bpf_jit_comp64.c

/*
 * bpf_jit_comp64.c: eBPF JIT compiler
 *
 * Copyright 2016 Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
 *		  IBM Corporation
 *
 * Based on the powerpc classic BPF JIT compiler by Matt Evans
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; version 2
 * of the License.
 */
#include <linux/moduleloader.h>
#include <asm/cacheflush.h>
#include <asm/asm-compat.h>
#include <linux/netdevice.h>
#include <linux/filter.h>
#include <linux/if_vlan.h>
#include <asm/kprobes.h>
#include <linux/bpf.h>

#include "bpf_jit64.h"

static void bpf_jit_fill_ill_insns(void *area, unsigned int size)
{
	memset32(area, BREAKPOINT_INSTRUCTION, size/4);
}

static inline void bpf_flush_icache(void *start, void *end)
{
	smp_wmb();
	flush_icache_range((unsigned long)start, (unsigned long)end);
}

static inline bool bpf_is_seen_register(struct codegen_context *ctx, int i)
{
	return (ctx->seen & (1 << (31 - b2p[i])));
}

static inline void bpf_set_seen_register(struct codegen_context *ctx, int i)
{
	ctx->seen |= (1 << (31 - b2p[i]));
}

static inline bool bpf_has_stack_frame(struct codegen_context *ctx)
{
	/*
	 * We only need a stack frame if:
	 * - we call other functions (kernel helpers), or
	 * - the bpf program uses its stack area
	 * The latter condition is deduced from the usage of BPF_REG_FP
	 */
	return ctx->seen & SEEN_FUNC || bpf_is_seen_register(ctx, BPF_REG_FP);
}

/*
 * When not setting up our own stackframe, the redzone usage is:
 *
 *		[	prev sp		] <-------------
 *		[	  ...       	] 		|
 * sp (r1) --->	[    stack pointer	] --------------
 *		[   nv gpr save area	] 6*8
 *		[    tail_call_cnt	] 8
 *		[    local_tmp_var	] 8
 *		[   unused red zone	] 208 bytes protected
 */
static int bpf_jit_stack_local(struct codegen_context *ctx)
{
	if (bpf_has_stack_frame(ctx))