bpf, mips: Limit to 33 tail calls (e49e6f6d) · Commits · 戴 / test

All BPF JIT compilers except RISC-V's and MIPS' enforce a 33-tail calls limit at runtime. In addition, a test was recently added, in tailcalls2, to check this limit. This patch updates the tail call limit in MIPS' JIT compiler to allow 33 tail calls. Fixes: ("MIPS: Add missing file for eBPF JIT.") Reported-by:

Mahshid Khezri <khezri.mahshid@gmail.com> Signed-off-by:

Paul Chaignon <paul.chaignon@orange.com> Signed-off-by:

Daniel Borkmann <daniel@iogearbox.net> Acked-by:

Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/b8eb2caac1c25453c539248e56ca22f74b5316af.1575916815.git.paul.chaignon@gmail.com

arch/mips/net/ebpf_jit.c

+5 −4

Original line number	Diff line number	Diff line
		@@ -604,6 +604,7 @@ static void emit_const_to_reg(struct jit_ctx *ctx, int dst, u64 value)
		static int emit_bpf_tail_call(struct jit_ctx *ctx, int this_idx)
		{
		int off, b_off;
		int tcc_reg;

		ctx->flags \|= EBPF_SEEN_TC;
		/*
		@@ -616,14 +617,14 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx, int this_idx)
		b_off = b_imm(this_idx + 1, ctx);
		emit_instr(ctx, bne, MIPS_R_AT, MIPS_R_ZERO, b_off);
		/*
		* if (--TCC < 0)
		* if (TCC-- < 0)
		* goto out;
		*/
		/* Delay slot */
		emit_instr(ctx, daddiu, MIPS_R_T5,
		(ctx->flags & EBPF_TCC_IN_V1) ? MIPS_R_V1 : MIPS_R_S4, -1);
		tcc_reg = (ctx->flags & EBPF_TCC_IN_V1) ? MIPS_R_V1 : MIPS_R_S4;
		emit_instr(ctx, daddiu, MIPS_R_T5, tcc_reg, -1);
		b_off = b_imm(this_idx + 1, ctx);
		emit_instr(ctx, bltz, MIPS_R_T5, b_off);
		emit_instr(ctx, bltz, tcc_reg, b_off);
		/*
		* prog = array->ptrs[index];
		* if (prog == NULL)

Admin message