[PATCH v3] net: filter: BPF 'JIT' compiler for PPC64
Matt Evans
matt at ozlabs.org
Thu Jul 21 11:51:00 EST 2011
An implementation of a code generator for BPF programs to speed up packet
filtering on PPC64, inspired by Eric Dumazet's x86-64 version.
Filter code is generated as an ABI-compliant function in module_alloc()'d mem
with stackframe & prologue/epilogue generated if required (simple filters don't
need anything more than an li/blr). The filter's local variables, M[], live in
registers. Supports all BPF opcodes, although "complicated" loads from negative
packet offsets (e.g. SKF_LL_OFF) are not yet supported.
There are a couple of further optimisations left for future work; many-pass
assembly with branch-reach reduction and a register allocator to push M[]
variables into volatile registers would improve the code quality further.
This currently supports big-endian 64-bit PowerPC only (but is fairly simple
to port to PPC32 or LE!).
Enabled in the same way as x86-64:
echo 1 > /proc/sys/net/core/bpf_jit_enable
Or, enabled with extra debug output:
echo 2 > /proc/sys/net/core/bpf_jit_enable
Signed-off-by: Matt Evans <matt at ozlabs.org>
---
V3: Added BUILD_BUG_ON to assert PACA CPU ID is 16bits, made a comment (in
LD_MSH) a bit clearer, ratelimited "Unknown opcode" error and moved
bpf_jit.S to bpf_jit_64.S (it doesn't make sense to rename bpf_jit_comp.c as
small portions will eventually get split out into _32/_64.c files when we do
32bit support).
arch/powerpc/Kconfig | 1 +
arch/powerpc/Makefile | 3 +-
arch/powerpc/include/asm/ppc-opcode.h | 40 ++
arch/powerpc/net/Makefile | 4 +
arch/powerpc/net/bpf_jit.h | 227 +++++++++++
arch/powerpc/net/bpf_jit_64.S | 138 +++++++
arch/powerpc/net/bpf_jit_comp.c | 694 +++++++++++++++++++++++++++++++++
7 files changed, 1106 insertions(+), 1 deletions(-)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 2729c66..39860fc 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -134,6 +134,7 @@ config PPC
select GENERIC_IRQ_SHOW_LEVEL
select HAVE_RCU_TABLE_FREE if SMP
select HAVE_SYSCALL_TRACEPOINTS
+ select HAVE_BPF_JIT if PPC64
config EARLY_PRINTK
bool
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index b7212b6..b94740f 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -154,7 +154,8 @@ core-y += arch/powerpc/kernel/ \
arch/powerpc/lib/ \
arch/powerpc/sysdev/ \
arch/powerpc/platforms/ \
- arch/powerpc/math-emu/
+ arch/powerpc/math-emu/ \
+ arch/powerpc/net/
core-$(CONFIG_XMON) += arch/powerpc/xmon/
core-$(CONFIG_KVM) += arch/powerpc/kvm/
diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h
index e472659..e980faa 100644
--- a/arch/powerpc/include/asm/ppc-opcode.h
+++ b/arch/powerpc/include/asm/ppc-opcode.h
@@ -71,6 +71,42 @@
#define PPC_INST_ERATSX 0x7c000126
#define PPC_INST_ERATSX_DOT 0x7c000127
+/* Misc instructions for BPF compiler */
+#define PPC_INST_LD 0xe8000000
+#define PPC_INST_LHZ 0xa0000000
+#define PPC_INST_LWZ 0x80000000
+#define PPC_INST_STD 0xf8000000
+#define PPC_INST_STDU 0xf8000001
+#define PPC_INST_MFLR 0x7c0802a6
+#define PPC_INST_MTLR 0x7c0803a6
+#define PPC_INST_CMPWI 0x2c000000
+#define PPC_INST_CMPDI 0x2c200000
+#define PPC_INST_CMPLW 0x7c000040
+#define PPC_INST_CMPLWI 0x28000000
+#define PPC_INST_ADDI 0x38000000
+#define PPC_INST_ADDIS 0x3c000000
+#define PPC_INST_ADD 0x7c000214
+#define PPC_INST_SUB 0x7c000050
+#define PPC_INST_BLR 0x4e800020
+#define PPC_INST_BLRL 0x4e800021
+#define PPC_INST_MULLW 0x7c0001d6
+#define PPC_INST_MULHWU 0x7c000016
+#define PPC_INST_MULLI 0x1c000000
+#define PPC_INST_DIVWU 0x7c0003d6
+#define PPC_INST_RLWINM 0x54000000
+#define PPC_INST_RLDICR 0x78000004
+#define PPC_INST_SLW 0x7c000030
+#define PPC_INST_SRW 0x7c000430
+#define PPC_INST_AND 0x7c000038
+#define PPC_INST_ANDDOT 0x7c000039
+#define PPC_INST_OR 0x7c000378
+#define PPC_INST_ANDI 0x70000000
+#define PPC_INST_ORI 0x60000000
+#define PPC_INST_ORIS 0x64000000
+#define PPC_INST_NEG 0x7c0000d0
+#define PPC_INST_BRANCH 0x48000000
+#define PPC_INST_BRANCH_COND 0x40800000
+
/* macros to insert fields into opcodes */
#define __PPC_RA(a) (((a) & 0x1f) << 16)
#define __PPC_RB(b) (((b) & 0x1f) << 11)
@@ -83,6 +119,10 @@
#define __PPC_T_TLB(t) (((t) & 0x3) << 21)
#define __PPC_WC(w) (((w) & 0x3) << 21)
#define __PPC_WS(w) (((w) & 0x1f) << 11)
+#define __PPC_SH(s) __PPC_WS(s)
+#define __PPC_MB(s) (((s) & 0x1f) << 6)
+#define __PPC_ME(s) (((s) & 0x1f) << 1)
+#define __PPC_BI(s) (((s) & 0x1f) << 16)
/*
* Only use the larx hint bit on 64bit CPUs. e500v1/v2 based CPUs will treat a
diff --git a/arch/powerpc/net/Makefile b/arch/powerpc/net/Makefile
new file mode 100644
index 0000000..266b395
--- /dev/null
+++ b/arch/powerpc/net/Makefile
@@ -0,0 +1,4 @@
+#
+# Arch-specific network modules
+#
+obj-$(CONFIG_BPF_JIT) += bpf_jit_64.o bpf_jit_comp.o
diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h
new file mode 100644
index 0000000..af1ab5e
--- /dev/null
+++ b/arch/powerpc/net/bpf_jit.h
@@ -0,0 +1,227 @@
+/* bpf_jit.h: BPF JIT compiler for PPC64
+ *
+ * Copyright 2011 Matt Evans <matt at ozlabs.org>, IBM Corporation
+ *
+ * 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.
+ */
+#ifndef _BPF_JIT_H
+#define _BPF_JIT_H
+
+#define BPF_PPC_STACK_LOCALS 32
+#define BPF_PPC_STACK_BASIC (48+64)
+#define BPF_PPC_STACK_SAVE (18*8)
+#define BPF_PPC_STACKFRAME (BPF_PPC_STACK_BASIC+BPF_PPC_STACK_LOCALS+ \
+ BPF_PPC_STACK_SAVE)
+#define BPF_PPC_SLOWPATH_FRAME (48+64)
+
+/*
+ * Generated code register usage:
+ *
+ * As normal PPC C ABI (e.g. r1=sp, r2=TOC), with:
+ *
+ * skb r3 (Entry parameter)
+ * A register r4
+ * X register r5
+ * addr param r6
+ * r7-r10 scratch
+ * skb->data r14
+ * skb headlen r15 (skb->len - skb->data_len)
+ * m[0] r16
+ * m[...] ...
+ * m[15] r31
+ */
+#define r_skb 3
+#define r_ret 3
+#define r_A 4
+#define r_X 5
+#define r_addr 6
+#define r_scratch1 7
+#define r_D 14
+#define r_HL 15
+#define r_M 16
+
+#ifndef __ASSEMBLY__
+
+/*
+ * Assembly helpers from arch/powerpc/net/bpf_jit.S:
+ */
+extern u8 sk_load_word[], sk_load_half[], sk_load_byte[], sk_load_byte_msh[];
+
+#define FUNCTION_DESCR_SIZE 24
+
+/*
+ * 16-bit immediate helper macros: HA() is for use with sign-extending instrs
+ * (e.g. LD, ADDI). If the bottom 16 bits is "-ve", add another bit into the
+ * top half to negate the effect (i.e. 0xffff + 1 = 0x(1)0000).
+ */
+#define IMM_H(i) ((uintptr_t)(i)>>16)
+#define IMM_HA(i) (((uintptr_t)(i)>>16) + \
+ (((uintptr_t)(i) & 0x8000) >> 15))
+#define IMM_L(i) ((uintptr_t)(i) & 0xffff)
+
+#define PLANT_INSTR(d, idx, instr) \
+ do { if (d) { (d)[idx] = instr; } idx++; } while (0)
+#define EMIT(instr) PLANT_INSTR(image, ctx->idx, instr)
+
+#define PPC_NOP() EMIT(PPC_INST_NOP)
+#define PPC_BLR() EMIT(PPC_INST_BLR)
+#define PPC_BLRL() EMIT(PPC_INST_BLRL)
+#define PPC_MTLR(r) EMIT(PPC_INST_MTLR | __PPC_RT(r))
+#define PPC_ADDI(d, a, i) EMIT(PPC_INST_ADDI | __PPC_RT(d) | \
+ __PPC_RA(a) | IMM_L(i))
+#define PPC_MR(d, a) PPC_OR(d, a, a)
+#define PPC_LI(r, i) PPC_ADDI(r, 0, i)
+#define PPC_ADDIS(d, a, i) EMIT(PPC_INST_ADDIS | \
+ __PPC_RS(d) | __PPC_RA(a) | IMM_L(i))
+#define PPC_LIS(r, i) PPC_ADDIS(r, 0, i)
+#define PPC_STD(r, base, i) EMIT(PPC_INST_STD | __PPC_RS(r) | \
+ __PPC_RA(base) | ((i) & 0xfffc))
+
+#define PPC_LD(r, base, i) EMIT(PPC_INST_LD | __PPC_RT(r) | \
+ __PPC_RA(base) | IMM_L(i))
+#define PPC_LWZ(r, base, i) EMIT(PPC_INST_LWZ | __PPC_RT(r) | \
+ __PPC_RA(base) | IMM_L(i))
+#define PPC_LHZ(r, base, i) EMIT(PPC_INST_LHZ | __PPC_RT(r) | \
+ __PPC_RA(base) | IMM_L(i))
+/* Convenience helpers for the above with 'far' offsets: */
+#define PPC_LD_OFFS(r, base, i) do { if ((i) < 32768) PPC_LD(r, base, i); \
+ else { PPC_ADDIS(r, base, IMM_HA(i)); \
+ PPC_LD(r, r, IMM_L(i)); } } while(0)
+
+#define PPC_LWZ_OFFS(r, base, i) do { if ((i) < 32768) PPC_LWZ(r, base, i); \
+ else { PPC_ADDIS(r, base, IMM_HA(i)); \
+ PPC_LWZ(r, r, IMM_L(i)); } } while(0)
+
+#define PPC_LHZ_OFFS(r, base, i) do { if ((i) < 32768) PPC_LHZ(r, base, i); \
+ else { PPC_ADDIS(r, base, IMM_HA(i)); \
+ PPC_LHZ(r, r, IMM_L(i)); } } while(0)
+
+#define PPC_CMPWI(a, i) EMIT(PPC_INST_CMPWI | __PPC_RA(a) | IMM_L(i))
+#define PPC_CMPDI(a, i) EMIT(PPC_INST_CMPDI | __PPC_RA(a) | IMM_L(i))
+#define PPC_CMPLWI(a, i) EMIT(PPC_INST_CMPLWI | __PPC_RA(a) | IMM_L(i))
+#define PPC_CMPLW(a, b) EMIT(PPC_INST_CMPLW | __PPC_RA(a) | __PPC_RB(b))
+
+#define PPC_SUB(d, a, b) EMIT(PPC_INST_SUB | __PPC_RT(d) | \
+ __PPC_RB(a) | __PPC_RA(b))
+#define PPC_ADD(d, a, b) EMIT(PPC_INST_ADD | __PPC_RT(d) | \
+ __PPC_RA(a) | __PPC_RB(b))
+#define PPC_MUL(d, a, b) EMIT(PPC_INST_MULLW | __PPC_RT(d) | \
+ __PPC_RA(a) | __PPC_RB(b))
+#define PPC_MULHWU(d, a, b) EMIT(PPC_INST_MULHWU | __PPC_RT(d) | \
+ __PPC_RA(a) | __PPC_RB(b))
+#define PPC_MULI(d, a, i) EMIT(PPC_INST_MULLI | __PPC_RT(d) | \
+ __PPC_RA(a) | IMM_L(i))
+#define PPC_DIVWU(d, a, b) EMIT(PPC_INST_DIVWU | __PPC_RT(d) | \
+ __PPC_RA(a) | __PPC_RB(b))
+#define PPC_AND(d, a, b) EMIT(PPC_INST_AND | __PPC_RA(d) | \
+ __PPC_RS(a) | __PPC_RB(b))
+#define PPC_ANDI(d, a, i) EMIT(PPC_INST_ANDI | __PPC_RA(d) | \
+ __PPC_RS(a) | IMM_L(i))
+#define PPC_AND_DOT(d, a, b) EMIT(PPC_INST_ANDDOT | __PPC_RA(d) | \
+ __PPC_RS(a) | __PPC_RB(b))
+#define PPC_OR(d, a, b) EMIT(PPC_INST_OR | __PPC_RA(d) | \
+ __PPC_RS(a) | __PPC_RB(b))
+#define PPC_ORI(d, a, i) EMIT(PPC_INST_ORI | __PPC_RA(d) | \
+ __PPC_RS(a) | IMM_L(i))
+#define PPC_ORIS(d, a, i) EMIT(PPC_INST_ORIS | __PPC_RA(d) | \
+ __PPC_RS(a) | IMM_L(i))
+#define PPC_SLW(d, a, s) EMIT(PPC_INST_SLW | __PPC_RA(d) | \
+ __PPC_RS(a) | __PPC_RB(s))
+#define PPC_SRW(d, a, s) EMIT(PPC_INST_SRW | __PPC_RA(d) | \
+ __PPC_RS(a) | __PPC_RB(s))
+/* slwi = rlwinm Rx, Ry, n, 0, 31-n */
+#define PPC_SLWI(d, a, i) EMIT(PPC_INST_RLWINM | __PPC_RA(d) | \
+ __PPC_RS(a) | __PPC_SH(i) | \
+ __PPC_MB(0) | __PPC_ME(31-(i)))
+/* srwi = rlwinm Rx, Ry, 32-n, n, 31 */
+#define PPC_SRWI(d, a, i) EMIT(PPC_INST_RLWINM | __PPC_RA(d) | \
+ __PPC_RS(a) | __PPC_SH(32-(i)) | \
+ __PPC_MB(i) | __PPC_ME(31))
+/* sldi = rldicr Rx, Ry, n, 63-n */
+#define PPC_SLDI(d, a, i) EMIT(PPC_INST_RLDICR | __PPC_RA(d) | \
+ __PPC_RS(a) | __PPC_SH(i) | \
+ __PPC_MB(63-(i)) | (((i) & 0x20) >> 4))
+#define PPC_NEG(d, a) EMIT(PPC_INST_NEG | __PPC_RT(d) | __PPC_RA(a))
+
+/* Long jump; (unconditional 'branch') */
+#define PPC_JMP(dest) EMIT(PPC_INST_BRANCH | \
+ (((dest) - (ctx->idx * 4)) & 0x03fffffc))
+/* "cond" here covers BO:BI fields. */
+#define PPC_BCC_SHORT(cond, dest) EMIT(PPC_INST_BRANCH_COND | \
+ (((cond) & 0x3ff) << 16) | \
+ (((dest) - (ctx->idx * 4)) & \
+ 0xfffc))
+#define PPC_LI32(d, i) do { PPC_LI(d, IMM_L(i)); \
+ if ((u32)(uintptr_t)(i) >= 32768) { \
+ PPC_ADDIS(d, d, IMM_HA(i)); \
+ } } while(0)
+#define PPC_LI64(d, i) do { \
+ if (!((uintptr_t)(i) & 0xffffffff00000000ULL)) \
+ PPC_LI32(d, i); \
+ else { \
+ PPC_LIS(d, ((uintptr_t)(i) >> 48)); \
+ if ((uintptr_t)(i) & 0x0000ffff00000000ULL) \
+ PPC_ORI(d, d, \
+ ((uintptr_t)(i) >> 32) & 0xffff); \
+ PPC_SLDI(d, d, 32); \
+ if ((uintptr_t)(i) & 0x00000000ffff0000ULL) \
+ PPC_ORIS(d, d, \
+ ((uintptr_t)(i) >> 16) & 0xffff); \
+ if ((uintptr_t)(i) & 0x000000000000ffffULL) \
+ PPC_ORI(d, d, (uintptr_t)(i) & 0xffff); \
+ } } while (0);
+
+static inline bool is_nearbranch(int offset)
+{
+ return (offset < 32768) && (offset >= -32768);
+}
+
+/*
+ * The fly in the ointment of code size changing from pass to pass is
+ * avoided by padding the short branch case with a NOP. If code size differs
+ * with different branch reaches we will have the issue of code moving from
+ * one pass to the next and will need a few passes to converge on a stable
+ * state.
+ */
+#define PPC_BCC(cond, dest) do { \
+ if (is_nearbranch((dest) - (ctx->idx * 4))) { \
+ PPC_BCC_SHORT(cond, dest); \
+ PPC_NOP(); \
+ } else { \
+ /* Flip the 'T or F' bit to invert comparison */ \
+ PPC_BCC_SHORT(cond ^ COND_CMP_TRUE, (ctx->idx+2)*4); \
+ PPC_JMP(dest); \
+ } } while(0)
+
+/* To create a branch condition, select a bit of cr0... */
+#define CR0_LT 0
+#define CR0_GT 1
+#define CR0_EQ 2
+/* ...and modify BO[3] */
+#define COND_CMP_TRUE 0x100
+#define COND_CMP_FALSE 0x000
+/* Together, they make all required comparisons: */
+#define COND_GT (CR0_GT | COND_CMP_TRUE)
+#define COND_GE (CR0_LT | COND_CMP_FALSE)
+#define COND_EQ (CR0_EQ | COND_CMP_TRUE)
+#define COND_NE (CR0_EQ | COND_CMP_FALSE)
+#define COND_LT (CR0_LT | COND_CMP_TRUE)
+
+#define SEEN_DATAREF 0x10000 /* might call external helpers */
+#define SEEN_XREG 0x20000 /* X reg is used */
+#define SEEN_MEM 0x40000 /* SEEN_MEM+(1<<n) = use mem[n] for temporary
+ * storage */
+#define SEEN_MEM_MSK 0x0ffff
+
+struct codegen_context {
+ unsigned int seen;
+ unsigned int idx;
+ int pc_ret0; /* bpf index of first RET #0 instruction (if any) */
+};
+
+#endif
+
+#endif
diff --git a/arch/powerpc/net/bpf_jit_64.S b/arch/powerpc/net/bpf_jit_64.S
new file mode 100644
index 0000000..ff4506e
--- /dev/null
+++ b/arch/powerpc/net/bpf_jit_64.S
@@ -0,0 +1,138 @@
+/* bpf_jit.S: Packet/header access helper functions
+ * for PPC64 BPF compiler.
+ *
+ * Copyright 2011 Matt Evans <matt at ozlabs.org>, IBM Corporation
+ *
+ * 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 <asm/ppc_asm.h>
+#include "bpf_jit.h"
+
+/*
+ * All of these routines are called directly from generated code,
+ * whose register usage is:
+ *
+ * r3 skb
+ * r4,r5 A,X
+ * r6 *** address parameter to helper ***
+ * r7-r10 scratch
+ * r14 skb->data
+ * r15 skb headlen
+ * r16-31 M[]
+ */
+
+/*
+ * To consider: These helpers are so small it could be better to just
+ * generate them inline. Inline code can do the simple headlen check
+ * then branch directly to slow_path_XXX if required. (In fact, could
+ * load a spare GPR with the address of slow_path_generic and pass size
+ * as an argument, making the call site a mtlr, li and bllr.)
+ *
+ * Technically, the "is addr < 0" check is unnecessary & slowing down
+ * the ABS path, as it's statically checked on generation.
+ */
+ .globl sk_load_word
+sk_load_word:
+ cmpdi r_addr, 0
+ blt bpf_error
+ /* Are we accessing past headlen? */
+ subi r_scratch1, r_HL, 4
+ cmpd r_scratch1, r_addr
+ blt bpf_slow_path_word
+ /* Nope, just hitting the header. cr0 here is eq or gt! */
+ lwzx r_A, r_D, r_addr
+ /* When big endian we don't need to byteswap. */
+ blr /* Return success, cr0 != LT */
+
+ .globl sk_load_half
+sk_load_half:
+ cmpdi r_addr, 0
+ blt bpf_error
+ subi r_scratch1, r_HL, 2
+ cmpd r_scratch1, r_addr
+ blt bpf_slow_path_half
+ lhzx r_A, r_D, r_addr
+ blr
+
+ .globl sk_load_byte
+sk_load_byte:
+ cmpdi r_addr, 0
+ blt bpf_error
+ cmpd r_HL, r_addr
+ ble bpf_slow_path_byte
+ lbzx r_A, r_D, r_addr
+ blr
+
+/*
+ * BPF_S_LDX_B_MSH: ldxb 4*([offset]&0xf)
+ * r_addr is the offset value, already known positive
+ */
+ .globl sk_load_byte_msh
+sk_load_byte_msh:
+ cmpd r_HL, r_addr
+ ble bpf_slow_path_byte_msh
+ lbzx r_X, r_D, r_addr
+ rlwinm r_X, r_X, 2, 32-4-2, 31-2
+ blr
+
+bpf_error:
+ /* Entered with cr0 = lt */
+ li r3, 0
+ /* Generated code will 'blt epilogue', returning 0. */
+ blr
+
+/* Call out to skb_copy_bits:
+ * We'll need to back up our volatile regs first; we have
+ * local variable space at r1+(BPF_PPC_STACK_BASIC).
+ * Allocate a new stack frame here to remain ABI-compliant in
+ * stashing LR.
+ */
+#define bpf_slow_path_common(SIZE) \
+ mflr r0; \
+ std r0, 16(r1); \
+ /* R3 goes in parameter space of caller's frame */ \
+ std r_skb, (BPF_PPC_STACKFRAME+48)(r1); \
+ std r_A, (BPF_PPC_STACK_BASIC+(0*8))(r1); \
+ std r_X, (BPF_PPC_STACK_BASIC+(1*8))(r1); \
+ addi r5, r1, BPF_PPC_STACK_BASIC+(2*8); \
+ stdu r1, -BPF_PPC_SLOWPATH_FRAME(r1); \
+ /* R3 = r_skb, as passed */ \
+ mr r4, r_addr; \
+ li r6, SIZE; \
+ bl skb_copy_bits; \
+ /* R3 = 0 on success */ \
+ addi r1, r1, BPF_PPC_SLOWPATH_FRAME; \
+ ld r0, 16(r1); \
+ ld r_A, (BPF_PPC_STACK_BASIC+(0*8))(r1); \
+ ld r_X, (BPF_PPC_STACK_BASIC+(1*8))(r1); \
+ mtlr r0; \
+ cmpdi r3, 0; \
+ blt bpf_error; /* cr0 = LT */ \
+ ld r_skb, (BPF_PPC_STACKFRAME+48)(r1); \
+ /* Great success! */
+
+bpf_slow_path_word:
+ bpf_slow_path_common(4)
+ /* Data value is on stack, and cr0 != LT */
+ lwz r_A, BPF_PPC_STACK_BASIC+(2*8)(r1)
+ blr
+
+bpf_slow_path_half:
+ bpf_slow_path_common(2)
+ lhz r_A, BPF_PPC_STACK_BASIC+(2*8)(r1)
+ blr
+
+bpf_slow_path_byte:
+ bpf_slow_path_common(1)
+ lbz r_A, BPF_PPC_STACK_BASIC+(2*8)(r1)
+ blr
+
+bpf_slow_path_byte_msh:
+ bpf_slow_path_common(1)
+ lbz r_X, BPF_PPC_STACK_BASIC+(2*8)(r1)
+ rlwinm r_X, r_X, 2, 32-4-2, 31-2
+ blr
diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c
new file mode 100644
index 0000000..73619d3
--- /dev/null
+++ b/arch/powerpc/net/bpf_jit_comp.c
@@ -0,0 +1,694 @@
+/* bpf_jit_comp.c: BPF JIT compiler for PPC64
+ *
+ * Copyright 2011 Matt Evans <matt at ozlabs.org>, IBM Corporation
+ *
+ * Based on the x86 BPF compiler, by Eric Dumazet (eric.dumazet at gmail.com)
+ *
+ * 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 <linux/netdevice.h>
+#include <linux/filter.h>
+#include "bpf_jit.h"
+
+#ifndef __BIG_ENDIAN
+/* There are endianness assumptions herein. */
+#error "Little-endian PPC not supported in BPF compiler"
+#endif
+
+int bpf_jit_enable __read_mostly;
+
+
+static inline void bpf_flush_icache(void *start, void *end)
+{
+ smp_wmb();
+ flush_icache_range((unsigned long)start, (unsigned long)end);
+}
+
+static void bpf_jit_build_prologue(struct sk_filter *fp, u32 *image,
+ struct codegen_context *ctx)
+{
+ int i;
+ const struct sock_filter *filter = fp->insns;
+
+ if (ctx->seen & (SEEN_MEM | SEEN_DATAREF)) {
+ /* Make stackframe */
+ if (ctx->seen & SEEN_DATAREF) {
+ /* If we call any helpers (for loads), save LR */
+ EMIT(PPC_INST_MFLR | __PPC_RT(0));
+ PPC_STD(0, 1, 16);
+
+ /* Back up non-volatile regs. */
+ PPC_STD(r_D, 1, -(8*(32-r_D)));
+ PPC_STD(r_HL, 1, -(8*(32-r_HL)));
+ }
+ if (ctx->seen & SEEN_MEM) {
+ /*
+ * Conditionally save regs r15-r31 as some will be used
+ * for M[] data.
+ */
+ for (i = r_M; i < (r_M+16); i++) {
+ if (ctx->seen & (1 << (i-r_M)))
+ PPC_STD(i, 1, -(8*(32-i)));
+ }
+ }
+ EMIT(PPC_INST_STDU | __PPC_RS(1) | __PPC_RA(1) |
+ (-BPF_PPC_STACKFRAME & 0xfffc));
+ }
+
+ if (ctx->seen & SEEN_DATAREF) {
+ /*
+ * If this filter needs to access skb data,
+ * prepare r_D and r_HL:
+ * r_HL = skb->len - skb->data_len
+ * r_D = skb->data
+ */
+ PPC_LWZ_OFFS(r_scratch1, r_skb, offsetof(struct sk_buff,
+ data_len));
+ PPC_LWZ_OFFS(r_HL, r_skb, offsetof(struct sk_buff, len));
+ PPC_SUB(r_HL, r_HL, r_scratch1);
+ PPC_LD_OFFS(r_D, r_skb, offsetof(struct sk_buff, data));
+ }
+
+ if (ctx->seen & SEEN_XREG) {
+ /*
+ * TODO: Could also detect whether first instr. sets X and
+ * avoid this (as below, with A).
+ */
+ PPC_LI(r_X, 0);
+ }
+
+ switch (filter[0].code) {
+ case BPF_S_RET_K:
+ case BPF_S_LD_W_LEN:
+ case BPF_S_ANC_PROTOCOL:
+ case BPF_S_ANC_IFINDEX:
+ case BPF_S_ANC_MARK:
+ case BPF_S_ANC_RXHASH:
+ case BPF_S_ANC_CPU:
+ case BPF_S_ANC_QUEUE:
+ case BPF_S_LD_W_ABS:
+ case BPF_S_LD_H_ABS:
+ case BPF_S_LD_B_ABS:
+ /* first instruction sets A register (or is RET 'constant') */
+ break;
+ default:
+ /* make sure we dont leak kernel information to user */
+ PPC_LI(r_A, 0);
+ }
+}
+
+static void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx)
+{
+ int i;
+
+ if (ctx->seen & (SEEN_MEM | SEEN_DATAREF)) {
+ PPC_ADDI(1, 1, BPF_PPC_STACKFRAME);
+ if (ctx->seen & SEEN_DATAREF) {
+ PPC_LD(0, 1, 16);
+ PPC_MTLR(0);
+ PPC_LD(r_D, 1, -(8*(32-r_D)));
+ PPC_LD(r_HL, 1, -(8*(32-r_HL)));
+ }
+ if (ctx->seen & SEEN_MEM) {
+ /* Restore any saved non-vol registers */
+ for (i = r_M; i < (r_M+16); i++) {
+ if (ctx->seen & (1 << (i-r_M)))
+ PPC_LD(i, 1, -(8*(32-i)));
+ }
+ }
+ }
+ /* The RETs have left a return value in R3. */
+
+ PPC_BLR();
+}
+
+/* Assemble the body code between the prologue & epilogue. */
+static int bpf_jit_build_body(struct sk_filter *fp, u32 *image,
+ struct codegen_context *ctx,
+ unsigned int *addrs)
+{
+ const struct sock_filter *filter = fp->insns;
+ int flen = fp->len;
+ u8 *func;
+ unsigned int true_cond;
+ int i;
+
+ /* Start of epilogue code */
+ unsigned int exit_addr = addrs[flen];
+
+ for (i = 0; i < flen; i++) {
+ unsigned int K = filter[i].k;
+
+ /*
+ * addrs[] maps a BPF bytecode address into a real offset from
+ * the start of the body code.
+ */
+ addrs[i] = ctx->idx * 4;
+
+ switch (filter[i].code) {
+ /*** ALU ops ***/
+ case BPF_S_ALU_ADD_X: /* A += X; */
+ ctx->seen |= SEEN_XREG;
+ PPC_ADD(r_A, r_A, r_X);
+ break;
+ case BPF_S_ALU_ADD_K: /* A += K; */
+ if (!K)
+ break;
+ PPC_ADDI(r_A, r_A, IMM_L(K));
+ if (K >= 32768)
+ PPC_ADDIS(r_A, r_A, IMM_HA(K));
+ break;
+ case BPF_S_ALU_SUB_X: /* A -= X; */
+ ctx->seen |= SEEN_XREG;
+ PPC_SUB(r_A, r_A, r_X);
+ break;
+ case BPF_S_ALU_SUB_K: /* A -= K */
+ if (!K)
+ break;
+ PPC_ADDI(r_A, r_A, IMM_L(-K));
+ if (K >= 32768)
+ PPC_ADDIS(r_A, r_A, IMM_HA(-K));
+ break;
+ case BPF_S_ALU_MUL_X: /* A *= X; */
+ ctx->seen |= SEEN_XREG;
+ PPC_MUL(r_A, r_A, r_X);
+ break;
+ case BPF_S_ALU_MUL_K: /* A *= K */
+ if (K < 32768)
+ PPC_MULI(r_A, r_A, K);
+ else {
+ PPC_LI32(r_scratch1, K);
+ PPC_MUL(r_A, r_A, r_scratch1);
+ }
+ break;
+ case BPF_S_ALU_DIV_X: /* A /= X; */
+ ctx->seen |= SEEN_XREG;
+ PPC_CMPWI(r_X, 0);
+ if (ctx->pc_ret0 != -1) {
+ PPC_BCC(COND_EQ, addrs[ctx->pc_ret0]);
+ } else {
+ /*
+ * Exit, returning 0; first pass hits here
+ * (longer worst-case code size).
+ */
+ PPC_BCC_SHORT(COND_NE, (ctx->idx*4)+12);
+ PPC_LI(r_ret, 0);
+ PPC_JMP(exit_addr);
+ }
+ PPC_DIVWU(r_A, r_A, r_X);
+ break;
+ case BPF_S_ALU_DIV_K: /* A = reciprocal_divide(A, K); */
+ PPC_LI32(r_scratch1, K);
+ /* Top 32 bits of 64bit result -> A */
+ PPC_MULHWU(r_A, r_A, r_scratch1);
+ break;
+ case BPF_S_ALU_AND_X:
+ ctx->seen |= SEEN_XREG;
+ PPC_AND(r_A, r_A, r_X);
+ break;
+ case BPF_S_ALU_AND_K:
+ if (!IMM_H(K))
+ PPC_ANDI(r_A, r_A, K);
+ else {
+ PPC_LI32(r_scratch1, K);
+ PPC_AND(r_A, r_A, r_scratch1);
+ }
+ break;
+ case BPF_S_ALU_OR_X:
+ ctx->seen |= SEEN_XREG;
+ PPC_OR(r_A, r_A, r_X);
+ break;
+ case BPF_S_ALU_OR_K:
+ if (IMM_L(K))
+ PPC_ORI(r_A, r_A, IMM_L(K));
+ if (K >= 65536)
+ PPC_ORIS(r_A, r_A, IMM_H(K));
+ break;
+ case BPF_S_ALU_LSH_X: /* A <<= X; */
+ ctx->seen |= SEEN_XREG;
+ PPC_SLW(r_A, r_A, r_X);
+ break;
+ case BPF_S_ALU_LSH_K:
+ if (K == 0)
+ break;
+ else
+ PPC_SLWI(r_A, r_A, K);
+ break;
+ case BPF_S_ALU_RSH_X: /* A >>= X; */
+ ctx->seen |= SEEN_XREG;
+ PPC_SRW(r_A, r_A, r_X);
+ break;
+ case BPF_S_ALU_RSH_K: /* A >>= K; */
+ if (K == 0)
+ break;
+ else
+ PPC_SRWI(r_A, r_A, K);
+ break;
+ case BPF_S_ALU_NEG:
+ PPC_NEG(r_A, r_A);
+ break;
+ case BPF_S_RET_K:
+ PPC_LI32(r_ret, K);
+ if (!K) {
+ if (ctx->pc_ret0 == -1)
+ ctx->pc_ret0 = i;
+ }
+ /*
+ * If this isn't the very last instruction, branch to
+ * the epilogue if we've stuff to clean up. Otherwise,
+ * if there's nothing to tidy, just return. If we /are/
+ * the last instruction, we're about to fall through to
+ * the epilogue to return.
+ */
+ if (i != flen - 1) {
+ /*
+ * Note: 'seen' is properly valid only on pass
+ * #2. Both parts of this conditional are the
+ * same instruction size though, meaning the
+ * first pass will still correctly determine the
+ * code size/addresses.
+ */
+ if (ctx->seen)
+ PPC_JMP(exit_addr);
+ else
+ PPC_BLR();
+ }
+ break;
+ case BPF_S_RET_A:
+ PPC_MR(r_ret, r_A);
+ if (i != flen - 1) {
+ if (ctx->seen)
+ PPC_JMP(exit_addr);
+ else
+ PPC_BLR();
+ }
+ break;
+ case BPF_S_MISC_TAX: /* X = A */
+ PPC_MR(r_X, r_A);
+ break;
+ case BPF_S_MISC_TXA: /* A = X */
+ ctx->seen |= SEEN_XREG;
+ PPC_MR(r_A, r_X);
+ break;
+
+ /*** Constant loads/M[] access ***/
+ case BPF_S_LD_IMM: /* A = K */
+ PPC_LI32(r_A, K);
+ break;
+ case BPF_S_LDX_IMM: /* X = K */
+ PPC_LI32(r_X, K);
+ break;
+ case BPF_S_LD_MEM: /* A = mem[K] */
+ PPC_MR(r_A, r_M + (K & 0xf));
+ ctx->seen |= SEEN_MEM | (1<<(K & 0xf));
+ break;
+ case BPF_S_LDX_MEM: /* X = mem[K] */
+ PPC_MR(r_X, r_M + (K & 0xf));
+ ctx->seen |= SEEN_MEM | (1<<(K & 0xf));
+ break;
+ case BPF_S_ST: /* mem[K] = A */
+ PPC_MR(r_M + (K & 0xf), r_A);
+ ctx->seen |= SEEN_MEM | (1<<(K & 0xf));
+ break;
+ case BPF_S_STX: /* mem[K] = X */
+ PPC_MR(r_M + (K & 0xf), r_X);
+ ctx->seen |= SEEN_XREG | SEEN_MEM | (1<<(K & 0xf));
+ break;
+ case BPF_S_LD_W_LEN: /* A = skb->len; */
+ BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4);
+ PPC_LWZ_OFFS(r_A, r_skb, offsetof(struct sk_buff, len));
+ break;
+ case BPF_S_LDX_W_LEN: /* X = skb->len; */
+ PPC_LWZ_OFFS(r_X, r_skb, offsetof(struct sk_buff, len));
+ break;
+
+ /*** Ancillary info loads ***/
+
+ /* None of the BPF_S_ANC* codes appear to be passed by
+ * sk_chk_filter(). The interpreter and the x86 BPF
+ * compiler implement them so we do too -- they may be
+ * planted in future.
+ */
+ case BPF_S_ANC_PROTOCOL: /* A = ntohs(skb->protocol); */
+ BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,
+ protocol) != 2);
+ PPC_LHZ_OFFS(r_A, r_skb, offsetof(struct sk_buff,
+ protocol));
+ /* ntohs is a NOP with BE loads. */
+ break;
+ case BPF_S_ANC_IFINDEX:
+ PPC_LD_OFFS(r_scratch1, r_skb, offsetof(struct sk_buff,
+ dev));
+ PPC_CMPDI(r_scratch1, 0);
+ if (ctx->pc_ret0 != -1) {
+ PPC_BCC(COND_EQ, addrs[ctx->pc_ret0]);
+ } else {
+ /* Exit, returning 0; first pass hits here. */
+ PPC_BCC_SHORT(COND_NE, (ctx->idx*4)+12);
+ PPC_LI(r_ret, 0);
+ PPC_JMP(exit_addr);
+ }
+ BUILD_BUG_ON(FIELD_SIZEOF(struct net_device,
+ ifindex) != 4);
+ PPC_LWZ_OFFS(r_A, r_scratch1,
+ offsetof(struct net_device, ifindex));
+ break;
+ case BPF_S_ANC_MARK:
+ BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4);
+ PPC_LWZ_OFFS(r_A, r_skb, offsetof(struct sk_buff,
+ mark));
+ break;
+ case BPF_S_ANC_RXHASH:
+ BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, rxhash) != 4);
+ PPC_LWZ_OFFS(r_A, r_skb, offsetof(struct sk_buff,
+ rxhash));
+ break;
+ case BPF_S_ANC_QUEUE:
+ BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,
+ queue_mapping) != 2);
+ PPC_LHZ_OFFS(r_A, r_skb, offsetof(struct sk_buff,
+ queue_mapping));
+ break;
+ case BPF_S_ANC_CPU:
+#ifdef CONFIG_SMP
+ /*
+ * PACA ptr is r13:
+ * raw_smp_processor_id() = local_paca->paca_index
+ */
+ BUILD_BUG_ON(FIELD_SIZEOF(struct paca_struct,
+ paca_index) != 2);
+ PPC_LHZ_OFFS(r_A, 13,
+ offsetof(struct paca_struct, paca_index));
+#else
+ PPC_LI(r_A, 0);
+#endif
+ break;
+
+ /*** Absolute loads from packet header/data ***/
+ case BPF_S_LD_W_ABS:
+ func = sk_load_word;
+ goto common_load;
+ case BPF_S_LD_H_ABS:
+ func = sk_load_half;
+ goto common_load;
+ case BPF_S_LD_B_ABS:
+ func = sk_load_byte;
+ common_load:
+ /*
+ * Load from [K]. Reference with the (negative)
+ * SKF_NET_OFF/SKF_LL_OFF offsets is unsupported.
+ */
+ ctx->seen |= SEEN_DATAREF;
+ if ((int)K < 0)
+ return -ENOTSUPP;
+ PPC_LI64(r_scratch1, func);
+ PPC_MTLR(r_scratch1);
+ PPC_LI32(r_addr, K);
+ PPC_BLRL();
+ /*
+ * Helper returns 'lt' condition on error, and an
+ * appropriate return value in r3
+ */
+ PPC_BCC(COND_LT, exit_addr);
+ break;
+
+ /*** Indirect loads from packet header/data ***/
+ case BPF_S_LD_W_IND:
+ func = sk_load_word;
+ goto common_load_ind;
+ case BPF_S_LD_H_IND:
+ func = sk_load_half;
+ goto common_load_ind;
+ case BPF_S_LD_B_IND:
+ func = sk_load_byte;
+ common_load_ind:
+ /*
+ * Load from [X + K]. Negative offsets are tested for
+ * in the helper functions, and result in a 'ret 0'.
+ */
+ ctx->seen |= SEEN_DATAREF | SEEN_XREG;
+ PPC_LI64(r_scratch1, func);
+ PPC_MTLR(r_scratch1);
+ PPC_ADDI(r_addr, r_X, IMM_L(K));
+ if (K >= 32768)
+ PPC_ADDIS(r_addr, r_addr, IMM_HA(K));
+ PPC_BLRL();
+ /* If error, cr0.LT set */
+ PPC_BCC(COND_LT, exit_addr);
+ break;
+
+ case BPF_S_LDX_B_MSH:
+ /*
+ * x86 version drops packet (RET 0) when K<0, whereas
+ * interpreter does allow K<0 (__load_pointer, special
+ * ancillary data). common_load returns ENOTSUPP if K<0,
+ * so we fall back to interpreter & filter works.
+ */
+ func = sk_load_byte_msh;
+ goto common_load;
+ break;
+
+ /*** Jump and branches ***/
+ case BPF_S_JMP_JA:
+ if (K != 0)
+ PPC_JMP(addrs[i + 1 + K]);
+ break;
+
+ case BPF_S_JMP_JGT_K:
+ case BPF_S_JMP_JGT_X:
+ true_cond = COND_GT;
+ goto cond_branch;
+ case BPF_S_JMP_JGE_K:
+ case BPF_S_JMP_JGE_X:
+ true_cond = COND_GE;
+ goto cond_branch;
+ case BPF_S_JMP_JEQ_K:
+ case BPF_S_JMP_JEQ_X:
+ true_cond = COND_EQ;
+ goto cond_branch;
+ case BPF_S_JMP_JSET_K:
+ case BPF_S_JMP_JSET_X:
+ true_cond = COND_NE;
+ /* Fall through */
+ cond_branch:
+ /* same targets, can avoid doing the test :) */
+ if (filter[i].jt == filter[i].jf) {
+ if (filter[i].jt > 0)
+ PPC_JMP(addrs[i + 1 + filter[i].jt]);
+ break;
+ }
+
+ switch (filter[i].code) {
+ case BPF_S_JMP_JGT_X:
+ case BPF_S_JMP_JGE_X:
+ case BPF_S_JMP_JEQ_X:
+ ctx->seen |= SEEN_XREG;
+ PPC_CMPLW(r_A, r_X);
+ break;
+ case BPF_S_JMP_JSET_X:
+ ctx->seen |= SEEN_XREG;
+ PPC_AND_DOT(r_scratch1, r_A, r_X);
+ break;
+ case BPF_S_JMP_JEQ_K:
+ case BPF_S_JMP_JGT_K:
+ case BPF_S_JMP_JGE_K:
+ if (K < 32768)
+ PPC_CMPLWI(r_A, K);
+ else {
+ PPC_LI32(r_scratch1, K);
+ PPC_CMPLW(r_A, r_scratch1);
+ }
+ break;
+ case BPF_S_JMP_JSET_K:
+ if (K < 32768)
+ /* PPC_ANDI is /only/ dot-form */
+ PPC_ANDI(r_scratch1, r_A, K);
+ else {
+ PPC_LI32(r_scratch1, K);
+ PPC_AND_DOT(r_scratch1, r_A,
+ r_scratch1);
+ }
+ break;
+ }
+ /* Sometimes branches are constructed "backward", with
+ * the false path being the branch and true path being
+ * a fallthrough to the next instruction.
+ */
+ if (filter[i].jt == 0)
+ /* Swap the sense of the branch */
+ PPC_BCC(true_cond ^ COND_CMP_TRUE,
+ addrs[i + 1 + filter[i].jf]);
+ else {
+ PPC_BCC(true_cond, addrs[i + 1 + filter[i].jt]);
+ if (filter[i].jf != 0)
+ PPC_JMP(addrs[i + 1 + filter[i].jf]);
+ }
+ break;
+ default:
+ /* The filter contains something cruel & unusual.
+ * We don't handle it, but also there shouldn't be
+ * anything missing from our list.
+ */
+ if (printk_ratelimit())
+ pr_err("BPF filter opcode %04x (@%d) unsupported\n",
+ filter[i].code, i);
+ return -ENOTSUPP;
+ }
+
+ }
+ /* Set end-of-body-code address for exit. */
+ addrs[i] = ctx->idx * 4;
+
+ return 0;
+}
+
+void bpf_jit_compile(struct sk_filter *fp)
+{
+ unsigned int proglen;
+ unsigned int alloclen;
+ u32 *image = NULL;
+ u32 *code_base;
+ unsigned int *addrs;
+ struct codegen_context cgctx;
+ int pass;
+ int flen = fp->len;
+
+ if (!bpf_jit_enable)
+ return;
+
+ addrs = kzalloc((flen+1) * sizeof(*addrs), GFP_KERNEL);
+ if (addrs == NULL)
+ return;
+
+ /*
+ * There are multiple assembly passes as the generated code will change
+ * size as it settles down, figuring out the max branch offsets/exit
+ * paths required.
+ *
+ * The range of standard conditional branches is +/- 32Kbytes. Since
+ * BPF_MAXINSNS = 4096, we can only jump from (worst case) start to
+ * finish with 8 bytes/instruction. Not feasible, so long jumps are
+ * used, distinct from short branches.
+ *
+ * Current:
+ *
+ * For now, both branch types assemble to 2 words (short branches padded
+ * with a NOP); this is less efficient, but assembly will always complete
+ * after exactly 3 passes:
+ *
+ * First pass: No code buffer; Program is "faux-generated" -- no code
+ * emitted but maximum size of output determined (and addrs[] filled
+ * in). Also, we note whether we use M[], whether we use skb data, etc.
+ * All generation choices assumed to be 'worst-case', e.g. branches all
+ * far (2 instructions), return path code reduction not available, etc.
+ *
+ * Second pass: Code buffer allocated with size determined previously.
+ * Prologue generated to support features we have seen used. Exit paths
+ * determined and addrs[] is filled in again, as code may be slightly
+ * smaller as a result.
+ *
+ * Third pass: Code generated 'for real', and branch destinations
+ * determined from now-accurate addrs[] map.
+ *
+ * Ideal:
+ *
+ * If we optimise this, near branches will be shorter. On the
+ * first assembly pass, we should err on the side of caution and
+ * generate the biggest code. On subsequent passes, branches will be
+ * generated short or long and code size will reduce. With smaller
+ * code, more branches may fall into the short category, and code will
+ * reduce more.
+ *
+ * Finally, if we see one pass generate code the same size as the
+ * previous pass we have converged and should now generate code for
+ * real. Allocating at the end will also save the memory that would
+ * otherwise be wasted by the (small) current code shrinkage.
+ * Preferably, we should do a small number of passes (e.g. 5) and if we
+ * haven't converged by then, get impatient and force code to generate
+ * as-is, even if the odd branch would be left long. The chances of a
+ * long jump are tiny with all but the most enormous of BPF filter
+ * inputs, so we should usually converge on the third pass.
+ */
+
+ cgctx.idx = 0;
+ cgctx.seen = 0;
+ cgctx.pc_ret0 = -1;
+ /* Scouting faux-generate pass 0 */
+ if (bpf_jit_build_body(fp, 0, &cgctx, addrs))
+ /* We hit something illegal or unsupported. */
+ goto out;
+
+ /*
+ * Pretend to build prologue, given the features we've seen. This will
+ * update ctgtx.idx as it pretends to output instructions, then we can
+ * calculate total size from idx.
+ */
+ bpf_jit_build_prologue(fp, 0, &cgctx);
+ bpf_jit_build_epilogue(0, &cgctx);
+
+ proglen = cgctx.idx * 4;
+ alloclen = proglen + FUNCTION_DESCR_SIZE;
+ image = module_alloc(max_t(unsigned int, alloclen,
+ sizeof(struct work_struct)));
+ if (!image)
+ goto out;
+
+ code_base = image + (FUNCTION_DESCR_SIZE/4);
+
+ /* Code generation passes 1-2 */
+ for (pass = 1; pass < 3; pass++) {
+ /* Now build the prologue, body code & epilogue for real. */
+ cgctx.idx = 0;
+ bpf_jit_build_prologue(fp, code_base, &cgctx);
+ bpf_jit_build_body(fp, code_base, &cgctx, addrs);
+ bpf_jit_build_epilogue(code_base, &cgctx);
+
+ if (bpf_jit_enable > 1)
+ pr_info("Pass %d: shrink = %d, seen = 0x%x\n", pass,
+ proglen - (cgctx.idx * 4), cgctx.seen);
+ }
+
+ if (bpf_jit_enable > 1)
+ pr_info("flen=%d proglen=%u pass=%d image=%p\n",
+ flen, proglen, pass, image);
+
+ if (image) {
+ if (bpf_jit_enable > 1)
+ print_hex_dump(KERN_ERR, "JIT code: ",
+ DUMP_PREFIX_ADDRESS,
+ 16, 1, code_base,
+ proglen, false);
+
+ bpf_flush_icache(code_base, code_base + (proglen/4));
+ /* Function descriptor nastiness: Address + TOC */
+ ((u64 *)image)[0] = (u64)code_base;
+ ((u64 *)image)[1] = local_paca->kernel_toc;
+ fp->bpf_func = (void *)image;
+ }
+out:
+ kfree(addrs);
+ return;
+}
+
+static void jit_free_defer(struct work_struct *arg)
+{
+ module_free(NULL, arg);
+}
+
+/* run from softirq, we must use a work_struct to call
+ * module_free() from process context
+ */
+void bpf_jit_free(struct sk_filter *fp)
+{
+ if (fp->bpf_func != sk_run_filter) {
+ struct work_struct *work = (struct work_struct *)fp->bpf_func;
+
+ INIT_WORK(work, jit_free_defer);
+ schedule_work(work);
+ }
+}
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