[PATCH 1/3] MIPS,bpf: Fix using smp_processor_id() in preemptible splat.
From: David Daney <hidden>
Date: 2017-08-18 23:40:44
Also in:
linux-mips, lkml
Subsystem:
bpf jit for mips (32-bit and 64-bit), bpf [general] (safe dynamic programs and tools), mips, the rest · Maintainers:
Johan Almbladh, Paul Burton, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Thomas Bogendoerfer, Linus Torvalds
If the kernel is configured with preemption enabled we were getting warning stack traces for use of current_cpu_type(). Fix by moving the test between preempt_disable()/preempt_enable() and caching the results of the CPU type tests for use during code generation. Signed-off-by: David Daney <redacted> --- arch/mips/net/ebpf_jit.c | 28 ++++++++++++++-------------- 1 file changed, 14 insertions(+), 14 deletions(-)
diff --git a/arch/mips/net/ebpf_jit.c b/arch/mips/net/ebpf_jit.c
index 3f87b96..721216b 100644
--- a/arch/mips/net/ebpf_jit.c
+++ b/arch/mips/net/ebpf_jit.c@@ -113,6 +113,7 @@ struct jit_ctx { u64 *reg_val_types; unsigned int long_b_conversion:1; unsigned int gen_b_offsets:1; + unsigned int use_bbit_insns:1; }; static void set_reg_val_type(u64 *rvt, int reg, enum reg_val_type type)
@@ -655,19 +656,6 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx, int this_idx) return build_int_epilogue(ctx, MIPS_R_T9); } -static bool use_bbit_insns(void) -{ - switch (current_cpu_type()) { - case CPU_CAVIUM_OCTEON: - case CPU_CAVIUM_OCTEON_PLUS: - case CPU_CAVIUM_OCTEON2: - case CPU_CAVIUM_OCTEON3: - return true; - default: - return false; - } -} - static bool is_bad_offset(int b_off) { return b_off > 0x1ffff || b_off < -0x20000;
@@ -1198,7 +1186,7 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, if (dst < 0) return dst; - if (use_bbit_insns() && hweight32((u32)insn->imm) == 1) { + if (ctx->use_bbit_insns && hweight32((u32)insn->imm) == 1) { if ((insn + 1)->code == (BPF_JMP | BPF_EXIT) && insn->off == 1) { b_off = b_imm(exit_idx, ctx); if (is_bad_offset(b_off))
@@ -1853,6 +1841,18 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) memset(&ctx, 0, sizeof(ctx)); + preempt_disable(); + switch (current_cpu_type()) { + case CPU_CAVIUM_OCTEON: + case CPU_CAVIUM_OCTEON_PLUS: + case CPU_CAVIUM_OCTEON2: + case CPU_CAVIUM_OCTEON3: + ctx.use_bbit_insns = 1; + default: + ctx.use_bbit_insns = 0; + } + preempt_enable(); + ctx.offsets = kcalloc(prog->len + 1, sizeof(*ctx.offsets), GFP_KERNEL); if (ctx.offsets == NULL) goto out_err;
--
2.9.5