On 16/11/22 12:14 am, Christophe Leroy wrote:
Le 14/11/2022 à 18:27, Christophe Leroy a écrit :
Le 14/11/2022 à 15:47, Hari Bathini a écrit :
Hi Christophe,
On 11/11/22 4:55 pm, Christophe Leroy wrote:
Le 10/11/2022 à 19:43, Hari Bathini a écrit :
Most BPF programs are small, but they consume a page each. For systems
with busy traffic and many BPF programs, this may also add significant
pressure on instruction TLB. High iTLB pressure usually slows down the
whole system causing visible performance degradation for production
workloads.
bpf_prog_pack, a customized allocator that packs multiple bpf programs
into preallocated memory chunks, was proposed [1] to address it. This
series extends this support on powerpc.
Patches 1 & 2 add the arch specific functions needed to support this
feature. Patch 3 enables the support for powerpc. The last patch
ensures cleanup is handled racefully.
Tested the changes successfully on a PowerVM. patch_instruction(),
needed for bpf_arch_text_copy(), is failing for ppc32. Debugging it.
Posting the patches in the meanwhile for feedback on these changes.
I did a quick test on ppc32, I don't get such a problem, only something
wrong in the dump print as traps intructions only are dumped, but
tcpdump works as expected:
Thanks for the quick test. Could you please share the config you used.
I am probably missing a few knobs in my conifg...
I also managed to test it on QEMU. The config is based on pmac32_defconfig.
I had the same config but hit this problem:
# echo 1 > /proc/sys/net/core/bpf_jit_enable; modprobe test_bpf
test_bpf: #0 TAX
------------[ cut here ]------------
WARNING: CPU: 0 PID: 96 at arch/powerpc/net/bpf_jit_comp.c:367
bpf_int_jit_compile+0x8a0/0x9f8
Modules linked in: test_bpf(+)
CPU: 0 PID: 96 Comm: modprobe Not tainted 6.1.0-rc5+ #116
Hardware name: PowerMac3,1 750CL 0x87210 PowerMac
NIP: c0038224 LR: c0037f74 CTR: 00000009
REGS: f1b41b10 TRAP: 0700 Not tainted (6.1.0-rc5+)
MSR: 00029032 <EE,ME,IR,DR,RI> CR: 82004882 XER: 20000000
GPR00: c0037f74 f1b41bd0 c12333c0 ffffffea c19747e0 c0123a08 c1974a00
c12333c0
GPR08: 00000000 00000b58 00009032 00000003 82004882 100d816a f2660000
00000000
GPR16: 00000000 c0c10000 00000000 c0c10000 c1913780 00000000 0000001a
100a2ee3
GPR24: 0000014c be857000 be857020 f1b41c00 c194c180 f1b46000 ffffffea
f1b46000
NIP [c0038224] bpf_int_jit_compile+0x8a0/0x9f8
LR [c0037f74] bpf_int_jit_compile+0x5f0/0x9f8
Call Trace:
[f1b41bd0] [c0037f74] bpf_int_jit_compile+0x5f0/0x9f8 (unreliable)
[f1b41ca0] [c0123790] bpf_prog_select_runtime+0x178/0x1c4
[f1b41cd0] [c06cc4b0] bpf_prepare_filter+0x524/0x624
[f1b41d20] [c06cc63c] bpf_prog_create+0x8c/0xd0
[f1b41d40] [be85083c] test_bpf_init+0x46c/0x11b0 [test_bpf]
[f1b41df0] [c0008534] do_one_initcall+0x58/0x1b8
[f1b41e60] [c00b6c38] do_init_module+0x54/0x1e4
[f1b41e80] [c00b8f80] sys_init_module+0x10c/0x174
[f1b41f10] [c0014390] system_call_exception+0x94/0x144
[f1b41f30] [c001a1ac] ret_from_syscall+0x0/0x2c
--- interrupt: c00 at 0xfef48ac
NIP: 0fef48ac LR: 10015de0 CTR: 00000000
REGS: f1b41f40 TRAP: 0c00 Not tainted (6.1.0-rc5+)
MSR: 0000d032 <EE,PR,ME,IR,DR,RI> CR: 88002224 XER: 20000000
GPR00: 00000080 aff34990 a7a8d380 a75c0010 00477e90 1051b9a0 0fedfdd8
0000d032
GPR08: 00000000 00000008 00478ffa 400f26fa 400f23c7 100d816a 00000000
00000000
GPR16: 00000000 1051b950 00000000 1051b92c 100d0000 100a2eab 100a2e97
100a2ee3
GPR24: 100a2ed5 1051b980 00000001 100d01a8 1051b920 a75c0010 1051b9a0
a7a86388
NIP [0fef48ac] 0xfef48ac
LR [10015de0] 0x10015de0
--- interrupt: c00
Instruction dump:
8081001c 38a00004 7f23cb78 4bfff5d1 7f23cb78 8081001c 480eba85 82410098
8261009c 82a100a4 82e100ac 4bfffce8 <0fe00000> 92010090 92410098 92e100ac
---[ end trace 0000000000000000 ]---
jited:1
kernel tried to execute exec-protected page (be857020) - exploit
attempt? (uid: 0)
BUG: Unable to handle kernel instruction fetch
Faulting instruction address: 0xbe857020
Vector: 400 (Instruction Access) at [f1b41c30]
pc: be857020
lr: be84eaa4: __run_one+0xec/0x248 [test_bpf]
sp: f1b41cf0
msr: 40009032
current = 0xc12333c0
pid = 96, comm = modprobe
Linux version 6.1.0-rc5+ (root@hbathini-Standard-PC-Q35-ICH9-2009)
(powerpc-linux-gnu-gcc (Ubuntu 11.3.0-1ubuntu1~22.04) 11.3.0, GNU ld
(GNU Binutils for Ubuntu) 2.38) #116 Wed Nov 16 20:48:10 IST 2022
enter ? for help
[link register ] be84eaa4 __run_one+0xec/0x248 [test_bpf]
[f1b41cf0] be84e9dc __run_one+0x24/0x248 [test_bpf] (unreliable)
[f1b41d40] be850c78 test_bpf_init+0x8a8/0x11b0 [test_bpf]
[f1b41df0] c0008534 do_one_initcall+0x58/0x1b8
[f1b41e60] c00b6c38 do_init_module+0x54/0x1e4
[f1b41e80] c00b8f80 sys_init_module+0x10c/0x174
[f1b41f10] c0014390 system_call_exception+0x94/0x144
[f1b41f30] c001a1ac ret_from_syscall+0x0/0x2c
--- Exception: c00 (System Call) at 0fef48ac
SP (aff34990) is in userspace
mon>
bpf_jit_binary_pack_finalize() function failed due to patch_instruction() ..
Also, I am hitting the same problem with the other config too..
Thanks
Hari
