MIPS,bpf: Fix using smp_processor_id() in preemptible splat.

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 <david.daney@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/arch/mips/net/ebpf_jit.c b/arch/mips/net/ebpf_jit.c
index 3f87b96da5c4cba03aa2cff0f506f72626d99dbf..721216b0f8e4d76cbc5b24c697c64f277af8bcb1 100644 (file)
--- 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 @@ jeq_common:
                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;