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Message-Id: <20180503230824.3462-12-daniel@iogearbox.net>
Date: Fri, 4 May 2018 01:08:22 +0200
From: Daniel Borkmann <daniel@...earbox.net>
To: ast@...nel.org
Cc: netdev@...r.kernel.org, Daniel Borkmann <daniel@...earbox.net>,
Michael Holzheu <holzheu@...ux.vnet.ibm.com>
Subject: [PATCH bpf-next v2 11/13] bpf, s390x: remove ld_abs/ld_ind
Since LD_ABS/LD_IND instructions are now removed from the core and
reimplemented through a combination of inlined BPF instructions and
a slow-path helper, we can get rid of the complexity from s390x JIT.
Tested on s390x instance on LinuxONE.
Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Cc: Michael Holzheu <holzheu@...ux.vnet.ibm.com>
Acked-by: Alexei Starovoitov <ast@...nel.org>
---
arch/s390/net/Makefile | 2 +-
arch/s390/net/bpf_jit.S | 116 ---------------------------------------
arch/s390/net/bpf_jit.h | 20 +------
arch/s390/net/bpf_jit_comp.c | 127 ++++---------------------------------------
4 files changed, 13 insertions(+), 252 deletions(-)
delete mode 100644 arch/s390/net/bpf_jit.S
diff --git a/arch/s390/net/Makefile b/arch/s390/net/Makefile
index e0d5f24..d4663b4 100644
--- a/arch/s390/net/Makefile
+++ b/arch/s390/net/Makefile
@@ -2,4 +2,4 @@
#
# Arch-specific network modules
#
-obj-$(CONFIG_BPF_JIT) += bpf_jit.o bpf_jit_comp.o
+obj-$(CONFIG_BPF_JIT) += bpf_jit_comp.o
diff --git a/arch/s390/net/bpf_jit.S b/arch/s390/net/bpf_jit.S
deleted file mode 100644
index 25bb464..0000000
--- a/arch/s390/net/bpf_jit.S
+++ /dev/null
@@ -1,116 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * BPF Jit compiler for s390, help functions.
- *
- * Copyright IBM Corp. 2012,2015
- *
- * Author(s): Martin Schwidefsky <schwidefsky@...ibm.com>
- * Michael Holzheu <holzheu@...ux.vnet.ibm.com>
- */
-
-#include <linux/linkage.h>
-#include "bpf_jit.h"
-
-/*
- * Calling convention:
- * registers %r7-%r10, %r11,%r13, and %r15 are call saved
- *
- * Input (64 bit):
- * %r3 (%b2) = offset into skb data
- * %r6 (%b5) = return address
- * %r7 (%b6) = skb pointer
- * %r12 = skb data pointer
- *
- * Output:
- * %r14= %b0 = return value (read skb value)
- *
- * Work registers: %r2,%r4,%r5,%r14
- *
- * skb_copy_bits takes 4 parameters:
- * %r2 = skb pointer
- * %r3 = offset into skb data
- * %r4 = pointer to temp buffer
- * %r5 = length to copy
- * Return value in %r2: 0 = ok
- *
- * bpf_internal_load_pointer_neg_helper takes 3 parameters:
- * %r2 = skb pointer
- * %r3 = offset into data
- * %r4 = length to copy
- * Return value in %r2: Pointer to data
- */
-
-#define SKF_MAX_NEG_OFF -0x200000 /* SKF_LL_OFF from filter.h */
-
-/*
- * Load SIZE bytes from SKB
- */
-#define sk_load_common(NAME, SIZE, LOAD) \
-ENTRY(sk_load_##NAME); \
- ltgr %r3,%r3; /* Is offset negative? */ \
- jl sk_load_##NAME##_slow_neg; \
-ENTRY(sk_load_##NAME##_pos); \
- aghi %r3,SIZE; /* Offset + SIZE */ \
- clg %r3,STK_OFF_HLEN(%r15); /* Offset + SIZE > hlen? */ \
- jh sk_load_##NAME##_slow; \
- LOAD %r14,-SIZE(%r3,%r12); /* Get data from skb */ \
- b OFF_OK(%r6); /* Return */ \
- \
-sk_load_##NAME##_slow:; \
- lgr %r2,%r7; /* Arg1 = skb pointer */ \
- aghi %r3,-SIZE; /* Arg2 = offset */ \
- la %r4,STK_OFF_TMP(%r15); /* Arg3 = temp bufffer */ \
- lghi %r5,SIZE; /* Arg4 = size */ \
- brasl %r14,skb_copy_bits; /* Get data from skb */ \
- LOAD %r14,STK_OFF_TMP(%r15); /* Load from temp bufffer */ \
- ltgr %r2,%r2; /* Set cc to (%r2 != 0) */ \
- br %r6; /* Return */
-
-sk_load_common(word, 4, llgf) /* r14 = *(u32 *) (skb->data+offset) */
-sk_load_common(half, 2, llgh) /* r14 = *(u16 *) (skb->data+offset) */
-
-/*
- * Load 1 byte from SKB (optimized version)
- */
- /* r14 = *(u8 *) (skb->data+offset) */
-ENTRY(sk_load_byte)
- ltgr %r3,%r3 # Is offset negative?
- jl sk_load_byte_slow_neg
-ENTRY(sk_load_byte_pos)
- clg %r3,STK_OFF_HLEN(%r15) # Offset >= hlen?
- jnl sk_load_byte_slow
- llgc %r14,0(%r3,%r12) # Get byte from skb
- b OFF_OK(%r6) # Return OK
-
-sk_load_byte_slow:
- lgr %r2,%r7 # Arg1 = skb pointer
- # Arg2 = offset
- la %r4,STK_OFF_TMP(%r15) # Arg3 = pointer to temp buffer
- lghi %r5,1 # Arg4 = size (1 byte)
- brasl %r14,skb_copy_bits # Get data from skb
- llgc %r14,STK_OFF_TMP(%r15) # Load result from temp buffer
- ltgr %r2,%r2 # Set cc to (%r2 != 0)
- br %r6 # Return cc
-
-#define sk_negative_common(NAME, SIZE, LOAD) \
-sk_load_##NAME##_slow_neg:; \
- cgfi %r3,SKF_MAX_NEG_OFF; \
- jl bpf_error; \
- lgr %r2,%r7; /* Arg1 = skb pointer */ \
- /* Arg2 = offset */ \
- lghi %r4,SIZE; /* Arg3 = size */ \
- brasl %r14,bpf_internal_load_pointer_neg_helper; \
- ltgr %r2,%r2; \
- jz bpf_error; \
- LOAD %r14,0(%r2); /* Get data from pointer */ \
- xr %r3,%r3; /* Set cc to zero */ \
- br %r6; /* Return cc */
-
-sk_negative_common(word, 4, llgf)
-sk_negative_common(half, 2, llgh)
-sk_negative_common(byte, 1, llgc)
-
-bpf_error:
-# force a return 0 from jit handler
- ltgr %r15,%r15 # Set condition code
- br %r6
diff --git a/arch/s390/net/bpf_jit.h b/arch/s390/net/bpf_jit.h
index 5e1e513..7822ea9 100644
--- a/arch/s390/net/bpf_jit.h
+++ b/arch/s390/net/bpf_jit.h
@@ -16,9 +16,6 @@
#include <linux/filter.h>
#include <linux/types.h>
-extern u8 sk_load_word_pos[], sk_load_half_pos[], sk_load_byte_pos[];
-extern u8 sk_load_word[], sk_load_half[], sk_load_byte[];
-
#endif /* __ASSEMBLY__ */
/*
@@ -36,15 +33,6 @@ extern u8 sk_load_word[], sk_load_half[], sk_load_byte[];
* | | |
* | BPF stack | |
* | | |
- * +---------------+ |
- * | 8 byte skbp | |
- * R15+176 -> +---------------+ |
- * | 8 byte hlen | |
- * R15+168 -> +---------------+ |
- * | 4 byte align | |
- * +---------------+ |
- * | 4 byte temp | |
- * | for bpf_jit.S | |
* R15+160 -> +---------------+ |
* | new backchain | |
* R15+152 -> +---------------+ |
@@ -57,17 +45,11 @@ extern u8 sk_load_word[], sk_load_half[], sk_load_byte[];
* The stack size used by the BPF program ("BPF stack" above) is passed
* via "aux->stack_depth".
*/
-#define STK_SPACE_ADD (8 + 8 + 4 + 4 + 160)
+#define STK_SPACE_ADD (160)
#define STK_160_UNUSED (160 - 12 * 8)
#define STK_OFF (STK_SPACE_ADD - STK_160_UNUSED)
-#define STK_OFF_TMP 160 /* Offset of tmp buffer on stack */
-#define STK_OFF_HLEN 168 /* Offset of SKB header length on stack */
-#define STK_OFF_SKBP 176 /* Offset of SKB pointer on stack */
#define STK_OFF_R6 (160 - 11 * 8) /* Offset of r6 on stack */
#define STK_OFF_TCCNT (160 - 12 * 8) /* Offset of tail_call_cnt on stack */
-/* Offset to skip condition code check */
-#define OFF_OK 4
-
#endif /* __ARCH_S390_NET_BPF_JIT_H */
diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index 78a19c9..b020bea 100644
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -47,23 +47,21 @@ struct bpf_jit {
#define BPF_SIZE_MAX 0xffff /* Max size for program (16 bit branches) */
-#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_REG_AX 64 /* code uses constant blinding */
-#define SEEN_STACK (SEEN_FUNC | SEEN_MEM | SEEN_SKB)
+#define SEEN_MEM (1 << 0) /* use mem[] for temporary storage */
+#define SEEN_RET0 (1 << 1) /* ret0_ip points to a valid return 0 */
+#define SEEN_LITERAL (1 << 2) /* code uses literals */
+#define SEEN_FUNC (1 << 3) /* calls C functions */
+#define SEEN_TAIL_CALL (1 << 4) /* code uses tail calls */
+#define SEEN_REG_AX (1 << 5) /* code uses constant blinding */
+#define SEEN_STACK (SEEN_FUNC | SEEN_MEM)
/*
* s390 registers
*/
#define REG_W0 (MAX_BPF_JIT_REG + 0) /* Work register 1 (even) */
#define REG_W1 (MAX_BPF_JIT_REG + 1) /* Work register 2 (odd) */
-#define REG_SKB_DATA (MAX_BPF_JIT_REG + 2) /* SKB data register */
-#define REG_L (MAX_BPF_JIT_REG + 3) /* Literal pool register */
-#define REG_15 (MAX_BPF_JIT_REG + 4) /* Register 15 */
+#define REG_L (MAX_BPF_JIT_REG + 2) /* Literal pool register */
+#define REG_15 (MAX_BPF_JIT_REG + 3) /* Register 15 */
#define REG_0 REG_W0 /* Register 0 */
#define REG_1 REG_W1 /* Register 1 */
#define REG_2 BPF_REG_1 /* Register 2 */
@@ -88,10 +86,8 @@ static const int reg2hex[] = {
[BPF_REG_9] = 10,
/* BPF stack pointer */
[BPF_REG_FP] = 13,
- /* Register for blinding (shared with REG_SKB_DATA) */
+ /* Register for blinding */
[BPF_REG_AX] = 12,
- /* SKB data pointer */
- [REG_SKB_DATA] = 12,
/* Work registers for s390x backend */
[REG_W0] = 0,
[REG_W1] = 1,
@@ -385,27 +381,6 @@ static void save_restore_regs(struct bpf_jit *jit, int op, u32 stack_depth)
}
/*
- * 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 BPF_REG_AX is not used.
- */
-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);
- if (!(jit->seen & SEEN_REG_AX))
- /* 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.
@@ -445,12 +420,6 @@ static void bpf_jit_prologue(struct bpf_jit *jit, u32 stack_depth)
EMIT6_DISP_LH(0xe3000000, 0x0024, REG_W1, REG_0,
REG_15, 152);
}
- if (jit->seen & SEEN_SKB) {
- emit_load_skb_data_hlen(jit);
- /* stg %b1,ST_OFF_SKBP(%r0,%r15) */
- EMIT6_DISP_LH(0xe3000000, 0x0024, BPF_REG_1, REG_0, REG_15,
- STK_OFF_SKBP);
- }
}
/*
@@ -483,12 +452,12 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i
{
struct bpf_insn *insn = &fp->insnsi[i];
int jmp_off, last, insn_count = 1;
- unsigned int func_addr, mask;
u32 dst_reg = insn->dst_reg;
u32 src_reg = insn->src_reg;
u32 *addrs = jit->addrs;
s32 imm = insn->imm;
s16 off = insn->off;
+ unsigned int mask;
if (dst_reg == BPF_REG_AX || src_reg == BPF_REG_AX)
jit->seen |= SEEN_REG_AX;
@@ -970,13 +939,6 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i
EMIT2(0x0d00, REG_14, REG_W1);
/* lgr %b0,%r2: load return value into %b0 */
EMIT4(0xb9040000, BPF_REG_0, REG_2);
- if ((jit->seen & SEEN_SKB) &&
- bpf_helper_changes_pkt_data((void *)func)) {
- /* 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_TAIL_CALL:
@@ -1176,73 +1138,6 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i
jmp_off = addrs[i + off + 1] - (addrs[i + 1] - 4);
EMIT4_PCREL(0xa7040000 | mask << 8, jmp_off);
break;
- /*
- * BPF_LD
- */
- case BPF_LD | BPF_ABS | BPF_B: /* b0 = *(u8 *) (skb->data+imm) */
- case BPF_LD | BPF_IND | BPF_B: /* b0 = *(u8 *) (skb->data+imm+src) */
- if ((BPF_MODE(insn->code) == BPF_ABS) && (imm >= 0))
- func_addr = __pa(sk_load_byte_pos);
- else
- func_addr = __pa(sk_load_byte);
- goto call_fn;
- case BPF_LD | BPF_ABS | BPF_H: /* b0 = *(u16 *) (skb->data+imm) */
- case BPF_LD | BPF_IND | BPF_H: /* b0 = *(u16 *) (skb->data+imm+src) */
- if ((BPF_MODE(insn->code) == BPF_ABS) && (imm >= 0))
- func_addr = __pa(sk_load_half_pos);
- else
- func_addr = __pa(sk_load_half);
- goto call_fn;
- case BPF_LD | BPF_ABS | BPF_W: /* b0 = *(u32 *) (skb->data+imm) */
- case BPF_LD | BPF_IND | BPF_W: /* b0 = *(u32 *) (skb->data+imm+src) */
- if ((BPF_MODE(insn->code) == BPF_ABS) && (imm >= 0))
- func_addr = __pa(sk_load_word_pos);
- else
- func_addr = __pa(sk_load_word);
- goto call_fn;
-call_fn:
- jit->seen |= SEEN_SKB | SEEN_RET0 | SEEN_FUNC;
- REG_SET_SEEN(REG_14); /* Return address of possible func call */
-
- /*
- * Implicit input:
- * BPF_REG_6 (R7) : skb pointer
- * REG_SKB_DATA (R12): skb data pointer (if no BPF_REG_AX)
- *
- * Calculated input:
- * BPF_REG_2 (R3) : offset of byte(s) to fetch in skb
- * BPF_REG_5 (R6) : return address
- *
- * Output:
- * BPF_REG_0 (R14): data read from skb
- *
- * Scratch registers (BPF_REG_1-5)
- */
-
- /* Call function: llilf %w1,func_addr */
- EMIT6_IMM(0xc00f0000, REG_W1, func_addr);
-
- /* Offset: lgfi %b2,imm */
- EMIT6_IMM(0xc0010000, BPF_REG_2, imm);
- if (BPF_MODE(insn->code) == BPF_IND)
- /* agfr %b2,%src (%src is s32 here) */
- EMIT4(0xb9180000, BPF_REG_2, src_reg);
-
- /* Reload REG_SKB_DATA if BPF_REG_AX is used */
- if (jit->seen & SEEN_REG_AX)
- /* lg %skb_data,data_off(%b6) */
- EMIT6_DISP_LH(0xe3000000, 0x0004, REG_SKB_DATA, REG_0,
- BPF_REG_6, offsetof(struct sk_buff, data));
- /* basr %b5,%w1 (%b5 is call saved) */
- EMIT2(0x0d00, BPF_REG_5, REG_W1);
-
- /*
- * Note: For fast access we jump directly after the
- * jnz instruction from bpf_jit.S
- */
- /* jnz <ret0> */
- EMIT4_PCREL(0xa7740000, jit->ret0_ip - jit->prg);
- break;
default: /* too complex, give up */
pr_err("Unknown opcode %02x\n", insn->code);
return -1;
--
2.9.5
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