64 位模式不支持 32 位 PUSH 和 POP 指令 [英] 64-bit mode does not support 32-bit PUSH and POP instructions

问题描述

NASM 返回如下错误:64 位模式不支持指令"
(或使用 YASM，操作数 1 的大小无效)

NASM returns an error like: "instruction not supported in 64-bit mode"
(Or with YASM, invalid size for operand 1)

主题指令为pop ecx和push ecx.
我可以用什么来代替它们，或者有其他方法可以解决这个问题吗?

The subject instructions are pop ecx and push ecx.
What can I use instead of them or is there an other way to fix this issue?

推荐答案

总体思路是您通常推送和弹出完整寄存器，即 64 位模式下的 64 位寄存器.push 的默认操作数大小为 64 位，32 位操作数大小不可用.执行每条PUSH指令在 x64 上推送 8 个字节的倍数?(是的，除非您专门使用 16 位推送，但 32 位不可用).

The general idea is that you normally push and pop full registers, i.e. 64-bit registers in 64-bit mode. push's default operand-size is 64-bit, and 32-bit operand-size is not available. Does each PUSH instruction push a multiple of 8 bytes on x64? (yes, unless you specifically use a 16-bit push, but 32-bit isn't available).

不能在 64 位模式下压入 32 位寄存器；相反，您可以推送和弹出包含您想要的 32 位值的整个 64 位寄存器，因此使用 push rax 而不是 push eax.内存引用也是如此——你可以push qword ptr[rax]，但不能push dword ptr[rax].

You cannot push a 32 bit register in 64 bit mode; instead, you can push and pop the whole 64 bit register that contains a 32-bit value you want, so that's push rax instead of push eax. The same holds for memory references - you can push qword ptr[rax], but not push dword ptr[rax].

但是:即使在 64 位模式下，您仍然可以推送:

But: even in 64 bit mode you can still push:

• 8 或 32 位立即数符号扩展为 64；这通常由您的汇编程序自动处理作为优化(如果您执行 push 1，它将使用最紧凑的编码对其进行编码，即 6A01，即带有 imm8 操作数).总是64 位推送，除非您明确指定 push word 1，无论汇编程序选择什么宽度.

• 8 or 32 bit immediates sign extended to 64; this is generally handled automatically by your assembler as an optimization (if you do push 1 it will encode it with the most compact encoding, which will be 6A01, i.e. with an imm8 operand). It's always a 64-bit push unless you explicitly specify push word 1, regardless of what width of immediate the assembler picks.

fs 和 gs 段注册但不是cs、ds、es、ss 寄存器(在 64 位模式下不重要，只能使用 mov，而不是 push，释放那些推送/弹出操作码以备将来使用).

the fs and gs segment registers but not the cs, ds, es, ss registers (which aren't important in 64-bit mode, and can only be read with mov, not push, freeing up those push/pop opcode for potential future use).

作为一个例外，段寄存器要么被零扩展，要么通过 16 位移动压入堆栈(即堆栈上的其他 48 位保持不变)；这并不是什么大问题，因为 pop fs 和 pop gs 只是丢弃这些额外的位.

As an exception, segment registers are either zero-extended or pushed on the stack with a 16-bit move (i.e. the other 48 bit on the stack are left unmodified); this isn't really much of a problem, since pop fs and pop gs just discard these extra bits.

您可以使用 push low32/mov dword [rsp+4], high32 模拟 push imm64.或者用 mov r64, imm64/push r64;mov 来注册(不是内存)是唯一可以采用 64 位立即数的 x86-64 指令.

You can emulate a push imm64 with push low32 / mov dword [rsp+4], high32. Or with mov r64, imm64 / push r64; mov to register (not memory) is the only x86-64 instruction that can take a 64-bit immediate.

使用 16 位操作数大小(66h 前缀)，您可以执行 16 位推送，将 RSP 调整为 2 而不是 8.但通常不要这样做，因为它会堆栈未对齐，直到您执行 16 位弹出或以其他方式纠正它.

With 16-bit operand-size (a 66h prefix), you can do a 16-bit push which adjusts RSP by 2 instead of 8. But normally don't do this because it will misalign the stack until you do a 16-bit pop or otherwise correct it.

• 16 位寄存器(push ax)和内存引用(push word ptr[rax])；
• 8 位符号扩展或 16 位立即数.推字123

• 16 bit registers (push ax) and memory references (push word ptr[rax]);
• 8-bit sign-extended or 16 bit immediates. push word 123

8 位寄存器在任何模式下都不能推送(除了作为更宽寄存器的一部分)，32 位推送/弹出在 64 位模式下不可用，即使使用 REX.W=0 前缀.

8-bit registers can't be pushed in any mode (except as part of a wider register), and 32-bit push/pop aren't available in 64-bit mode, even with a REX.W=0 prefix.

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