diff mbox series

[RFCv2,bpf-next,02/18] libbpf: try to load vmlinux BTF from the kernel first

Message ID 166256551073.1434226.11702276674514019182.stgit@firesoul (mailing list archive)
State RFC
Delegated to: BPF
Headers show
Series XDP-hints: XDP gaining access to HW offload hints via BTF | expand

Checks

Context Check Description
bpf/vmtest-bpf-next-PR fail PR summary
bpf/vmtest-bpf-next-VM_Test-1 pending Logs for ${{ matrix.test }} on ${{ matrix.arch }} with ${{ matrix.toolchain }}
bpf/vmtest-bpf-next-VM_Test-2 fail Logs for build for s390x with gcc
bpf/vmtest-bpf-next-VM_Test-3 fail Logs for build for x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-4 fail Logs for build for x86_64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-5 success Logs for llvm-toolchain
bpf/vmtest-bpf-next-VM_Test-6 success Logs for set-matrix
netdev/tree_selection success Clearly marked for bpf-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix success Link
netdev/cover_letter success Series has a cover letter
netdev/patch_count fail Series longer than 15 patches (and no cover letter)
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/cc_maintainers warning 13 maintainers not CCed: andrii@kernel.org john.fastabend@gmail.com jolsa@kernel.org song@kernel.org yhs@fb.com daniel@iogearbox.net martin.lau@linux.dev haoluo@google.com kuba@kernel.org kpsingh@kernel.org hawk@kernel.org davem@davemloft.net sdf@google.com
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 56 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Jesper Dangaard Brouer Sept. 7, 2022, 3:45 p.m. UTC 
From: Larysa Zaremba <larysa.zaremba@intel.com>

Try to acquire vmlinux BTF the same way it's being done for module
BTFs. Use btf_load_next_with_info() and resort to the filesystem
lookup only if it fails.

Also, adjust debug messages in btf__load_vmlinux_btf() to reflect
that it actually tries to load vmlinux BTF.

Signed-off-by: Larysa Zaremba <larysa.zaremba@intel.com>
Signed-off-by: Alexander Lobakin <alexandr.lobakin@intel.com>
---
 tools/lib/bpf/btf.c |   32 ++++++++++++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index cad11c56cf1f..1fd12a2e1b08 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -4744,6 +4744,25 @@  struct btf *btf_load_next_with_info(__u32 start_id, struct bpf_btf_info *info,
 	}
 }
 
+static struct btf *btf_load_vmlinux_from_kernel(void)
+{
+	char name[BTF_NAME_BUF_LEN] = { };
+	struct bpf_btf_info info;
+	struct btf *btf;
+
+	memset(&info, 0, sizeof(info));
+	info.name = ptr_to_u64(name);
+	info.name_len = sizeof(name);
+
+	btf = btf_load_next_with_info(0, &info, NULL, true);
+	if (!libbpf_get_error(btf)) {
+		close(btf->fd);
+		btf__set_fd(btf, -1);
+	}
+
+	return btf;
+}
+
 /*
  * Probe few well-known locations for vmlinux kernel image and try to load BTF
  * data out of it to use for target BTF.
@@ -4770,6 +4789,15 @@  struct btf *btf__load_vmlinux_btf(void)
 	struct btf *btf;
 	int i, err;
 
+	btf = btf_load_vmlinux_from_kernel();
+	err = libbpf_get_error(btf);
+	pr_debug("loading vmlinux BTF from kernel: %d\n", err);
+	if (!err)
+		return btf;
+
+	pr_info("failed to load vmlinux BTF from kernel: %d, will look through filesystem\n",
+		err);
+
 	uname(&buf);
 
 	for (i = 0; i < ARRAY_SIZE(locations); i++) {
@@ -4783,14 +4811,14 @@  struct btf *btf__load_vmlinux_btf(void)
 		else
 			btf = btf__parse_elf(path, NULL);
 		err = libbpf_get_error(btf);
-		pr_debug("loading kernel BTF '%s': %d\n", path, err);
+		pr_debug("loading vmlinux BTF '%s': %d\n", path, err);
 		if (err)
 			continue;
 
 		return btf;
 	}
 
-	pr_warn("failed to find valid kernel BTF\n");
+	pr_warn("failed to find valid vmlinux BTF\n");
 	return libbpf_err_ptr(-ESRCH);
 }