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bpf, mips: Implement DADDI workarounds for JIT

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For DADDI errata we just workaround by disable immediate operation
for BPF_ADD / BPF_SUB to avoid generation of DADDIU.

All other use cases in JIT won't cause overflow thus they are all safe.

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Acked-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Link: https://lore.kernel.org/bpf/20230228113305.83751-2-jiaxun.yang@flygoat.com
This commit is contained in:
Jiaxun Yang
2023-02-28 11:33:04 +00:00
committed by Daniel Borkmann
parent c8ee37bde4
commit bbefef2f07
2 changed files with 4 additions and 1 deletions
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4
arch/mips/net/bpf_jit_comp.c
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@@ -218,9 +218,13 @@ bool valid_alu_i(u8 op, s32 imm)
/* All legal eBPF values are valid */
return true;
case BPF_ADD:
if (IS_ENABLED(CONFIG_CPU_DADDI_WORKAROUNDS))
return false;
/* imm must be 16 bits */
return imm >= -0x8000 && imm <= 0x7fff;
case BPF_SUB:
if (IS_ENABLED(CONFIG_CPU_DADDI_WORKAROUNDS))
return false;
/* -imm must be 16 bits */
return imm >= -0x7fff && imm <= 0x8000;
case BPF_AND: