Kernel/linux-next
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git synced 2025-01-04 04:02:26 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

samples/bpf: fix symbol mismatch by compiler optimization

Browse Source 
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>
Link: https://lore.kernel.org/r/20230818090119.477441-5-danieltimlee@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Daniel T. Lee 2023-08-18 18:01:14 +09:00 committed by Alexei Starovoitov
parent 4a0ee78890
commit 02dabc247a
2 changed files with 3 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
samples/bpf/offwaketime.bpf.c
View File

@ -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);

3
samples/bpf/tracex1.bpf.c
View File

@ -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;