ARM64 中堆栈指针的行为

Question

由于 ARM64 中缺少 PUSH 和 POP 指令，我无法理解 SP 在 ARM64 中的工作方式。

如果我要 PUSH/POP，SP decrement/increment 是 4、8 还是 16 字节？

我在阅读文档说堆栈帧必须按 16 字节对齐，但是当我调试时，情况似乎并非如此。

Answer 1

堆栈是向上增长还是向下增长完全取决于您正在查看的系统的 ABI。也就是说，我必须处理的所有 arm64 代码都有向下增长的堆栈。
这样，一个普通的推送看起来像这样：

stp x29, x30, [sp, -0x10]!

像这样的普通流行音乐：

ldp x29, x30, [sp], 0x10

这显然 pushes/pops 一次两个寄存器，因此一次修改堆栈指针 16 个字节，这将我们带到下一部分：

堆栈对齐检查。堆栈指针是否必须与 16 字节边界对齐也取决于您正在使用的 ABI，但这是一个可以配置的实际硬件功能。请参阅 the ARMv8 Reference Manual，SCTLR_EL[123] 包括为每个异常级别打开或关闭此功能的位。引自 SCTLR_EL1，例如：

SA0, bit [4]

    SP Alignment check enable for EL0. When set to 1, if a load or store instruction
    executed at EL0 uses the SP as the base address and the SP is not aligned to a
    16-byte boundary, then a SP alignment fault exception is generated. For more
    information, see _SP alignment checking on page D1-2333_.

    When ARMv8.1-VHE is implemented, and the value of HCR_EL2.{E2H, TGE} is {1, 1},
    this bit has no effect on execution at EL0.

    In a system where the PE resets into EL1, this field resets to an architecturally
    UNKNOWN value.

SA, bit [3]

    SP Alignment check enable. When set to 1, if a load or store instruction executed
    at EL1 uses the SP as the base address and the SP is not aligned to a 16-byte
    boundary, then a SP alignment fault exception is generated. For more information,
    see _SP alignment checking on page D1-2333_.

    When ARMv8.1-VHE is implemented, and the value of HCR_EL2.{E2H, TGE} is {1, 1},
    this bit has no effect on the PE.

    In a system where the PE resets into EL1, this field resets to an architecturally
    UNKNOWN value.

ARM64 中堆栈指针的行为

Behaviors of stack pointer in ARM64

assembly

abi

memory-alignment

stack-memory

arm64