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bpf, x32: 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 x32 JIT.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Daniel Borkmann 2018-05-04 01:08:23 +02:00 committed by Alexei Starovoitov
parent e1cf4befa2
commit 24dea04767
1 changed files with 1 additions and 135 deletions
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136
arch/x86/net/bpf_jit_comp32.c
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@ -175,19 +175,13 @@ static const u8 bpf2ia32[][2] = {
#define SCRATCH_SIZE 96
/* Total stack size used in JITed code */
#define _STACK_SIZE \
(stack_depth + \
+ SCRATCH_SIZE + \
+ 4 /* Extra space for skb_copy_bits buffer */)
#define _STACK_SIZE (stack_depth + SCRATCH_SIZE)
#define STACK_SIZE ALIGN(_STACK_SIZE, STACK_ALIGNMENT)
/* Get the offset of eBPF REGISTERs stored on scratch space. */
#define STACK_VAR(off) (off)
/* Offset of skb_copy_bits buffer */
#define SKB_BUFFER STACK_VAR(SCRATCH_SIZE)
/* Encode 'dst_reg' register into IA32 opcode 'byte' */
static u8 add_1reg(u8 byte, u32 dst_reg)
{
@ -2276,134 +2270,6 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image,
return -EFAULT;
}
break;
case BPF_LD | BPF_ABS | BPF_W:
case BPF_LD | BPF_ABS | BPF_H:
case BPF_LD | BPF_ABS | BPF_B:
case BPF_LD | BPF_IND | BPF_W:
case BPF_LD | BPF_IND | BPF_H:
case BPF_LD | BPF_IND | BPF_B:
{
int size;
const u8 *r6 = bpf2ia32[BPF_REG_6];
/* Setting up first argument */
/* mov eax,dword ptr [ebp+off] */
EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX),
STACK_VAR(r6[0]));
/* Setting up second argument */
if (BPF_MODE(code) == BPF_ABS) {
/* mov %edx, imm32 */
EMIT1_off32(0xBA, imm32);
} else {
if (sstk)
/* mov edx,dword ptr [ebp+off] */
EMIT3(0x8B, add_2reg(0x40, IA32_EBP,
IA32_EDX),
STACK_VAR(src_lo));
else
/* mov edx,src_lo */
EMIT2(0x8B, add_2reg(0xC0, src_lo,
IA32_EDX));
if (imm32) {
if (is_imm8(imm32))
/* add %edx,imm8 */
EMIT3(0x83, 0xC2, imm32);
else
/* add %edx,imm32 */
EMIT2_off32(0x81, 0xC2, imm32);
}
}
/* Setting up third argument */
switch (BPF_SIZE(code)) {
case BPF_W:
size = 4;
break;
case BPF_H:
size = 2;
break;
case BPF_B:
size = 1;
break;
default:
return -EINVAL;
}
/* mov ecx,val */
EMIT2(0xB1, size);
/* movzx ecx,ecx */
EMIT3(0x0F, 0xB6, add_2reg(0xC0, IA32_ECX, IA32_ECX));
/* mov ebx,ebp */
EMIT2(0x8B, add_2reg(0xC0, IA32_EBP, IA32_EBX));
/* add %ebx,imm8 */
EMIT3(0x83, add_1reg(0xC0, IA32_EBX), SKB_BUFFER);
/* push ebx */
EMIT1(0x53);
/* Setting up function pointer to call */
/* mov ebx,imm32*/
EMIT2_off32(0xC7, add_1reg(0xC0, IA32_EBX),
(unsigned int)bpf_load_pointer);
EMIT2(0xFF, add_1reg(0xD0, IA32_EBX));
/* add %esp,4 */
EMIT3(0x83, add_1reg(0xC0, IA32_ESP), 4);
/* xor edx,edx */
EMIT2(0x33, add_2reg(0xC0, IA32_EDX, IA32_EDX));
/* mov dword ptr [ebp+off],eax */
EMIT3(0x89, add_2reg(0x40, IA32_EBP, IA32_EDX),
STACK_VAR(r0[0]));
/* mov dword ptr [ebp+off],edx */
EMIT3(0x89, add_2reg(0x40, IA32_EBP, IA32_EDX),
STACK_VAR(r0[1]));
/*
* Check if return address is NULL or not.
* If NULL then jump to epilogue else continue
* to load the value from retn address
*/
EMIT3(0x83, add_1reg(0xF8, IA32_EAX), 0);
jmp_offset = ctx->cleanup_addr - addrs[i];
switch (BPF_SIZE(code)) {
case BPF_W:
jmp_offset += 7;
break;
case BPF_H:
jmp_offset += 10;
break;
case BPF_B:
jmp_offset += 6;
break;
}
EMIT2_off32(0x0F, IA32_JE + 0x10, jmp_offset);
/* Load value from the address */
switch (BPF_SIZE(code)) {
case BPF_W:
/* mov eax,[eax] */
EMIT2(0x8B, 0x0);
/* Emit 'bswap eax' */
EMIT2(0x0F, add_1reg(0xC8, IA32_EAX));
break;
case BPF_H:
EMIT3(0x0F, 0xB7, 0x0);
EMIT1(0x66);
EMIT3(0xC1, add_1reg(0xC8, IA32_EAX), 8);
break;
case BPF_B:
EMIT3(0x0F, 0xB6, 0x0);
break;
}
/* mov dword ptr [ebp+off],eax */
EMIT3(0x89, add_2reg(0x40, IA32_EBP, IA32_EAX),
STACK_VAR(r0[0]));
break;
}
/* STX XADD: lock *(u32 *)(dst + off) += src */
case BPF_STX | BPF_XADD | BPF_W:
/* STX XADD: lock *(u64 *)(dst + off) += src */