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-rw-r--r--Documentation/ABI/testing/sysfs-kernel-btf17
-rw-r--r--kernel/bpf/Makefile3
-rw-r--r--kernel/bpf/sysfs_btf.c51
-rwxr-xr-xscripts/link-vmlinux.sh52
4 files changed, 104 insertions, 19 deletions
diff --git a/Documentation/ABI/testing/sysfs-kernel-btf b/Documentation/ABI/testing/sysfs-kernel-btf
new file mode 100644
index 000000000000..5390f8001f96
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-kernel-btf
@@ -0,0 +1,17 @@
+What: /sys/kernel/btf
+Date: Aug 2019
+KernelVersion: 5.5
+Contact: bpf@vger.kernel.org
+Description:
+ Contains BTF type information and related data for kernel and
+ kernel modules.
+
+What: /sys/kernel/btf/kernel
+Date: Aug 2019
+KernelVersion: 5.5
+Contact: bpf@vger.kernel.org
+Description:
+ Read-only binary attribute exposing kernel's own BTF type
+ information with description of all internal kernel types. See
+ Documentation/bpf/btf.rst for detailed description of format
+ itself.
diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile
index 29d781061cd5..e1d9adb212f9 100644
--- a/kernel/bpf/Makefile
+++ b/kernel/bpf/Makefile
@@ -22,3 +22,6 @@ obj-$(CONFIG_CGROUP_BPF) += cgroup.o
ifeq ($(CONFIG_INET),y)
obj-$(CONFIG_BPF_SYSCALL) += reuseport_array.o
endif
+ifeq ($(CONFIG_SYSFS),y)
+obj-$(CONFIG_DEBUG_INFO_BTF) += sysfs_btf.o
+endif
diff --git a/kernel/bpf/sysfs_btf.c b/kernel/bpf/sysfs_btf.c
new file mode 100644
index 000000000000..092e63b9758b
--- /dev/null
+++ b/kernel/bpf/sysfs_btf.c
@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Provide kernel BTF information for introspection and use by eBPF tools.
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/kobject.h>
+#include <linux/init.h>
+#include <linux/sysfs.h>
+
+/* See scripts/link-vmlinux.sh, gen_btf() func for details */
+extern char __weak _binary__btf_kernel_bin_start[];
+extern char __weak _binary__btf_kernel_bin_end[];
+
+static ssize_t
+btf_kernel_read(struct file *file, struct kobject *kobj,
+ struct bin_attribute *bin_attr,
+ char *buf, loff_t off, size_t len)
+{
+ memcpy(buf, _binary__btf_kernel_bin_start + off, len);
+ return len;
+}
+
+static struct bin_attribute bin_attr_btf_kernel __ro_after_init = {
+ .attr = { .name = "kernel", .mode = 0444, },
+ .read = btf_kernel_read,
+};
+
+static struct kobject *btf_kobj;
+
+static int __init btf_kernel_init(void)
+{
+ int err;
+
+ if (!_binary__btf_kernel_bin_start)
+ return 0;
+
+ btf_kobj = kobject_create_and_add("btf", kernel_kobj);
+ if (IS_ERR(btf_kobj)) {
+ err = PTR_ERR(btf_kobj);
+ btf_kobj = NULL;
+ return err;
+ }
+
+ bin_attr_btf_kernel.size = _binary__btf_kernel_bin_end -
+ _binary__btf_kernel_bin_start;
+
+ return sysfs_create_bin_file(btf_kobj, &bin_attr_btf_kernel);
+}
+
+subsys_initcall(btf_kernel_init);
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index a7124f895b24..cb93832c6ad7 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -56,8 +56,8 @@ modpost_link()
}
# Link of vmlinux
-# ${1} - optional extra .o files
-# ${2} - output file
+# ${1} - output file
+# ${@:2} - optional extra .o files
vmlinux_link()
{
local lds="${objtree}/${KBUILD_LDS}"
@@ -70,9 +70,9 @@ vmlinux_link()
--start-group \
${KBUILD_VMLINUX_LIBS} \
--end-group \
- ${1}"
+ ${@:2}"
- ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} -o ${2} \
+ ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} -o ${1} \
-T ${lds} ${objects}
else
objects="-Wl,--whole-archive \
@@ -81,9 +81,9 @@ vmlinux_link()
-Wl,--start-group \
${KBUILD_VMLINUX_LIBS} \
-Wl,--end-group \
- ${1}"
+ ${@:2}"
- ${CC} ${CFLAGS_vmlinux} -o ${2} \
+ ${CC} ${CFLAGS_vmlinux} -o ${1} \
-Wl,-T,${lds} \
${objects} \
-lutil -lrt -lpthread
@@ -92,23 +92,34 @@ vmlinux_link()
}
# generate .BTF typeinfo from DWARF debuginfo
+# ${1} - vmlinux image
+# ${2} - file to dump raw BTF data into
gen_btf()
{
- local pahole_ver;
+ local pahole_ver
+ local bin_arch
if ! [ -x "$(command -v ${PAHOLE})" ]; then
info "BTF" "${1}: pahole (${PAHOLE}) is not available"
- return 0
+ return 1
fi
pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
if [ "${pahole_ver}" -lt "113" ]; then
info "BTF" "${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.13"
- return 0
+ return 1
fi
- info "BTF" ${1}
+ info "BTF" ${2}
+ vmlinux_link ${1}
LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1}
+
+ # dump .BTF section into raw binary file to link with final vmlinux
+ bin_arch=$(${OBJDUMP} -f ${1} | grep architecture | \
+ cut -d, -f1 | cut -d' ' -f2)
+ ${OBJCOPY} --dump-section .BTF=.btf.kernel.bin ${1} 2>/dev/null
+ ${OBJCOPY} -I binary -O ${CONFIG_OUTPUT_FORMAT} -B ${bin_arch} \
+ --rename-section .data=.BTF .btf.kernel.bin ${2}
}
# Create ${2} .o file with all symbols from the ${1} object file
@@ -153,6 +164,7 @@ sortextable()
# Delete output files in case of error
cleanup()
{
+ rm -f .btf.*
rm -f .tmp_System.map
rm -f .tmp_kallsyms*
rm -f .tmp_vmlinux*
@@ -215,6 +227,13 @@ ${MAKE} -f "${srctree}/scripts/Makefile.modpost" vmlinux.o
info MODINFO modules.builtin.modinfo
${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo
+btf_kernel_bin_o=""
+if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then
+ if gen_btf .tmp_vmlinux.btf .btf.kernel.bin.o ; then
+ btf_kernel_bin_o=.btf.kernel.bin.o
+ fi
+fi
+
kallsymso=""
kallsyms_vmlinux=""
if [ -n "${CONFIG_KALLSYMS}" ]; then
@@ -246,11 +265,11 @@ if [ -n "${CONFIG_KALLSYMS}" ]; then
kallsyms_vmlinux=.tmp_vmlinux2
# step 1
- vmlinux_link "" .tmp_vmlinux1
+ vmlinux_link .tmp_vmlinux1 ${btf_kernel_bin_o}
kallsyms .tmp_vmlinux1 .tmp_kallsyms1.o
# step 2
- vmlinux_link .tmp_kallsyms1.o .tmp_vmlinux2
+ vmlinux_link .tmp_vmlinux2 .tmp_kallsyms1.o ${btf_kernel_bin_o}
kallsyms .tmp_vmlinux2 .tmp_kallsyms2.o
# step 3
@@ -261,18 +280,13 @@ if [ -n "${CONFIG_KALLSYMS}" ]; then
kallsymso=.tmp_kallsyms3.o
kallsyms_vmlinux=.tmp_vmlinux3
- vmlinux_link .tmp_kallsyms2.o .tmp_vmlinux3
-
+ vmlinux_link .tmp_vmlinux3 .tmp_kallsyms2.o ${btf_kernel_bin_o}
kallsyms .tmp_vmlinux3 .tmp_kallsyms3.o
fi
fi
info LD vmlinux
-vmlinux_link "${kallsymso}" vmlinux
-
-if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then
- gen_btf vmlinux
-fi
+vmlinux_link vmlinux "${kallsymso}" "${btf_kernel_bin_o}"
if [ -n "${CONFIG_BUILDTIME_EXTABLE_SORT}" ]; then
info SORTEX vmlinux