#include <linux/netdevice.h>
#include <linux/filter.h>
#include <linux/init.h>
+#include <linux/bpf.h>
#include <asm/cacheflush.h>
#include <asm/dis.h>
#include "bpf_jit.h"
int base_ip; /* Base address for literal pool */
int ret0_ip; /* Address of return 0 */
int exit_ip; /* Address of exit */
+ int tail_call_start; /* Tail call start offset */
+ int labels[1]; /* Labels for local jumps */
};
-#define BPF_SIZE_MAX 4096 /* Max size for program */
+#define BPF_SIZE_MAX 0x7ffff /* Max size for program (20 bit signed displ) */
#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_TAIL_CALL 32 /* code uses tail calls */
+#define SEEN_SKB_CHANGE 64 /* code changes skb data */
#define SEEN_STACK (SEEN_FUNC | SEEN_MEM | SEEN_SKB)
/*
#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_1 REG_W1 /* Register 1 */
#define REG_2 BPF_REG_1 /* Register 2 */
#define REG_14 BPF_REG_0 /* Register 14 */
_EMIT6(op1 | __disp, op2); \
})
-#define EMIT6_DISP(op1, op2, b1, b2, b3, disp) \
-({ \
- _EMIT6_DISP(op1 | reg(b1, b2) << 16 | \
- reg_high(b3) << 8, op2, disp); \
- REG_SET_SEEN(b1); \
- REG_SET_SEEN(b2); \
- REG_SET_SEEN(b3); \
-})
-
#define _EMIT6_DISP_LH(op1, op2, disp) \
({ \
- unsigned int __disp_h = ((u32)disp) & 0xff000; \
- unsigned int __disp_l = ((u32)disp) & 0x00fff; \
+ u32 _disp = (u32) disp; \
+ unsigned int __disp_h = _disp & 0xff000; \
+ unsigned int __disp_l = _disp & 0x00fff; \
_EMIT6(op1 | __disp_l, op2 | __disp_h >> 4); \
})
REG_SET_SEEN(b3); \
})
+#define EMIT6_PCREL_LABEL(op1, op2, b1, b2, label, mask) \
+({ \
+ int rel = (jit->labels[label] - jit->prg) >> 1; \
+ _EMIT6(op1 | reg(b1, b2) << 16 | (rel & 0xffff), \
+ op2 | mask << 12); \
+ REG_SET_SEEN(b1); \
+ REG_SET_SEEN(b2); \
+})
+
+#define EMIT6_PCREL_IMM_LABEL(op1, op2, b1, imm, label, mask) \
+({ \
+ int rel = (jit->labels[label] - jit->prg) >> 1; \
+ _EMIT6(op1 | (reg_high(b1) | mask) << 16 | \
+ (rel & 0xffff), op2 | (imm & 0xff) << 8); \
+ REG_SET_SEEN(b1); \
+ BUILD_BUG_ON(((unsigned long) imm) > 0xff); \
+})
+
#define EMIT6_PCREL(op1, op2, b1, b2, i, off, mask) \
({ \
/* Branch instruction needs 6 bytes */ \
*/
static void save_regs(struct bpf_jit *jit, u32 rs, u32 re)
{
- u32 off = 72 + (rs - 6) * 8;
+ u32 off = STK_OFF_R6 + (rs - 6) * 8;
if (rs == re)
/* stg %rs,off(%r15) */
*/
static void restore_regs(struct bpf_jit *jit, u32 rs, u32 re)
{
- u32 off = 72 + (rs - 6) * 8;
+ u32 off = STK_OFF_R6 + (rs - 6) * 8;
if (jit->seen & SEEN_STACK)
off += STK_OFF;
} while (re <= 15);
}
+/*
+ * For SKB access %b1 contains the SKB pointer. For "bpf_jit.S"
+ * we store the SKB header length on the stack and the SKB data
+ * pointer in REG_SKB_DATA.
+ */
+static void emit_load_skb_data_hlen(struct bpf_jit *jit)
+{
+ /* Header length: llgf %w1,<len>(%b1) */
+ EMIT6_DISP_LH(0xe3000000, 0x0016, REG_W1, REG_0, BPF_REG_1,
+ offsetof(struct sk_buff, len));
+ /* s %w1,<data_len>(%b1) */
+ EMIT4_DISP(0x5b000000, REG_W1, BPF_REG_1,
+ offsetof(struct sk_buff, data_len));
+ /* stg %w1,ST_OFF_HLEN(%r0,%r15) */
+ EMIT6_DISP_LH(0xe3000000, 0x0024, REG_W1, REG_0, REG_15, STK_OFF_HLEN);
+ /* lg %skb_data,data_off(%b1) */
+ EMIT6_DISP_LH(0xe3000000, 0x0004, REG_SKB_DATA, REG_0,
+ BPF_REG_1, offsetof(struct sk_buff, data));
+}
+
/*
* Emit function prologue
*
* Save registers and create stack frame if necessary.
* See stack frame layout desription in "bpf_jit.h"!
*/
-static void bpf_jit_prologue(struct bpf_jit *jit)
+static void bpf_jit_prologue(struct bpf_jit *jit, bool is_classic)
{
+ if (jit->seen & SEEN_TAIL_CALL) {
+ /* xc STK_OFF_TCCNT(4,%r15),STK_OFF_TCCNT(%r15) */
+ _EMIT6(0xd703f000 | STK_OFF_TCCNT, 0xf000 | STK_OFF_TCCNT);
+ } else {
+ /* j tail_call_start: NOP if no tail calls are used */
+ EMIT4_PCREL(0xa7f40000, 6);
+ _EMIT2(0);
+ }
+ /* Tail calls have to skip above initialization */
+ jit->tail_call_start = jit->prg;
/* Save registers */
save_restore_regs(jit, REGS_SAVE);
/* Setup literal pool */
EMIT6_DISP_LH(0xe3000000, 0x0024, REG_W1, REG_0,
REG_15, 152);
}
- /*
- * For SKB access %b1 contains the SKB pointer. For "bpf_jit.S"
- * we store the SKB header length on the stack and the SKB data
- * pointer in REG_SKB_DATA.
- */
- if (jit->seen & SEEN_SKB) {
- /* Header length: llgf %w1,<len>(%b1) */
- EMIT6_DISP_LH(0xe3000000, 0x0016, REG_W1, REG_0, BPF_REG_1,
- offsetof(struct sk_buff, len));
- /* s %w1,<data_len>(%b1) */
- EMIT4_DISP(0x5b000000, REG_W1, BPF_REG_1,
- offsetof(struct sk_buff, data_len));
- /* stg %w1,ST_OFF_HLEN(%r0,%r15) */
+ if (jit->seen & SEEN_SKB)
+ emit_load_skb_data_hlen(jit);
+ if (jit->seen & SEEN_SKB_CHANGE)
+ /* stg %b1,ST_OFF_SKBP(%r0,%r15) */
EMIT6_DISP_LH(0xe3000000, 0x0024, REG_W1, REG_0, REG_15,
- STK_OFF_HLEN);
- /* lg %skb_data,data_off(%b1) */
- EMIT6_DISP_LH(0xe3000000, 0x0004, REG_SKB_DATA, REG_0,
- BPF_REG_1, offsetof(struct sk_buff, data));
+ STK_OFF_SKBP);
+ /* Clear A (%b0) and X (%b7) registers for converted BPF programs */
+ if (is_classic) {
+ if (REG_SEEN(BPF_REG_A))
+ /* lghi %ba,0 */
+ EMIT4_IMM(0xa7090000, BPF_REG_A, 0);
+ if (REG_SEEN(BPF_REG_X))
+ /* lghi %bx,0 */
+ EMIT4_IMM(0xa7090000, BPF_REG_X, 0);
}
- /* BPF compatibility: clear A (%b0) and X (%b7) registers */
- if (REG_SEEN(BPF_REG_A))
- /* lghi %ba,0 */
- EMIT4_IMM(0xa7090000, BPF_REG_A, 0);
- if (REG_SEEN(BPF_REG_X))
- /* lghi %bx,0 */
- EMIT4_IMM(0xa7090000, BPF_REG_X, 0);
}
/*
REG_SET_SEEN(BPF_REG_5);
jit->seen |= SEEN_FUNC;
/* lg %w1,<d(imm)>(%l) */
- EMIT6_DISP(0xe3000000, 0x0004, REG_W1, REG_0, REG_L,
- EMIT_CONST_U64(func));
+ EMIT6_DISP_LH(0xe3000000, 0x0004, REG_W1, REG_0, REG_L,
+ EMIT_CONST_U64(func));
/* basr %r14,%w1 */
EMIT2(0x0d00, REG_14, REG_W1);
/* lgr %b0,%r2: load return value into %b0 */
EMIT4(0xb9040000, BPF_REG_0, REG_2);
+ if (bpf_helper_changes_skb_data((void *)func)) {
+ jit->seen |= SEEN_SKB_CHANGE;
+ /* lg %b1,ST_OFF_SKBP(%r15) */
+ EMIT6_DISP_LH(0xe3000000, 0x0004, BPF_REG_1, REG_0,
+ REG_15, STK_OFF_SKBP);
+ emit_load_skb_data_hlen(jit);
+ }
break;
}
+ case BPF_JMP | BPF_CALL | BPF_X:
+ /*
+ * Implicit input:
+ * B1: pointer to ctx
+ * B2: pointer to bpf_array
+ * B3: index in bpf_array
+ */
+ jit->seen |= SEEN_TAIL_CALL;
+
+ /*
+ * if (index >= array->map.max_entries)
+ * goto out;
+ */
+
+ /* llgf %w1,map.max_entries(%b2) */
+ EMIT6_DISP_LH(0xe3000000, 0x0016, REG_W1, REG_0, BPF_REG_2,
+ offsetof(struct bpf_array, map.max_entries));
+ /* clgrj %b3,%w1,0xa,label0: if %b3 >= %w1 goto out */
+ EMIT6_PCREL_LABEL(0xec000000, 0x0065, BPF_REG_3,
+ REG_W1, 0, 0xa);
+
+ /*
+ * if (tail_call_cnt++ > MAX_TAIL_CALL_CNT)
+ * goto out;
+ */
+
+ if (jit->seen & SEEN_STACK)
+ off = STK_OFF_TCCNT + STK_OFF;
+ else
+ off = STK_OFF_TCCNT;
+ /* lhi %w0,1 */
+ EMIT4_IMM(0xa7080000, REG_W0, 1);
+ /* laal %w1,%w0,off(%r15) */
+ EMIT6_DISP_LH(0xeb000000, 0x00fa, REG_W1, REG_W0, REG_15, off);
+ /* clij %w1,MAX_TAIL_CALL_CNT,0x2,label0 */
+ EMIT6_PCREL_IMM_LABEL(0xec000000, 0x007f, REG_W1,
+ MAX_TAIL_CALL_CNT, 0, 0x2);
+
+ /*
+ * prog = array->ptrs[index];
+ * if (prog == NULL)
+ * goto out;
+ */
+
+ /* sllg %r1,%b3,3: %r1 = index * 8 */
+ EMIT6_DISP_LH(0xeb000000, 0x000d, REG_1, BPF_REG_3, REG_0, 3);
+ /* lg %r1,prog(%b2,%r1) */
+ EMIT6_DISP_LH(0xe3000000, 0x0004, REG_1, BPF_REG_2,
+ REG_1, offsetof(struct bpf_array, ptrs));
+ /* clgij %r1,0,0x8,label0 */
+ EMIT6_PCREL_IMM_LABEL(0xec000000, 0x007d, REG_1, 0, 0, 0x8);
+
+ /*
+ * Restore registers before calling function
+ */
+ save_restore_regs(jit, REGS_RESTORE);
+
+ /*
+ * goto *(prog->bpf_func + tail_call_start);
+ */
+
+ /* lg %r1,bpf_func(%r1) */
+ EMIT6_DISP_LH(0xe3000000, 0x0004, REG_1, REG_1, REG_0,
+ offsetof(struct bpf_prog, bpf_func));
+ /* bc 0xf,tail_call_start(%r1) */
+ _EMIT4(0x47f01000 + jit->tail_call_start);
+ /* out: */
+ jit->labels[0] = jit->prg;
+ break;
case BPF_JMP | BPF_EXIT: /* return b0 */
last = (i == fp->len - 1) ? 1 : 0;
if (last && !(jit->seen & SEEN_RET0))
jit->lit = jit->lit_start;
jit->prg = 0;
- bpf_jit_prologue(jit);
+ bpf_jit_prologue(jit, bpf_prog_was_classic(fp));
for (i = 0; i < fp->len; i += insn_count) {
insn_count = bpf_jit_insn(jit, fp, i);
if (insn_count < 0)
if (jit.prg_buf) {
set_memory_ro((unsigned long)header, header->pages);
fp->bpf_func = (void *) jit.prg_buf;
- fp->jited = true;
+ fp->jited = 1;
}
free_addrs:
kfree(jit.addrs);
Code Review / kvmfornfv.git / blobdiff