/*
* BPF Jit compiler for s390.
*
* Minimum build requirements:
*
* - HAVE_MARCH_Z196_FEATURES: laal, laalg
* - HAVE_MARCH_Z10_FEATURES: msfi, cgrj, clgrj
* - HAVE_MARCH_Z9_109_FEATURES: alfi, llilf, clfi, oilf, nilf
* - PACK_STACK
* - 64BIT
*
* Copyright IBM Corp. 2012,2015
*
* Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
* Michael Holzheu <holzheu@linux.vnet.ibm.com>
*/
#define KMSG_COMPONENT "bpf_jit"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
#include <linux/netdevice.h>
#include <linux/filter.h>
#include <linux/init.h>
#include <asm/cacheflush.h>
#include <asm/dis.h>
#include "bpf_jit.h"
int bpf_jit_enable __read_mostly;
struct bpf_jit {
u32 seen; /* Flags to remember seen eBPF instructions */
u32 seen_reg[16]; /* Array to remember which registers are used */
u32 *addrs; /* Array with relative instruction addresses */
u8 *prg_buf; /* Start of program */
int size; /* Size of program and literal pool */
int size_prg; /* Size of program */
int prg; /* Current position in program */
int lit_start; /* Start of literal pool */
int lit; /* Current position in literal pool */
int base_ip; /* Base address for literal pool */
int ret0_ip; /* Address of return 0 */
int exit_ip; /* Address of exit */
};
#define BPF_SIZE_MAX 4096 /* Max size for program */
#define SEEN_SKB 1 /* skb access */
#define SEEN_MEM 2 /* use mem[] for temporary storage */
#define SEEN_RET0 4 /* ret0_ip points to a valid return 0 */
#define SEEN_LITERAL 8 /* code uses literals */
#define SEEN_FUNC 16 /* calls C functions */
#define SEEN_STACK (SEEN_FUNC | SEEN_MEM | SEEN_SKB)
/*
* s390 registers
*/
#define REG_W0 (__MAX_BPF_REG+0) /* Work register 1 (even) */
#define REG_W1 (__MAX_BPF_REG+1) /* Work register 2 (odd) */
#define REG_SKB_DATA (__MAX_BPF_REG+2) /* SKB data register */
#define REG_L (__MAX_BPF_REG+3) /* Literal pool register */
#define REG_15 (__MAX_BPF_REG+4) /* Register 15 */
#define REG_0 REG_W0 /* Register 0 */
#define REG_2 BPF_REG_1 /* Register 2 */
#define REG_14 BPF_REG_0 /* Register 14 */
/*
* Mapping of BPF registers to s390 registers
*/
static const int reg2hex[] = {
/* Return code */
[BPF_REG_0] = 14,
/* Function parameters */
[BPF_REG_1] = 2,
[BPF_REG_2] = 3,
[BPF_REG_3] = 4,
[BPF_REG_4] = 5,
[BPF_REG_5] = 6,
/* Call saved registers */
[BPF_REG_6] = 7,
[BPF_REG_7] = 8,
[BPF_REG_8] = 9,
[BPF_REG_9] = 10,
/* BPF stack pointer */
[BPF_REG_FP] = 13,
/* SKB data pointer */
[REG_SKB_DATA] = 12,
/* Work registers for s390x backend */
[REG_W0] = 0,
[REG_W1] = 1,
[REG_L] = 11,
[REG_15] = 15,
};
static inline u32 reg(u32 dst_reg, u32 src_reg)
{
return reg2hex[dst_reg] << 4 | reg2hex[src_reg];
}
static inline u32 reg_high(u32 reg)
{
return reg2hex[reg] << 4;
}
static inline void reg_set_seen(struct bpf_jit *jit, u32 b1)
{
u32 r1 = reg2hex[b1];
if (!jit->seen_reg[r1] && r1 >= 6 && r1 <= 15)
jit->seen_reg[r1] = 1;
}
#define REG_SET_SEEN(b1) \
({ \
reg_set_seen(jit, b1); \
})
#define REG_SEEN(b1) jit->seen_reg[reg2hex[(b1)]]
/*
* EMIT macros for code generation
*/
#define _EMIT2(op) \
({ \
if (jit->prg_buf) \
*(u16 *) (jit->prg_buf + jit->prg) = op; \
ji