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bpf, ppc64: remove ld_abs/ld_ind

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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 ppc64 JIT.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Sandipan Das <sandipan@linux.vnet.ibm.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Daniel Borkmann 2018-05-04 01:08:21 +02:00 committed by Alexei Starovoitov
parent 4db25cc988
commit dbf44daf7c
4 changed files with 11 additions and 317 deletions
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2
arch/powerpc/net/Makefile
View File

@ -3,7 +3,7 @@
# Arch-specific network modules
#
ifeq ($(CONFIG_PPC64),y)
obj-$(CONFIG_BPF_JIT) += bpf_jit_asm64.o bpf_jit_comp64.o
obj-$(CONFIG_BPF_JIT) += bpf_jit_comp64.o
else
obj-$(CONFIG_BPF_JIT) += bpf_jit_asm.o bpf_jit_comp.o
endif

37
arch/powerpc/net/bpf_jit64.h
View File

@ -20,7 +20,7 @@
* with our redzone usage.
*
* [ prev sp ] <-------------
* [ nv gpr save area ] 8*8 |
* [ nv gpr save area ] 6*8 |
* [ tail_call_cnt ] 8 |
* [ local_tmp_var ] 8 |
* fp (r31) --> [ ebpf stack space ] upto 512 |
@ -28,8 +28,8 @@
* sp (r1) ---> [ stack pointer ] --------------
*/
/* for gpr non volatile registers BPG_REG_6 to 10, plus skb cache registers */
#define BPF_PPC_STACK_SAVE (8*8)
/* for gpr non volatile registers BPG_REG_6 to 10 */
#define BPF_PPC_STACK_SAVE (6*8)
/* for bpf JIT code internal usage */
#define BPF_PPC_STACK_LOCALS 16
/* stack frame excluding BPF stack, ensure this is quadword aligned */
@ -39,10 +39,8 @@
#ifndef __ASSEMBLY__
/* BPF register usage */
#define SKB_HLEN_REG (MAX_BPF_JIT_REG + 0)
#define SKB_DATA_REG (MAX_BPF_JIT_REG + 1)
#define TMP_REG_1 (MAX_BPF_JIT_REG + 2)
#define TMP_REG_2 (MAX_BPF_JIT_REG + 3)
#define TMP_REG_1 (MAX_BPF_JIT_REG + 0)
#define TMP_REG_2 (MAX_BPF_JIT_REG + 1)
/* BPF to ppc register mappings */
static const int b2p[] = {
@ -63,40 +61,23 @@ static const int b2p[] = {
[BPF_REG_FP] = 31,
/* eBPF jit internal registers */
[BPF_REG_AX] = 2,
[SKB_HLEN_REG] = 25,
[SKB_DATA_REG] = 26,
[TMP_REG_1] = 9,
[TMP_REG_2] = 10
};
/* PPC NVR range -- update this if we ever use NVRs below r24 */
#define BPF_PPC_NVR_MIN 24
/* Assembly helpers */
#define DECLARE_LOAD_FUNC(func) u64 func(u64 r3, u64 r4); \
u64 func##_negative_offset(u64 r3, u64 r4); \
u64 func##_positive_offset(u64 r3, u64 r4);
DECLARE_LOAD_FUNC(sk_load_word);
DECLARE_LOAD_FUNC(sk_load_half);
DECLARE_LOAD_FUNC(sk_load_byte);
#define CHOOSE_LOAD_FUNC(imm, func) \
(imm < 0 ? \
(imm >= SKF_LL_OFF ? func##_negative_offset : func) : \
func##_positive_offset)
/* PPC NVR range -- update this if we ever use NVRs below r27 */
#define BPF_PPC_NVR_MIN 27
#define SEEN_FUNC 0x1000 /* might call external helpers */
#define SEEN_STACK 0x2000 /* uses BPF stack */
#define SEEN_SKB 0x4000 /* uses sk_buff */
#define SEEN_TAILCALL 0x8000 /* uses tail calls */
#define SEEN_TAILCALL 0x4000 /* uses tail calls */
struct codegen_context {
/*
* This is used to track register usage as well
* as calls to external helpers.
* - register usage is tracked with corresponding
* bits (r3-r10 and r25-r31)
* bits (r3-r10 and r27-r31)
* - rest of the bits can be used to track other
* things -- for now, we use bits 16 to 23
* encoded in SEEN_* macros above

180
arch/powerpc/net/bpf_jit_asm64.S
View File

@ -1,180 +0,0 @@
/*
* bpf_jit_asm64.S: Packet/header access helper functions
* for PPC64 BPF compiler.
*
* Copyright 2016, Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
* IBM Corporation
*
* Based on bpf_jit_asm.S by Matt Evans
*
* 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 <asm/ptrace.h>
#include "bpf_jit64.h"
/*
* All of these routines are called directly from generated code,
* with the below register usage:
* r27 skb pointer (ctx)
* r25 skb header length
* r26 skb->data pointer
* r4 offset
*
* Result is passed back in:
* r8 data read in host endian format (accumulator)
*
* r9 is used as a temporary register
*/
#define r_skb r27
#define r_hlen r25
#define r_data r26
#define r_off r4
#define r_val r8
#define r_tmp r9
_GLOBAL_TOC(sk_load_word)
cmpdi r_off, 0
blt bpf_slow_path_word_neg
b sk_load_word_positive_offset
_GLOBAL_TOC(sk_load_word_positive_offset)
/* Are we accessing past headlen? */
subi r_tmp, r_hlen, 4
cmpd r_tmp, r_off
blt bpf_slow_path_word
/* Nope, just hitting the header. cr0 here is eq or gt! */
LWZX_BE r_val, r_data, r_off
blr /* Return success, cr0 != LT */
_GLOBAL_TOC(sk_load_half)
cmpdi r_off, 0
blt bpf_slow_path_half_neg
b sk_load_half_positive_offset
_GLOBAL_TOC(sk_load_half_positive_offset)
subi r_tmp, r_hlen, 2
cmpd r_tmp, r_off
blt bpf_slow_path_half
LHZX_BE r_val, r_data, r_off
blr
_GLOBAL_TOC(sk_load_byte)
cmpdi r_off, 0
blt bpf_slow_path_byte_neg
b sk_load_byte_positive_offset
_GLOBAL_TOC(sk_load_byte_positive_offset)
cmpd r_hlen, r_off
ble bpf_slow_path_byte
lbzx r_val, r_data, r_off
blr
/*
* Call out to skb_copy_bits:
* Allocate a new stack frame here to remain ABI-compliant in
* stashing LR.
*/
#define bpf_slow_path_common(SIZE) \
mflr r0; \
std r0, PPC_LR_STKOFF(r1); \
stdu r1, -(STACK_FRAME_MIN_SIZE + BPF_PPC_STACK_LOCALS)(r1); \
mr r3, r_skb; \
/* r4 = r_off as passed */ \
addi r5, r1, STACK_FRAME_MIN_SIZE; \
li r6, SIZE; \
bl skb_copy_bits; \
nop; \
/* save r5 */ \
addi r5, r1, STACK_FRAME_MIN_SIZE; \
/* r3 = 0 on success */ \
addi r1, r1, STACK_FRAME_MIN_SIZE + BPF_PPC_STACK_LOCALS; \
ld r0, PPC_LR_STKOFF(r1); \
mtlr r0; \
cmpdi r3, 0; \
blt bpf_error; /* cr0 = LT */
bpf_slow_path_word:
bpf_slow_path_common(4)
/* Data value is on stack, and cr0 != LT */
LWZX_BE r_val, 0, r5
blr
bpf_slow_path_half:
bpf_slow_path_common(2)
LHZX_BE r_val, 0, r5
blr
bpf_slow_path_byte:
bpf_slow_path_common(1)
lbzx r_val, 0, r5
blr
/*
* Call out to bpf_internal_load_pointer_neg_helper
*/
#define sk_negative_common(SIZE) \
mflr r0; \
std r0, PPC_LR_STKOFF(r1); \
stdu r1, -STACK_FRAME_MIN_SIZE(r1); \
mr r3, r_skb; \
/* r4 = r_off, as passed */ \
li r5, SIZE; \
bl bpf_internal_load_pointer_neg_helper; \
nop; \
addi r1, r1, STACK_FRAME_MIN_SIZE; \
ld r0, PPC_LR_STKOFF(r1); \
mtlr r0; \
/* R3 != 0 on success */ \
cmpldi r3, 0; \
beq bpf_error_slow; /* cr0 = EQ */
bpf_slow_path_word_neg:
lis r_tmp, -32 /* SKF_LL_OFF */
cmpd r_off, r_tmp /* addr < SKF_* */
blt bpf_error /* cr0 = LT */
b sk_load_word_negative_offset
_GLOBAL_TOC(sk_load_word_negative_offset)
sk_negative_common(4)
LWZX_BE r_val, 0, r3
blr
bpf_slow_path_half_neg:
lis r_tmp, -32 /* SKF_LL_OFF */
cmpd r_off, r_tmp /* addr < SKF_* */
blt bpf_error /* cr0 = LT */
b sk_load_half_negative_offset
_GLOBAL_TOC(sk_load_half_negative_offset)
sk_negative_common(2)
LHZX_BE r_val, 0, r3
blr
bpf_slow_path_byte_neg:
lis r_tmp, -32 /* SKF_LL_OFF */
cmpd r_off, r_tmp /* addr < SKF_* */
blt bpf_error /* cr0 = LT */
b sk_load_byte_negative_offset
_GLOBAL_TOC(sk_load_byte_negative_offset)
sk_negative_common(1)
lbzx r_val, 0, r3
blr
bpf_error_slow:
/* fabricate a cr0 = lt */
li r_tmp, -1
cmpdi r_tmp, 0
bpf_error:
/*
* Entered with cr0 = lt
* Generated code will 'blt epilogue', returning 0.
*/
li r_val, 0
blr

109
arch/powerpc/net/bpf_jit_comp64.c
View File

@ -59,7 +59,7 @@ static inline bool bpf_has_stack_frame(struct codegen_context *ctx)
* [ prev sp ] <-------------
* [ ... ] |
* sp (r1) ---> [ stack pointer ] --------------
* [ nv gpr save area ] 8*8
* [ nv gpr save area ] 6*8
* [ tail_call_cnt ] 8
* [ local_tmp_var ] 8
* [ unused red zone ] 208 bytes protected
@ -88,21 +88,6 @@ static int bpf_jit_stack_offsetof(struct codegen_context *ctx, int reg)
BUG();
}
static void bpf_jit_emit_skb_loads(u32 *image, struct codegen_context *ctx)
{
/*
* Load skb->len and skb->data_len
* r3 points to skb
*/
PPC_LWZ(b2p[SKB_HLEN_REG], 3, offsetof(struct sk_buff, len));
PPC_LWZ(b2p[TMP_REG_1], 3, offsetof(struct sk_buff, data_len));
/* header_len = len - data_len */
PPC_SUB(b2p[SKB_HLEN_REG], b2p[SKB_HLEN_REG], b2p[TMP_REG_1]);
/* skb->data pointer */
PPC_BPF_LL(b2p[SKB_DATA_REG], 3, offsetof(struct sk_buff, data));
}
static void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx)
{
int i;
@ -145,18 +130,6 @@ static void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx)
if (bpf_is_seen_register(ctx, i))
PPC_BPF_STL(b2p[i], 1, bpf_jit_stack_offsetof(ctx, b2p[i]));
/*
* Save additional non-volatile regs if we cache skb
* Also, setup skb data
*/
if (ctx->seen & SEEN_SKB) {
PPC_BPF_STL(b2p[SKB_HLEN_REG], 1,
bpf_jit_stack_offsetof(ctx, b2p[SKB_HLEN_REG]));
PPC_BPF_STL(b2p[SKB_DATA_REG], 1,
bpf_jit_stack_offsetof(ctx, b2p[SKB_DATA_REG]));
bpf_jit_emit_skb_loads(image, ctx);
}
/* Setup frame pointer to point to the bpf stack area */
if (bpf_is_seen_register(ctx, BPF_REG_FP))
PPC_ADDI(b2p[BPF_REG_FP], 1,
@ -172,14 +145,6 @@ static void bpf_jit_emit_common_epilogue(u32 *image, struct codegen_context *ctx
if (bpf_is_seen_register(ctx, i))
PPC_BPF_LL(b2p[i], 1, bpf_jit_stack_offsetof(ctx, b2p[i]));
/* Restore non-volatile registers used for skb cache */
if (ctx->seen & SEEN_SKB) {
PPC_BPF_LL(b2p[SKB_HLEN_REG], 1,
bpf_jit_stack_offsetof(ctx, b2p[SKB_HLEN_REG]));
PPC_BPF_LL(b2p[SKB_DATA_REG], 1,
bpf_jit_stack_offsetof(ctx, b2p[SKB_DATA_REG]));
}
/* Tear down our stack frame */
if (bpf_has_stack_frame(ctx)) {
PPC_ADDI(1, 1, BPF_PPC_STACKFRAME + ctx->stack_size);
@ -753,23 +718,10 @@ emit_clear:
ctx->seen |= SEEN_FUNC;
func = (u8 *) __bpf_call_base + imm;
/* Save skb pointer if we need to re-cache skb data */
if ((ctx->seen & SEEN_SKB) &&
bpf_helper_changes_pkt_data(func))
PPC_BPF_STL(3, 1, bpf_jit_stack_local(ctx));
bpf_jit_emit_func_call(image, ctx, (u64)func);
/* move return value from r3 to BPF_REG_0 */
PPC_MR(b2p[BPF_REG_0], 3);
/* refresh skb cache */
if ((ctx->seen & SEEN_SKB) &&
bpf_helper_changes_pkt_data(func)) {
/* reload skb pointer to r3 */
PPC_BPF_LL(3, 1, bpf_jit_stack_local(ctx));
bpf_jit_emit_skb_loads(image, ctx);
}
break;
/*
@ -886,65 +838,6 @@ cond_branch:
PPC_BCC(true_cond, addrs[i + 1 + off]);
break;
/*
* Loads from packet header/data
* Assume 32-bit input value in imm and X (src_reg)
*/
/* Absolute loads */
case BPF_LD | BPF_W | BPF_ABS:
func = (u8 *)CHOOSE_LOAD_FUNC(imm, sk_load_word);
goto common_load_abs;
case BPF_LD | BPF_H | BPF_ABS:
func = (u8 *)CHOOSE_LOAD_FUNC(imm, sk_load_half);
goto common_load_abs;
case BPF_LD | BPF_B | BPF_ABS:
func = (u8 *)CHOOSE_LOAD_FUNC(imm, sk_load_byte);
common_load_abs:
/*
* Load from [imm]
* Load into r4, which can just be passed onto
* skb load helpers as the second parameter
*/
PPC_LI32(4, imm);
goto common_load;
/* Indirect loads */
case BPF_LD | BPF_W | BPF_IND:
func = (u8 *)sk_load_word;
goto common_load_ind;
case BPF_LD | BPF_H | BPF_IND:
func = (u8 *)sk_load_half;
goto common_load_ind;
case BPF_LD | BPF_B | BPF_IND:
func = (u8 *)sk_load_byte;
common_load_ind:
/*
* Load from [src_reg + imm]
* Treat src_reg as a 32-bit value
*/
PPC_EXTSW(4, src_reg);
if (imm) {
if (imm >= -32768 && imm < 32768)
PPC_ADDI(4, 4, IMM_L(imm));
else {
PPC_LI32(b2p[TMP_REG_1], imm);
PPC_ADD(4, 4, b2p[TMP_REG_1]);
}
}
common_load:
ctx->seen |= SEEN_SKB;
ctx->seen |= SEEN_FUNC;
bpf_jit_emit_func_call(image, ctx, (u64)func);
/*
* Helper returns 'lt' condition on error, and an
* appropriate return value in BPF_REG_0
*/
PPC_BCC(COND_LT, exit_addr);
break;
/*
* Tail call
*/