kernel/git/stable/linux.git/arch/mips/net, branch linux-5.16.y

bpf: Change value of MAX_TAIL_CALL_CNT from 32 to 33

2022-01-27T11:02:14+00:00

[ Upstream commit ebf7f6f0a6cdcc17a3da52b81e4b3a98c4005028 ] In the current code, the actual max tail call count is 33 which is greater than MAX_TAIL_CALL_CNT (defined as 32). The actual limit is not consistent with the meaning of MAX_TAIL_CALL_CNT and thus confusing at first glance. We can see the historical evolution from commit 04fd61ab36ec ("bpf: allow bpf programs to tail-call other bpf programs") and commit f9dabe016b63 ("bpf: Undo off-by-one in interpreter tail call count limit"). In order to avoid changing existing behavior, the actual limit is 33 now, this is reasonable. After commit 874be05f525e ("bpf, tests: Add tail call test suite"), we can see there exists failed testcase. On all archs when CONFIG_BPF_JIT_ALWAYS_ON is not set: # echo 0 > /proc/sys/net/core/bpf_jit_enable # modprobe test_bpf # dmesg | grep -w FAIL Tail call error path, max count reached jited:0 ret 34 != 33 FAIL On some archs: # echo 1 > /proc/sys/net/core/bpf_jit_enable # modprobe test_bpf # dmesg | grep -w FAIL Tail call error path, max count reached jited:1 ret 34 != 33 FAIL Although the above failed testcase has been fixed in commit 18935a72eb25 ("bpf/tests: Fix error in tail call limit tests"), it would still be good to change the value of MAX_TAIL_CALL_CNT from 32 to 33 to make the code more readable. The 32-bit x86 JIT was using a limit of 32, just fix the wrong comments and limit to 33 tail calls as the constant MAX_TAIL_CALL_CNT updated. For the mips64 JIT, use "ori" instead of "addiu" as suggested by Johan Almbladh. For the riscv JIT, use RV_REG_TCC directly to save one register move as suggested by Björn Töpel. For the other implementations, no function changes, it does not change the current limit 33, the new value of MAX_TAIL_CALL_CNT can reflect the actual max tail call count, the related tail call testcases in test_bpf module and selftests can work well for the interpreter and the JIT. Here are the test results on x86_64: # uname -m x86_64 # echo 0 > /proc/sys/net/core/bpf_jit_enable # modprobe test_bpf test_suite=test_tail_calls # dmesg | tail -1 test_bpf: test_tail_calls: Summary: 8 PASSED, 0 FAILED, [0/8 JIT'ed] # rmmod test_bpf # echo 1 > /proc/sys/net/core/bpf_jit_enable # modprobe test_bpf test_suite=test_tail_calls # dmesg | tail -1 test_bpf: test_tail_calls: Summary: 8 PASSED, 0 FAILED, [8/8 JIT'ed] # rmmod test_bpf # ./test_progs -t tailcalls #142 tailcalls:OK Summary: 1/11 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Tiezhu Yang Signed-off-by: Daniel Borkmann Tested-by: Johan Almbladh Tested-by: Ilya Leoshkevich Acked-by: Björn Töpel Acked-by: Johan Almbladh Acked-by: Ilya Leoshkevich Link: https://lore.kernel.org/bpf/1636075800-3264-1-git-send-email-yangtiezhu@loongson.cn Signed-off-by: Sasha Levin

mips, bpf: Fix reference to non-existing Kconfig symbol

2021-11-30T16:19:36+00:00

The Kconfig symbol for R10000 ll/sc errata workaround in the MIPS JIT was misspelled, causing the workaround to not take effect when enabled. Fixes: 72570224bb8f ("mips, bpf: Add JIT workarounds for CPU errata") Reported-by: Lukas Bulwahn Signed-off-by: Johan Almbladh Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20211130160824.3781635-1-johan.almbladh@anyfinetworks.com

bpf, mips: Fix comment on tail call count limiting

2021-10-11T13:29:38+00:00

In emit_tail_call() of bpf_jit_comp32.c, "blez t2" (t2 <= 0) is not consistent with the comment "t2 < 0", update the comment to keep consistency. Signed-off-by: Tiezhu Yang Signed-off-by: Daniel Borkmann Acked-by: Johan Almbladh Link: https://lore.kernel.org/bpf/1633915150-13220-3-git-send-email-yangtiezhu@loongson.cn

bpf, mips: Clean up config options about JIT

2021-10-11T13:29:37+00:00

The config options MIPS_CBPF_JIT and MIPS_EBPF_JIT are useless, remove them in arch/mips/Kconfig, and then modify arch/mips/net/Makefile. Signed-off-by: Tiezhu Yang Signed-off-by: Daniel Borkmann Acked-by: Johan Almbladh Link: https://lore.kernel.org/bpf/1633915150-13220-2-git-send-email-yangtiezhu@loongson.cn

mips, bpf: Optimize loading of 64-bit constants

2021-10-07T21:51:29+00:00

This patch shaves off a few instructions when loading sparse 64-bit constants to register. The change is covered by additional tests in lib/test_bpf.c. Signed-off-by: Johan Almbladh Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20211007142828.634182-1-johan.almbladh@anyfinetworks.com

mips, bpf: Fix Makefile that referenced a removed file

2021-10-07T21:51:13+00:00

This patch removes a stale Makefile reference to the cBPF JIT that was removed. Fixes: ebcbacfa50ec ("mips, bpf: Remove old BPF JIT implementations") Signed-off-by: Johan Almbladh Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20211007142339.633899-1-johan.almbladh@anyfinetworks.com

mips, bpf: Remove old BPF JIT implementations

2021-10-06T19:28:34+00:00

This patch removes the old 32-bit cBPF and 64-bit eBPF JIT implementations. They are replaced by a new eBPF implementation that supports both 32-bit and 64-bit MIPS CPUs. Signed-off-by: Johan Almbladh Signed-off-by: Daniel Borkmann Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20211005165408.2305108-8-johan.almbladh@anyfinetworks.com

mips, bpf: Enable eBPF JITs

2021-10-06T19:28:30+00:00

This patch enables the new eBPF JITs for 32-bit and 64-bit MIPS. It also disables the old cBPF JIT to so cBPF programs are converted to use the new JIT. Workarounds for R4000 CPU errata are not implemented by the JIT, so the JIT is disabled if any of those workarounds are configured. Signed-off-by: Johan Almbladh Signed-off-by: Daniel Borkmann Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20211005165408.2305108-7-johan.almbladh@anyfinetworks.com

mips, bpf: Add JIT workarounds for CPU errata

2021-10-06T19:28:25+00:00

This patch adds workarounds for the following CPU errata to the MIPS eBPF JIT, if enabled in the kernel configuration. - R10000 ll/sc weak ordering - Loongson-3 ll/sc weak ordering - Loongson-2F jump hang The Loongson-2F nop errata is implemented in uasm, which the JIT uses, so no additional mitigations are needed for that. Signed-off-by: Johan Almbladh Signed-off-by: Daniel Borkmann Signed-off-by: Andrii Nakryiko Reviewed-by: Jiaxun Yang Link: https://lore.kernel.org/bpf/20211005165408.2305108-6-johan.almbladh@anyfinetworks.com

mips, bpf: Add new eBPF JIT for 64-bit MIPS

2021-10-06T19:28:20+00:00

This is an implementation on of an eBPF JIT for 64-bit MIPS III-V and MIPS64r1-r6. It uses the same framework introduced by the 32-bit JIT. Signed-off-by: Johan Almbladh Signed-off-by: Daniel Borkmann Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20211005165408.2305108-5-johan.almbladh@anyfinetworks.com