diff mbox series

[bpf-next,4/9] samples/bpf: fix symbol mismatch by compiler optimization

Message ID 20230818090119.477441-5-danieltimlee@gmail.com (mailing list archive)
State Accepted
Commit 02dabc247ad68b41758bf39f11e2d682b8b32dd7
Delegated to: BPF
Headers show
Series samples/bpf: make BPF programs more libbpf aware | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for bpf-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 9 this patch: 9
netdev/cc_maintainers success CCed 12 of 12 maintainers
netdev/build_clang success Errors and warnings before: 9 this patch: 9
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
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: 9 this patch: 9
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 21 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
bpf/vmtest-bpf-next-VM_Test-29 success Logs for veristat
bpf/vmtest-bpf-next-VM_Test-10 success Logs for test_progs on aarch64 with gcc
bpf/vmtest-bpf-next-VM_Test-12 success Logs for test_progs on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-11 fail Logs for test_progs on s390x with gcc
bpf/vmtest-bpf-next-VM_Test-13 success Logs for test_progs on x86_64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-14 success Logs for test_progs_no_alu32 on aarch64 with gcc
bpf/vmtest-bpf-next-VM_Test-15 success Logs for test_progs_no_alu32 on s390x with gcc
bpf/vmtest-bpf-next-VM_Test-16 success Logs for test_progs_no_alu32 on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-17 success Logs for test_progs_no_alu32 on x86_64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-7 success Logs for test_maps on s390x with gcc
bpf/vmtest-bpf-next-VM_Test-25 success Logs for test_verifier on s390x with gcc
bpf/vmtest-bpf-next-VM_Test-0 success Logs for ShellCheck
bpf/vmtest-bpf-next-VM_Test-5 success Logs for set-matrix
bpf/vmtest-bpf-next-VM_Test-1 success Logs for build for aarch64 with gcc
bpf/vmtest-bpf-next-VM_Test-3 success Logs for build for x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-4 success Logs for build for x86_64 with llvm-16
bpf/vmtest-bpf-next-PR fail merge-conflict
bpf/vmtest-bpf-next-VM_Test-2 success Logs for build for s390x with gcc
bpf/vmtest-bpf-next-VM_Test-9 success Logs for test_maps on x86_64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-6 success Logs for test_maps on aarch64 with gcc
bpf/vmtest-bpf-next-VM_Test-8 success Logs for test_maps on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-18 success Logs for test_progs_no_alu32_parallel on aarch64 with gcc
bpf/vmtest-bpf-next-VM_Test-19 success Logs for test_progs_no_alu32_parallel on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-20 success Logs for test_progs_no_alu32_parallel on x86_64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-21 success Logs for test_progs_parallel on aarch64 with gcc
bpf/vmtest-bpf-next-VM_Test-22 success Logs for test_progs_parallel on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-23 success Logs for test_progs_parallel on x86_64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-24 success Logs for test_verifier on aarch64 with gcc
bpf/vmtest-bpf-next-VM_Test-26 success Logs for test_verifier on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-27 success Logs for test_verifier on x86_64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-28 success Logs for veristat

Commit Message

Daniel T. Lee Aug. 18, 2023, 9:01 a.m. UTC 
Currently, multiple kprobe programs are suffering from symbol mismatch
due to compiler optimization. These optimizations might induce
additional suffix to the symbol name such as '.isra' or '.constprop'.

    # egrep ' finish_task_switch| __netif_receive_skb_core' /proc/kallsyms
    ffffffff81135e50 t finish_task_switch.isra.0
    ffffffff81dd36d0 t __netif_receive_skb_core.constprop.0
    ffffffff8205cc0e t finish_task_switch.isra.0.cold
    ffffffff820b1aba t __netif_receive_skb_core.constprop.0.cold

To avoid this, this commit replaces the original kprobe section to
kprobe.multi in order to match symbol with wildcard characters. Here,
asterisk is used for avoiding symbol mismatch.

Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
---
 samples/bpf/offwaketime.bpf.c | 2 +-
 samples/bpf/tracex1.bpf.c     | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/samples/bpf/offwaketime.bpf.c b/samples/bpf/offwaketime.bpf.c
index 8e5105811178..3200a0f44969 100644
--- a/samples/bpf/offwaketime.bpf.c
+++ b/samples/bpf/offwaketime.bpf.c
@@ -118,7 +118,7 @@  int oncpu(struct trace_event_raw_sched_switch *ctx)
 	/* record previous thread sleep time */
 	u32 pid = ctx->prev_pid;
 #else
-SEC("kprobe/finish_task_switch")
+SEC("kprobe.multi/finish_task_switch*")
 int oncpu(struct pt_regs *ctx)
 {
 	struct task_struct *p = (void *) PT_REGS_PARM1(ctx);
diff --git a/samples/bpf/tracex1.bpf.c b/samples/bpf/tracex1.bpf.c
index bb78bdbffa87..f3be14a03964 100644
--- a/samples/bpf/tracex1.bpf.c
+++ b/samples/bpf/tracex1.bpf.c
@@ -22,11 +22,12 @@ 
  * Number of arguments and their positions can change, etc.
  * In such case this bpf+kprobe example will no longer be meaningful
  */
-SEC("kprobe/__netif_receive_skb_core")
+SEC("kprobe.multi/__netif_receive_skb_core*")
 int bpf_prog1(struct pt_regs *ctx)
 {
 	/* attaches to kprobe __netif_receive_skb_core,
 	 * looks for packets on loobpack device and prints them
+	 * (wildcard is used for avoiding symbol mismatch due to optimization)
 	 */
 	char devname[IFNAMSIZ];
 	struct net_device *dev;