On Tue, Nov 22, 2022 at 02:48:07PM +0100, Jiri Olsa wrote: > On Mon, Nov 21, 2022 at 11:32:43PM -0800, Chen Hu wrote: > > With CONFIG_X86_KERNEL_IBT enabled, the test_verifier triggers the > > following BUG: > > > > traps: Missing ENDBR: bpf_kfunc_call_test_release+0x0/0x30 > > ------------[ cut here ]------------ > > kernel BUG at arch/x86/kernel/traps.c:254! > > invalid opcode: 0000 [#1] PREEMPT SMP > > <TASK> > > asm_exc_control_protection+0x26/0x50 > > RIP: 0010:bpf_kfunc_call_test_release+0x0/0x30 > > Code: 00 48 c7 c7 18 f2 e1 b4 e8 0d ca 8c ff 48 c7 c0 00 f2 e1 b4 c3 > > 0f 1f 44 00 00 66 0f 1f 00 0f 1f 44 00 00 0f 0b 31 c0 c3 66 90 > > <66> 0f 1f 00 0f 1f 44 00 00 48 85 ff 74 13 4c 8d 47 18 b8 ff ff ff > > bpf_map_free_kptrs+0x2e/0x70 > > array_map_free+0x57/0x140 > > process_one_work+0x194/0x3a0 > > worker_thread+0x54/0x3a0 > > ? rescuer_thread+0x390/0x390 > > kthread+0xe9/0x110 > > ? kthread_complete_and_exit+0x20/0x20 > > > > This is because there are no compile-time references to the destructor > > kfuncs, bpf_kfunc_call_test_release() for example. So objtool marked > > them sealable and ENDBR in the functions were sealed (converted to NOP) > > by apply_ibt_endbr(). If there is no compile time reference to it, what stops an LTO linker from throwing it out in the first place?
