* 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
+ blt bpf_slow_path_word_neg
+ .globl sk_load_word_positive_offset
+sk_load_word_positive_offset:
/* Are we accessing past headlen? */
subi r_scratch1, r_HL, 4
cmpd r_scratch1, r_addr
.globl sk_load_half
sk_load_half:
cmpdi r_addr, 0
- blt bpf_error
+ blt bpf_slow_path_half_neg
+ .globl sk_load_half_positive_offset
+sk_load_half_positive_offset:
subi r_scratch1, r_HL, 2
cmpd r_scratch1, r_addr
blt bpf_slow_path_half
.globl sk_load_byte
sk_load_byte:
cmpdi r_addr, 0
- blt bpf_error
+ blt bpf_slow_path_byte_neg
+ .globl sk_load_byte_positive_offset
+sk_load_byte_positive_offset:
cmpd r_HL, r_addr
ble bpf_slow_path_byte
lbzx r_A, r_D, r_addr
/*
* BPF_S_LDX_B_MSH: ldxb 4*([offset]&0xf)
- * r_addr is the offset value, already known positive
+ * r_addr is the offset value
*/
.globl sk_load_byte_msh
sk_load_byte_msh:
+ cmpdi r_addr, 0
+ blt bpf_slow_path_byte_msh_neg
+ .globl sk_load_byte_msh_positive_offset
+sk_load_byte_msh_positive_offset:
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).
lbz r_X, BPF_PPC_STACK_BASIC+(2*8)(r1)
rlwinm r_X, r_X, 2, 32-4-2, 31-2
blr
+
+/* Call out to bpf_internal_load_pointer_neg_helper:
+ * 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 sk_negative_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); \
+ stdu r1, -BPF_PPC_SLOWPATH_FRAME(r1); \
+ /* R3 = r_skb, as passed */ \
+ mr r4, r_addr; \
+ li r5, SIZE; \
+ bl bpf_internal_load_pointer_neg_helper; \
+ /* 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; \
+ cmpldi r3, 0; \
+ beq bpf_error_slow; /* cr0 = EQ */ \
+ mr r_addr, r3; \
+ ld r_skb, (BPF_PPC_STACKFRAME+48)(r1); \
+ /* Great success! */
+
+bpf_slow_path_word_neg:
+ lis r_scratch1,-32 /* SKF_LL_OFF */
+ cmpd r_addr, r_scratch1 /* addr < SKF_* */
+ blt bpf_error /* cr0 = LT */
+ .globl sk_load_word_negative_offset
+sk_load_word_negative_offset:
+ sk_negative_common(4)
+ lwz r_A, 0(r_addr)
+ blr
+
+bpf_slow_path_half_neg:
+ lis r_scratch1,-32 /* SKF_LL_OFF */
+ cmpd r_addr, r_scratch1 /* addr < SKF_* */
+ blt bpf_error /* cr0 = LT */
+ .globl sk_load_half_negative_offset
+sk_load_half_negative_offset:
+ sk_negative_common(2)
+ lhz r_A, 0(r_addr)
+ blr
+
+bpf_slow_path_byte_neg:
+ lis r_scratch1,-32 /* SKF_LL_OFF */
+ cmpd r_addr, r_scratch1 /* addr < SKF_* */
+ blt bpf_error /* cr0 = LT */
+ .globl sk_load_byte_negative_offset
+sk_load_byte_negative_offset:
+ sk_negative_common(1)
+ lbz r_A, 0(r_addr)
+ blr
+
+bpf_slow_path_byte_msh_neg:
+ lis r_scratch1,-32 /* SKF_LL_OFF */
+ cmpd r_addr, r_scratch1 /* addr < SKF_* */
+ blt bpf_error /* cr0 = LT */
+ .globl sk_load_byte_msh_negative_offset
+sk_load_byte_msh_negative_offset:
+ sk_negative_common(1)
+ lbz r_X, 0(r_addr)
+ rlwinm r_X, r_X, 2, 32-4-2, 31-2
+ blr
+
+bpf_error_slow:
+ /* fabricate a cr0 = lt */
+ li r_scratch1, -1
+ cmpdi r_scratch1, 0
+bpf_error:
+ /* Entered with cr0 = lt */
+ li r3, 0
+ /* Generated code will 'blt epilogue', returning 0. */
+ blr
PPC_BLR();
}
+#define CHOOSE_LOAD_FUNC(K, func) \
+ ((int)K < 0 ? ((int)K >= SKF_LL_OFF ? func##_negative_offset : func) : func##_positive_offset)
+
/* Assemble the body code between the prologue & epilogue. */
static int bpf_jit_build_body(struct sk_filter *fp, u32 *image,
struct codegen_context *ctx,
/*** Absolute loads from packet header/data ***/
case BPF_S_LD_W_ABS:
- func = sk_load_word;
+ func = CHOOSE_LOAD_FUNC(K, sk_load_word);
goto common_load;
case BPF_S_LD_H_ABS:
- func = sk_load_half;
+ func = CHOOSE_LOAD_FUNC(K, sk_load_half);
goto common_load;
case BPF_S_LD_B_ABS:
- func = sk_load_byte;
+ func = CHOOSE_LOAD_FUNC(K, sk_load_byte);
common_load:
- /*
- * Load from [K]. Reference with the (negative)
- * SKF_NET_OFF/SKF_LL_OFF offsets is unsupported.
- */
+ /* Load from [K]. */
ctx->seen |= SEEN_DATAREF;
- if ((int)K < 0)
- return -ENOTSUPP;
PPC_LI64(r_scratch1, func);
PPC_MTLR(r_scratch1);
PPC_LI32(r_addr, K);
common_load_ind:
/*
* Load from [X + K]. Negative offsets are tested for
- * in the helper functions, and result in a 'ret 0'.
+ * in the helper functions.
*/
ctx->seen |= SEEN_DATAREF | SEEN_XREG;
PPC_LI64(r_scratch1, func);
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;
+ func = CHOOSE_LOAD_FUNC(K, sk_load_byte_msh);
goto common_load;
break;
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