ar -CROSS_COMPILE = +HOSTCC = $(CC) +HOSTLD = $(LD) +HOSTAR = $(AR) +#CROSS_COMPILE = OUTPUT ?= $(srctree)/tools/bpf/resolve_btfids/ @@ -56,16 +56,16 @@ $(OUTPUT) $(OUTPUT)/libsubcmd $(LIBBPF_OUT): $(SUBCMDOBJ): fixdep FORCE | $(OUTPUT)/libsubcmd $(Q)$(MAKE) -C $(SUBCMD_SRC) OUTPUT=$(SUBCMD_OUT) \ - DESTDIR=$(SUBCMD_DESTDIR) $(HOST_OVERRIDES) prefix= subdir= \ + DESTDIR=$(SUBCMD_DESTDIR) prefix= subdir= \ $(abspath $@) install_headers $(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(LIBBPF_OUT) $(Q)$(MAKE) $(submake_extras) -C $(LIBBPF_SRC) OUTPUT=$(LIBBPF_OUT) \ - DESTDIR=$(LIBBPF_DESTDIR) $(HOST_OVERRIDES) prefix= subdir= \ + DESTDIR=$(LIBBPF_DESTDIR) prefix= subdir= \ $(abspath $@) install_headers -LIBELF_FLAGS := $(shell $(HOSTPKG_CONFIG) libelf --cflags 2>/dev/null) -LIBELF_LIBS := $(shell $(HOSTPKG_CONFIG) libelf --libs 2>/dev/null || echo -lelf) +LIBELF_FLAGS := $(shell $(PKG_CONFIG) libelf --cflags 2>/dev/null) +LIBELF_LIBS := $(shell $(PKG_CONFIG) libelf --libs 2>/dev/null || echo -lelf) HOSTCFLAGS_resolve_btfids += -g \ -I$(srctree)/tools/include \ @@ -84,7 +84,7 @@ $(BINARY_IN): fixdep FORCE prepare | $(OUTPUT) $(BINARY): $(BPFOBJ) $(SUBCMDOBJ) $(BINARY_IN) $(call msg,LINK,$@) - $(Q)$(HOSTCC) $(BINARY_IN) $(KBUILD_HOSTLDFLAGS) -o $@ $(BPFOBJ) $(SUBCMDOBJ) $(LIBS) + $(Q)$(CC) $(BINARY_IN) $(KBUILD_HOSTLDFLAGS) -o $@ $(BPFOBJ) $(SUBCMDOBJ) $(LIBS) clean_objects := $(wildcard $(OUTPUT)/*.o \ $(OUTPUT)/.*.o.cmd \ diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index a38a3001527c..5cd193c04448 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -171,7 +171,7 @@ INCLUDE_DIR := $(SCRATCH_DIR)/include BPFOBJ := $(BUILD_DIR)/libbpf/libbpf.a ifneq ($(CROSS_COMPILE),) HOST_BUILD_DIR := $(BUILD_DIR)/host -HOST_SCRATCH_DIR := $(OUTPUT)/host-tools +HOST_SCRATCH_DIR := $(SCRATCH_DIR) HOST_INCLUDE_DIR := $(HOST_SCRATCH_DIR)/include else HOST_BUILD_DIR := $(BUILD_DIR) This causes `resolve_btfids` to be compiled in the target endianess and gets magically run provided that the hosts has `qemu-s390x-static` and a functional binfmt_misc [2] on the host, but having this using host architecture per [1] is likely better. Here are steps to reproduce the issue on Ubuntu 23.10 and assuming danobi/vmtest [3] is installed: XPLATFORM="s390x" XARCH="s390" # Set up repo for s390x cat <<EOF >> /etc/apt/sources.list.d/s390x.list deb [arch=s390x] http://ports.ubuntu.com/ubuntu-ports mantic main restricted deb [arch=s390x] http://ports.ubuntu.com/ubuntu-ports mantic-updates main restricted EOF sudo dpkg --add-architecture s390x apt install qemu-system-s390x qemu-user-static g{cc,++}-"${XARCH}-linux-gnu" {libelf-dev,libssl-dev,pkgconf}:s390x KBUILD_OUTPUT_DIR="/tmp/kbuild-${XPLATFORM}" mkdir "${KBUILD_OUTPUT_DIR}" cat tools/testing/selftests/bpf/config{,.vm,.${XPLATFORM}} > ${KBUILD_OUTPUT_DIR}/.config make ARCH="${XARCH}" CROSS_COMPILE="${XPLATFORM}-linux-gnu-" O="${KBUILD_OUTPUT_DIR}" -j$((4 * $(nproc))) olddefconfig make ARCH="${XARCH}" CROSS_COMPILE="${XPLATFORM}-linux-gnu-" O="${KBUILD_OUTPUT_DIR}" -j$((4 * $(nproc))) all # No need for a s390x ubuntu 23.10 rootfs, we only care about booting the kernel vmtest -k "${KBUILD_OUTPUT_DIR}/arch/s390/boot/bzImage" -a s390x "uname -m" | cat For the chroot route, see [4]. [0] https://lore.kernel.org/linux-kernel/20240201155339.2b5936be@canb.auug.org.au/T/ [1] https://lore.kernel.org/bpf/cover.1706717857.git.vmalik@redhat.com/ [2] https://en.wikipedia.org/wiki/Binfmt_misc [3] https://github.com/danobi/vmtest [4] https://chantra.github.io/bpfcitools/bpf-cross-compile.html Manu > > === Changelog === > > Changes from v3: > * Rebase to bpf-next and add missing annotation on new kfunc > > Changes from v2: > * Only WARN() for vmlinux kfuncs > > Changes from v1: > * Move WARN_ON() up a call level > * Also return error when kfunc set is not properly tagged > * Use BTF_KFUNCS_START/END instead of flags > * Rename BTF_SET8_KFUNC to BTF_SET8_KFUNCS > > Daniel Xu (3): > bpf: btf: Support flags for BTF_SET8 sets > bpf: btf: Add BTF_KFUNCS_START/END macro pair > bpf: treewide: Annotate BPF kfuncs in BTF > > Documentation/bpf/kfuncs.rst | 8 +++---- > drivers/hid/bpf/hid_bpf_dispatch.c | 8 +++---- > fs/verity/measure.c | 4 ++-- > include/linux/btf_ids.h | 21 +++++++++++++++---- > kernel/bpf/btf.c | 8 +++++++ > kernel/bpf/cpumask.c | 4 ++-- > kernel/bpf/helpers.c | 8 +++---- > kernel/bpf/map_iter.c | 4 ++-- > kernel/cgroup/rstat.c | 4 ++-- > kernel/trace/bpf_trace.c | 8 +++---- > net/bpf/test_run.c | 8 +++---- > net/core/filter.c | 20 +++++++++--------- > net/core/xdp.c | 4 ++-- > net/ipv4/bpf_tcp_ca.c | 4 ++-- > net/ipv4/fou_bpf.c | 4 ++-- > net/ipv4/tcp_bbr.c | 4 ++-- > net/ipv4/tcp_cubic.c | 4 ++-- > net/ipv4/tcp_dctcp.c | 4 ++-- > net/netfilter/nf_conntrack_bpf.c | 4 ++-- > net/netfilter/nf_nat_bpf.c | 4 ++-- > net/xfrm/xfrm_interface_bpf.c | 4 ++-- > net/xfrm/xfrm_state_bpf.c | 4 ++-- > .../selftests/bpf/bpf_testmod/bpf_testmod.c | 8 +++---- > 23 files changed, 87 insertions(+), 66 deletions(-) > > -- > 2.42.1 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
Hi Manu, On Fri, Feb 02, 2024 at 03:09:05PM -0800, Manu Bretelle wrote: > On Sun, Jan 28, 2024 at 06:24:05PM -0700, Daniel Xu wrote: > > === Description === > > > > This is a bpf-treewide change that annotates all kfuncs as such inside > > .BTF_ids. This annotation eventually allows us to automatically generate > > kfunc prototypes from bpftool. > > > > We store this metadata inside a yet-unused flags field inside struct > > btf_id_set8 (thanks Kumar!). pahole will be taught where to look. > > > > More details about the full chain of events are available in commit 3's > > description. > > > > The accompanying pahole and bpftool changes can be viewed > > here on these "frozen" branches [0][1]. > > > > [0]: https://github.com/danobi/pahole/tree/kfunc_btf-v3-mailed > > [1]: https://github.com/danobi/linux/tree/kfunc_bpftool-mailed > > > I hit a similar issue to [0] on master > 943b043aeecc ("selftests/bpf: Fix bench runner SIGSEGV") > when cross-compiling on x86_64 (LE) to s390x (BE). > I do have CONFIG_DEBUG_INFO_BTF enable and the issue would not trigger if > I disabled CONFIG_DEBUG_INFO_BTF (and with the fix mentioned in [0]). > > What seems to happen is that `tools/resolve_btfids` is ran in the context of the > host endianess and if I printk before the WARN_ON: > diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c > index ef380e546952..a9ed7a1a4936 100644 > --- a/kernel/bpf/btf.c > +++ b/kernel/bpf/btf.c > @@ -8128,6 +8128,7 @@ int register_btf_kfunc_id_set(enum bpf_prog_type prog_type, > * WARN() for initcall registrations that do not check errors. > */ > if (!(kset->set->flags & BTF_SET8_KFUNCS)) { > + printk("Flag 0x%08X, expected 0x%08X\n", kset->set->flags, BTF_SET8_KFUNCS); > WARN_ON(!kset->owner); > return -EINVAL; > } > > the boot logs would show: > Flag 0x01000000, expected 0x00000001 > > The issue did not happen prior to > 6f3189f38a3e ("bpf: treewide: Annotate BPF kfuncs in BTF") > has only 0 was written before. > > It seems [1] will be addressing cross-compilation, but it did not fix it as is > by just applying on top of master, so probably some of the changes will also need > to be ported to `tools/include/linux/btf_ids.h`? > > A hacky workaround to cross-compilation I have is to apply: > > diff --git a/tools/bpf/resolve_btfids/Makefile b/tools/bpf/resolve_btfids/Makefile > index 4b8079f294f6..b706e7ab066f 100644 > --- a/tools/bpf/resolve_btfids/Makefile > +++ b/tools/bpf/resolve_btfids/Makefile > @@ -22,10 +22,10 @@ HOST_OVERRIDES := AR="$(HOSTAR)" CC="$(HOSTCC)" LD="$(HOSTLD)" ARCH="$(HOSTARCH) > CROSS_COMPILE="" EXTRA_CFLAGS="$(HOSTCFLAGS)" > RM ?= rm > -HOSTCC ?= gcc > -HOSTLD ?= ld > -HOSTAR ?= ar > -CROSS_COMPILE = > +HOSTCC = $(CC) > +HOSTLD = $(LD) > +HOSTAR = $(AR) > +#CROSS_COMPILE = > OUTPUT ?= $(srctree)/tools/bpf/resolve_btfids/ > @@ -56,16 +56,16 @@ $(OUTPUT) $(OUTPUT)/libsubcmd $(LIBBPF_OUT): > $(SUBCMDOBJ): fixdep FORCE | $(OUTPUT)/libsubcmd > $(Q)$(MAKE) -C $(SUBCMD_SRC) OUTPUT=$(SUBCMD_OUT) \ > - DESTDIR=$(SUBCMD_DESTDIR) $(HOST_OVERRIDES) prefix= subdir= \ > + DESTDIR=$(SUBCMD_DESTDIR) prefix= subdir= \ > $(abspath $@) install_headers > $(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(LIBBPF_OUT) > $(Q)$(MAKE) $(submake_extras) -C $(LIBBPF_SRC) OUTPUT=$(LIBBPF_OUT) \ > - DESTDIR=$(LIBBPF_DESTDIR) $(HOST_OVERRIDES) prefix= subdir= \ > + DESTDIR=$(LIBBPF_DESTDIR) prefix= subdir= \ > $(abspath $@) install_headers > -LIBELF_FLAGS := $(shell $(HOSTPKG_CONFIG) libelf --cflags 2>/dev/null) > -LIBELF_LIBS := $(shell $(HOSTPKG_CONFIG) libelf --libs 2>/dev/null || echo -lelf) > +LIBELF_FLAGS := $(shell $(PKG_CONFIG) libelf --cflags 2>/dev/null) > +LIBELF_LIBS := $(shell $(PKG_CONFIG) libelf --libs 2>/dev/null || echo -lelf) > HOSTCFLAGS_resolve_btfids += -g \ > -I$(srctree)/tools/include \ > @@ -84,7 +84,7 @@ $(BINARY_IN): fixdep FORCE prepare | $(OUTPUT) > $(BINARY): $(BPFOBJ) $(SUBCMDOBJ) $(BINARY_IN) > $(call msg,LINK,$@) > - $(Q)$(HOSTCC) $(BINARY_IN) $(KBUILD_HOSTLDFLAGS) -o $@ $(BPFOBJ) $(SUBCMDOBJ) $(LIBS) > + $(Q)$(CC) $(BINARY_IN) $(KBUILD_HOSTLDFLAGS) -o $@ $(BPFOBJ) $(SUBCMDOBJ) $(LIBS) > clean_objects := $(wildcard $(OUTPUT)/*.o \ > $(OUTPUT)/.*.o.cmd \ > diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile > index a38a3001527c..5cd193c04448 100644 > --- a/tools/testing/selftests/bpf/Makefile > +++ b/tools/testing/selftests/bpf/Makefile > @@ -171,7 +171,7 @@ INCLUDE_DIR := $(SCRATCH_DIR)/include > BPFOBJ := $(BUILD_DIR)/libbpf/libbpf.a > ifneq ($(CROSS_COMPILE),) > HOST_BUILD_DIR := $(BUILD_DIR)/host > -HOST_SCRATCH_DIR := $(OUTPUT)/host-tools > +HOST_SCRATCH_DIR := $(SCRATCH_DIR) > HOST_INCLUDE_DIR := $(HOST_SCRATCH_DIR)/include > else > HOST_BUILD_DIR := $(BUILD_DIR) > > This causes `resolve_btfids` to be compiled in the target endianess and gets > magically run provided that the hosts has `qemu-s390x-static` and a functional > binfmt_misc [2] on the host, but having this using host architecture per [1] > is likely better. This is kinda surprising to me. I don't recall seeing any code inside resolve_btfids that touches the set8 flags field -- only the ids in the flexible array member. Would be interested to see what the value of the set8 flags field is before resolve_btfids is run. I'm a bit busy until Sunday afternoon but I'll try to take a look around then. Might be a good opportunity to play with poke [0]. Thanks, Daniel [0]: http://www.jemarch.net/poke
On Fri, Feb 02, 2024 at 03:09:05PM -0800, Manu Bretelle wrote: > On Sun, Jan 28, 2024 at 06:24:05PM -0700, Daniel Xu wrote: > > === Description === > > > > This is a bpf-treewide change that annotates all kfuncs as such inside > > .BTF_ids. This annotation eventually allows us to automatically generate > > kfunc prototypes from bpftool. > > > > We store this metadata inside a yet-unused flags field inside struct > > btf_id_set8 (thanks Kumar!). pahole will be taught where to look. > > > > More details about the full chain of events are available in commit 3's > > description. > > > > The accompanying pahole and bpftool changes can be viewed > > here on these "frozen" branches [0][1]. > > > > [0]: https://github.com/danobi/pahole/tree/kfunc_btf-v3-mailed > > [1]: https://github.com/danobi/linux/tree/kfunc_bpftool-mailed > > > I hit a similar issue to [0] on master > 943b043aeecc ("selftests/bpf: Fix bench runner SIGSEGV") > when cross-compiling on x86_64 (LE) to s390x (BE). > I do have CONFIG_DEBUG_INFO_BTF enable and the issue would not trigger if > I disabled CONFIG_DEBUG_INFO_BTF (and with the fix mentioned in [0]). > > What seems to happen is that `tools/resolve_btfids` is ran in the context of the > host endianess and if I printk before the WARN_ON: > diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c > index ef380e546952..a9ed7a1a4936 100644 > --- a/kernel/bpf/btf.c > +++ b/kernel/bpf/btf.c > @@ -8128,6 +8128,7 @@ int register_btf_kfunc_id_set(enum bpf_prog_type prog_type, > * WARN() for initcall registrations that do not check errors. > */ > if (!(kset->set->flags & BTF_SET8_KFUNCS)) { > + printk("Flag 0x%08X, expected 0x%08X\n", kset->set->flags, BTF_SET8_KFUNCS); > WARN_ON(!kset->owner); > return -EINVAL; > } > > the boot logs would show: > Flag 0x01000000, expected 0x00000001 > > The issue did not happen prior to > 6f3189f38a3e ("bpf: treewide: Annotate BPF kfuncs in BTF") > has only 0 was written before. > > It seems [1] will be addressing cross-compilation, but it did not fix it as is > by just applying on top of master, so probably some of the changes will also need > to be ported to `tools/include/linux/btf_ids.h`? the fix in [1] is fixing flags in set8's pairs, but not the global flags it looks like Viktor's fix should now also swap that as well? like in the change below on top of Viktor's changes (untested) jirka --- diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c index d01603ef6283..c44d57fec390 100644 --- a/tools/bpf/resolve_btfids/main.c +++ b/tools/bpf/resolve_btfids/main.c @@ -706,6 +706,8 @@ static int sets_patch(struct object *obj) * correctly translate everything. */ if (need_bswap) { + set8->flags = bswap_32(set8->flags); + for (i = 0; i < cnt; i++) { set8->pairs[i].flags = bswap_32(set8->pairs[i].flags);
On Sat, Feb 03, 2024 at 03:40:24PM +0100, Jiri Olsa wrote: > On Fri, Feb 02, 2024 at 03:09:05PM -0800, Manu Bretelle wrote: > > On Sun, Jan 28, 2024 at 06:24:05PM -0700, Daniel Xu wrote: > > > === Description === > > > > > > This is a bpf-treewide change that annotates all kfuncs as such inside > > > .BTF_ids. This annotation eventually allows us to automatically generate > > > kfunc prototypes from bpftool. > > > > > > We store this metadata inside a yet-unused flags field inside struct > > > btf_id_set8 (thanks Kumar!). pahole will be taught where to look. > > > > > > More details about the full chain of events are available in commit 3's > > > description. > > > > > > The accompanying pahole and bpftool changes can be viewed > > > here on these "frozen" branches [0][1]. > > > > > > [0]: https://github.com/danobi/pahole/tree/kfunc_btf-v3-mailed > > > [1]: https://github.com/danobi/linux/tree/kfunc_bpftool-mailed > > > > > > I hit a similar issue to [0] on master > > 943b043aeecc ("selftests/bpf: Fix bench runner SIGSEGV") > > when cross-compiling on x86_64 (LE) to s390x (BE). > > I do have CONFIG_DEBUG_INFO_BTF enable and the issue would not trigger if > > I disabled CONFIG_DEBUG_INFO_BTF (and with the fix mentioned in [0]). > > > > What seems to happen is that `tools/resolve_btfids` is ran in the context of the > > host endianess and if I printk before the WARN_ON: > > diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c > > index ef380e546952..a9ed7a1a4936 100644 > > --- a/kernel/bpf/btf.c > > +++ b/kernel/bpf/btf.c > > @@ -8128,6 +8128,7 @@ int register_btf_kfunc_id_set(enum bpf_prog_type prog_type, > > * WARN() for initcall registrations that do not check errors. > > */ > > if (!(kset->set->flags & BTF_SET8_KFUNCS)) { > > + printk("Flag 0x%08X, expected 0x%08X\n", kset->set->flags, BTF_SET8_KFUNCS); > > WARN_ON(!kset->owner); > > return -EINVAL; > > } > > > > the boot logs would show: > > Flag 0x01000000, expected 0x00000001 > > > > The issue did not happen prior to > > 6f3189f38a3e ("bpf: treewide: Annotate BPF kfuncs in BTF") > > has only 0 was written before. > > > > It seems [1] will be addressing cross-compilation, but it did not fix it as is > > by just applying on top of master, so probably some of the changes will also need > > to be ported to `tools/include/linux/btf_ids.h`? > > the fix in [1] is fixing flags in set8's pairs, but not the global flags > > it looks like Viktor's fix should now also swap that as well? like in the > change below on top of Viktor's changes (untested) > > jirka > > > --- > diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c > index d01603ef6283..c44d57fec390 100644 > --- a/tools/bpf/resolve_btfids/main.c > +++ b/tools/bpf/resolve_btfids/main.c > @@ -706,6 +706,8 @@ static int sets_patch(struct object *obj) > * correctly translate everything. > */ > if (need_bswap) { > + set8->flags = bswap_32(set8->flags); > + > for (i = 0; i < cnt; i++) { > set8->pairs[i].flags = > bswap_32(set8->pairs[i].flags); > That should work. Here are a few tests I ran: $ md5sum /tmp/kbuild-s390x/vmlinux.* eb658e51e089f3c5b2c8909a29dc9997 /tmp/kbuild-s390x/vmlinux.a # plain vmlinux before running resolv_btfids (all 0s) ea907cd46a1a73b8276b5f2a82af00ca /tmp/kbuild-s390x/vmlinux.before_resolv # x86_64 resolv_btfids on master without Viktor's patch 980a40c3a3ff563d1c2d1ebdd5071a23 /tmp/kbuild-s390x/vmlinux.resolv_native # x86_64 resolv_btfids on master with Viktor's patch b986d19e242719ebea41c578235da662 /tmp/kbuild-s390x/vmlinux.resolv_native_patch_viktor # x86_64 resolv_btfids on master with Viktor's patch and your suggested patch 4edd8752ff01129945bd442689b1927b /tmp/kbuild-s390x/vmlinux.resolv_native_patch_viktor_patched # s390x resolv_btfids run with qemu-s390x-static 4edd8752ff01129945bd442689b1927b /tmp/kbuild-s390x/vmlinux.resolv_s390x and some hexdiff of those binaries: # difference between master's native build and s390x build.... has byte swapping for set8 and others diff -ruN <(xxd /tmp/kbuild-s390x/vmlinux.resolv_s390x) <(xxd /tmp/kbuild-s390x/vmlinux.resolv_native) > diff_s390x_native.diff https://gist.github.com/chantra/c3d58637a08a6f7340953dc155bb18cc # difference betwee Viktor's version and s390x build.... squinting my eyes I only see the global set8 is missing diff -ruN <(xxd /tmp/kbuild-s390x/vmlinux.resolv_s390x) <(xxd /tmp/kbuild-s390x/vmlinux.resolv_native_patch_viktor) > diff_s390x_native_viktor.diff https://gist.github.com/chantra/61cfff02b456ae72d3c0161ce1897097 Have a good weekend all! Manu
On 2/3/24 19:45, Manu Bretelle wrote: > On Sat, Feb 03, 2024 at 03:40:24PM +0100, Jiri Olsa wrote: >> On Fri, Feb 02, 2024 at 03:09:05PM -0800, Manu Bretelle wrote: >>> On Sun, Jan 28, 2024 at 06:24:05PM -0700, Daniel Xu wrote: >>>> === Description === >>>> >>>> This is a bpf-treewide change that annotates all kfuncs as such inside >>>> .BTF_ids. This annotation eventually allows us to automatically generate >>>> kfunc prototypes from bpftool. >>>> >>>> We store this metadata inside a yet-unused flags field inside struct >>>> btf_id_set8 (thanks Kumar!). pahole will be taught where to look. >>>> >>>> More details about the full chain of events are available in commit 3's >>>> description. >>>> >>>> The accompanying pahole and bpftool changes can be viewed >>>> here on these "frozen" branches [0][1]. >>>> >>>> [0]: https://github.com/danobi/pahole/tree/kfunc_btf-v3-mailed >>>> [1]: https://github.com/danobi/linux/tree/kfunc_bpftool-mailed >>> >>> >>> I hit a similar issue to [0] on master >>> 943b043aeecc ("selftests/bpf: Fix bench runner SIGSEGV") >>> when cross-compiling on x86_64 (LE) to s390x (BE). >>> I do have CONFIG_DEBUG_INFO_BTF enable and the issue would not trigger if >>> I disabled CONFIG_DEBUG_INFO_BTF (and with the fix mentioned in [0]). >>> >>> What seems to happen is that `tools/resolve_btfids` is ran in the context of the >>> host endianess and if I printk before the WARN_ON: >>> diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c >>> index ef380e546952..a9ed7a1a4936 100644 >>> --- a/kernel/bpf/btf.c >>> +++ b/kernel/bpf/btf.c >>> @@ -8128,6 +8128,7 @@ int register_btf_kfunc_id_set(enum bpf_prog_type prog_type, >>> * WARN() for initcall registrations that do not check errors. >>> */ >>> if (!(kset->set->flags & BTF_SET8_KFUNCS)) { >>> + printk("Flag 0x%08X, expected 0x%08X\n", kset->set->flags, BTF_SET8_KFUNCS); >>> WARN_ON(!kset->owner); >>> return -EINVAL; >>> } >>> >>> the boot logs would show: >>> Flag 0x01000000, expected 0x00000001 >>> >>> The issue did not happen prior to >>> 6f3189f38a3e ("bpf: treewide: Annotate BPF kfuncs in BTF") >>> has only 0 was written before. >>> >>> It seems [1] will be addressing cross-compilation, but it did not fix it as is >>> by just applying on top of master, so probably some of the changes will also need >>> to be ported to `tools/include/linux/btf_ids.h`? >> >> the fix in [1] is fixing flags in set8's pairs, but not the global flags >> >> it looks like Viktor's fix should now also swap that as well? like in the >> change below on top of Viktor's changes (untested) >> >> jirka >> >> >> --- >> diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c >> index d01603ef6283..c44d57fec390 100644 >> --- a/tools/bpf/resolve_btfids/main.c >> +++ b/tools/bpf/resolve_btfids/main.c >> @@ -706,6 +706,8 @@ static int sets_patch(struct object *obj) >> * correctly translate everything. >> */ >> if (need_bswap) { >> + set8->flags = bswap_32(set8->flags); >> + >> for (i = 0; i < cnt; i++) { >> set8->pairs[i].flags = >> bswap_32(set8->pairs[i].flags); >> > > That should work. Here are a few tests I ran: > > $ md5sum /tmp/kbuild-s390x/vmlinux.* > eb658e51e089f3c5b2c8909a29dc9997 /tmp/kbuild-s390x/vmlinux.a > # plain vmlinux before running resolv_btfids (all 0s) > ea907cd46a1a73b8276b5f2a82af00ca /tmp/kbuild-s390x/vmlinux.before_resolv > # x86_64 resolv_btfids on master without Viktor's patch > 980a40c3a3ff563d1c2d1ebdd5071a23 /tmp/kbuild-s390x/vmlinux.resolv_native > # x86_64 resolv_btfids on master with Viktor's patch > b986d19e242719ebea41c578235da662 /tmp/kbuild-s390x/vmlinux.resolv_native_patch_viktor > # x86_64 resolv_btfids on master with Viktor's patch and your suggested patch > 4edd8752ff01129945bd442689b1927b /tmp/kbuild-s390x/vmlinux.resolv_native_patch_viktor_patched > # s390x resolv_btfids run with qemu-s390x-static > 4edd8752ff01129945bd442689b1927b /tmp/kbuild-s390x/vmlinux.resolv_s390x > > > and some hexdiff of those binaries: > > > # difference between master's native build and s390x build.... has byte swapping for set8 and others > diff -ruN <(xxd /tmp/kbuild-s390x/vmlinux.resolv_s390x) <(xxd /tmp/kbuild-s390x/vmlinux.resolv_native) > diff_s390x_native.diff > https://gist.github.com/chantra/c3d58637a08a6f7340953dc155bb18cc > > # difference betwee Viktor's version and s390x build.... squinting my eyes I only see the global set8 is missing > diff -ruN <(xxd /tmp/kbuild-s390x/vmlinux.resolv_s390x) <(xxd /tmp/kbuild-s390x/vmlinux.resolv_native_patch_viktor) > diff_s390x_native_viktor.diff > https://gist.github.com/chantra/61cfff02b456ae72d3c0161ce1897097 Thanks for the testing Manu! Jiri's suggested fix is now a part of [1]. Viktor [1] https://lore.kernel.org/bpf/cover.1707157553.git.vmalik@redhat.com/ > > Have a good weekend all! > > Manu >