George Guo d9263793f7 LoongArch, bpf: Fix jit to skip speculation barrier opcode ... [ Upstream commit a6f6a95f25 ] Just skip the opcode(BPF_ST | BPF_NOSPEC) in the BPF JIT instead of failing to JIT the entire program, given LoongArch currently has no couterpart of a speculation barrier instruction. To verify the issue, use the ltp testcase as shown below. Also, Wang says: I can confirm there's currently no speculation barrier equivalent on LonogArch. (Loongson says there are builtin mitigations for Spectre-V1 and V2 on their chips, and AFAIK efforts to port the exploits to mips/LoongArch have all failed a few years ago.) Without this patch: $ ./bpf_prog02 [...] bpf_common.c:123: TBROK: Failed verification: ??? (524) [...] Summary: passed 0 failed 0 broken 1 skipped 0 warnings 0 With this patch: $ ./bpf_prog02 [...] Summary: passed 0 failed 0 broken 0 skipped 0 warnings 0 Fixes: 5dc615520c ("LoongArch: Add BPF JIT support") Signed-off-by: George Guo <guodongtai@kylinos.cn> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: WANG Xuerui <git@xen0n.name> Cc: Tiezhu Yang <yangtiezhu@loongson.cn> Link: https://lore.kernel.org/bpf/20230328071335.2664966-1-guodongtai@kylinos.cn Signed-off-by: Sasha Levin <sashal@kernel.org>		2023-04-20 12:36:53 +02:00
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Makefile	…
bpf_jit.c	LoongArch, bpf: Fix jit to skip speculation barrier opcode	2023-04-20 12:36:53 +02:00
bpf_jit.h	LoongArch, bpf: Use 4 instructions for function address in JIT	2023-03-10 09:28:23 +01:00