LoongArch: BPF: Don't sign extend memory load operand
[ Upstream commit fe575755 ] The `cgrp_local_storage` test triggers a kernel panic like: # ./test_progs -t cgrp_local_storage Can't find bpf_testmod.ko kernel module: -2 WARNING! Selftests relying on bpf_testmod.ko will be skipped. [ 550.930632] CPU 1 Unable to handle kernel paging request at virtual address 0000000000000080, era == ffff80000200be34, ra == ffff80000200be00 [ 550.931781] Oops[#1]: [ 550.931966] CPU: 1 PID: 1303 Comm: test_progs Not tainted 6.7.0-rc2-loong-devel-g2f56bb0d2327 #35 a896aca3f4164f09cc346f89f2e09832e07be5f6 [ 550.932215] Hardware name: QEMU QEMU Virtual Machine, BIOS unknown 2/2/2022 [ 550.932403] pc ffff80000200be34 ra ffff80000200be00 tp 9000000108350000 sp 9000000108353dc0 [ 550.932545] a0 0000000000000000 a1 0000000000000517 a2 0000000000000118 a3 00007ffffbb15558 [ 550.932682] a4 00007ffffbb15620 a5 90000001004e7700 a6 0000000000000021 a7 0000000000000118 [ 550.932824] t0 ffff80000200bdc0 t1 0000000000000517 t2 0000000000000517 t3 00007ffff1c06ee0 [ 550.932961] t4 0000555578ae04d0 t5 fffffffffffffff8 t6 0000000000000004 t7 0000000000000020 [ 550.933097] t8 0000000000000040 u0 00000000000007b8 s9 9000000108353e00 s0 90000001004e7700 [ 550.933241] s1 9000000004005000 s2 0000000000000001 s3 0000000000000000 s4 0000555555eb2ec8 [ 550.933379] s5 00007ffffbb15bb8 s6 00007ffff1dafd60 s7 000055555663f610 s8 00007ffff1db0050 [ 550.933520] ra: ffff80000200be00 bpf_prog_98f1b9e767be2a84_on_enter+0x40/0x200 [ 550.933911] ERA: ffff80000200be34 bpf_prog_98f1b9e767be2a84_on_enter+0x74/0x200 [ 550.934105] CRMD: 000000b0 (PLV0 -IE -DA +PG DACF=CC DACM=CC -WE) [ 550.934596] PRMD: 00000004 (PPLV0 +PIE -PWE) [ 550.934712] EUEN: 00000003 (+FPE +SXE -ASXE -BTE) [ 550.934836] ECFG: 00071c1c (LIE=2-4,10-12 VS=7) [ 550.934976] ESTAT: 00010000 [PIL] (IS= ECode=1 EsubCode=0) [ 550.935097] BADV: 0000000000000080 [ 550.935181] PRID: 0014c010 (Loongson-64bit, Loongson-3A5000) [ 550.935291] Modules linked in: [ 550.935391] Process test_progs (pid: 1303, threadinfo=000000006c3b1c41, task=0000000061f84a55) [ 550.935643] Stack : 00007ffffbb15bb8 0000555555eb2ec8 0000000000000000 0000000000000001 [ 550.935844] 9000000004005000 ffff80001b864000 00007ffffbb15450 90000000029aa034 [ 550.935990] 0000000000000000 9000000108353ec0 0000000000000118 d07d9dfb09721a09 [ 550.936175] 0000000000000001 0000000000000000 9000000108353ec0 0000000000000118 [ 550.936314] 9000000101d46ad0 900000000290abf0 000055555663f610 0000000000000000 [ 550.936479] 0000000000000003 9000000108353ec0 00007ffffbb15450 90000000029d7288 [ 550.936635] 00007ffff1dafd60 000055555663f610 0000000000000000 0000000000000003 [ 550.936779] 9000000108353ec0 90000000035dd1f0 00007ffff1dafd58 9000000002841c5c [ 550.936939] 0000000000000119 0000555555eea5a8 00007ffff1d78780 00007ffffbb153e0 [ 550.937083] ffffffffffffffda 00007ffffbb15518 0000000000000040 00007ffffbb15558 [ 550.937224] ... [ 550.937299] Call Trace: [ 550.937521] [<ffff80000200be34>] bpf_prog_98f1b9e767be2a84_on_enter+0x74/0x200 [ 550.937910] [<90000000029aa034>] bpf_trace_run2+0x90/0x154 [ 550.938105] [<900000000290abf0>] syscall_trace_enter.isra.0+0x1cc/0x200 [ 550.938224] [<90000000035dd1f0>] do_syscall+0x48/0x94 [ 550.938319] [<9000000002841c5c>] handle_syscall+0xbc/0x158 [ 550.938477] [ 550.938607] Code: 580009ae 50016000 262402e4 <28c20085> 14092084 03a00084 16000024 03240084 00150006 [ 550.938851] [ 550.939021] ---[ end trace 0000000000000000 ]--- Further investigation shows that this panic is triggered by memory load operations: ptr = bpf_cgrp_storage_get(&map_a, task->cgroups->dfl_cgrp, 0, BPF_LOCAL_STORAGE_GET_F_CREATE); The expression `task->cgroups->dfl_cgrp` involves two memory load. Since the field offset fits in imm12 or imm14, we use ldd or ldptrd instructions. But both instructions have the side effect that it will signed-extended the imm operand. Finally, we got the wrong addresses and panics is inevitable. Use a generic ldxd instruction to avoid this kind of issues. With this change, we have: # ./test_progs -t cgrp_local_storage Can't find bpf_testmod.ko kernel module: -2 WARNING! Selftests relying on bpf_testmod.ko will be skipped. test_cgrp_local_storage:PASS:join_cgroup /cgrp_local_storage 0 nsec #48/1 cgrp_local_storage/tp_btf:OK test_attach_cgroup:PASS:skel_open 0 nsec test_attach_cgroup:PASS:prog_attach 0 nsec test_attach_cgroup:PASS:prog_attach 0 nsec libbpf: prog 'update_cookie_tracing': failed to attach: ERROR: strerror_r(-524)=22 test_attach_cgroup:FAIL:prog_attach unexpected error: -524 #48/2 cgrp_local_storage/attach_cgroup:FAIL test_recursion:PASS:skel_open_and_load 0 nsec libbpf: prog 'on_lookup': failed to attach: ERROR: strerror_r(-524)=22 libbpf: prog 'on_lookup': failed to auto-attach: -524 test_recursion:FAIL:skel_attach unexpected error: -524 (errno 524) #48/3 cgrp_local_storage/recursion:FAIL #48/4 cgrp_local_storage/negative:OK #48/5 cgrp_local_storage/cgroup_iter_sleepable:OK test_yes_rcu_lock:PASS:skel_open 0 nsec test_yes_rcu_lock:PASS:skel_load 0 nsec libbpf: prog 'yes_rcu_lock': failed to attach: ERROR: strerror_r(-524)=22 libbpf: prog 'yes_rcu_lock': failed to auto-attach: -524 test_yes_rcu_lock:FAIL:skel_attach unexpected error: -524 (errno 524) #48/6 cgrp_local_storage/yes_rcu_lock:FAIL #48/7 cgrp_local_storage/no_rcu_lock:OK #48 cgrp_local_storage:FAIL All error logs: test_cgrp_local_storage:PASS:join_cgroup /cgrp_local_storage 0 nsec test_attach_cgroup:PASS:skel_open 0 nsec test_attach_cgroup:PASS:prog_attach 0 nsec test_attach_cgroup:PASS:prog_attach 0 nsec libbpf: prog 'update_cookie_tracing': failed to attach: ERROR: strerror_r(-524)=22 test_attach_cgroup:FAIL:prog_attach unexpected error: -524 #48/2 cgrp_local_storage/attach_cgroup:FAIL test_recursion:PASS:skel_open_and_load 0 nsec libbpf: prog 'on_lookup': failed to attach: ERROR: strerror_r(-524)=22 libbpf: prog 'on_lookup': failed to auto-attach: -524 test_recursion:FAIL:skel_attach unexpected error: -524 (errno 524) #48/3 cgrp_local_storage/recursion:FAIL test_yes_rcu_lock:PASS:skel_open 0 nsec test_yes_rcu_lock:PASS:skel_load 0 nsec libbpf: prog 'yes_rcu_lock': failed to attach: ERROR: strerror_r(-524)=22 libbpf: prog 'yes_rcu_lock': failed to auto-attach: -524 test_yes_rcu_lock:FAIL:skel_attach unexpected error: -524 (errno 524) #48/6 cgrp_local_storage/yes_rcu_lock:FAIL #48 cgrp_local_storage:FAIL Summary: 0/4 PASSED, 0 SKIPPED, 1 FAILED No panics any more (The test still failed because lack of BPF trampoline which I am actively working on). Fixes: 5dc61552 ("LoongArch: Add BPF JIT support") Signed-off-by:Hengqi Chen <hengqi.chen@gmail.com> Signed-off-by:
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