Commit bbefef2f authored by Jiaxun Yang's avatar Jiaxun Yang Committed by Daniel Borkmann
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bpf, mips: Implement DADDI workarounds for JIT 



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: default avatarJiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Reviewed-by: default avatarPhilippe Mathieu-Daudé <philmd@linaro.org>
Acked-by: default avatarJohan Almbladh <johan.almbladh@anyfinetworks.com>
Link: https://lore.kernel.org/bpf/20230228113305.83751-2-jiaxun.yang@flygoat.com
parent c8ee37bd

arch/mips/Kconfig

+0 −1
Original line number Diff line number Diff line
@@ -64,7 +64,6 @@ config MIPS 
	select HAVE_DMA_CONTIGUOUS

	select HAVE_DYNAMIC_FTRACE

	select HAVE_EBPF_JIT if !CPU_MICROMIPS && \

				!CPU_DADDI_WORKAROUNDS && \

				!CPU_R4000_WORKAROUNDS && \

				!CPU_R4400_WORKAROUNDS

	select HAVE_EXIT_THREAD

arch/mips/net/bpf_jit_comp.c

+4 −0
Original line number Diff line number Diff line
@@ -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: