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Commit 0424c5a4 authored by Alexei Starovoitov's avatar Alexei Starovoitov
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Merge branch 'remove-jited-size-limits' 

Ilya Leoshkevich says:

====================
This patch series introduces usage of relative long jumps and loads in
order to lift 64/512k size limits on JITed BPF programs on s390.

Patch 1 introduces long relative branches.
Patch 2 changes the way literal pool is arranged in order to be
compatible with long relative loads.
Patch 3 changes the way literal pool base register is loaded for large
programs.
Patch 4 replaces regular loads with long relative loads where they are
totally superior.
Patch 5 introduces long relative loads as an alternative way to load
constants in large programs. Regular loads are kept and still used for
small programs.
Patch 6 removes the size limit check.
====================
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parents a25ecd9d d1242b10
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Showing with 268 additions and 80 deletions
arch/s390/net/bpf_jit_comp.c
View file @ 0424c5a4
......@@ -24,6 +24,7 @@
#include <linux/init.h>
#include <linux/bpf.h>
#include <linux/mm.h>
#include <linux/kernel.h>
#include <asm/cacheflush.h>
#include <asm/dis.h>
#include <asm/facility.h>
......@@ -39,8 +40,10 @@ struct bpf_jit {
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 lit32_start; /* Start of 32-bit literal pool */
int lit32; /* Current position in 32-bit literal pool */
int lit64_start; /* Start of 64-bit literal pool */
int lit64; /* Current position in 64-bit literal pool */
int base_ip; /* Base address for literal pool */
int exit_ip; /* Address of exit */
int r1_thunk_ip; /* Address of expoline thunk for 'br %r1' */
......@@ -49,8 +52,6 @@ struct bpf_jit {
int labels[1]; /* Labels for local jumps */
};
#define BPF_SIZE_MAX 0xffff /* Max size for program (16 bit branches) */
#define SEEN_MEM BIT(0) /* use mem[] for temporary storage */
#define SEEN_LITERAL BIT(1) /* code uses literals */
#define SEEN_FUNC BIT(2) /* calls C functions */
......@@ -189,6 +190,12 @@ static inline void reg_set_seen(struct bpf_jit *jit, u32 b1)
_EMIT4((op) | __pcrel); \
})
#define EMIT4_PCREL_RIC(op, mask, target) \
({ \
int __rel = ((target) - jit->prg) / 2; \
_EMIT4((op) | (mask) << 20 | (__rel & 0xffff)); \
})
#define _EMIT6(op1, op2) \
({ \
if (jit->prg_buf) { \
......@@ -250,17 +257,22 @@ static inline void reg_set_seen(struct bpf_jit *jit, u32 b1)
#define EMIT6_PCREL_RILB(op, b, target) \
({ \
int rel = ((target) - jit->prg) / 2; \
unsigned int rel = (int)((target) - jit->prg) / 2; \
_EMIT6((op) | reg_high(b) << 16 | rel >> 16, rel & 0xffff);\
REG_SET_SEEN(b); \
})
#define EMIT6_PCREL_RIL(op, target) \
({ \
int rel = ((target) - jit->prg) / 2; \
unsigned int rel = (int)((target) - jit->prg) / 2; \
_EMIT6((op) | rel >> 16, rel & 0xffff); \
})
#define EMIT6_PCREL_RILC(op, mask, target) \
({ \
EMIT6_PCREL_RIL((op) | (mask) << 20, (target)); \
})
#define _EMIT6_IMM(op, imm) \
({ \
unsigned int __imm = (imm); \
......@@ -273,28 +285,38 @@ static inline void reg_set_seen(struct bpf_jit *jit, u32 b1)
REG_SET_SEEN(b1); \
})
#define EMIT_CONST_U32(val) \
#define _EMIT_CONST_U32(val) \
({ \
unsigned int ret; \
ret = jit->lit - jit->base_ip; \
jit->seen |= SEEN_LITERAL; \
ret = jit->lit32; \
if (jit->prg_buf) \
*(u32 *) (jit->prg_buf + jit->lit) = (u32) (val);\
jit->lit += 4; \
*(u32 *)(jit->prg_buf + jit->lit32) = (u32)(val);\
jit->lit32 += 4; \
ret; \
})
#define EMIT_CONST_U64(val) \
#define EMIT_CONST_U32(val) \
({ \
unsigned int ret; \
ret = jit->lit - jit->base_ip; \
jit->seen |= SEEN_LITERAL; \
_EMIT_CONST_U32(val) - jit->base_ip; \
})
#define _EMIT_CONST_U64(val) \
({ \
unsigned int ret; \
ret = jit->lit64; \
if (jit->prg_buf) \
*(u64 *) (jit->prg_buf + jit->lit) = (u64) (val);\
jit->lit += 8; \
*(u64 *)(jit->prg_buf + jit->lit64) = (u64)(val);\
jit->lit64 += 8; \
ret; \
})
#define EMIT_CONST_U64(val) \
({ \
jit->seen |= SEEN_LITERAL; \
_EMIT_CONST_U64(val) - jit->base_ip; \
})
#define EMIT_ZERO(b1) \
({ \
if (!fp->aux->verifier_zext) { \
......@@ -322,6 +344,49 @@ static bool is_codegen_pass(struct bpf_jit *jit)
return jit->prg_buf;
}
/*
* Return whether "rel" can be encoded as a short PC-relative offset
*/
static bool is_valid_rel(int rel)
{
return rel >= -65536 && rel <= 65534;
}
/*
* Return whether "off" can be reached using a short PC-relative offset
*/
static bool can_use_rel(struct bpf_jit *jit, int off)
{
return is_valid_rel(off - jit->prg);
}
/*
* Return whether given displacement can be encoded using
* Long-Displacement Facility
*/
static bool is_valid_ldisp(int disp)
{
return disp >= -524288 && disp <= 524287;
}
/*
* Return whether the next 32-bit literal pool entry can be referenced using
* Long-Displacement Facility
*/
static bool can_use_ldisp_for_lit32(struct bpf_jit *jit)
{
return is_valid_ldisp(jit->lit32 - jit->base_ip);
}
/*
* Return whether the next 64-bit literal pool entry can be referenced using
* Long-Displacement Facility
*/
static bool can_use_ldisp_for_lit64(struct bpf_jit *jit)
{
return is_valid_ldisp(jit->lit64 - jit->base_ip);
}
/*
* Fill whole space with illegal instructions
*/
......@@ -446,9 +511,16 @@ static void bpf_jit_prologue(struct bpf_jit *jit, u32 stack_depth)
save_restore_regs(jit, REGS_SAVE, stack_depth);
/* Setup literal pool */
if (is_first_pass(jit) || (jit->seen & SEEN_LITERAL)) {
/* basr %r13,0 */
if (!is_first_pass(jit) &&
is_valid_ldisp(jit->size - (jit->prg + 2))) {
/* basr %l,0 */
EMIT2(0x0d00, REG_L, REG_0);
jit->base_ip = jit->prg;
} else {
/* larl %l,lit32_start */
EMIT6_PCREL_RILB(0xc0000000, REG_L, jit->lit32_start);
jit->base_ip = jit->lit32_start;
}
}
/* Setup stack and backchain */
if (is_first_pass(jit) || (jit->seen & SEEN_STACK)) {
......@@ -525,9 +597,9 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
int i, bool extra_pass)
{
struct bpf_insn *insn = &fp->insnsi[i];
int jmp_off, last, insn_count = 1;
u32 dst_reg = insn->dst_reg;
u32 src_reg = insn->src_reg;
int last, insn_count = 1;
u32 *addrs = jit->addrs;
s32 imm = insn->imm;
s16 off = insn->off;
......@@ -566,9 +638,8 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
u64 imm64;
imm64 = (u64)(u32) insn[0].imm | ((u64)(u32) insn[1].imm) << 32;
/* lg %dst,<d(imm)>(%l) */
EMIT6_DISP_LH(0xe3000000, 0x0004, dst_reg, REG_0, REG_L,
EMIT_CONST_U64(imm64));
/* lgrl %dst,imm */
EMIT6_PCREL_RILB(0xc4080000, dst_reg, _EMIT_CONST_U64(imm64));
insn_count = 2;
break;
}
......@@ -697,9 +768,18 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
EMIT4_IMM(0xa7080000, REG_W0, 0);
/* lr %w1,%dst */
EMIT2(0x1800, REG_W1, dst_reg);
if (!is_first_pass(jit) && can_use_ldisp_for_lit32(jit)) {
/* dl %w0,<d(imm)>(%l) */
EMIT6_DISP_LH(0xe3000000, 0x0097, REG_W0, REG_0, REG_L,
EMIT_CONST_U32(imm));
} else {
/* lgfrl %dst,imm */
EMIT6_PCREL_RILB(0xc40c0000, dst_reg,
_EMIT_CONST_U32(imm));
jit->seen |= SEEN_LITERAL;
/* dlr %w0,%dst */
EMIT4(0xb9970000, REG_W0, dst_reg);
}
/* llgfr %dst,%rc */
EMIT4(0xb9160000, dst_reg, rc_reg);
if (insn_is_zext(&insn[1]))
......@@ -721,9 +801,18 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
EMIT4_IMM(0xa7090000, REG_W0, 0);
/* lgr %w1,%dst */
EMIT4(0xb9040000, REG_W1, dst_reg);
if (!is_first_pass(jit) && can_use_ldisp_for_lit64(jit)) {
/* dlg %w0,<d(imm)>(%l) */
EMIT6_DISP_LH(0xe3000000, 0x0087, REG_W0, REG_0, REG_L,
EMIT_CONST_U64(imm));
} else {
/* lgrl %dst,imm */
EMIT6_PCREL_RILB(0xc4080000, dst_reg,
_EMIT_CONST_U64(imm));
jit->seen |= SEEN_LITERAL;
/* dlgr %w0,%dst */
EMIT4(0xb9870000, REG_W0, dst_reg);
}
/* lgr %dst,%rc */
EMIT4(0xb9040000, dst_reg, rc_reg);
break;
......@@ -746,9 +835,19 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
EMIT_ZERO(dst_reg);
break;
case BPF_ALU64 | BPF_AND | BPF_K: /* dst = dst & imm */
if (!is_first_pass(jit) && can_use_ldisp_for_lit64(jit)) {
/* ng %dst,<d(imm)>(%l) */
EMIT6_DISP_LH(0xe3000000, 0x0080, dst_reg, REG_0, REG_L,
EMIT6_DISP_LH(0xe3000000, 0x0080,
dst_reg, REG_0, REG_L,
EMIT_CONST_U64(imm));
} else {
/* lgrl %w0,imm */
EMIT6_PCREL_RILB(0xc4080000, REG_W0,
_EMIT_CONST_U64(imm));
jit->seen |= SEEN_LITERAL;
/* ngr %dst,%w0 */
EMIT4(0xb9800000, dst_reg, REG_W0);
}
break;
/*
* BPF_OR
......@@ -768,9 +867,19 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
EMIT_ZERO(dst_reg);
break;
case BPF_ALU64 | BPF_OR | BPF_K: /* dst = dst | imm */
if (!is_first_pass(jit) && can_use_ldisp_for_lit64(jit)) {
/* og %dst,<d(imm)>(%l) */
EMIT6_DISP_LH(0xe3000000, 0x0081, dst_reg, REG_0, REG_L,
EMIT6_DISP_LH(0xe3000000, 0x0081,
dst_reg, REG_0, REG_L,
EMIT_CONST_U64(imm));
} else {
/* lgrl %w0,imm */
EMIT6_PCREL_RILB(0xc4080000, REG_W0,
_EMIT_CONST_U64(imm));
jit->seen |= SEEN_LITERAL;
/* ogr %dst,%w0 */
EMIT4(0xb9810000, dst_reg, REG_W0);
}
break;
/*
* BPF_XOR
......@@ -792,9 +901,19 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
EMIT_ZERO(dst_reg);
break;
case BPF_ALU64 | BPF_XOR | BPF_K: /* dst = dst ^ imm */
if (!is_first_pass(jit) && can_use_ldisp_for_lit64(jit)) {
/* xg %dst,<d(imm)>(%l) */
EMIT6_DISP_LH(0xe3000000, 0x0082, dst_reg, REG_0, REG_L,
EMIT6_DISP_LH(0xe3000000, 0x0082,
dst_reg, REG_0, REG_L,
EMIT_CONST_U64(imm));
} else {
/* lgrl %w0,imm */
EMIT6_PCREL_RILB(0xc4080000, REG_W0,
_EMIT_CONST_U64(imm));
jit->seen |= SEEN_LITERAL;
/* xgr %dst,%w0 */
EMIT4(0xb9820000, dst_reg, REG_W0);
}
break;
/*
* BPF_LSH
......@@ -1040,9 +1159,8 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
REG_SET_SEEN(BPF_REG_5);
jit->seen |= SEEN_FUNC;
/* lg %w1,<d(imm)>(%l) */
EMIT6_DISP_LH(0xe3000000, 0x0004, REG_W1, REG_0, REG_L,
EMIT_CONST_U64(func));
/* lgrl %w1,func */
EMIT6_PCREL_RILB(0xc4080000, REG_W1, _EMIT_CONST_U64(func));
if (__is_defined(CC_USING_EXPOLINE) && !nospec_disable) {
/* brasl %r14,__s390_indirect_jump_r1 */
EMIT6_PCREL_RILB(0xc0050000, REG_14, jit->r1_thunk_ip);
......@@ -1071,9 +1189,17 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
/* 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));
/* clrj %b3,%w1,0xa,label0: if (u32)%b3 >= (u32)%w1 goto out */
/* if ((u32)%b3 >= (u32)%w1) goto out; */
if (!is_first_pass(jit) && can_use_rel(jit, jit->labels[0])) {
/* clrj %b3,%w1,0xa,label0 */
EMIT6_PCREL_LABEL(0xec000000, 0x0077, BPF_REG_3,
REG_W1, 0, 0xa);
} else {
/* clr %b3,%w1 */
EMIT2(0x1500, BPF_REG_3, REG_W1);
/* brcl 0xa,label0 */
EMIT6_PCREL_RILC(0xc0040000, 0xa, jit->labels[0]);
}
/*
* if (tail_call_cnt++ > MAX_TAIL_CALL_CNT)
......@@ -1088,9 +1214,16 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
EMIT4_IMM(0xa7080000, REG_W0, 1);
/* laal %w1,%w0,off(%r15) */
EMIT6_DISP_LH(0xeb000000, 0x00fa, REG_W1, REG_W0, REG_15, off);
if (!is_first_pass(jit) && can_use_rel(jit, jit->labels[0])) {
/* clij %w1,MAX_TAIL_CALL_CNT,0x2,label0 */
EMIT6_PCREL_IMM_LABEL(0xec000000, 0x007f, REG_W1,
MAX_TAIL_CALL_CNT, 0, 0x2);
} else {
/* clfi %w1,MAX_TAIL_CALL_CNT */
EMIT6_IMM(0xc20f0000, REG_W1, MAX_TAIL_CALL_CNT);
/* brcl 0x2,label0 */
EMIT6_PCREL_RILC(0xc0040000, 0x2, jit->labels[0]);
}
/*
* prog = array->ptrs[index];
......@@ -1102,11 +1235,16 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
EMIT4(0xb9160000, REG_1, BPF_REG_3);
/* sllg %r1,%r1,3: %r1 *= 8 */
EMIT6_DISP_LH(0xeb000000, 0x000d, REG_1, REG_1, REG_0, 3);
/* lg %r1,prog(%b2,%r1) */
EMIT6_DISP_LH(0xe3000000, 0x0004, REG_1, BPF_REG_2,
/* ltg %r1,prog(%b2,%r1) */
EMIT6_DISP_LH(0xe3000000, 0x0002, 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);
if (!is_first_pass(jit) && can_use_rel(jit, jit->labels[0])) {
/* brc 0x8,label0 */
EMIT4_PCREL_RIC(0xa7040000, 0x8, jit->labels[0]);
} else {
/* brcl 0x8,label0 */
EMIT6_PCREL_RILC(0xc0040000, 0x8, jit->labels[0]);
}
/*
* Restore registers before calling function
......@@ -1263,36 +1401,83 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
goto branch_oc;
branch_ks:
is_jmp32 = BPF_CLASS(insn->code) == BPF_JMP32;
/* lgfi %w1,imm (load sign extend imm) */
EMIT6_IMM(0xc0010000, REG_W1, imm);
/* crj or cgrj %dst,%w1,mask,off */
EMIT6_PCREL(0xec000000, (is_jmp32 ? 0x0076 : 0x0064),
dst_reg, REG_W1, i, off, mask);
/* cfi or cgfi %dst,imm */
EMIT6_IMM(is_jmp32 ? 0xc20d0000 : 0xc20c0000,
dst_reg, imm);
if (!is_first_pass(jit) &&
can_use_rel(jit, addrs[i + off + 1])) {
/* brc mask,off */
EMIT4_PCREL_RIC(0xa7040000,
mask >> 12, addrs[i + off + 1]);
} else {
/* brcl mask,off */
EMIT6_PCREL_RILC(0xc0040000,
mask >> 12, addrs[i + off + 1]);
}
break;
branch_ku:
is_jmp32 = BPF_CLASS(insn->code) == BPF_JMP32;
/* lgfi %w1,imm (load sign extend imm) */
EMIT6_IMM(0xc0010000, REG_W1, imm);
/* clrj or clgrj %dst,%w1,mask,off */
EMIT6_PCREL(0xec000000, (is_jmp32 ? 0x0077 : 0x0065),
dst_reg, REG_W1, i, off, mask);
/* clfi or clgfi %dst,imm */
EMIT6_IMM(is_jmp32 ? 0xc20f0000 : 0xc20e0000,
dst_reg, imm);
if (!is_first_pass(jit) &&
can_use_rel(jit, addrs[i + off + 1])) {
/* brc mask,off */
EMIT4_PCREL_RIC(0xa7040000,
mask >> 12, addrs[i + off + 1]);
} else {
/* brcl mask,off */
EMIT6_PCREL_RILC(0xc0040000,
mask >> 12, addrs[i + off + 1]);
}
break;
branch_xs:
is_jmp32 = BPF_CLASS(insn->code) == BPF_JMP32;
if (!is_first_pass(jit) &&
can_use_rel(jit, addrs[i + off + 1])) {
/* crj or cgrj %dst,%src,mask,off */
EMIT6_PCREL(0xec000000, (is_jmp32 ? 0x0076 : 0x0064),
dst_reg, src_reg, i, off, mask);
} else {
/* cr or cgr %dst,%src */
if (is_jmp32)
EMIT2(0x1900, dst_reg, src_reg);
else
EMIT4(0xb9200000, dst_reg, src_reg);
/* brcl mask,off */
EMIT6_PCREL_RILC(0xc0040000,
mask >> 12, addrs[i + off + 1]);
}
break;
branch_xu:
is_jmp32 = BPF_CLASS(insn->code) == BPF_JMP32;
if (!is_first_pass(jit) &&
can_use_rel(jit, addrs[i + off + 1])) {
/* clrj or clgrj %dst,%src,mask,off */
EMIT6_PCREL(0xec000000, (is_jmp32 ? 0x0077 : 0x0065),
dst_reg, src_reg, i, off, mask);
} else {
/* clr or clgr %dst,%src */
if (is_jmp32)
EMIT2(0x1500, dst_reg, src_reg);
else
EMIT4(0xb9210000, dst_reg, src_reg);
/* brcl mask,off */
EMIT6_PCREL_RILC(0xc0040000,
mask >> 12, addrs[i + off + 1]);
}
break;
branch_oc:
/* brc mask,jmp_off (branch instruction needs 4 bytes) */
jmp_off = addrs[i + off + 1] - (addrs[i + 1] - 4);
EMIT4_PCREL(0xa7040000 | mask << 8, jmp_off);
if (!is_first_pass(jit) &&
can_use_rel(jit, addrs[i + off + 1])) {
/* brc mask,off */
EMIT4_PCREL_RIC(0xa7040000,
mask >> 12, addrs[i + off + 1]);
} else {
/* brcl mask,off */
EMIT6_PCREL_RILC(0xc0040000,
mask >> 12, addrs[i + off + 1]);
}
break;
}
default: /* too complex, give up */
......@@ -1336,9 +1521,10 @@ static int bpf_set_addr(struct bpf_jit *jit, int i)
static int bpf_jit_prog(struct bpf_jit *jit, struct bpf_prog *fp,
bool extra_pass)
{
int i, insn_count;
int i, insn_count, lit32_size, lit64_size;
jit->lit = jit->lit_start;
jit->lit32 = jit->lit32_start;
jit->lit64 = jit->lit64_start;
jit->prg = 0;
bpf_jit_prologue(jit, fp->aux->stack_depth);
......@@ -1354,8 +1540,15 @@ static int bpf_jit_prog(struct bpf_jit *jit, struct bpf_prog *fp,
}
bpf_jit_epilogue(jit, fp->aux->stack_depth);
jit->lit_start = jit->prg;
jit->size = jit->lit;
lit32_size = jit->lit32 - jit->lit32_start;
lit64_size = jit->lit64 - jit->lit64_start;
jit->lit32_start = jit->prg;
if (lit32_size)
jit->lit32_start = ALIGN(jit->lit32_start, 4);
jit->lit64_start = jit->lit32_start + lit32_size;
if (lit64_size)
jit->lit64_start = ALIGN(jit->lit64_start, 8);
jit->size = jit->lit64_start + lit64_size;
jit->size_prg = jit->prg;
return 0;
}
......@@ -1436,12 +1629,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
/*
* Final pass: Allocate and generate program
*/
if (jit.size >= BPF_SIZE_MAX) {
fp = orig_fp;
goto free_addrs;
}
header = bpf_jit_binary_alloc(jit.size, &jit.prg_buf, 2, jit_fill_hole);
header = bpf_jit_binary_alloc(jit.size, &jit.prg_buf, 8, jit_fill_hole);
if (!header) {
fp = orig_fp;
goto free_addrs;
......
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