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Message-Id: <20180503230824.3462-13-daniel@iogearbox.net>
Date: Fri, 4 May 2018 01:08:23 +0200
From: Daniel Borkmann <daniel@...earbox.net>
To: ast@...nel.org
Cc: netdev@...r.kernel.org, Daniel Borkmann <daniel@...earbox.net>
Subject: [PATCH bpf-next v2 12/13] bpf, x32: 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 x32 JIT.
Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Acked-by: Alexei Starovoitov <ast@...nel.org>
---
arch/x86/net/bpf_jit_comp32.c | 136 +-----------------------------------------
1 file changed, 1 insertion(+), 135 deletions(-)
diff --git a/arch/x86/net/bpf_jit_comp32.c b/arch/x86/net/bpf_jit_comp32.c
index 61e6134..0cc04e3 100644
--- a/arch/x86/net/bpf_jit_comp32.c
+++ b/arch/x86/net/bpf_jit_comp32.c
@@ -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 */
--
2.9.5
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